Diff Rebuild-Clutch LSD

[tlrid3r]

After feeling a bit down with the performance of the OEM diff, feeling a bit open and not much torque transfer. After 110k miles and many track days, the viscous LSD is not working its best. So decided to send the diff for rebuild. Sent the to Brendan at Speed GarageWorks in Washington. Here are some pics of the process.

Speed GarageWorks provided constant updates and all the pictures after I shipped it out. I'll be installing it soon and updating with progress. I'm really happy how Speed Garageworks was there the during whole process with info and updates

Removed and Drained the Diff.
I made a Crate to ship it, I wanted to make sure no damage would occur.





After Speed GarageWorks received and disassembly





I decided to keep my stock Gears, but treated with shot ping blasted and REM polishing




New Bearings




e39 Clutch LSD



Reassembly

[amrazM]

I had no idea E9x m3 used a viscous lsd at the rear, e39 m5 unit is what 188mm?

What’s the locking factor on the new unit?

[tlrid3r]

Originally Posted by amrazM

I had no idea E9x m3 used a viscous lsd at the rear, e39 m5 unit is what 188mm?

What's the locking factor on the new unit?

From what I recall 210mm unit

35/60 ramps

[RomanK]

What is the brand of the new clutchpacks?
It is seems like racingdiffs.com

[tlrid3r]

Originally Posted by RomanK

What is the brand of the new clutchpacks?
It is seems like racingdiffs.com

Honestly I don't know the brand. Brendan over speed garageworks uses good quality and provides a guarantee even with track use. I'm just finishing the break-in of the bearing and clutches. I have a track day on the 30th of March to truly test it out, but I can feel the increase balance and grip on some spirited drives.

I'll report back later with more input

[gte869h]

Please....report back. How did the e39 LSD hold up? I opted to go wavetrac for my diff build, but having a hard time locating specs for ring gear bolt torque, pinion bearing preload, ring gear backlash, and carrier side bearing preload. It was way easier to find these for my SpecE46 build.

Could your shop share the numbers for the community? Thanks bro!

[GORDON.M3]

Nice build, the e39 diff is a great unit.. man I miss that car, a good friend had one and it put the power down to wheels so nicely.

[tlrid3r]

Originally Posted by gte869h

Please....report back. How did the e39 LSD hold up? I opted to go wavetrac for my diff build, but having a hard time locating specs for ring gear bolt torque, pinion bearing preload, ring gear backlash, and carrier side bearing preload. It was way easier to find these for my SpecE46 build.

Could your shop share the numbers for the community? Thanks bro!

Sorry for the delay,

been off the forums, just busy with work. I have ran the diff 3 times on track.
Mostly noticed a good difference on corner exits grip, I have some solo data, but don't have the time to compile it. It's clear to me I'm on the throttle sooner, it can be from confidence and grip. The diff is consistent, quite and zero issue since the first day.
I manage to run a 1:40 flat at laguna seca. Not bad for a street going car with a few upgrades.

Brendan over at Speed Garageworks, did a great job providing pics, but I didn't get any the details on the rebuild setting specs. I don't have FB, but here is a link to his fb page:
https://www.facebook.com/speedgarageworks/

Brendan has huge knowledge just reach out to him.
I glad I work with him and I'll be a return customer with my Trans. I'll be rebuilding my ZF6 of my e92 m3 with Brendan.

thanks

[Redd]

Nice! Why did u choose to go with an E39 diff vs other more popular units like OS Giken or Wavetrac?

[Speedgarageworks]

Thanks Thiago for posting up about the differential, really glad you're enjoying it and that it is what you were looking for.

The e39 M5 diff is a great option for the 210mm differential builds. 2 big reasons for one of these compared to an aftermarket differential are cost and reliability. BMW has been using the design for the carrier since the 1980s with minor tweaks and the e39 was the last of these differentials so it had all of the r&d behind the 20+ years of use and was also less expensive than other options.

This differential is a clutch type so it has preload in the differential lockup at all times, meaning it won't free spin like an open differential or an m variable or wavetrac. This creates some tuneability in the differential to suit the driving style. Depending on driving style this can be a positive or a negative. We tuned Thiago's with 30/60 ramps which allows the differential to lockup more aggressively on acceleration but to lockup less on deceleration. So on turn in his differential locks up less than in mid corner and corner exit. This allows for throttle steering mid corner without trying to kick you sideways on corner entry like on an even ramp amount. It creates a much more driver oriented approach when using the clutch type since the lockup is always there and in tight parking lots it doesnt have the forgiveness of a m variable acting like an open differential, and on track it can be less forgiving.

I apologize for rambling, feel free to ask any questions and I'm glad to help out.

Brendan

[gte869h]

Originally Posted by Speedgarageworks

Thanks Thiago for posting up about the differential, really glad you're enjoying it and that it is what you were looking for.

The e39 M5 diff is a great option for the 210mm differential builds. 2 big reasons for one of these compared to an aftermarket differential are cost and reliability. BMW has been using the design for the carrier since the 1980s with minor tweaks and the e39 was the last of these differentials so it had all of the r&d behind the 20+ years of use and was also less expensive than other options.

This differential is a clutch type so it has preload in the differential lockup at all times, meaning it won't free spin like an open differential or an m variable or wavetrac. This creates some tuneability in the differential to suit the driving style. Depending on driving style this can be a positive or a negative. We tuned Thiago's with 30/60 ramps which allows the differential to lockup more aggressively on acceleration but to lockup less on deceleration. So on turn in his differential locks up less than in mid corner and corner exit. This allows for throttle steering mid corner without trying to kick you sideways on corner entry like on an even ramp amount. It creates a much more driver oriented approach when using the clutch type since the lockup is always there and in tight parking lots it doesnt have the forgiveness of a m variable acting like an open differential, and on track it can be less forgiving.

I apologize for rambling, feel free to ask any questions and I'm glad to help out.

Brendan

Thanks Brendan, what are the preload numbers for pinion and carrier on the e92 with the newer ball bearing design? What backlash did you dial in?

I’ve got the motorsports 4.10 gears and will be doing my build next weekend.

[Scharbag]

I am looking at an E39 core. What parts are required to make this work? I assume the ring from the 6MT E92 can bolt to the E39 carrier? Are the output shafts the same?

Thank for any help with this.

Cheers,

[tlrid3r]

Originally Posted by Scharbag

I am looking at an E39 core. What parts are required to make this work? I assume the ring from the 6MT E92 can bolt to the E39 carrier? Are the output shafts the same?

Thank for any help with this.

Cheers,

From my knowledge you use everything from e92 M diff. Just the LSD unit is from e39 M

[Scharbag]

Now I need to figure out what to do with this lump...

[tlrid3r]

Originally Posted by Scharbag

Now I need to figure out what to do with this lump...

Are you attempting to do all yourself?

[bigjae1976]

You need equal length 210mm axle stubs which should come with the E39 M5 diff. You'll need to swap the ring gear.

I believe the M5 diff is a 2 clutch with 45/45 ramps.

I don't think you'll need to machine the ring gear holes to 14mm.

I swapped a diff from an E24 635CSi and went with a 4 clutch conversion. The LSD rebuild part wasn't that hard.

[Scharbag]

Originally Posted by tlrid3r

Are you attempting to do all yourself?

I am in no rush. Need to do a bunch of research and see what I need to do. Will likely get help to make sure I don't F it up.

Also, I would likely want to refresh the diff, see if 30/60 or 45/45 is what I want and get 4.10 gears. It will be a bit of a project.

[bigjae1976]

Originally Posted by Scharbag

I am in no rush. Need to do a bunch of research and see what I need to do. Will likely get help to make sure I don't F it up.

Also, I would likely want to refresh the diff, see if 30/60 or 45/45 is what I want and get 4.10 gears. It will be a bit of a project.

I just built my 3.73 4 clutch ZF LSD for my E46 M3. It's not as hard as most lead you to believe. A hydraulic press and a big impact makes life a lot easier.

It goes:

With an empty case, install the LSD unit and set preload by adjusting the carrier shims.

Remove, install pinion gear but DO NOT crush the washer or install the input seat. Snug the pinion nut to take out any up/down play in the pinion.

Install LSD. Apply gear marking compound (I used diaper rash cream) to the ring gear, front and back of a couple of gear teeth. Based on the contact pattern, make shin adjustments.

Once gear pattern is good, take a backlash measurement. Should be good.

Remove LSD and clean gear compound off.
Crush sleeve on pinion to set preload. I used an impact with a big holder made from steel bolted to the pinion flange. Hit it with the impact - really short blasts - check preload and repeat.

Doesn't take much once the bearing starts to drag. Go slow. Once at spec, install pinion seal and recheck pinion preload.

Reinstall LSD, check gear pattern and backlash one more time.

If all good...finish assembling and done.

[Scharbag]

I started a new discussion as not to thread-jack.

:P