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Discussion Starter #1
Hello, my name is Tyler.
1990 mk3 600hp
single turbo e85
r154 Spec twin disk SS

I am going to be giving an overview, and complete product and experience review of the Spec Twin disk Super Street (800tq) clutches. I am no grammar wizard so go ahead and excuse any mistakes.
The clutch was purchased on supra store with all of the following.
-New Master Cylinder
-Billet Slave Cylinder
-Stainless Lines and Fittings
-Clutch Discs
-Billet Flywheel
-Track Spec Hardware
-Clutch Alignment Tool

Initial impressions were great. Beautiful machine and manufacturing work. Felt good and the new flywheel was very light. Was excited from the "bolt on" process with no fabrication and or shimming needed.

First Install- Transmission would not properly go into and out of gear. Horrible engagement. Ended up bleeding the clutch 3x and adjusting the master cylinder throw. Seemed to have no improvement to initial problem. Spoke to spec support over the phone and was told the likely problem is a backwards clutch disk. Unlikely but no other option but to drop the transmission again.

Second Install- Disk was not backwards. Spoke to spec again and said the clutch would have to be shimmed. I was very confused at this response because the complete clutch kit called for a "bolt in with no shimming required." I was very agitated by this reply because if they would of just said shimming may be required i would of measured and shimmed the damn thing before installing. There was no kit they sold to shim this clutch. They said i could measure the gap and they would send me one. But no time to wait.

6 sheets of metal , jb weld and some tin snips. Fabricated was done :ROFLMAO:

The clutch was reinstalled. It then had a very difficult time releasing the pressure plate and cycling through gears. Adjusted the throw on the master cylinder and the clutch would BARELY disengage with it crammed into the floorboard. Went ahead and put the 500mile break in period on the clutch. It slowly started to disengage easier and my foot was finally not having to push the clutch into the dirt.

First Hits... Unfortunately more problems... Clutch would stick at high rpm and not go into the next gear or exit the current gear. Driving around at normal throttle >5lbs of boost drove fine. Only when at wot it would stick like this~ Spec Twin Disk Issues

Called Spec once again and said the only option would be dropping the transmission for a third time and sending them the clutch to check for bent disk etc
Clutch Disengagement before fixed
Spec Disengagement

I had read on some ls1 forum pages that other people with this clutch had similar problems and the solution was called the drill mod. Basically you drill out the hydraulic line from the master to the throw out bearing. Increasing the flow and pressure of the line. Therefor causing the throwout bearing to have more pressure to disengage the disk when under high load.


Ended up drilling to much, and causing the line to leak when reinstalled. Only go about 1/2 inch deep.
After being once again beyond annoyed at this clutch i ended up contacting a local hydraulic supply company and they made a custom hose with a larger diameter opening made.

Plugged this new line in and the clutch has been working fine ever since. It still has a hard time disengaging in 1st gear but i plan on upgrading the other line that connects after this setup to get a less flow restrictions and fix this problem completely. I have a video of how much faster the throw-out bearing engages if u want send a dm.

Car has been holding power well and not had any slipping of the clutch. Currently getting another 200 or so HP installed and will write a post in the next months to recap and see if clutch is still holding up.

Overall i would not recommend this clutch just due to the long list of problems i had from the beginning. This forum post i hope helps people dealing with or looking to buy a spec clutch. You have to understand this is a simplified and straight forward what i did that worked. This does not include all the things i tried that did not fix the problem.
Big thanks to @ FluxCapacitor for helping along the install process.

215 Posts
Great writeup and info! Thanks for sharing!
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