LetsGetThisDone

iTrader: (1)

IIRC, Dallas J runs an Mfactory clutch front diff with good results in his SM autocross car.

griceiv

iTrader: (2)

the carbon pucks under the helical gears (6 of them) are not the problem. The wavetrac works fine if you have traction available on the inside tire. Its ability to lock when one tire has minimal traction is very limited relative to a clutch type diff. It's just the reality of comparing a single friction surface of ~1.5" diameter to 8+ friction surfaces of ~4" diameter.

The wavetrac is an extremely well designed and built unit that is much stronger than the factory torsen, but it is not the highest performing option available.

griceiv

iTrader: (2)

I've tried front clutch diffs from cusco, ATS, and carbonetic (plus a pre-production unit from OSGiken but since nobody can buy it yet it's sort of irrelevant). I think reliability of the cusco and ATS are good. The carbonetic exploded spider gears, apparently sintered metal vs the forged version found in the ATS. Even though carbonetic was really just marketing alias for the ATS diffs the carbonetic diffs never got the upgraded spider gears.

The downside of the clutch diffs is they eventually wear out and the preload decreases (edit: and they're really expensive). Street driving them will accelerate the wear. If I were street driving I would choose the wavetrac.

alpinaturbo

iTrader: (5)

Griceiv

Do you mostly track or AX, please?

I know several winning Time Attack competitors from Europe who compete in extreme class with 700-800bhp 2300-2500lb developed Evo's, using Wavetrac.

So now that for first time I looked at the friction pads, 1.5" dia disc holder, I am reasoning through if on track where we avoid curbs (damage & driving off-line), if Wavetrac is still valid solution compared to Cusco 450F 1-way?

The EU competitors often drive in rainy conditions with challgingly modest traction even with 4WD and Wets.

Perhaps as long as wheel/tire (inside) touches ground there is enough reactive force to allow Wavetrac to hook up both front wheels enough to guarantee plehty of traction.

It's 4WD car so each wheel puts down 1/4 total torque.

It seems that for track oriented cat Cusco equivalent is best default solution.
For mostly street car Wavetrac for sure.

Griceiv,

How did the Cusco work - managing traction and understeer?

griceiv

iTrader: (2)

Autox.

I don't have much experience with track driving, but I believe the locking performance expectation of the diff goes down in higher gears because there is less torque that needs to be put down. I would imagine a wavetrac works just fine on a road course.

LetsGetThisDone

iTrader: (1)

Even in tighter 2nd gear corners on a track, they're never as tight as autocross, so with less steering input, there is less dynamic camber, and there is more available traction for acceleration.

kikiturbo

and to come back to topic.... mrfred mentions weak stock helical front diff... I wasnt aware that it was a problem.... I have seen older front diffs break its bolts but that was due to bolt design.. not diff itself..

alpinaturbo

iTrader: (5)

I'll blatantly blow the horn on behalf of knowledgeable but restrained genius,
You should know that Kikiturbo tunes ACD maps, and optimizes others ACD maps, aside from building all mechanicals, turbo kits, porting, tuning, and more.

So be assured his feedback based on the experience with ACD+AYC "rest of the world" Evo, and USDM Evo models, as well as successful rally Evo's which are a lot like USDM- ACD with RS rear diff.


Getting back to FRONT LSD:

I discussed with couple of highly experienced road race Evo chassis specialists, and both advised that Wavetrac is only front LSD they use, and pointed out how plates (wear) material in Plated Mechanical LSD gets into gearbox oil, and generally mechanical LSD plates require different oil(somewahat opposite requirements) oils not recommended for gearbox.

For race car the oil issue is moderate compromise, but for more club level and dual purpose car, Wavetrac is easier the better choice.
As far as performance, neither felt that Wavetrac gave up any performance to Plated Mechanical LSD on track, or road.

This is theirs point of view, their experience, and preferred method.

mrfred

iTrader: (50)

Ivica, thanks much on this. I had suspected that this would be a problem for plate diffs, and you have just confirmed it.

kyoo

iTrader: (29)

all ACD-only chatter moved to the ACD Tuning thread https://www.evolutionm.net/forums/ev...t9as-read.html

sorry about that, we steered way off topic. very good info re: how wear material from a clutch plate front diff would get into the gearbox oil. I was wondering earlier if there would be any reason NOT to run a 1-way clutch for the front diff. that would be a huge one for me.

kikiturbo

yes, front diff shares the oil with the box. As fas as oil is concerned, there are appropriate oils with additives for plate diffs, usually having an LS designation at the end. We already use such oil in the ACD. Having said that, one would need to change the gearbox oil more frequently due to oil contamination.

LetsGetThisDone

iTrader: (1)

The issue with using an LS gear oil for the clutch diff is that the synchro's in the trans do not want an LS oil..

kyoo

iTrader: (29)

i believe in the states we use GL4 in the gearbox (and front diff) and GL5 for t-case, rear diff. I'm assuming then the clutch plate would want GL5, but the additive packages are different, may not be optimal, plus the different wear metals flowing through with the clutch diff

kaj

iTrader: (60)

The downside of having a transaxle (sharing oil)...

kikiturbo

the ACD clutch plate wants an LS oil, just like the plate diff

the guys on the uk forums who run plate diffs and normal syncho gearbox use IIRC millers GL4/5 LS trans oil with success. I plan on using motul gear 300 LS, that I normally use in the transfer box with ACD.

I agree that it is not optimal, from the wear standpoint, as we need to remember that the plate diffs are usually used in combination with dogboxes.
Having said that, Ralliart just specifies Diaqueen LSD oil for the gearbox with ralliart plate front diff...