135i 6mt 215 Diff disassembly

mal86

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Dec 15, 2017
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135i N54 6mt
Preparing my for car the next season of having fun at my not so local racetrack. Planning to swap out the open differential for a plate LSD. Got a hold of a used complete pumpkin with less miles on it than my car has. This one looked better than the one on my car as well. Decided to swap the pumpkins around as I'd like to have my spare pumpkin with less wear. I took the newer shinier pumpkin, opened the lid to check everything was OK inside and started to clean away the original gasket. Decided that a proper gasket would be better than the sticky stuff, at least if the lid will be going off again. Made a gasket out of 1.2mm gasket paper, filled it up with oil and made the swap.

Now, as both my differentials are the welded crown wheel type, I have to get a new or used bolted final drive to be able to fit an LSD. This means that I have to remove the pinion completely in order to match the new crown wheel with the new pinion. I could not find much information about this online, so figured I'd create some content to try to explain how I removed all parts from the pumpkin. Getting it all back together correctly will be a different story.

If you're lucky and have a bolted crown wheel, you are blessed and do not need to do all this in order to install your LSD. If you're like me, unlucky, and like to see how things are put together, here is how I did it. Remember to mark what parts come from what side, as the differential bearings and circlips are part of the backlash adjustment.

Parts Overview
Overview Parts.jpg


Differential Bearing Assembly Sketch
Differential bearing.jpg


Pinion Assembly Sketch
Pinion Assembly.jpg

First I drained the unit of fluid, cracked the back lid open 8x M10 bolts, 16mm head.

Next I pulled the output flanges out, made a small bracket to fit a glide hammer to it. These did not require a lot of force to pull out.

Then I yanked the shaft seals out. These were pretty easy to get out using a spanner and putting half the open end under the seal and using the edge of the output flange "hole" in the differential as a fulcrum.

If you are removing the pinion to replace the final drive, now is probably the most fitting time to undo the 65mm double hex nut holding the pinion in place. I used a hammer and wedged it between the differential and the bottom part of the housing to lock it in place. Secured the housing to a large table using a screw clamp. Then a 65mm socket and a 3/4" ratchet with a 2m pipe as leverage to loosen and remove the nut. This nut is secured with thread locking compound, looked like green loctite. Heating the nut with a torch helps here. Also, this nut does not have links threads like the one connecting the differential to the driveshaft.

I then used a large circlip plyer to remove the inner circlips holding the differential bearings, a light tap on the bearing race helps if these are stuck.

When removing the differential bearings, any rust on the surface for the shaft seal will halt the bearing. These bearings have a clearance fit and if there is no rust on the surface, will slide out easily.

Now the differential can be rotated so the shaft for the planet wheels is vertical and removed from the pumpkin.

Put the pumpkin on its back, with the surface for the lid down against the table. Then hold the pinion while tapping the spline shaft, mine took some force to come out.

I used an internal bearing puller to remove the outer races of the pinion bearings. The front bearing race did not require too much force to pull out. For the rear bearing race, I used two aluminum bars against the surface for the lid as a brace for the bearing puller. This was because it did not seem like a good idea to put the bearing puller forces against the internal lubrication channels of the housing. The rear bearing race required some force to pull out, its also easy to lock the bearing puller on a different edge than the bearing here, so check your tool position before pulling. Behind this race, there was a shim on my diff. This is probably where to adjust the pinion position in relation the the crown wheel to get the teeth meshing correct.

For the inner race of the rear pinion bearing I used a bearing splitter. There is just enough air between the race and the pinion to get it wedged between. I tightened the splitter up pretty good, and started to heat the race with a torch. I then used a hammer on the splitter to try to shock the bearing loose, this was probably necessary because I was a sissy with the torch. After some heating and hammering the bearing started to come off, this was by far the tightest fit of all the bearings and took a lot of force to move.

If anyone has a better way to remove these parts from the pumpkin, please post it so the next guy can benefit from it. I know I could have used it.

That's it, now to get an LSD, some bearings and a new final drive!
 

doublespaces

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Fantastic first post! If I'm understanding this correctly, you are explaining the differential assembly only, do you intend to also provide the steps you took to machine the welded bead off and convert to a bolted type?
 

Traf

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Aug 3, 2017
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Wouldn't it be easier to switch to a M3 LSD ? You get beefier axles and way more upgrade possibilities down the road.
 

drunkenup

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Dec 16, 2017
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Wouldn't it be easier to switch to a M3 LSD ? You get beefier axles and way more upgrade possibilities down the road.

The OEM M3 viscolok is very slow to react, only locks on acceleration, and chances are, if you are doing the work to put an E9x M3 pumpkin in, which if I'm not mistaken means a custom driveshaft and half shafts/M3 rear sub on a 135i, it's a used example that does not perform like new anymore. There is plenty of discussion of how mediocre of a unit it is on m3post. The time trial builds often swap to OSG or other 1.5 way clutch type diffs. I'd much rather put a new wavetrac than do the work for a worn out M3 diff
 
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Traf

Sergeant
Aug 3, 2017
332
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The OEM M3 viscolok is very slow to react, only locks on acceleration, and chances are, if you are doing the work to put an E9x M3 pumpkin in, which if I'm not mistaken means a custom driveshaft and half shafts/M3 rear sub on a 135i, it's a used example that does not perform like new anymore. There is plenty of discussion of how mediocre of a unit it is on m3post. The time trial builds often swap to OSG or other 1.5 way clutch type diffs. I'd much rather put a new wavetrac than do the work for a worn out M3 diff
Funny you say that, i'm currently building the diff.
Sweet old ZF core

IMG_20171216_200809.jpg
 
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mal86

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Dec 15, 2017
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135i N54 6mt
@doublespaces - I'm showing the disassembly, for now that's as far as I've gotten. I did not plan to machine the weld, this is because it would add another unknown to the pinion and backlash adjustment. To be honest I'm not sure I have the required skill set for this (yet). I was planning on writing how I chose to put it back together with a bought final drive and an LSD. Then a follow up if it all worked out or not.
@Traf - You are correct, if it is a direct bolt on, it is a lot easier. But if I need new or custom driveshaft and axles, for me my current route is the easiest.

Had some time to work on the diff today, and found some damage on the inner race of the rear pinion. A minor crack on a "valley" between the first and second ball race, this was where I first attempted to pull the race off from, not a good idea it seems. Also after cleaning all the parts and using some thin oil on them to prevent rust, I found that the bearings do not feel like new. I'm not sure if this is from wear, or from me trying different ways during the disassembly.
 
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mal86

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Dec 15, 2017
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135i N54 6mt
I replaced my differential fluid this spring, and got annoyed by having to pump out the old fluid through the single hole BMW gave us. When I started working on my "future LSD" I planned a drain plug. Today I fixed it!

Drain Plug 03.jpg

Marked the location of the hole to be, magnetic plug hanging about.


Drain Plug 04.jpg

Not the best picture I've taken. Housing locked in place, almost straight, looks worse then it was.

Drain Plug 05.jpg

I used a spot face cutter to machine a surface for the plug to seal against. Threaded 1/4" BSPP.

Drain Plug 06.jpg

Voila, a magnetic drain plug!

Bearing Puller 01.jpg

I then used this awesome bearing puller to remove the inner races of the differential bearings, which I completely forgot previously.

Gasket 01.jpg

Rear cover gasket in the making, tedious work.

Part Cleaning.jpg

Final cleaning before preparing for sand blasting.

Sand Blast Prep 02.jpg

Housing and output flanges ready for sand blasting!


Trying to get a hold of the bearings for this differential now. Are there anyone who were able to buy new FAG bearings out there? I know you can buy uprated tapered roller bearings, but was hoping to get the original ball bearings for it.

FAG Part numbers.
Front Pinion Bearing: FAG F-237541
Rear Pinion Bearing: FAG F-237542
Differential Bearing: FAG F-237543 ( You need two of these)
 

mal86

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Dec 15, 2017
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135i N54 6mt
Delayed update!

This January I sandblasted, primed and painted the pumpkin.
Primer 03.jpg


Paint 02.jpg

I've made some progress on this, just need to write it all up.
 

mal86

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Dec 15, 2017
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135i N54 6mt
February I received the LSD!
LSD 00.jpg


An attempt was made.
Crown Wheel Attempt.jpg

I now have a 215 differential and crown wheel paperweight.
I'd probably make it work if I were to try it again though, here's roughly how:

Place the crown wheel correctly, to prevent excessive shimming measure the location of the backside of the wheel in relation to the bearing shoulder. You need to place the wheel at the same location on the LSD, you'll see that this puts the cut to the right of the weld when orienting the same as the above picture. This means you can not cut the weld, but have to cut to the right of it, and the safest will probably be to cut through the differential here.

You could cut the weld and shim the wheel on the LSD to correct position, but as I see it, this leaves you with a smaller locating face and shorter thread engagement on the wheel.

Follow by using internal cutters to machine away all unnecessary material from the center and outwards, do not exceed ø132mm! Stay at ø130mm and eat your way inwards. When confident that you are ready to cut the wheel off, make a final cut matching the diameter of the LSD, mine was ø132.00mm. This cut should part the wheel off, remember that the wheel is an interference fit to the OEM differential, and will stay until coerced properly.

Afterwards, put the wheel in a mill, drill and tap the correct holes for mounting on the LSD.

I made a mess of this, and ordered a new final drive from mfactory.
 
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mal86

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Dec 15, 2017
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135i N54 6mt
March. Assembly of the LSD!

I purchased new bearings and seals. I went with the OEM big pinion bearing F-237542.02 and aftermarket small pinion bearing F-237541. Differential bearings were aftermarket aswell, F-237543. Bearings came from bearings-online.uk. Seals from ECStuning the first time, then from a more local webshop called koed.no, because I accidentally ordered some of the seals for an AT version of the diff.

I grinded the inside of the inner race on the big pinion bearing to use it as a press tool for assembly. I also put some aluminium under the pinion to prevent any damage when pressing the bearing on.
Big Pinion Bearing 03.jpg



Same technique for pressing in the outer race, used the old outer race as a tool.
Big Pinion Bearing 02.jpg

Under this bearing in this picture, the original pinion shim is placed, this one is important to remember.


For the outer race on the small pinion bearing, I used the same technique again.
Adjustment 05.jpg



Same stuff when assembling the inner race of the differential bearings.
LSD 01.jpg

To prevent any damage to the bearing cage on the differential, it's a good idea to always have it resting on the extra inner race.
Carrier Stand.jpg
 

mal86

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Dec 15, 2017
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135i N54 6mt
Adjusting pinion and backlash! Now entering the deep unknown.
I used shim washers for adjusting the backlash to check the pinion depth. DIN 988, you can get these in all sizes and thicknesses. I bought ø100x80x0.1mm for the pinion depth and ø105x85x0.1 along with ø105x85x0.2 for adjusting backlash.
I "reset" the crush sleeve by using a hydraulic hose coupling presser to gently press the bulge and increase the length.


Hindsight note, if I were to do this again, I'd do things in this order.
Assemble differential in carrier and adjust to correct bearing preload.
Remove differential from carrier.
Set Pinion bearing preload to slightly lower than correct value.
Reassemble differential in carrier with shim for correct preload.
Check backlash, and adjust if necessary.
If backlash was adjusted and feeling picky, remove pinion to recheck differential bearing preload.
Assemble pinion with slightly lower than correct bearing preload and differential with correct preload and backlash.
Check pinion depth. Adjust if necessary.
If pinion depth needs adjustment check pinion preload and backlash again.
And if backlash needs adjustment after pinion depth adjustment, check differential preload afterwards.
Check pinion depth again.
Once everything checks out, the pinion nut can be removed and the pinion seal can be assembled.
Adjust pinion to correct bearing preload.
Verify pinion depth and backlash to be within nominal values.

This has been a time consuming process, with lots of googling, thinking and considering.

Adjustment 01.jpg

Here I thought it looked like the pinion depth could be adjusted.


Adjustment 02.jpg

Here I was happy with pinion depth.

The numbers are measured thickness of shim + locking ring. I went with metric mechanic backlash values, even though those are aimed at 188 and 210 differentials. I could not find any other values for 215 differentials, anyone with knowledge on this are welcome to chime in as I'm flying blind here.

MM backlash: 0,0762 - 0,0889
MM differential preload: 9-11 in/lbs
MM pinion preload: 14-16 in lbs

Edit: Typo
 
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mal86

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Dec 15, 2017
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135i N54 6mt
At the end of march I switched my spare pumpkin with the LSD. Since it's a clutch type I also had to code out the OEM E-diff, this turned out to be a hassle. After a lot of googling I found a complete computer image for Oracle VM that had all the right stuff for flashing, using Oracle VM for coding was pretty easy. I followed a guide to teach you how to enable the digital speedometer, and after that I felt confident enough to code out the E-diff.

Great success!
Success.jpg
 

mal86

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Dec 15, 2017
11
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135i N54 6mt
I recently got to try the car on Rudskogen racetrack. Comparing the experience from last years trip and trying to drift the car with E-diff.

I am agreeing with everybody else who has an LSD, if you're gonna use the car for any kind of shenanigans, get an LSD!

Last year all I did was battle the e-diff, it would move the rear of the car all over the place when breaking traction, during the drift and when ending the drift (this really scared me a few times, trying to put power when ending a drift is dangerous with e-diff). Now I'm a new guy to drifting, and still have A LOT to learn, and the e-diff completely killed my confidence in my driving skills.

This year with the LSD, after the initial "warm-up" to driving the car on and beyond the traction limit. The car has completely transformed the way it drives, breaking traction in turns is incredibly predictable. Maintaining a drift through a corner is a breeze, ending a drift with full throttle is simple now! It is nothing less than amazing fun to drive.

Also, as for the differential assembly, I'm not completely sure I'd trust the preload numbers. I'm gonna do more research.
After the install, there were lots of new sounds from the rear, almost all of them disappeared after a few miles, though I still have a tiny amount of whine coming from the differential. I may have missed the preload settings for the bearings, maybe some debris got inside and scarred one of the bearing races. Although I did flush the housing two times before assembling it on the car. I did change from OEM differential bushings to mfactory solid rubber bushings at the same time as I put in the differential.
For now the car is perfectly drive able, but I'm planning to strip it down and inspect everything some time in the future.