Update on the pint battery project

 

WARNING!   The following article is from a tinkerer who can't do anything the easy way.   The information provided is based on many assumptions and should not be followed too closely without your own research and testing. DO YOUR RESEARCH, TAKE PLENTY OF PRECAUTIONS , HAVE A PLAN, ALWAYS ERR ON THE SIDE OF SAFETY.  Any injury, critical malfunctions, explosions and death due to following elements of details or procedure contained in these articles are at the risk of anyone reading these article and attempting to follow this information without a reasonable amount of knowledge in constructing Lithium Ion batteries and a strong knowledge of electricity is doing so at your own risk!  Constructing large Lithium packs require an understanding and respecting of the dangers as well taking plenty amounts of precautions in constructing even a small pack.  Do not attempt constructing any type of battery packs without proper prior instruction or training and again, having basic electrical knowledge, properly layout the pack plans are important.  This is a project that I am researching and the total amount of equipment I own would make this worth trying.  The actual expense if one were to start from scratch would out strip the amount in savings that is listed in my blogs.  The information within these blogs are starting points for what is required to construct a battery pack and does not have all the answers, such as, technical details of voltage drop issues, internal resistance considerations, charging methods or structural techniques and so on. Those details depend on the application of the battery pack and exceed the scope of these articles.  

Size Up of the Battery Module

Dimensions inside the battery module is a left to right of 168mm by 137mm and up to down.  There is a slight bulge in the middle giving another 2mm or so, but it is better to work from the smallest measurements.  This is only the space that the batteries inhabit and ignores the divider that is the wire channel which is made of two plastic tabs.  

 

Real world fit

Although the max width of the module is 168mm and the 8 cells across is 168mm on paper (21x8=168), the slight thickness caused by the vinyl jackets and the cell crimps, make the total width a little more than the 21mm of the specified 21 by 700 millimeter size.

To get the top group of 8 cells to fit without the need to snip out plastic, I looked at staggering the cells. I tried adding shims under cells 9, 11, 13, 15.  The height is around 3.5mm and the remaining headroom from battery to lid will be about 1.5mm.  That means the depth of the compartment is about 25mm.

This is not the final arrangement as the polarity will still have to decided when the time comes, but it doesn't really matter negative or positive first as long as the start and end are established and comply with the BMS order of connections.

My first concept of the 21700 batteries and how they fall into position as mentioned prior.

Numbers Minor Conundrum Encountered and it's all about nothing. 

When I first started my research on the BMS layout, it was from an article by the Board Garage.  Later I found the similar published layout from someone who goes by the name "That-Canadian".  At first glance the two BMS pinout charts could not look any different.  When I gave it a closer look, I notice that they sort of run in a similar pattern.

Two Pinout Charts

Numbers Key

When I wrote out the numbers in a line with the primary ends in the same places, it is sort of easy to see that the charts are the same and only the counting directions were different.  Both the positive and negative sides start or end with the highest and lowest numbers, as well, the middle cell is the same number.  

What still remains it the question of securing the layout

To start off, the cells will have a dab of hot melt glue to position them into their groups and to make it easy to spot weld later.  Then it is the touchy strategy of joining the groups together as an example of cell 9 to cell 8 is a massive connector and possibly on both sides to handle the amperage.  Then the question of how much insulation will fit?  I won't be much or about 1 to 1.5 mm of space remains depending on where.  The lower groups of six cells could be furnished with up to 4mm of foam padding as they don't require a staggered arrangement, but the above group of seven to eight cells may not have much room. Between the groups a reasonable amount of insulation and padding can be added to divide cells 1 to 7, however a special provision to allow cell 1 with a positive wire to be well shielded from any problems or interaction with cell 15.                                                                                                                                                                                                                                                                                                                                                                                  

                                                                                            

Another thought is space needed to run all the wires

Routing for the BMS wires will have to come from three bundles.  It may be necessary to have a groups that are the eight temperature sensor wires and however best to route the 'B' numbered wires into a upper and lower group.  The goal is to not have to alter the battery module in any way.

Pint Battery So Far

Almost Ready to Build It

WARNING!   The following article is from a tinkerer who can't do anything the easy way.   The information provided is based on many assumptions and should not be followed too closely without your own research and testing. DO YOUR RESEARCH, TAKE PLENTY OF PRECAUTIONS , HAVE A PLAN, ALWAYS ERR ON THE SIDE OF SAFETY.  Any injury, critical malfunctions, explosions and death due to following elements of details or procedure contained in these articles are at the risk of anyone reading these article and attempting to follow this information without a reasonable amount of knowledge in constructing Lithium Ion batteries and a strong knowledge of electricity is doing so at your own risk!  Constructing large Lithium packs require an understanding and respecting of the dangers as well taking plenty amounts of precautions in constructing even a small pack.  Do not attempt constructing any type of battery packs without proper prior instruction or training and again, having basic electrical knowledge, properly layout the pack plans are important.  This is a project that I am researching and the total amount of equipment I own would make this worth trying.  The actual expense if one were to start from scratch would out strip the amount in savings that is listed in my blogs.  The information within these blogs are starting points for what is required to construct a battery pack and does not have all the answers, such as, technical details of voltage drop issues, internal resistance considerations, charging methods or structural techniques and so on. Those details depend on the application of the battery pack and exceed the scope of these articles.  

Model: Pint (not Mint, but the later sand color rails)

Hardware: 5314

Firmware: Gemini 5050

 Concept version 4

Coming from the general layout from the previous post, I have taken some liberties on the cell path or the "flow".  Here is my version of the 15S1P battery pack and one big or controversial detail is the start and end of the pack (#1 and #15) are right next to each other.  I admit I've not looked at many pack setups or access to any, but I will not hide my concern that this may pose a short circuit danger could somehow happen if the two cells touch or wires come loose and contact some other part.  This is a serious subject of, if the pack were to receive high current draw that could melt insulation or a shock that moves the cells around, there would be little to stop a unwelcomed contact and then a thermal runaway situation.

Current Facts and the Figures

The XT60 connectors are rated for a nominal around 30 amps and I believe the 12 gauge wire leads will be the same maximum at 30 amps as well.  The purported Pint amps is 10-15 during nominal movement and a max of 30 amps if in high torque situations.  So it is safe to say that the margin is narrow and the extra shielding is warranted.  The .2x10mm nickel strips were claimed to have around 25 to 35 amp handling and the limiting factor is the length of the the strips also the number of welds per contact point.  Six is recommended and I would say that is the minimum.  I read somewhere that a single spot weld would carry about 9 amps

If I were to proceed with the build in the above arrangement, the negative wire will have shielding along the length of CELL #15 and as well the positive wire secured in the same manner.  However, in the extreme scenario of failure, I would have both output wires passing along a curtain short-circuit.  And the perfect storm is the constant 30+ amp draw for a critical length of time.  The saving point is that I'm looking to race the Pint nor do I intend to go very fast.  The published peak amperage is 28 amps at 16mph while on an average maybe 7% grade.  Sadly, In my rides I may have up to 12% and some small spots or at 100 feet is a elevation of 12 feet and a potential max amps of 30.

Feeling Out the Flaws

The concept of the placement of the positive lead along the side of a cell was to reduce vibration damage, as reported in a few forums.  The run of the negative lead is now longer as well and would run along the same cell, but towards the lid of the module.  A concern is the increased wire resistance due to the length, which I am very aware of even it the amount is considered negligent (0.00132 ohms per inch) or an increase from .0013 to about .003 ohms.  If I keep the positive wire short, I'll remove the potential issues of heat, but still have the issue of damage from vibration and it is true I could make a wraparound lug to solve that.  The potential heat that could melt the battery cover or even the Pint module is a consideration to solve sooner than later if it does exist at all.  This is why I will do a load test to prove these concern one way or another.

Example of a short wire to the XT60 - not to scale, but you get the idea.

Another design decision is the cells are grouped as eight cells on the upper with shielding to prevent wear and abrasion damage against the group of six cells beneath.  Cell number 7 is the odd cell due to the location and its need to jut out at the bottom of the pack that will cause some loss of rigidity of the overall pack.  

Prior to receiving the 21700 cells, I decided to modeled the pack as accurately as possible to get a sense of gap and placement of connectors and insulation.  The cells that meet end to end have folded connectors (Cell 1 to 2, 3 to 4, 5 to 6) and will benefit from a compression tape strategy to give increased surface contact for more stable amperage transfer.  

The last concern is the one dangling cell number 7 and although the same compression can be applied to stabilize it, the needed jumper to the lower group of six is a weak point.  The hope is to use a set of strips of nickel to form the connection instead of a wire.  This allows the connection to be flat against the cells and pack cover and removing a failure point where solder spots could push into a cells jacket.

Still pending for when the cells become available, a possibility of staggering the batteries before spot welding and reducing the width be a tiny 2 to 3 millimeters.  This will only be necessary or useful if the batteries are too tight.

Latest Supplies List:

• Nickel Tabs .2mm x 10mm
• Fish Paper rings for 21700
• Fish Paper strips for high abrasion spots
• Kapton 1/2", 1", 2", tape to secure wires
• Hot melt glue to secure cells and positions
• 15 count cells - Molicel P42A 21700 4200mAh 45A Battery
• 4 count thermal sensors- NTCLE413E2103F102L
• 1 count 26 pin plug - ZPDR-26V-S
• 26 count - SZPD-002T-P0.3 terminal pins
• 14 feet - 26 gauge silicon coated wire 
• 24 inches - 12 gauge silicon coated wire (12 inches red and black)

Onewheel Pint battery project - need more range...cheap

WARNING!   The following article is from a tinkerer who can't do anything the easy way.   The information provided is based on many assumptions and should not be followed too closely without your own research and testing. DO YOUR RESEARCH, TAKE PLENTY OF PRECAUTIONS , HAVE A PLAN, ALWAYS ERR ON THE SIDE OF SAFETY.  Any injury, critical malfunctions, explosions and death due to following elements of details or procedure contained in these articles are at the risk of anyone reading these article and attempting to follow this information without a reasonable amount of knowledge in constructing Lithium Ion batteries and a strong knowledge of electricity is doing so at your own risk!  Constructing large Lithium packs require an understanding and respecting of the dangers as well taking plenty amounts of precautions in constructing even a small pack.  Do not attempt constructing any type of battery packs without proper prior instruction or training and again, having basic electrical knowledge, properly layout the pack plans are important.  This is a project that I am researching and the total amount of equipment I own would make this worth trying.  The actual expense if one were to start from scratch would out strip the amount in savings that is listed in my blogs.  The information within these blogs are starting points for what is required to construct a battery pack and does not have all the answers, such as, technical details of voltage drop issues, internal resistance considerations, charging methods or structural techniques and so on. Those details depend on the application of the battery pack and exceed the scope of these articles.  

The Pain of My Range

Although I've not done that much riding on my Onewheel Pint (less than 300 miles) for the past three years of ownership, it is time to deal with the big reason I didn't do as much riding in the first place.   At some point, I had a wild idea to ride it to work and actually tried it two times...yes, should have gotten an XR.  However, I was stopped by an unavoidable problem.  It is the well known thing called "range anxiety" and I have an obvious geographic issue that makes it so.

I live about 5.2 miles from my work as the crow flies and so the claimed range of my Pint should be close enough?  The reality is that the path deemed safest to ride is also, no surprise, longer than the "as crows fly" range and my weight does not help (192lb) either.  The best path work to home is 6.4 to 6.7 miles depending on which side of the street and how many intersections, however, all that and facing a steady incline of 125 feet elevation by the end. 

So the home to work ride, in contrast, is not the issue. When I attempted it, the Pint was left with around 15% of charge remaining upon my arrival at the front door of work.  Going home was a disappointing 5.3 miles of range with the board shutting down and more hilly terrain to go.  In fact, the last 3/4 mile leg of the trip is a long climb of maybe 40 feet before a small down hill and again a climb around 30 more feet of elevation. 

On the second try, I included a shortcut by way of a foot path that led to a pedestrian access stairs to reduce the roundabout bicycle path by nearly a quarter mile.  This gave me a slightly shorter total and less than a half mile from home before the red light bar appeared.

How Much Is the Point?

For only $300 to $400 dollars I could purchase a high capacity pack from qualified third party builders and that would be that or for $1100 buy a Pint X, but then I'm cheap remember (actually I like to build stuff).  So I looked into how much it might cost to build a high capacity battery since I already own the battery spot welder, load tester, power bench and have some knowledge about batteries.  

Napkin sketch would add up to about $115 dollars and that is the batteries, nickel tabs, fish paper, glue, tape, wires and shrink wrap.  If I'm not too far off, that is a savings of almost $200 at least.  As well, I noted that If I count up the remaining supplies, another pack could be built for a little less than $100 dollars and maybe a third.

Research So Far

My first round of digging around for battery layout diagrams originally netted the very helpful, but limited article from "The Board Garage" which was what inspired me to even write about building this battery pack.

The only thing is that the article's details seemed just a little watered down, maybe to prevent legal issues I suppose?  I noticed missing was at detailed battery wiring diagram or the information on the type of thermistors to use.  Although, to be fair the article's intent was to repair an existing pack and not build one from scratch.

This minor omission may also be a measure to prevent anyone from just slapping together the parts to "manufacture" their own battery packs to sell, but not actually know what the dangers are if done poorly.  However, from a dead pack starting point, the information would easily help anyone to piece together how to make a new pack as the original intention of the article was to reuse those existing key components.

From the article, an included pinout chart was a little tricky to understand on first glance.  It's not immediately clear the orientation of the plug by the face or looking on, but it was a little more clear when I looked up the datasheet for the 26 pin connector (ZPDR-26V-S) and maybe when I disassemble the OEM battery box to be sure.  The clues might be the locations of the unused pins and the images on the web shows that this chart was arranged in the manner to facilitate loading the connector pins (SZPD-002T-P0.3) into the plug during assembly.

Battery Planning

The original Pint OEM batteries are the 18650 size lithium Ion cells in the neighborhood of 2700 mAh each and arranged in a 15s1p configuration in a frame of eight over seven and the large capacity version to be constructed will consist of 21700 cells and not quite double at 4200 mAh each.  All fifteen 21700s must be a careful arrangement to best fit the limited space of the original module case.  The larger capacity cells claimed to deliver up to 15 miles of range, however, will effect the ability to read the power level bar on the board.  

The lack of a diagram required me to come up with one based on images out of the article and other sources.  A reasonable diagram of the battery cells looked something like the below layout, but not final.  I would say this is the common arrangement of the cells.  However, I'm not too crazy about the short positive output wire, nor the big jumper wire that is near the middle as well the next cell with a shorter jumper.  There is the argument that I should not venture too far from the seemingly standard design, but I wonder about the jumpers found in the middle of the series of cells.

This is another extract of what the common layout of the cells as found in a third party pack, but I am still not happy with the path of the cells and the jumper locations

The "Tap" markers are for the BMS wires to be attached. However, from the information I could glean, one area was an odd arrangement between taps B6, B7, B8 and in my version I arranged it slightly different.  Cell 7 and cell 8 from the article had their positive ends facing and require two longer connections to bridge to the next cluster, where I inverted cell 8 and only require one long connection and eliminated the odd bridge between cell 8 and cell 9.

At the time of this writing, I lack solid information on the type of temperature sensor or thermistors needed prompted a long search and looking at a few datasheets.  However, the correct component must match the OEM version's resistance or Ohm range or the BMS will not accurately balance the cells.  Rumored was that the sensor is NTCLE413E2103F102L and only after I build the pack will I know if this was right.

Tools I have

• Spot welder to attach the nickel strips
• Wire connection crimper tool for 26 gauge wires to .3 pins
• Temperature controlled soldering iron to attach the BMS wires to tabs
• Power supply bench for the charging via a built in battery charger mode to test
• Load tester to simulate use and inspect the performance
• Voltmeter to check all voltages of each cells during charge and discharge
• Heat gun to seal things up as well as other bit and tools.
• Lithium Ion cell charger that will take 21700 size cells to help assure that I'm starting out with all cells at the same levels.

For Sure the Firmware is Good

My version of the Pint is somewhat an early version known as a Gemini 5050.  It will have the ability to use a larger capacity pack with no known limits.  I understand that the later versions monitor the amperage and cut off the current ignoring the remaining battery power effectively treating all battery packs as a stock capacity.  However, the lack of an accurate power level bar would be a small price compared to the gains.

The article did put me on the right track for the part number of the connector and I have the makings of a list of a few other components such as wire gauges and nickel connectors for welding.

When I actually get underway, I'll then have to show some images of the actual build.

As of so far (late 2024)

Battery to BMS socket         ZPDR-26V-S            $  .61 ea.

Pins for Socket  (26 needed)  SZPD-002T-P0.3        $  .10 ea.

Thermal sensor (4 needed)     NTCLE413E2103F102L    $ 1.68 ea.

Nickel .2mm x 10mm tabs                             $ 11.00                    

Fish Paper rings 21700 size                         $  8.00

Fish Paper Sheets                                   $  4.00

26ga. Silicone coated wire (6 color set x 20 feet)  $ 16.00                  

Molicel 21700 4200mAh (15 needed)INR-21700-P42A      $ 3.95 ea.

Some Notes to Remember

• Unplugging the Power Pack from the BMS connector first and then the XT60 after.
• Arrange the 21700 cells in the battery tray and glue in the 3 groups for accurate fit.
• test possible insulation placement and the effects on fit.

The Impossible Darkroom - How realistic is it to plan this and build it

 

I call this, My efficiency Darkroom - Or the biggest darkroom allowed or my wife will kill me.

I've missed out on having a full darkroom a bunch of times.  The closest was just over 20 years ago and it was without running water.  I now have a tiny space and this is the design I came up with.  Having a tight 7 foot by 6.5 foot space to work around, it is further hampered by pipes and household wiring running all around above.  The dry side wall will host a set of shelves on the back for storage.  The wet side is all flag stone and will require a very fancy wall stud installation to get the most use from that side.  The custom epoxy coated sink will be one of the most complex builds.  Another issue is the manner the drainage works and if I can legally put chemicals down this type of drain.  However, the design for drainage has the option to bypass into a collection tank.  I can tap near by water lines and will have to improvise a water temperature control unit to save money.  The entry side is simply a heavy curtain in a light trap channel, however, the opposite wall is also flagstone and pipes run along it as well a meter.  An access hatch must also be kept clear and to make things more interesting, the space is invaded by spiders as well.

Although I have not compiled a cut list or decided on types of materials, it is easy to see that this will not be under my $100 limit for supplies.  The primary part of the project is the wet side.  An existing temporary dry side stands now and is not very efficient.

Sink portion will require over 2 dozen pieces to form.

The sink is a composite of pine boards to keep the cost low, the real money is the epoxy resin coat to waterproof it all.  Outside dimensions are 7 foot by 2 foot and with a 6 inch high rim.  The base will not be easy as it has to have a mid-board to hide the pipes as well a valve to capture chemicals to a separate container.  The back wall will depend on actual vertical space available as well as the clearance of a set of sewage pipes that run across the entire space above.  The issue of light trapping the above plumbing will be a mosaic of plastic sheets and shields to block light leaks.  Also needed is a path for the air duct to drain off the fumes as well a fresh air vent.  

The existing dry side will be modified, if possible, adding light tight drawers and storage for accessories.  The enlarger table will be reinforced to hold the weight of the Beseler 45 MCRX and its dichroic head as well as the extra space below to house the expanse of film holders I've collected over the years.    When complete, this setup should be capable of handling 20X24 as well color processing.  

And this happens

 

While driving up to an intersection, the on coming vehicle make a left turn behind.  The teenage driver totally misjudged his turning circle. The left is was torn and the fasteners ripped from the wheel well liner.

For my next project that is not car related, the darkroom sink

 The concept here is a simple box and ribs with slanted valleys for drainage.  The main pine carpentry will be the form and the waterproof will be some form of either epoxy coat or even truck bed liner spray.  The Form will be custom fitted to the space.  The ribs should have around 2 inches of gap to make cleaning easier.  The faucet will be mounted on a separate board and that is mounted to the frame of the sink. I'm estimating about $60 dollars of wood and a coating kit between $40 to $85.  To put it into perspective, a real darkroom sink starts at $700.  The water temperature mixing might be carried out with a contraption of half inch pipes feeding into a one inch and a half inch pipe with a center port out.  One tube ported to inject water across and the other to inject with two streams towards the other side or at least that is the hope.

Trailing Arms, oh what a pain and an understatement

 

Jeep Patriot Trailing Arm Bushing Replacement

It's been going on for over 3 years hearing the squeaking and at 110K miles, like anything else in the rear suspension, it was time to fix it.  The noise was from the lower rear of the body like old timbers in an old wooding bridge, creaking and groaning.  Every uneven rut or a speed bump at low speed, the creaking would reverberate.  

 

The Jeep Patriot has trailing arms, part of the rear suspension and is part of how a vehicle flexes during bumps and turns.  The cause of all that racket was the bushings, the item that isolates the shock and vibrations from the road to the body.  It was now one of the last things on my list of major replacements for the year, barring any sudden discoveries.  

I did embarking on this repair with some research before starting.  It is a good idea to know what to expect and to plan out the tools I'll need.  However, from only one video and a few user group mentions on the subject, it was shaping to be a project I'll be mostly doing in the dark as for as details.  

The video I found was helpful to a point, however, inconsistencies made it more a general reference or outline than an instructional.  For example, it was not mentioned about the needed 15mm socket to remove the bolts that hold up the trailing arm, the brake line brackets are also an issue and there was no mention of the stabilizing rods being part of the challenge of loosening the arms.  The video gives mentions of sockets, ball-joint tubes kits, pry bar, reciprocating saw, block of wood and jacks, but I would find that this list was overly simplistic.  The actual task and the problems encountered will required many times the tools to solve the stumbled upon problems.  

Why am I doing it this way?

It might be pointed out that I should just change the entire trailing arm.  I'm sure most mechanic would argue it as the right way to deal with this.  However, I didn't want to detach the upper and lower control arms, the ABS sensor, the calipers, the hub assembly and axle, the backing plate, the e-brake assembly, the camber links and also requiring a rear alignment job when I'm done.  Seemed quicker just to work on the trailing arm bushings by themselves.

The task summary was as follows: 

On the driver's side, watch out for the fuel connection, fuel tank, e-brake and soft hydraulic hose as well as the bracket with connection.  On the passenger's side, was everything, but not fuel connection.  A each items should be managed or dealt with first before allowing the trailing arm to move down.  It is very helpful to have a second jack was needed to pivot the arm down to allow for clearance to work without the fuel tank getting the way.  Cut a notch in the old bushings, knock them out with a hammer and use the ball-joint press to install the new bushings.

My actual start went this way. 

 The sided I started on was the left side and first the e-brake cable on its bracket was to be undone from near the trailing arm bolts, after cleaning off the rust, I used a 13mm socket to remove it.  After removing the 13mm bolt, it was simple to unhook it from the bracket and moved is aside.  The fuel connection might have been disconnected and moved, but I didn't want to fuss with fuel and chose to guard the path of the trailing arm with a pry bar later.  However, the brake line must be freed from its bracket or the drop of the trailing arm will strain the line.  The brake line connection was held by a flange and secured with a 8mm bolt that is held from behind by a captive nut and I didn't see that at first due to the rust and almost ripped the entire bracket off with the impact gun.  I thankfully stopped in time...I hope.  Fiddling with the pivoting and gain access to the bushing by placing a bottle jack in the available corner of the hub assembly.  Then I marked the positions of the flange's plane in relation to the trailing arm as well the depth of the seated old bushing.  These measurements are the guide for the installation of the new bushing.

There is not a good way to describe this part:

Finding the proper angles and pivots points are the next thing.  The bushing was held in place with two 15mm bolts.  If you unbolt before lifting, the movement of the tailing arm may be managed.  However, the trick of the arm will want to move inwards thanks to the little camber link and bring the arms towards the fuel tank.  If I thought of disconnecting the links from the trailing arm, then the next procedure might have been less a hassle.  I didn't attempt to remove them and maybe I should have.  The decision to proceed without removing the camber connections and save me from needing an alignment job later but meant a dance of the little bottle jack on the hub assembly bracket to finesse the flex of the arm to cause the bushing end to pivot down.  At a certain amount of lifting as you near the position equal to the normal height when the vehicle is on the ground, the bracket is able to pivot further downward.  When the bushing could drop low enough and I could reach with a saw, I stopped pumping the little jack and wedged a block of wood between the arm and the body being careful not to damage the brake line.

The recommended removal of the old bushing was to cut it and this is due to the gas tank's proximity making the ball-joint press not able to fit in the removal position.  However, one cut is not enough and depending on how much rust the need to compress the protruding end or outboard side of the bushing, means that multiple cuts are needed to clear the seated diameter of the bushing.  It is a good idea to use a wire wheel to remove any rust on it prior to removal of the bushing.  If you cut away the rubber core of the bushing, this would make it easier to see and allow careful cutting of the bushing cup.  The idea was not to damage the trailing arm itself.  In my first attempt I got very close to bottom of the cup and used a hand saw for a few more strokes.  It would be thin enough I could simply break the metal.  I could observe that the cut compressed closed when I started to hammer on the rim of the bushing cup. So the more cuts the greater the reduction in the diameter.  Each time the feathered line of the blade's path starts to disappears from view, I would stop and check the depth with a fine point tool and hand saw the rest of the way.  Leaving a thin metal kerf with the few careful strokes, gives a margin of error.  When I had four cuts, I started to hammer on them to drive the cup wall inward towards the center at first and then the rim of the bushing to drive it inboard.  Two dozen good whacks later, the bushing shot out of the trailing arm.

It is never easy

By the end of the single side, being the left, I amassed a very large pile additional needed tools to tackle the issues I had run into.  So far, I mentioned the hand saw.  A handy item that takes the saw blades as the reciprocating saw.  Painter's tape to mark with a marker the location of the flange angle.  Drift punch for flattening the cuts as they bulge.  Channel lock wrench to help rock the cup.  Wire wheel and drill driver for cleaning up the mounting surface.  Pry bars for the few leveraging points needed to keep the trailing arm in position.  Clamps to holt the wood blocks in place while hammering the bushing. The one or two wrench sizes grew to my entire tool chest of sockets and box end wrenches.  Extra light was needed and the addition of a zip-tie to reduce the slop of the push tube on the holder.    

The video also demonstrated the installation of the new bushing with a standard ball-joint press, however, that was not sufficient and I luckily had the large version of the press.  In the video, the lack of a pushing tube was a bad example of how to install the bushing.  The video shows the guy forcing the bushing without the pusher tube and just utilizing the open tail of the press right up against the bushing.  During my attempt, I watched the bushing center distort out of the assembly, it was clear that I required the pusher tube or risk damaging the bushing.   However, that was another problem to solve.  Due to the poor fit of the tube to the holder, I caused the bushing to go in very slanted and at the risk of having to cut it out.  I stopped and was able to back it out with some hit with a hammer.  

The Problems with most Ball Joint Press Kits and the Bushing

This is based on my OTC ball-joint kit

Although I decided on using the pusher tube arrangement, I discovered how crude the fit between the holder and tube was and it hindering the alignment.  

The Left Side:

In my first attempt on the left side trailing arm, I managed to get the parts near poised enough to work and push straight.  However, that required a lot of tape to hold them together in groups.  I used painter's tape and put the pusher tube holder and then all of that to the end of the bushing.  

The Right Side:

On this side, things were not staying aligned. The holder kept slipping and the pusher tube didn't stay perched on the bushing to drive it correctly towards the receiving tube.  This meant I could not turn the  press bolt tight enough to lock things straight.  It was a challenge to one hand holding the press and tubes with one hand while trying to spin it tight.  A couple of tries with the pusher tube tilted and could not stay on the holder even with tape.  The tube to the bushing  fit was poor (illustration shows the lack of contact space and the tenuous positions).  

The Problem:

The rim of the bushing is about 3.125 inches in diameter (O.D.) and a slight more than a quarter inch thick rim, however, the tube was a maximum of 2.755 inches and could only perch on the tip of the inside rim.  The holder had stepped shoulders and the closest one didn't properly line up with the tube I selected for the pushing either, as illustrated above.  All these misalignments made for a good many failed attempts installing.  Only 3/16 of an inch shoulder and the tube had only a slight 1/16 of an inch to perch on the holder's shoulder with plenty of room to fall off.  I tried to first solved this by fashioning a spacer from a piece of zip-tie fitted to the inside of the tube and taped down to hold it in position and that did worked a bit.

Although the left side was just stable enough to install and only a few tries to then slide into place, the trial and error attempts on the left side would scar the edges of the tube and holder.  The right side could not stay align at all, slipping out due to the rounded edges, each time everything went crooked or wonky would add more rounded edges and scars.  After having the dozed attempts on the right side and  failing, I returned to an idea I came up with prior to doing all this.   When I first tested the tubes fit against the bushings to find the needed tubes from the kit,  I quickly discovered the poor fit issue.  I had imagined an intermediate plate to correct the poor fit between the two surfaces of the bushing and tube.  A simple horseshoe plate to allow the to surfaces to stay aligned during the pressing.  So I stopped trying to make the tube seat on the edge of the bushing and went into action to come back after a few minutes with a very nasty piece of metal saw work, ugly filing job as well some viscous licks with the angle grinder.  I made something that worked like the above image, however, was very ugly. 

Another difficulty was the receiving tube, it was prepared prior to the attempt when I realized it isn't allowing the new bushing to fit inside it.  A tube has an inside diameter of 2.756 inch with a scallop opened side.  The end of the bushing that should push through the trailing arm and then the receiving tube is about 2.762 inches in diameter.  The receiving tube was too narrow for the bushing to fit inside.  To solved this, I had my drum sanding attachment and 80 grit sanding tubes mounted on my drill press.  Setting the platform to limit my sanding to only 2/5th depth of the opening of the scalloped side.  I ground out enough to give the bushing a slightly snug, but easy to slide in and out fit.

With the modified receiving tube, I later pushed it on to the old bushing to mark the depth needed with I mount the new bushing.  The correct depth as the original was important to avoid needed an alignment of the rear tracking when all is done.  The old and new bushings were the same cup heights and that meant I could easily duplicate the seating of the new bushing later.

When all the loosening and dropping of the trailing arm was accomplished.  The clearing of these obstructions allowed me to position the large press and the modified pusher tube with holder and the modified receiving tube with holder around the bushing.  A small shot of WD-40 to help things along and started cranking on the press.  Finally and slowly I made steady progress.  The bushing made its way to the tape mark on the scalloped opening of the receiving tube.  The left side done and it took only 4 hours of fussing and making mistakes and fishing more tools.  The right side took 3 hours of fussing and making the shim that I should have had for the left side.

The instructions should be as follows:

• Jack Jeep up and secondary jack point and not at pinch weld.  You will need the room to work.  
• I use a AGM Jack Rod to add safety.  
• Have a jack stand, just in case, under the sub-frame.  
• Have handy another hydraulic jack for adjusting the trailing arm position to work.  
• Tire off.  
• Free the e-brake bracket via the 15mm bolt.  
• Fee the brake line off of its bracket via the 8mm bolt and not the other side.
• Free the two 16mm bolts holding the trailing arm.  
• Guide the trailing arm down to avoid the fuel connector if you are on the left side.  If you remove the connection with the trailing arm control arm, this would make things easier, however, the alignment cam should be preserved.  
• Make marks to help align the degree of the level of the bushing flanges to the trailing arm as the alignment is not match horizontal to the arm, but tilted.
• When the trailing arm is cleared and in a safe position to work, start cutting the old bushing. 
• Taking brief cuts to not cut past the bushing housing and into the trailing arm.  The cuts remove the locking tension of the bushing housing to the trailing arm.  It should be three or more cuts to make it loose enough to knock out with a hammer.
• Need is the larger version of the "ball joint" press.  The 2.75" I.D. receiving tube and the 2.75 O.D. pushing tube.  Note: the bushing is about 2.762" O.D. at the point of the seating.  My only examples of this tube was at 2.74" and 2.758".  I took the 2.74" and used a sanding drum in a drill press to grind away enough clearance to allow the bushing to easily slide into the tube at the full seated depth
• Wire brush slightly the first third of the new bushing to allow for snug seating of it to the trailing arm and align to marks for the angle it should be mounted. Tap in with hammer.
• Tape together the needed tubes and shimming the tubes to fit the holders as centered as possible.
• The press, tubes and bushing on the trailing arm.  A small squirt of oil will help too.
• Start cranking on the press until the depth mark is reached.
• The return of the two 15mm bolts are best replaced by remounting the tire and lowering it back to normal to make the alignment and adjusting the bolts easier.
• The remaining bolts for the brake line and e-brake can be down while on the ground.  However, I lifted back up and removed the tire to better see the installation.

That is it and I hope it worked.