Lower spring rate diff belleville washers?

[FredK]

I read in another thread there are many different thicknesses of belleville washers that are used to preload the center stack in a BMW clutch-type diff.

Does anyone have a source for these for a 188mm diff? I'd like to screw around with center section preload when I build up a diff this winter.

[TXBDan]

I wonder if Dan over at Diffsonline in Wilmington could help you out. I once had a detailed parts list with shim options for an E30 diff, but that was like 15 years ago and i can't find it. Hit me up when you do it and i'll come check it out! I rebuilt an E30 diff once, but i reused all the original shims. Real fun project.

[guymandude]

I seem to remember reading somewhere that the e30 had lighter belleville washers. I am still waiting for my local pnp to get one in again so I can confirm. I am not 100% sure how these are measured. I am assuming thickness and overall height along with ID OD. I have also considered buying some from a place like fastenal by size and thickness and trying them out but it would be a lot of work.

[spyderg0d]

I think you stack the washers to create preload and thus increasing lockup.. But im not posative.

[pbonsalb]

I assume you have already searched and found this and are still looking for an answer

https://www.bimmerforums.com/forum/s...36-Diff-Thread

[wanganstyle]

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[FredK]

I assume you have already searched and found this and are still looking for an answer

https://www.bimmerforums.com/forum/s...36-Diff-Thread

Thanks, that thread does not list any information about where to source lower spring rate bellevilles for diff center section tuning. I don't want to run an unsprung center section because from what I gather, they lose locking ability very quickly since there isn't anything present to account for wear.

[pbonsalb]

Maybe KMP has them?
https://www.kmpdrivetrain.com/drivet...differentials/

[TheJuggernaut]

Thanks, that thread does not list any information about where to source lower spring rate bellevilles for diff center section tuning. I don't want to run an unsprung center section because from what I gather, they lose locking ability very quickly since there isn't anything present to account for wear.

Have a look at how the locking actually works. In a way it's no different than a brake caliper. As long as the piston doesn't fall out of the caliper and there's anything left on the pad and rotor, it's going to do its job.

I've tried it both ways and I'm not a fan of the spring-less option. Especially on tighter tracks where you're going in and out of lock, I'd experience inconsistent locking behaviour, sometimes experiencing added understeer for no apparent reason, gone in the next lap through the same corner. Dan from Diffsonline told me this happens with the 0 preload diffs because the pin doesn't reset consistently.

[FredK]

Maybe KMP has them?
https://www.kmpdrivetrain.com/drivet...differentials/

oh very interesting! Thank you for the link! I know ZF makes the parts, it's just a matter of finding who resells the parts!

Have a look at how the locking actually works. In a way it's no different than a brake caliper. As long as the piston doesn't fall out of the caliper and there's anything left on the pad and rotor, it's going to do its job.

I've tried it both ways and I'm not a fan of the spring-less option. Especially on tighter tracks where you're going in and out of lock, I'd experience inconsistent locking behaviour, sometimes experiencing added understeer for no apparent reason, gone in the next lap through the same corner. Dan from Diffsonline told me this happens with the 0 preload diffs because the pin doesn't reset consistently.

I agree, I have a 3 plate diff built to the normal "slap together after removing the 4mm shim" that's pretty predictable, but I'm going to be building a 4 plate 50/65 diff that I'd like to be able to tune, if I don't like the way it feels.

[wanganstyle]

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[TheJuggernaut]

No point to bullshit about what is good or not unless you have results to back it up.

Didn't you just promise to be quiet for a decade? Regardless, it shouldn't matter to an intelligent person but if appeal to authority is your standard, Dan builds diffs for James Clay.