Med-case LSD rebuild

[BrandC]

Hi all,
I'm looking into installing higher lock-up clutch plates into a 4.10 medium case LSD. I know Bimmerworld sells slightly higher lock-up plates, does anyone know anywhere else that sells plates as well?

Also, if anyone can chime in with how they like their LSD rebuild, what application they are using it for, and what % lock-up they are using that would be awesome.

I plan to rebuild the LSD for drifting purposes, but mostly grip duty. Opinions are welcomed, TIA.

-Brandon

[PiercedE30]

http://www.r3vlimited.com/board/showthread.php?t=92714

That's from when I tore mine down. I had a 4.10 open from my old auto and took the LSD unit from a 3.73 and put the ring gear on it. I still need to pull the unit apart again to get the spacing right. You may want to get an extra set of inverted hex bolts (M8x1.0) because you WILL strip some of them. Hell, I still need to get some more because I stripped them ALL, again.

[BrandC]

Hey thanks Jon,
What percentage lock-up is your rebuild supposed to take you to? Very good write-up/picture tutorial.

I took a diff. class and yes, LSD's are not mysterious things. Actually they are very straight forward parts unlike transmissions...

[whakiewes]

All of the motorsport parts are available to give you up to a 60% lock. You just need to find a dealer of motorsport parts which is few and far between in the US. PTG, Salas Racing, and a few others I know have sources. Bimmerworld is the best bet though. Their discs are very nice and have a ton of grab. Most people underestimate how much 25%, or even up to 40% is. A used, 150k mile LSD might be holding 10-15%. When we rebuilt a Porsche LSD back to the factory 40% lock, there was a noticable difference in low speed understeer and even at 40% the inside wheel would try to hop for the first 1000 miles or so.

The best bet would be to order the bimmerworld clutches and oem spring plates. You won't be dissapointed in that setup. If you insist on going better though and want a full out performance diff, KAAZ makes a 1.5 way limited slip unit using much beefier parts. Product number is DBW3010 and its a direct bolt in unit other then having to remove and reinstall ring gears. Retail is about $1200 on the LSD unit. If you are interested in going that route, your welcome to give me a PM and I can help you get one. The unit itself would be far superior then a motorsports diff, but its not OEM.

Wes

[whakiewes]

I also noticed that you have a 318is. If you still have the factory small case LSD, then there are no parts that are readily available to rebuild your LSD. You would need to upgrade to a 325/M3 medium case. There is a KAAZ unit for the small case though, DBW1810. Again a direct bolt in.

[BrandC]

I also noticed that you have a 318is. If you still have the factory small case LSD, then there are no parts that are readily available to rebuild your LSD. You would need to upgrade to a 325/M3 medium case. There is a KAAZ unit for the small case though, DBW1810. Again a direct bolt in.

Yeah I am rebuilding and also upgrading to a medium-case diff. I have looked into the KAAZ units and am thinking I won't need it until I get some more drifting seat time. For now, I just want higher lock-up and to refresh the LSD plates themselves.

I will probably go with the Bimmerworld plates with at least 30-40% lock-up, maybe higher. Thanks for the tips everybody.

[etxxz]

very interesting....i might be game for this. how many bimmerworld clutches will we need to buy? i counted two or six from that thread.

i have a transmissions guy that will align do the preload w.e it needs to be done. i tried installing an LSD once and it clunked on reverse like mofo so w/o the right tools/knowlege, never again.

[whakiewes]

Bimmerworld plates are no thicker (thus providing more locking ability) then factory 25% clutch packs, but are created using a grabbier material. Similar to convential clutches, material doesn't nessacarily dictate how much it can hold, but more as to how it engages. So while the Bimmerworld disks will still allow 75% slippage, they engage at a much faster rate and are more precise. I have heard from various sources though that the discs recieved from Bimmerworld are just slightly thicker then factory clutch packs are rated, and thus would have a higher locking ability. I was told they are exactly the same, but as with any aftermarket part, variations in production do occur.

If you are looking for more locking and engagement ability, you might rather seek out motorsport parts and have the ramp angles altered. Mechanical LSD's work much in the way they sound, mechanically, so rather then using a band aid (cerametallic discs), one might find a better use of increasing the ramp angles and with such increasing the reaction time of the LSD to lock. Motorsport clutch packs I know are still available, but I am sure they are costly. Typically, a diff like above, would retail around $1500 or so. I just say this since with drifting you need predictability and consistency with your LSD, and since you will be using unconventional methods of hanging the 'ass-out', having a 40 or 60% lock won't hurt you. If you intend on participating in more tracking events though, the Bimmerworld solution may be a better alternative for a more stockish car.

When you see the LSD apart, there are various parts. There are only two clutch packs (i.e. you need to order two clutches from Bimmerworld for a total of $120), but there are more spring plates and washers that are used as mediums of friction. So while there may be 10-12 pieces internally of the LSD, there are only two clutch packs, consisting of a clutch disc, spring plates, and washers.

Wes

[PiercedE30]

The spring plates are just *belleville* washers. There are a number of places that you can get them, made to your specs, online.

[matt]

Belleville washers.

And I believe that Korman can also get Motorsport parts. And Turner Motorsports.

[PiercedE30]

Yea, didn't know how to spell it.

[etxxz]

interesting...now, i dont see anyone modifying the ramp angles (less angle?)so what would be the way to increase % lock if the bimmerworld clutch packs are the same as OEM? if they were thicker then its another story

i'm sure there's a gain from replacing 100k maybe 200k old clutches, but i'm just saying...

[BrandC]

Bimmerworld plates are no thicker (thus providing more locking ability) then factory 25% clutch packs, but are created using a grabbier material. Similar to convential clutches, material doesn't nessacarily dictate how much it can hold, but more as to how it engages. So while the Bimmerworld disks will still allow 75% slippage, they engage at a much faster rate and are more precise. I have heard from various sources though that the discs recieved from Bimmerworld are just slightly thicker then factory clutch packs are rated, and thus would have a higher locking ability. I was told they are exactly the same, but as with any aftermarket part, variations in production do occur.

If you are looking for more locking and engagement ability, you might rather seek out motorsport parts and have the ramp angles altered. Mechanical LSD's work much in the way they sound, mechanically, so rather then using a band aid (cerametallic discs), one might find a better use of increasing the ramp angles and with such increasing the reaction time of the LSD to lock. Motorsport clutch packs I know are still available, but I am sure they are costly. Typically, a diff like above, would retail around $1500 or so. I just say this since with drifting you need predictability and consistency with your LSD, and since you will be using unconventional methods of hanging the 'ass-out', having a 40 or 60% lock won't hurt you. If you intend on participating in more tracking events though, the Bimmerworld solution may be a better alternative for a more stockish car.

When you see the LSD apart, there are various parts. There are only two clutch packs (i.e. you need to order two clutches from Bimmerworld for a total of $120), but there are more spring plates and washers that are used as mediums of friction. So while there may be 10-12 pieces internally of the LSD, there are only two clutch packs, consisting of a clutch disc, spring plates, and washers.

Wes

Wes,
Thanks for the valuable information. I will do some more homework on my LSD rebuild. I agree with what you said, I need predictability for drifting. I am a novice driver though, and my car will be more stockish for now than road race oriented. However, I will still be looking into that KAAZ unit or the other places people mentioned.

So if I did want 30-40% lock-up, that means I have to change the "ramp angle"? I don't know what is meant by this, could you explain further?

[BrandC]

The spring plates are just *belleville* washers. There are a number of places that you can get them, made to your specs, online.

Wait, so if I understand correctly, replacing the OEM Belleville washers/spring plates with thicker ones will yield higher lock-up %?

[etxxz]

^^ that is basically shimmin your LSD. i did that with the ae86 i used to have but later upgraded a trd 1.5way and that was a whole different ball game.