Good tech brought to the thread, and I'm definitely wrong ...

What does the front end feel like when the inside goes airborne and the Torsen gets confused?

Matt

 

front end feels fine, there's no power being delivered through it. the ACD on the other hand gets pretty pissed.

 

Dave,
what was the weight of project white? qty of fuel, w/ or w/out driver, etc.

 

for me personally i've never actually gotten the tire airborne - as long as it's in contact with the ground the helical diff should be doing what it's designed to do though right?


how so?

 

it does what you can see at 1:19 in this video right before i shift.
http://www.youtube.com/watch?v=gAM0EO7poTo

...that might have been both back wheels off the ground. the wheel speed data showed a couple hops with both back tires spinning the same speed and spiking.

 

does the car wobble left to right when that happens? Feels like you're being shaken inside the car?

My car does a very similar thing at PGP and I haven't been able to figure out what the hell it is.

Only does it when I'm hard on throttle coming out of a corner. It tosses me around inside the car.

EDIT: nice two footing!

 

niice vid - do u have an upgraded rear diff btw? that program with the camera is awesome.. i bet it could really see the before after effects of a rear diff on the g's and whatever

 

Marshall,

I've had that very same thing happen a couple times on my 03 w/viscous center. Not sure it's ACD related. Sure feels crazy.

Also totally agree on the front inside wheelspin. It definitely occurs. If you watch video around 35 seconds you can hear the rev limiter pop, then go silent and pop again. The trend with short stroke dampers certainly doesn't help the situation. I have spoken with Jon @ TRE about front diffs. What he basically said was that the clutch type front diffs are fantastic in the dirt where the lockup is tolerable on turn in and totally necessary on exit. When used on asphalt they don't work very well. He's had customer's swap back to torsen (OEM, Quaife, etc) from clutch type. I was really interested in trying one but my car has been sitting for a year now.

http://holunfie.blogspot.com/2007/04...-diff-and.html


All,

As for the GSC 40/60 Center Diff I have one. With the lower power levels on my car (298 hp/320tq, dynojet) it was very subtle, but did help the car to rotate. There was a more profound effect with the TRE rear diff though once I added it. Everyone I knew that ran one liked it. Don't know of anyone running one with ACD though.

If you're interested pics are here:


http://bp1.blogger.com/_rOf08BWxyfo/...h/100_3575.JPG

John

 

how much did the GSC diff end up costing you... installed and the works?

 

i believe the 60/40 replaced the acd function

 

I did the install myself. Just need new bearings for the diff and probably shims for preload unless the original can be reused. If you damage the speedo gear when removing that will be another part. Figure less than $100 in parts.

Kyooch,

The center diff has 2 parts. The acd or viscous coupler which are in the TC and the actual differential which is in the transmission. This diff replaces the portion in the transmission. It also comes with a billet "spool" if you will that would replace the vc. Most people don't use this part as it doesn't allow any slippage between the frt and rr wheels.

John

 

gotcha - so you could have the "best of both worlds" so to speak (if acd is in fact actually better than the viscous in the first place).. suddenly i'm interested, though i think someone mentioned it's not sold anymore

 

I run a Quaife front diff in my RS. The car doesn't make 500 ft lbs of torque at 4000 rpm like project white did. I've had no front wheel spin in the RS but I'm guessing because of the power band. As a aside note, no change in 60' times going with the Quaife over the stock RS front limited slip.

Just adding information to the topic.

Not sure if I mentioned, I finished my rear diff, ended up building a 12 disc set up instead of just an 8. Very interesting what you can learn DOING something like that. I've got a few spare rear doffs, if this works I'll set my other spares up too.

 

Mine does this quite a bit under power on corner exit. It even does it on corner exit on the road course at 100mph. I often have near 100% weight transfer in the front so it makes sense that the inside front tire would start to spin on power application, then the ACD would start to lock. Seems like the ACD cycles rapidly, thus causing the rhythmic "hopping" as it locks and unlocks.

After reading the past few pages it seems a 1-way clutch style front diff may be a solution to this. . .

EVOlutionary

 

Nope, GSC doesn't make it anymore. Look for the Cusco 35:65 Tarmac gear. That is the original and I believe it is still made, but it is $$$.

Read up here:
https://www.evolutionm.net/forums/ev...ntre-diff.html