Ok, I've been fighting this damn car for the past year trying to get the stupid thing to hook up at the track

It is an 03' evo with a 2.3l stroker, hta86 yada yada ya. It has ran a best of 9.97 @144mph with a "lucky" 1.54 60ft.

Tires are hoosier 26" QTP dot slicks.

here is the problem. When I launch the car it moves about 5 feet then it's up in tire spin, the passenger front tire always goes completely up in tire smoke. We video taped it from the starting line and I noticed the front right tire would just spin and go into tire smoke while the other tires just kinda rolled along. Rear wouldn't spin and driver side front wouldn't spin either. Not even a wrinkle out of the rear tires, but however, it squats hard on a launch, that tells me it's weight transferring to the rear and therefore getting some of the power to the rear wheels.

I've cut 1.3 60fts on these same tires in my talon before. So I know it's not a tire issue.

Now here is the funny part. If I roll into it (no launching) the car straight hooks up at the track with no tire spin from a 1st gear roll. But when I launch it, it just smokes the hell out of the passenger front tire and sits on the rev limiter 5-10 feet out Resulting a garbage 1.61 60ft's or worse.

Another funny thing is. I've gone as far as dropping the boost level down to wastegate spring in 1st gear controlled via AEM EMS (24lbs of boost), pulled -7 degrees of timing out of the entire 1st gear pull, and added over 6% of fuel just to kill some power to get the stupid thing to hook up, and still have these issues. I even dropped the 2step down as far as 5500rpm and it still goes up in tire smoke.

To me it just seems the VCU (viscous coupling) is not transferring power to the rear on a launch, but from a roll on in 1st gear the VCU locks up and hooks all 4. It almost seems it's more FWD biased with a RWD assist on launching only.

Every once in a blue moon it will transfer power to the front and rear evenly and the car will hook and pull off a mid to low 1.5 60ft. But I would say that only happens 5% of the time. 95% of the time it's not transferring power from front to rear properly.

I guess my question is, has anyone encountered this problem? If so, what did it end up being? Shot VCU? Or center diff? I had my trans out last month and looked over the center diff and everything looked good there. I still have yet to pull the VCU out of the transfer case and inspect that but plan to this week sometime.

here is a video of the one tire fire wonder. As you can see on the 2nd pass, the passenger tire just completely goes up in tire smoke.
http://www.youtube.com/watch?v=sWBA78YEvZw

My theory is when that tire starts to spin, the vcu goes limp and just slips rather then transferring the power to the rear tires like it SHOULD.

I'm damn near ready to set this car on fire I know the car has a solid 9.7 or 9.60 pass in it if I can just get the damn thing to hook up properly.

With as much boost I am pulling out of 1st gear, the amount of timing I am pulling out of 1st gear and the launch RPM you would think it would bog the living hell out of it, but it doesn't. Anyone else have these issues?

 

My understanding is that the VC is a slow acting device intended to get you unstuck from a snow bank. So, for time attack it wouldn't matter wether it is working or not working - it is out of the picture.

 

Ok so for drag racing purposes how would one go about getting it to lock into 50/50 split right away from the get go?

I know in the DSM days we would just weld the center diff to make it AWD all the time, and that gave us about 40-50% more traction. My talon went from 1.6 60fts down to 1.4 60fts by welding the center diff.. but I have never seen or heard of anyone doing that to an evo and I really wouldn't want to either.

Is there a billet replacement to replace the VCU to lock it in AWD all the time? Or are people just upgrading there center diffs to a GSC unit or cusco unit?

 

Nice video non the less! I would give Jon at TRE a call.

 

Ya, if I could ever get ahold of the guy But thanks man, appreciate the kind words.

 

1st problem is QTP IMO.. I have had my Evo hookup and run 8's on MT 24's.. We all have this issue.. I have videos of my car with both front tires lit up.. its all SLICK, CHASSIS, SUSPENSION related to get it all to work together.. The GSC unit i dont think exists anymore and we just use a regular RS LSD in the tcase.. If the track is not prepped well is the next issue.. Your car makes some good power and TQ so you have to get the whole combo right.. the 1st part is Tires & Suspension..

 

Thank you Mike for chiming in, I was hoping you would. Anyway, I've cut as low as 1.32 60ft's on these tires with the talon. I would imagine it wouldn't be too hard to cut 1.4x's on these with the evo?

I have noticed when that right front tire does hook up all 4 will rotate on the launch, but the times,, well most of the time I should say, when that tire goes up in tire smoke, the rest of the tires just kinda roll along and don't bite. I wish there was a way we can lock our center diffs in full AWD mode all the time, kinda like what we did with the dsm's by welding the center diff. Made things so much easier to launch and a hell of a lot more consistent 60's.
This crap is really starting to **** me off

next question is, where can I get a RS front LSD? Can you get them Mike? If so can you PM me a price?

 

sorry for grave digging .. but my fpblack car is having this problem on the street...

my rf tire goes up in smoke and is spinning me into second to about 60-65 when i no lift..
im about 525whp and 470tq...

did you ever come up with the solution?