Project__E46 M3 LSD Rebuild

This project will be linked to:

https://github.com/yeukfung/ohrc/projects/1

Background

My friend recently bought a E46 M3, and everything seems good, while he found that the differential started leaking oil, he found an indy to replace all 3 oil seals and no more leaking.

However, some whining noise started to occurs when the car drive up to 50km/h, and clucking noise happens when accelerating from stop.

He come to 老馬復康俱樂部, and we identified there is a serious play on the right drive shaft attached to differential...

checking online, it seems common problem, so we decided to replace the shim...

then after the entire differential has been taken out, it's found that something wrong with the pinion gear https://www.instagram.com/p/CIV4KnKhM6e/

and it just cannot rotated properly, and with quite a lot of resistance. comparing to what I saw online, all of them turns smoothly.

so I believe the previous indy didn't following the torque requirement (0.6-0.8Nm of rotation force), that we MUST tight the bolt progressively, little by little, there is no way to undo.

Then, I asked my friend to have a full rebuild, and it takes a longer time to wait for everything arriving to my workshop...

and today I have been working on the bearing and bearing cap removal, there is a bearing surface which is rough as hell, no wonder why it create un-smooth rotation and noise. https://www.instagram.com/p/CIznOQ6BhLU/

will continue to work on it once I have time

stay tuned.

2020-12-17 Some notes for installing the middle pinion gear set

Today I have finally pushed all the bearing out, everything goes smoothly, but some issue will be a little hack if you don't have proper tools

1. for installation of pinion gear bearing, there are several method, some will freeze the pinion rod, and heat-up the bearing, then can simply put the bearing to the rod without any press, for me, I have to find something that has inner diameter of 46mm to 50mm, and hard enough to support the press, luckily I found that the bushing attached to differential case can fit the purpose nicely.

2. for pressing the pinion gear, if using new crush ring, a huge amount of force has to applied via press to break the crush ring into curve shape, once break in, the pinion gear has no more play, and rotational force is 0.3Nm, which the target is 0.6Nm-0.8Nm, so I will tighten the bolt 10 degree each time and check each time to see how the rotational force increase and my target is 0.6Nm.

3. installing the locking nut is tricky, the previous indy do it wrongly, which we will need to install it as U shape facing outward, and punch two side to the gap area of the flange.

2020-12-18 Some notes for installing LSD unit, and rolling torque

• it's found that the rolling torque spec around the web varies, some say 0.6Nm to 0.8Nm, while some say it's valid on used bearing, for new bearing, we should use 1.2Nm up, for the case when I try to torque, I attempt to torque to 0.8Nm, while in some how, it's in 1Nm level, so just between 0.8 to 1.2Nm for new bearing, I am happy with the result (or say no choice :-D)

• during the installation of clutch plates, the difference between used one and new is 1mm!!!, what a big number.

• installation of the freeplay shim is fairly straightforward, just remove the old one and take the new in.

• once everything is installed, torque the hex screen to 8Nm

• then install the crown gear by using plastic hammer to tap into a little bit, which the original screw can start to engage the thread, then put 3 screw in 120 degree separation, and torque it evenly one by one for few turns, until the crown gear is proper in place

• apply the thread lock 243 or 245 , and apply 170Nm of force to the bolt

once above is done, then we are ready to put the gear back in!!!

2020-12-22 Everything is done today

• during the installation of the flange, right hand side with shorter teeth is easy to install, however for the left hand side, the long teeth will across 3 rotation section, and when the time I inserted, only 2 section is able to insert, but left one section out of phase, i was clueless and stucked over half hour. Finally I found a work around, is to rotate the right side, but hold left side, then the final section will moved according the right flange, once the alignment is matched, the left flange can be inserted smoothly

• jacking out the front differential bushing isn't fun job, as lack of special tools to handle, but finally using quite a lot of trail and error, i finally managed to take that out, and everything is good

• installing the differential is much better to have 2 ppl help, and also be very careful to insert the propshaft washer carefully, or else try to clean it with brake cleaner, and stick the washer tightly, or else it will drop out

• when installing the anti-roll bar, we must take off the right CV join, or else will not be enough space, therefore better to leave that open before the anti-roll bar installation.

after the car started, everything is smooth, quite, and my friend reporting nice ride, and instant response on the car, and she shift far much smoother, and it's really a good car now.