First off, car is an Evo IX SE with 16,000 miles. Only pertinent mods would be the twin disc.

Okay, this started happening after my Excedy Twin install last year. The shop ended up not tightening the front motor mount bolt when they buttoned everything up and after a 1000 miles or so, the bolt came loose and I would get a bad shake (obviously) when starting out in 1st gear. I guess the easiest way to describe the "shake" is it feels like wheel hop from a fwd during a launch. Anyways, I got another bolt and torqued it. This fixed the problem when starting out from first gear.

Fast forward to my first autox after the clutch install. I decided to launch the car during one of my runs and the car started shaking, although not as violent as when the bolt was missing. However, it is bad enough that I am not going to launch the car out of fear of additional driveline damage. I checked all motor mounts/tranny mount and didn't notice any bolts missing and/or being loose. What other things could be the culprit?

Also, the car drives and shifts fine during normal/spirited driving and full-up during HPDE etc...

Thanks in advance.

 

Well i see you already know what wheel hop feels like. Are you sure that this isn't all that it was?

See if there's a difference between slipping a tad, and slipping the clutch alot...that could eliminate and/or add some things to the possibilities.

 

Sounds like a problem with the clutch. Which one are you using? A ceramic one I am guessing.

 

That may very well be. I will play around with the amount of slip a litlle bit.

I am using the Excedy Twin HD. What problem with the clutch could there be that would replicate wheel hop?

 

I think it's the amount of slip or lack thereof that's causing that vibration. I have a Exedy twin as well and I've gotten what you're experiencing, I think.

 

Okay. I will be installing some things next week and will go over all the bolts just to make sure and then try slipping the clutch more in the future when launching.

 

I have the same shake when I come off the clutch too fast in first. Stock clutch though!

 

My car also does this with a exedy twin disc

But mine shakes violently only when i launch