Differential Swap Question (E39 M5 LSD)

[RomanK]

Originally Posted by Scharbag

Thanks. Why did the 2 clutch system fail?

I think because of clutch material. The locking factor was very small and I almost not felt it. I felt the working of my diff right after I installation, but after the 2-3 weeks running it, I understood that it has too small locking factor... One wheel spins pretty simple under acceleration on the corner without any influence of the second wheel...

After the installing 4 clutches kit - it became good. Maybe the best way is 6 clutch packs variant with machining of diff housing... But I am good with 4 clutches now.

[Scharbag]

Originally Posted by RomanK

I think because of clutch material. The locking factor was very small and I almost not felt it. I felt the working of my diff right after I installation, but after the 2-3 weeks running it, I understood that it has too small locking factor... One wheel spins pretty simple under acceleration on the corner without any influence of the second wheel...

After the installing 4 clutches kit - it became good. Maybe the best way is 6 clutch packs variant with machining of diff housing... But I am good with 4 clutches now.

Thanks.

It looks like the disc materials for the 2 clutch system from RacingDiffs has changed. Mine have holes in them where yours in your post did not. Is this correct?

RomanK - I updated some info. Initial lockup on the bench was ~120ftlb right after tightening the carrier cap bolts and checking everything was free to spin. RacingDiffs said that initial lockup should be ~115Nm reducing to 100Nm after break-in. When I checked on a lug nut last night, I measured 89ftlb. Given a 22" torque wrench and the lug being offset from center by 2.75", this gives me ~100ftlb breakaway torque after 1 light drive. 100ftlb is ~135Nm, a little higher than what they said to expect (115Nm) but there is a lot of error in there as I ballparked some of the measurements and I was not perfectly in line with the lug center - I just wanted to check to make sure it was close. After I can break the LSD in properly (once the snow melts), I will check the torque again using the axle nut and report back.

If my 2 clutch system wears out really fast, I will order the 4 clutch setup with variable ramps. Are you still running 45/45? I would think the 30/60 ramps would likely offer great on throttle lockup and reduce the off throttle understeer.

As for machining, I will likely not do that to this carrier. I do not race this car. I just hated the delay of the GKN unit.

Cheers,

[Scharbag]

One more question - does anyone have the dimensions for the pinion shim for the E9x M3 platform? Just looking for OD/ID.

Any help is greatly appreciated.

Cheers,

[RomanK]

Originally Posted by Scharbag

It looks like the disc materials for the 2 clutch system from RacingDiffs has changed. Mine have holes in them where yours in your post did not. Is this correct?

Yes... I bought the clutch kit three years ago... so this very possible that they changed the material.

Originally Posted by Scharbag

If my 2 clutch system wears out really fast, I will order the 4 clutch setup with variable ramps. Are you still running 45/45? I would think the 30/60 ramps would likely offer great on throttle lockup and reduce the off throttle understeer.

Yes I am running stock ramps 45/45. I think it is good for me... I don't think that 30/60 with 4 clutchs set will works good. I think with 30 degrees and 4 clutch set there will be too high locking factor.

[Scharbag]

Just a quick update on the diff after a few miles.

Everything seems to be working great! Diff still drives awesome and it has transformed how the car drives. I really like it.

I checked the pre-load again via the lug nuts - did not want to take the centre cap out of the wheel. Average torque is about 118Nm of pre-load. This is a little higher than expected but certainly not out of whack. Clutches may still bed in a little more as I have less than 1000KM on this setup.

I have no chatter when cornering in parking lots and everything seems very smooth. As I said, really happy with this setup.

Cheers,

[Scharbag]

Update

Checked the breakaway torque and it has dropped to around 90Nm. Seems OK.

I did just order a 4 clutch setup from RacingDiffs.com cause they were on sale...

[Bakerboy]

Originally Posted by Scharbag

Update

Checked the breakaway torque and it has dropped to around 90Nm. Seems OK.

I did just order a 4 clutch setup from RacingDiffs.com cause they were on sale...

I got inspiration from your thread and few others to do this build myself.

I just got myself a e36 evo diff (same as e39 m5) and took advantage of the racing diffs promo also, I went stage 3 with the ramp angle adjustment

[Scharbag]

Originally Posted by Bakerboy

I got inspiration from your thread and few others to do this build myself.

I just got myself a e36 evo diff (same as e39 m5) and took advantage of the racing diffs promo also, I went stage 3 with the ramp angle adjustment

Just got mine

[Bakerboy]

Originally Posted by Scharbag

Just got mine

How you planing to set it up, ramp angles and preload?

[Scharbag]

Originally Posted by Bakerboy

How you planing to set it up, ramp angles and preload?

I am going to use the 50/65 ramp. Pre-load will be what it will be with the supplied shims. I do like my ZF LSD a lot more than the GKZ that comes with the M3. This is more for fun than anything. If I were going to track the car, I would enlist the help of an expert and buy a built diff.

Cheers,

[Bakerboy]

Originally Posted by Scharbag

I am going to use the 50/65 ramp. Pre-load will be what it will be with the supplied shims. I do like my ZF LSD a lot more than the GKZ that comes with the M3. This is more for fun than anything. If I were going to track the car, I would enlist the help of an expert and buy a built diff.

Cheers,

Ok cheers, I use mine on track and planning to do the build myself,

As long as the core is assembled correctly, back lash is set, what can go wrong

How did you set the pinion crush. What torque setting?

I'm changing final drive at same time to 3.45 (dct)

[jvictormp]

Originally Posted by Bakerboy

Ok cheers, I use mine on track and planning to do the build myself,

As long as the core is assembled correctly, back lash is set, what can go wrong

How did you set the pinion crush. What torque setting?

I'm changing final drive at same time to 3.45 (dct)

Nice!! We should have more DIY about this subject!!

[Scharbag]

Originally Posted by Bakerboy

Ok cheers, I use mine on track and planning to do the build myself,

As long as the core is assembled correctly, back lash is set, what can go wrong

How did you set the pinion crush. What torque setting?

I'm changing final drive at same time to 3.45 (dct)

I did not have to change the pinion. Just used the ring gear in the new carrier.

[Scharbag]

Put the 4 clutches in today. Some figure 8s in a parking lot and then a quick rip. Felt pretty good. Quick lockup on acceleration but not too much understeer. Running 50/65 ramps. I will check the preload once it is broken in.

Blue Motul 75w140 is strange to work with. I could only think of smurfs...

[Bakerboy]

Originally Posted by Scharbag

Put the 4 clutches in today. Some figure 8s in a parking lot and then a quick rip. Felt pretty good. Quick lockup on acceleration but not too much understeer. Running 50/65 ramps. I will check the preload once it is broken in.

Blue Motul 75w140 is strange to work with. I could only think of smurfs...

Anymore feedback on how it feels?

Mine still on the bench in the garage

[Scharbag]

Originally Posted by Bakerboy

Anymore feedback on how it feels?

Mine still on the bench in the garage

Unfortunately we got some snow. So, not a lot of miles on it yet.

I will report back as soon as I can.

Cheers,

[Bakerboy]

Originally Posted by Scharbag

Unfortunately we got some snow. So, not a lot of miles on it yet.

I will report back as soon as I can.

Cheers,

Got a quick question mate

I've just dropped the e92 dct diff and can see that the bolts for the diff input shafts are a different size than the donor lsd diff (where the main driveshafts bolt to the halfshafts) thicker on the e92

From my understanding I will need to use the halfshafts from the donor on my e92 one

Did you face this issue, if so how did you overcome, redrilling and tapping or using spacers with older style bolts?

[Scharbag]

Originally Posted by Bakerboy

Got a quick question mate

I've just dropped the e92 dct diff and can see that the bolts for the diff input shafts are a different size than the donor lsd diff (where the main driveshafts bolt to the halfshafts) thicker on the e92

From my understanding I will need to use the halfshafts from the donor on my e92 one

Did you face this issue, if so how did you overcome, redrilling and tapping or using spacers with older style bolts?

What kind of car are you working on? An M3 or 335is?

[Bakerboy]

Originally Posted by Scharbag

What kind of car are you working on? An M3 or 335is?

I have E92 m3

The donor diff is sourced from a e36 m3 evo

I'm wondering if I just need to get a hold of some 5 series halfshafts (input shafts)

[Scharbag]

Originally Posted by Bakerboy

I have E92 m3

The donor diff is sourced from a e36 m3 evo

I'm wondering if I just need to get a hold of some 5 series halfshafts (input shafts)

Ahh. Not sure exactly what you need but the E39 M5 output flanges bolt to the E9x M3 half shafts just fine. I did not have to modify anything to make my setup work.

Cheers,

[bigjae1976]

Scharbag What's up? Glad you took the dive and did this. Rebuilding the LSD isn't too bad at all! Just gotta stay organized.

I've since swapped my R&P to a 3.91. I opened the LSD to check out the internals, everything looked really good after a year of track abuse. I do lean on the diff and slide the rear axle a bit. I reassembled the LSD pumpkin and the top cap wouldn't sit flush. Like an idiot, I pinched one of the spider gear lash shims (smaller rings that fit inside of the clutches/steels). Ugh...can't buy them so I had to have a machine shop make some.

I'm subbing to get your feedback on the 50/65 ramps. I'd like to do 30/60 but the car still feels great with the 45/45.

Originally Posted by Bakerboy

I have E92 m3

The donor diff is sourced from a e36 m3 evo

I'm wondering if I just need to get a hold of some 5 series halfshafts (input shafts)

equal length stubs from an 210mm diff will fit. So if your E36 diff came with the axle stubs...those are the ones.

[Bakerboy]

Originally Posted by bigjae1976

Scharbag What's up? Glad you took the dive and did this. Rebuilding the LSD isn't too bad at all! Just gotta stay organized.

I've since swapped my R&P to a 3.91. I opened the LSD to check out the internals, everything looked really good after a year of track abuse. I do lean on the diff and slide the rear axle a bit. I reassembled the LSD pumpkin and the top cap wouldn't sit flush. Like an idiot, I pinched one of the spider gear lash shims (smaller rings that fit inside of the clutches/steels). Ugh...can't buy them so I had to have a machine shop make some.

I'm subbing to get your feedback on the 50/65 ramps. I'd like to do 30/60 but the car still feels great with the 45/45.

equal length stubs from an 210mm diff will fit. So if your E36 diff came with the axle stubs...those are the ones.

Definitely not the right ones mate

I think I need ones from e39 m5 or any 102 equal length flanges

The bolt size is incorrect on the e36 variant and is a slightly different size/shape