well i mean if it is trying to turn the wheels, how does it know which wheel is the outside wheel that needs to get more power until one of them breaks traction? i really think its the diff just making noise from the difference in distance traveled - i mean it only happens at really tight angles

 

I had a chance to get to autox this weekend in the rain with the TRE diff for the first time. It was very interesting, alot of oversteer available quite easily. It also allowed me to race with the rain setting on the acd race flash, where I just pretty much left it at that setting all day. Before the rear diff I would get understeer from losing traction on the front tires due to the rain, but now the diff seemed to help 'kick out' the rear so I can throttle around the slaloms a bit. This techniqued worked well but it was very easy to go in too hot around a cone and spin out. I dont know how much of a difference the acd flash and diff did my themselves, as the last time I autoxed in the rain I was on a completely different setup. I did notice that if you paid attention it was easy to read the cars behavior at its limit right before the rear would totally lose it. Going top of 2nd gear around a slalom got the rear squirrely and I did manage to spin out onto the grass. I dropped tire pressures that day to 34 psi rears and 35 fronts, I wanted to try rear pressures lower cause it was still very loose in the rear. I think its just cause I do need a front swaybar and could definately use some coilovers at this point. My robispec springs have been awesome so far though.

Here are some pics of the evo getting dirty, this was after I cleaned it up before I ran out again.





I was so happy to see I didnt break anything when I spun out. I slid into some trees and luckily stopped a few feet from some redwoods.lol

 

I put the diaqueen in the diff.... super quiet.

 

+1 to that, same here...

 

I had always used the Diaqueen along with some Redline LSD additive to reduce the locking. My TRE rear diff never made any noises at all.

Then, at Nationals this year I was trying to get rid of front end push, so I drained the rear diff fluid and filled it with Redline 75/140 NS (think that's what it's called). Huge and immediately noticeable difference. Along with the greater locking and and greater power oversteer - I now have all the noises that everyone has talked about. Turning while coasting - nothing. Give it a little gas and the rear diff ratchets loudly as the plates are forced to slip past eachother by the rear wheels having different speeds. . . give it alot of gas and the diff locks and the rear steps out. . .

 

exactly - diaqueen may be quieter but it should be making some noise if it's doing it's job, or trying to anyway

 

Ya, If I get tired of the diff noise I might switch to something with friction modifiers in it when autox season is over.

 

thanks this answers my previous question of what exactly the noise is.. does it wear the diff when it does this?

 

I'm late looking at this thread but.......I can't understand anyone having problems getting an EVO to rotate. The BadBish is so loose in the rear it's like a drift car and Project White was the same. Both cars had a three way adjustable 25mm Progressive rear bar, one has N1's on it and the other S1's. Stock front bars.

An alignment and rear bar will get any EVO to handle like a RWD.

I'm sure there are some benefits to the rear diff mods but getting an EVO to rotate can surely be done easier than that.

 

im not sure if rotation is as much the final goal as is getting the car to really power through mid corner to corner exit.. i'm not sure if a big rear bar will allow the evo to the same? im sure you known all of this but i think the diff will actually allow the car to go faster through the corner, rather than just in a more desirable fashion?

 

Dave,
Tires (size and compound)
Springs (front and rear rates)
Alignment including toe.
What kind of racing that you've experienced massive oversteer on.


I'd bet you're running on street tires not wider than 255's
I bet you're running 8-10k springs 10k at MAX
I bet you're not running any camber. (-2 in the front and nearly 0 in the rear) Probably 0 toe all the way around...maybe even toe in in the front since you drag race so often.
And I bet you experienced this either on spirited driving or an auto-x (which you probably don't have much experience doing either)

Just my guesses. Reasons why you're loose in the rear, poor alignment, lots of weight transfer, no droop, you're spinning all 4 and not just the rear...the rear just has less grip, and your driving style is probably doesn't help.

 

It seems to me that the rear on the Evo gains grip at a faster rate than the front. That is, if you have a neutral handling car and switch to stickier tires or switch from slick asphault to grippy concrete - the car will then tend to push more. Don't know exactly why, but I would guess it has do do with the huge front weight bias . . .

 

something to do with the Pacejka curve of a street tire versus a r comp/slick?

 

Please explain. Never heard that term before. How do we explain what happens when keeping the same tire and switching from asphalt to concrete??

 

edited.....

Quote from R/T:

"I fought the understeer from day one.
Started with this setup going around a tight auto-x like course called PGP. (go kart track actually)
RE01R's, works springs, and 25mm rear bar full stiff.
Result: the car understeered on corner entrance, understeered steady state mid corner... and REALLY understeered on corner exit. The front tires were overworked soo badly they cried (aloud). The car would not turn!
My first attempt at fixing it.
Skunk2 pro-c coilovers 12k rear springs, 10k fronts
Hoosier 285/30/18's
TONS more camber up front, WAY less camber in the rear, MORE air pressure, + toe out in the rear. (adding grip in the front and removing it in the rear...decreasing grip in the rear)
Gruppe-S ACD reflash
Result: Turn in was better, mid corner I was able to trail brake and lift throttle oversteer. I had to REALLY brake late and I had to lift VERY hard to get the car to rotate even the smallest amount. Rotation still sucked. CORNER EXIT: SUCK SUCK SUCK SUCK. The ACD just made the car do burnouts with the inside rear tire... the car felt SLOWER on corner exit and wouldn't put power down. SUCKED!"

Rather than my first response, I found this in this thread. All I can say is my EVO (S) do not handle like you are describing. None of them, not the Bish, not Project White and not the Magnum. Not the other two I've owned either. Would all of them but the Magnum be faster if it gripped more in the rear? Of course, I was simply pointing out that you can get an EVO to rotate without a rear diff.