Looking for a 3.90 to 4.10 diff.

[grannyknot]

Originally Posted by maupineda

Is the large pinion bearing there a ball bearing? If so, you receive the E92 kit, which is identical to the E46 v2 and Z4M except for that item, ours is a taper roller bearing. That is not compatible with our pumpkin

You had me worried for a second, the pic is the largest bearing and the other 3 are also taper bearings, All from KOYO, made in Japan.

Originally Posted by ZStig

what's the labor estimate to install those gears?

I couldn't tell you, I'm going to be installing them, I'm sure it wouldn't be cheap.
When I have rebuilt diffs in the past I take them up to a transmission/diff specialist near me for them to check over my work and make sure the preload and lash are correct, they charge me $300 for that.

[maupineda]

Glad it was ok for you. In my case I had to source the large pinion bearing separately. Not expensive, just a small issue

[F360C]

Originally Posted by maupineda

Glad it was ok for you. In my case I had to source the large pinion bearing separately. Not expensive, just a small issue

Had the same issue with ordering the kit from them. I wish he would update his website.

I am about to swap to a ZF 3 clutch LSD with 30/60ramps. I think instead of ordering his kit i'll just source bearings somewhere else since I know the part numbers now.

[Vanne]

I got the other bits from summit. Parts aside, for the crown and pin and the race diff from racingdiffs, output shafts and all the other bits and pieces, the cost was about a grand 500 for the install.this included the initial wasted time/labour opening up the z4m pumpkin. This was at Gear Masters DXB, probably the only shop I would take transfer case/transmission/diff rebuilds to in Dubai.

[grannyknot]

Originally Posted by F360C

Had the same issue with ordering the kit from them. I wish he would update his website.

I am about to swap to a ZF 3 clutch LSD with 30/60ramps. I think instead of ordering his kit i'll just source bearings somewhere else since I know the part numbers now.

Your right, their website is a little haphazard and confusing, I think he has learned his lesson because he suggested the proper kit for my Z4M.

"Hi Chris,

No worries, this is the correct one RD4060 GKN v2 Advanced - comes with clutches, plates, free play delete, preload shim and Bearings and oil seals kit:
https://racingdiffs.com/collections/...42833941922028

Price is discounted on a summer sale 423e + 58e DHL Express worldwide shipping. "

[Vanne]

Lol yeah no doubt after I was in his ear 2 years and a bit ago. Initally sent me the e46 kit which doesn't have enough plates for the OEM z4m pumpkin.that said, I have absolutely no hesitation to recommend Racingdiffs.. they work with you untill it's sorted.. excellent company and they stand behind Thier stuff.
Might help if your gear bloke is also Serbian. Lolol.. pretty sure we did the ground work together for the Z4M as they initially thought it was the same diff as the E46 M3.

[grannyknot]

Everything has arrived to complete the job now, the ring and pinion gear and disassembly tool came in yesterday.
I thought the 3.91 ratio would be mentioned with the engraving but just looks like some kind of code, can anyone decipher?
The second pic looks like I don't have a thumb.

[PayamFSU]

What was the name of the kit ? I can't find it on the site

[grannyknot]

Originally Posted by PayamFSU

What was the name of the kit ? I can't find it on the site

Post #27 above, " No worries, this is the correct one RD4060 GKN v2 Advanced - comes with clutches, plates, free play delete, preload shim and Bearings and oil seals kit:
https://racingdiffs.com/collections/...42833941922028

Price is discounted on a summer sale 423e + 58e DHL Express worldwide shipping."

[F360C]

FYI to everyone... You can buy the Timken bearings already REM polished from https://negearpolishing.com

He doesnt have all the bearings listed on his website yet but if you email him he can provide them. Super friendly and knowledgable about gears... he did the REM polishing on my 4.10. I have him also do the REM on my 3.91

[grannyknot]

I started tearing down the LSD today, a couple of things, if you do this don't waste your time putting extensions on the end of the opening tool.
I put a 10ft extension on the handle and only managed to bend it and it didn't budge the ring one bit.
A 2lb mallet and sharp hard blows had the ring off in minutes.
Also, the 8mm Allen screws in the tool are only snugged up a bit, you want to tighten them down well before you start hammering.

I bought the Victor-Reins diff input shaft seal because I wanted to avoid buying the seal that was originally used - because it always leaks.
As it turns out V-R sells the exact same seal as was installed at the factory, don't want that so I'm going to use the Racing Diffs seal, it seems to be built a little beefier and you can see the seal spring is heavier weight so that might solve the leaking.
The Racing Diffs side axles seals also use a stronger seal spring.

The last pic is of some of the clutch pack discs, not sure they are all that bad for 91,000 mi but I'm replacing them anyway just because I'm in there.

[Vanne]

did you get the correct amount of plates?

[grannyknot]

Originally Posted by Vanne

did you get the correct amount of plates?

I think so, with all the new plates stacked in order it comes up to the same height as the original stack.
However there is this extra conical spring plate that is left over, I've sent a couple of pics to Aleksandar at RD to find out what it is, maybe from another kit
Vanne, do you recognize it?

[maupineda]

It is there to give more preload and reduce the clunk noise. IMO you should use your stock clutches and since you are there, you can only add the free play shim and close it. With more preload you will wear down the clutches more quickly, in exchange you would get more lock and performance, but at the cost of durability.

Also, is known no aftermarket clutches will last as long.

Did you measure breakaway torque before opening? If 50 to 60 NM, your diff is in spec. The RD spec calls for 100NM, but again, that will wear down your diff quicker.

Is your car a weekend toy, or track?

So you know, our diffs are used on the M5/6 S85 engine cars with 130NM more torque, so is more than good in our lower torque cars.

One more advice I can give, check the numbers engraved on your old pinion and adjust the pinion shim accordingly. Those engravings mean 100’s of mm. I see your pinion has a +1, or one 100 of a mm, or in plain English, 0.1mm.

[grannyknot]

Originally Posted by maupineda

It is there to give more preload and reduce the clunk noise. IMO you should use your stock clutches and since you are there, you can only add the free play shim and close it. With more preload you will wear down the clutches more quickly, in exchange you would get more lock and performance, but at the cost of durability.

Also, is known no aftermarket clutches will last as long.

Did you measure breakaway torque before opening? If 50 to 60 NM, your diff is in spec. The RD spec calls for 100NM, but again, that will wear down your diff quicker.

Is your car a weekend toy, or track?

So you know, our diffs are used on the M5/6 S85 engine cars with 130NM more torque, so is more than good in our lower torque cars.

One more advice I can give, check the numbers engraved on your old pinion and adjust the pinion shim accordingly. Those engravings mean 100’s of mm. I see your pinion has a +1, or one 100 of a mm, or in plain English, 0.1mm.

Hmmm, I never had a cluck noise, there was a small amount of slop in the P/S axle hub and I think that is what the small cone spring washer is for.
The car will mostly be used as a weekend car with a couple of track sessions
per year.
Forgot to measure the break away torque before disassembly but 50-60 nm of break away is fine with me so I'll just reuse the stock cone spring disc.
Thanks

[grannyknot]

I got everything back together and it is very hard to turn the input shaft, ring and pinion gears have zero lash so now I'm looking for a set of adjustment shims.
I could just order this set from RacingDiffs, https://racingdiffs.com/products/bmw...33487154151559
But I was wondering if anyone knew of a different option.
Thanks

[maupineda]

For the V2 diff, if you follow the RD process, you will need to adjust side shims as you are effectively changing the width of the carrier. Did you measure how far off was your diff cap from the original position? if you measure the thread pitch you can estimate pretty accurately how much you change the width of the carrier and adjust the shims accordingly to go back to the original width. Also, did you adjust the shim for the pinion?

Don't proceed without making sure all is to spec, or it will whine at best, and self destroy at worse.

[grannyknot]

Originally Posted by maupineda

For the V2 diff, if you follow the RD process, you will need to adjust side shims as you are effectively changing the width of the carrier. Did you measure the how far off was your diff cap from the original position? if you measure the pitch you can estimate pretty accurately you change the width of the carrier and adjust the shims to go back to the original width. Also, did you adjust the shim for the pinion?

Don't proceed without making sure all is to spec, or it will whine at best, and self destroy at worse.

Shim for the pinion? Are you referring to the collapsible sleeve ?

[maupineda]

No, there is a shim behind the big pinion bearing race. This shim is to set the pinion depth, which you need adjust to compensate for any pinion height difference from nominal, that was the inscription on the pinion itself. I assume you never read my post above.

Though easy, this job requires extreme precision or you will bang your head on the wall and regret. Measure twice, cut once.

[grannyknot]

Originally Posted by maupineda

No, there is a shim behind the big pinion bearing race. This shim is to set the pinion depth, which you need adjust to compensate for any pinion height difference from nominal, that was the inscription on the pinion itself. I assume you never read my post above.

Though easy, this job requires extreme precision or you will bang your head on the wall and regret. Measure twice, cut once.

Ah yes, that shim, I did read your post but it kind of washed over me.
Okay lesson learned, I'll remove the pinion and do some accurate measuring this time. Some how I got the idea that changing ratios in these diffs was a straight across swap.
I have the shim kit coming and another collapsible sleeve as well.
I do really appreciate yours and everyone else's advice and comments, I don't pretend to know everything and hopefully this will also help someone in the future.

[grannyknot]

Just want to clarify again what is being done to this Z4M LSD diff.
New bearings and seals all around, new clutch pack and a change of gear ratio from stock 3.60:1 to 3.90:1
First 2 pics are the old ring and pinion, last 2 pics are the new ring and pinion.
If you can't read it the old pinion specs are, XMK3628 10 25 +20288

[maupineda]

Originally Posted by grannyknot

Ah yes, that shim, I did read your post but it kind of washed over me.
Okay lesson learned, I'll remove the pinion and do some accurate measuring this time. Some how I got the idea that changing ratios in these diffs was a straight across swap.
I have the shim kit coming and another collapsible sleeve as well.
I do really appreciate yours and everyone else's advice and comments, I don't pretend to know everything and hopefully this will also help someone in the future.

This video shows you what I was trying to convey, the incriptions on the pinions will tell you where your shim needs to go, it will be an approximation since we don't have the actual BMW tools, but it will be extremely accurate. it can be you are so lucky that the offset on both of your pinions would be the same.

My pinion also reads +1, just as yours.