I'm over my SPEC super twin clutch
01-06-2016, 06:04 PM
#21
Melting Slicks
Thread Starter
In 2008 I agonized over clutch selection for over a year. Price, reliability, feel, durability, ease of installation was of great concern.
SPEC Twin was $1300. back then!
SO,, Approx. 12 Forum Members got together and contacted SPEC and they did a GROUP PURCHASE us. If I remember correctly it was right around $1100.
Shortly after purchase, several of the Group Purchase guys had some serious SPEC Clutch installation & reliability issues. Slippage, warped disk, burnt up throw out bearings, sever vibration issues, etc..... Spec took care of the warped disk issues..
I thought I wasted my hard earned clutch money.
Here's what panned out and why some of those issues were encountered:
- The installation people failed to take the critical measurements needed for proper slave cylinder height and just installed the shim or didn't bother to install it at all.
The clutch would burn up very shortly after install OR not disengage and burn up the throw out bearing and or damage the synchros! -
- When the drive train was reinstalled into the bell housing (Trans/Differential & TT) all at once, the installers let the entire drivetrain weight rest inside the bell housing before the TT was fully inserted and bolted to the bell housing. That in turn bent the two disk hubs causing them to warp.
- Improper bleeding and improper TICK master cylinder adjustment was also another very common issue. Results in poor peddle engagement height, hard shifts or pressure plate damage.
-After fully understanding all of those issues and taking the proper steps to eliminate them, my SPEC Twin install went very well and it has been a really good clutch.
-Its not an ON/OFF engagement clutch. I have very good engagement and release height.
My wife on occasion has driven the car with out too much bitching. The TICK high volume Master makes the peddle much more stiff than if I would have used a normal volume Tick or an OEM master. At that time, only the high volume TICK was being offered.
I used great pains measure both critical measurements to determine shim size for the slave cylinder despite EVERYONES recommendation to JUST INSTALL the shim that came with the clutch. In my case, NO SHIM was needed for proper slave height. I remembered that I measured everything 4-5 times!
-I made a decision to break up the drive train into TWO parts. The transmission & differential as one install and the Torque tube as a separate install. Installing the TT into the new clutch is SO much easier and there is little if any chance of bending the disk hubs.
I went to great pains to not have issues with drive train harmonics/ vibrations. I had the SPEC Flywheel matched balanced to the old OEM ZO6 Fly wheel and installed the new flywheel in the same relationship back on the crank. NO VIBRATIONS.
I spent a good number of hours adjusting and readjusting the clutch peddle adjustment rod to get proper peddle height, correct clutch disengagement and engagement. I have a fairly big cam so, take off from a dead stop would sound like it could be an issue. I can easily slip enough to easily take off. Do I stall the engine???. If Im not paying attention, it happens every now and them. Do I wish it had LESS PEDDLE PRESSURE. Sure! But, I'm use to it now and will live with it for the reliability.
My SPEC has been error free and I serve it plenty of abuse. Granted, I'm only at 450 RWHP, but I cant complain... That's why I installed it! OVERKILL!
For some, its a LOVE or HATE the SPEC relationship.
Bill
SPEC Twin was $1300. back then!
SO,, Approx. 12 Forum Members got together and contacted SPEC and they did a GROUP PURCHASE us. If I remember correctly it was right around $1100.
Shortly after purchase, several of the Group Purchase guys had some serious SPEC Clutch installation & reliability issues. Slippage, warped disk, burnt up throw out bearings, sever vibration issues, etc.....
Spec took care of the warped disk issues..I thought I wasted my hard earned clutch money.
Here's what panned out and why some of those issues were encountered:
- The installation people failed to take the critical measurements needed for proper slave cylinder height and just installed the shim or didn't bother to install it at all.
The clutch would burn up very shortly after install OR not disengage and burn up the throw out bearing and or damage the synchros! -
- When the drive train was reinstalled into the bell housing (Trans/Differential & TT) all at once, the installers let the entire drivetrain weight rest inside the bell housing before the TT was fully inserted and bolted to the bell housing. That in turn bent the two disk hubs causing them to warp.
- Improper bleeding and improper TICK master cylinder adjustment was also another very common issue. Results in poor peddle engagement height, hard shifts or pressure plate damage.
-After fully understanding all of those issues and taking the proper steps to eliminate them, my SPEC Twin install went very well and it has been a really good clutch.
-Its not an ON/OFF engagement clutch. I have very good engagement and release height.
My wife on occasion has driven the car with out too much bitching. The TICK high volume Master makes the peddle much more stiff than if I would have used a normal volume Tick or an OEM master. At that time, only the high volume TICK was being offered.
I used great pains measure both critical measurements to determine shim size for the slave cylinder despite EVERYONES recommendation to JUST INSTALL the shim that came with the clutch. In my case, NO SHIM was needed for proper slave height. I remembered that I measured everything 4-5 times!
-I made a decision to break up the drive train into TWO parts. The transmission & differential as one install and the Torque tube as a separate install. Installing the TT into the new clutch is SO much easier and there is little if any chance of bending the disk hubs.
I went to great pains to not have issues with drive train harmonics/ vibrations. I had the SPEC Flywheel matched balanced to the old OEM ZO6 Fly wheel and installed the new flywheel in the same relationship back on the crank. NO VIBRATIONS.
I spent a good number of hours adjusting and readjusting the clutch peddle adjustment rod to get proper peddle height, correct clutch disengagement and engagement. I have a fairly big cam so, take off from a dead stop would sound like it could be an issue. I can easily slip enough to easily take off. Do I stall the engine???. If Im not paying attention, it happens every now and them. Do I wish it had LESS PEDDLE PRESSURE. Sure! But, I'm use to it now and will live with it for the reliability.
My SPEC has been error free and I serve it plenty of abuse. Granted, I'm only at 450 RWHP, but I cant complain... That's why I installed it! OVERKILL!
For some, its a LOVE or HATE the SPEC relationship.
Bill
i appreciate the post bill, that was very informative and will continue to help people who continue to purchase spec clutches. unfortunately i will no longer be using them.
NOW, had i came across your post and was buying one, id feel very comfortable installing it myself and enjoying it.
thanks to all who have posted and helped with info, i guess ill continue to debate myself and research. ill bump this once a clutch is purchased and installed for a real world review.
as it follows my order of liking at this point is ACT, RXT, MANTIC
01-06-2016, 06:27 PM
#22
Race Director
I don't think I have anything to add that'd change your mind, but Just one bit of advice... Before you give up on that clutch, maybe try going to a new, stock MC first. Much easier/cheaper to try than a new clutch. I've got a RPS carbon twin, and it's like yours' and I still have the Tick MC.
01-06-2016, 07:22 PM
#24
Safety Car
I don't have a dog in this hunt, but I'd pay attention to what CTD says.
He has installed all the units his own bad self. And always with high hopes ended up frustrated and disappointed with the end results.
Including his testing the light flywheel stuff.
He loves the RST.
Btw, I'm tuning a car with the RXT. It's on or off. Horrible. To me it ruins the whole car.
Ron
He has installed all the units his own bad self. And always with high hopes ended up frustrated and disappointed with the end results.
Including his testing the light flywheel stuff.
He loves the RST.
Btw, I'm tuning a car with the RXT. It's on or off. Horrible. To me it ruins the whole car.
Ron
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~STOLEN~ (01-07-2016)
01-06-2016, 07:31 PM
#25
I have a McLeod RST in one of my cars, and I love it. Before that I had a SPEC clutch, and, well, I'm not doing a SPEC again. Some friends also have McLeods, and they swear by them; both RST and RXT. That said, I have heard from some that their RXTs can be difficult.
The installation of the McLeods can be a little tricky, but I haven't had any issues with any of them and I'm by no means a professional mechanic. I've also dealt with McLeod support a couple of times for different reasons and clutches, and have always been left very happy.
The installation of the McLeods can be a little tricky, but I haven't had any issues with any of them and I'm by no means a professional mechanic. I've also dealt with McLeod support a couple of times for different reasons and clutches, and have always been left very happy.
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~STOLEN~ (01-07-2016)
01-06-2016, 08:46 PM
#26
I have the ACT twin in mine. Know it is a pain to find a good clutch. Was able to try the ACT in another car and liked it so that's what I went with. If you could try someones car to get an idea that would be ideal. Don't know why ACT does not come up more often as a choice. There are other good clutches out there as mentioned, but That clutch doesn't come up as often. Not popular in the corvette world. I have had mine in the car for 6 years at 510 RWHP. Stock feel and can be slipped like stock ( HUGE plus ). The one I have is rated to 800 Torque. Not an issue for me but if you are looking at 750-800 I would go with a higher spec'd one. So far been extremely happy with this clutch. No chatter or anything. Smooth operation.
Good luck with your choice.
Good luck with your choice.
Last edited by RedRiderZR1; 01-06-2016 at 08:48 PM.
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~STOLEN~ (01-07-2016)
01-07-2016, 07:34 PM
#27
Melting Slicks
Thread Starter
I don't think I have anything to add that'd change your mind, but Just one bit of advice... Before you give up on that clutch, maybe try going to a new, stock MC first. Much easier/cheaper to try than a new clutch. I've got a RPS carbon twin, and it's like yours' and I still have the Tick MC.
This has me wondering because I would much rather replace the cms as opposed to the clutch.
I just don't to trade a working setup to something that may be failing at heavy use (hard shifting pedal sticks to the floor) I think it may be a shim issue but spec specifica6stated NO shim required.
Hmm still liking the act as well 1070.00 on ebay and holds 875tq
Stock like engagement
Would replace the throw out bearing and pilot bearing as well while this thing is apart again
01-07-2016, 11:43 PM
#28
I have an RXT Twin in my car, its a little touchy when cold but once its got some heat in it I have no problems and no regrets. It is slipable and pedal feel is like stock, you just have a clutch thats a little grabby it you let it out too fast without enough RPM. I an start in 2nd or 3rd gear with this clutch fairly easily in a car with a 250/258 cam.
I would buy it again
I would buy it again
01-08-2016, 04:01 PM
#29
Race Director
This has me wondering because I would much rather replace the cms as opposed to the clutch.
I just don't to trade a working setup to something that may be failing at heavy use (hard shifting pedal sticks to the floor) I think it may be a shim issue but spec specifica6stated NO shim required.
Hmm still liking the act as well 1070.00 on ebay and holds 875tq
Stock like engagement
Would replace the throw out bearing and pilot bearing as well while this thing is apart again
I just don't to trade a working setup to something that may be failing at heavy use (hard shifting pedal sticks to the floor) I think it may be a shim issue but spec specifica6stated NO shim required.
Hmm still liking the act as well 1070.00 on ebay and holds 875tq
Stock like engagement
Would replace the throw out bearing and pilot bearing as well while this thing is apart again
Even Tick admits to higher effort, and short engagement area with certain twin clutches. They used a 3/4" Tilton in the standard model, but they also sell them with 5/8" bodies. It's easy to change a stock MC, and a Tick requires you to remove the pedal assy. GM redesigned the stock MC in '04, I believe, so if you bought a replacement, it'd be the newer style.