Comp Coupe Buttonwillow

[Exhlr8n]

Got to take the VCC out to Buttonwillow for our 1st shake down run.

Since it was my 1st time in the car, I tried to take it fairly easy, never got to push it very hard anyways because of the loose rear. The Front end did stay planted, just point and go..!

Motor ran great, pulls really hard in the mid range, sounds vicious and has a nasty growl and crackle with the shorty pipes.

It has the 15" Rotors and 6 piston Bembos, bled the brakes( has the Tilton 3 reservoir set up) and put put new performance friction pads on the front, rears pads were good. Braking was Okay, but nothing compared to the ACR-E's.

Only issues were some:

1. Excessive bucking/lurching in the pits and a little clunking in the drive train. I figured it was just probably the clutch and EMCO tranny.

2. The Back end would get loose under early corner exit acceleration, or heavy load changes with braking (caused a couple spin outs). Ran the Michelin slicks to psi 30 on the 1st 2 sessions, on the start of the 3rd session, we lowered to 26 psi and added more Wing to try and plant the rear better. Seemed better at 1st with the changes, but as I started to push it after warming up, it came loose again and spun out. When it lets loose it does it with Zero warning, it's hooked then instantly breaks loose.

Took it to the pits to inspect. Our first thought was maybe it was a loose tranny or differential mount. Turns out the driver side differential housing mount was broke in 1/2. (Yikes)

What year housing do I need to replace this one? 2001, 2003?

3. Brakes maybe a little spongy and didn't bite as hard as I thought they would.

1a.jpg1c.jpg1d.jpg1e.jpgDiff Break.jpg

[RedTanRT/10]

Tom, glad you got it out on the track. Man, it looks really great in those pictures!!!

sounds like that broken rear end was the cause of all that over steer.

To your questions/comments:

Bucking/lurching, that's the EMCO sequential. Shift to second quickly around the paddock and it will run smoother, I only use first gear to get it going or to park in my garage. Plus, that tranny and the triple disc clutch take some time to learn to drive around slowly.

Loose back end, as you found out your broke something in the diff area. I'm sure that's the cause. Also, I've never run with those Michelin's but I would think you need to start cold in the 25-26 psi range vs. 30. I run R-7's and start in the early am at 29 front and 28 rear and keep going down as the day goes on. At the Vegas event, 3rd session was 85-90 degree's and I had 25.5-26.0 in the rears to start.

With the exception of your hybrid motor set up, and the unique CC parts, everything else is Gen 3 2003-2006. So the diff housing, axles, hubs, etc. are stock Gen 3.

Brakes, real surprised they felt spongy and soft. I've got that big Brembo set up but my calipers are their Endurance set up (really big pads). I personally would have a hard time believing I give up much vs. the ACR carbons. Maybe the front pads needed to be bedded? Also, they work best with heat in them. I drag the brakes 1/4 to 1/3 of the warm up lap to get heat in them, you should try that.

Lastly, I'd get with Ross about set up. He corner weighted, set up the shocks and set up the wing angle on mine. He also found a couple of minor suspension issues too. He knows most every track you'll be at very well. You'll need to bring him your shim kit as he doesn't have spares for the CC.

Best wishes and you, Lance, Ben and I can talk about everything when we all go to Laguna.

[Exhlr8n]

Hi Mike,

Thanks for your input, much appreciated!

30 psi was the hot psi, we started at 25-26. On the start of the 3rd session, we added a lot more wing and dropped 4 psi to see if it would stick a little better.

Felt better for the 2 warm up laps, and the 1st half of the hot lap, as I started to get on it a little more the rear came out again, it had "ZERO" warning too, no forgiveness,

We did bed the brake pads in 8 or 9 times @ 60 to 20 mph and a few @ 80-20 mph. They did feel better with a little heat in them. I will try dragging them like you mentioned in the warm up lap.

I did start to drive the paddock in 2nd, helped a little with the bucking, but I'm guessing the broken diff cover/mount didn't help with that either.

I really,really liked the tranny shifting, it gets to it quick..!

Got some good advice from another forum member, regarding rear sway bar adjustment and rear spring set up.

Talked with Ross today, he is racing up in Seattle right now, so I will touch bases with him next week on the set-up. He may have a diff cover/mount for me too!

[steve911]

Please look very closely at the front mount ears of your diff while it is out for the cover change. The bat wing fracture puts a ton of stress on those mounts.

[Exhlr8n]

Anyone running the Delrin Diff Mounts that viperpartsusa sell?

[Exhlr8n]

Thanks Steve,

I plan on looking at the drive line, half shafts, shocks, mounts too!

[steve911]

I am. I am also running the Delrin lower rear shock mount too. No complaints here on any of the products.

[Simms]

Great to see another Comp Coupe out on the track and you enjoying it.