redtopz

I picked up a 99 FRC corvette that ran ITE in SCCA. I have done some mods and restoration to convert it to ST2. Just completed my first race weekend with it and it ran pretty well. Except the clutch is making nasty noises both on the dyno and in the paddock. And according to my data I lost about 3 seconds per lap shifting gears at Infineon. It took me over 3/4 second for each shift. If I tried to shift faster the shifter would just refuse to go into gear. BTW, what is a typical upshift duration for racers? So I am going to pull the clutch and slave and replace it with a new one. I think the car already has an aluminum flywheel. Thinking about the following clutches:

1. LS6 or LS7 with aluminum flywheel
2. Spec clutch
3. Quartermaster (but I like to drive the car into my trailer)
4. Exedy twin disc (I was given this clutch for free and it's sitting in my shop but looks pretty used).

The car also has a custom built (heads/cam/fast 90 intake) LS1 engine that was putting down 422 rwhp. I had it detuned to 372 rwhp by pulling timing up top. It has a stage 2 ARE dry sump and each time I check the catch can there is water in it. I am strongly considering pulling the engine while I do the clutch swap, selling it, and replacing with a crate LS6. I also want to update the ECU from the 99 operating system to the 02-04 version in my ZO6. Would you ST2 guys recommend the LS6 swap or trying to work with the engine I have? I like the idea of a stock engine for reliability. Thanks.

Some pics from the race that my friend took (#78 Corvette):

http://s240.photobucket.com/albums/f...2-13-Infineon/

SIK02SS

How much tq? Do you have a dyno chart you want to share? LS7 clutches are heavy iirc and overkill if all you want is a stock ls6. So your dumping water out of your catch can? Do you have a breather on it that's letting cold air in and condensing with the hot air in the pcv system?

davidfarmer

I'd go LS6 with Quartermaster.......

ssdeuce

redtopz

The torque is not high enough to have any real benefit over a crate LS6. I think it puts down 388 tq to the wheels through 3.73 rear gears. There is a catch can with breather connected to the dry sump reservoir. I'm not sure how water is getting into the oil, but it's too much to be just from condensation. It has a rag wrapped around it and it's inside a sealed box. I had this problem with my gto and shortly thereafter found a cracked piston. The car definitely has an aluminum flywheel. It looks like new from the front.

Yeah, I think I should swap in a crate LS6. I have a strong feeling this engine won't last long because I have gone through a couple "built" LS2 engines myself on a drag car and seen many more fail at the track. Fortunately I got a great deal on this car so a $3200 LS6 won't hurt too bad. I really loved the feel of the aero along with my LG coilovers.

The other feature I like about this car is the combination of a MN6 tranny with 3.73 gears. It results in first through third nearly identical to my C5Z, but a shorter gear in 4th. The car pulls harder in 4th. However the tranny is leaking also so I should have it looked at while everything is out. Is the MN6 as durable as the MN12?

BTW, did you see your decals on the car?

mgarfias

I know where you can get an LS6 (new) for $2775 + shipping. Also, have you considered a tilton clutch?

redtopz

Wow, that's a steal! When I tell other racecar owners how much our engines cost they can't believe it . BTW, I already have a crate LS6 sitting in my shop which is one reason why I'm so tempted to pull this LS1 out. My buddy is a GM parts manager and hooked me up last year with a spare. But I'm sure there are a few T1 guys who would want to ****** that engine up.

Can I use a tilton clutch with the aluminum flywheel I already have? I would definitely like to shift faster because right now it seems to take an eternity.

trackboss

No. Stick a tilton 5.5" triple assembly in there and be done with it.

mgarfias

Nope, tilton has their own flywheel setup, steel, but really light weight.

Tiltons are going to be like on/off switches. I looked into putting one in, but street use is basically out after putting them in. A plus for them, is that they use their own throwout/slave setup, so you won't have to deal with the POS oem crap.

Here: http://www.tiltonracing.com/content....st2&id=428&m=d

AU N EGL

We have heard more then a few 'built' LS2s become history.

drivinhard

tilton or QM and you'll never look back

RAFTRACER

You may consider the Quarter Master 7.25 " Optimum V..... a little more durable than the 5.5 stuff. We all know how fun it is to put clutches in these cars especially with long headers. I use the 7.25 unit and I have been happy with it....and I drive it into the trailer....

redtopz

Well I think I'm convinced to go with a tilton or QM. Price will play a factor because it looks like the tilton carbon triple is about half of what my car cost . The 7.25" QM that Raft is running sounds like a good clutch for me because I don't want to repeat this process anytime soon and I know I won't winch my car. I'm going to start pulling everything out today.

Here's a short vid of my car in action last weekend. I was more aggressive with shifting during qualifying but I was short shifting to 4th all weekend because I didn't trust the engine at sustained high rpms.

Katech_Zach

Sent PM

geerookie

Just a heads up......This deal is all gone I just got off the phone and they can't get anymore at that price.

mgarfias

Sorry dude. I had called when Oli popped his motor, at that time they still had 4 left. Then again, at the price they were willing to sell for, it makes sense that they all left.

redtopz

I pulled my drivetrain yesterday, but left the slave cylinder dangling on the hydraulic line because I couldn't figure out how to disconnect this $%#$$#@# fitting. I tried to push/pull and tried to get a fuel disconnect tool in there, but nothing worked yet. I might just replace the whole line with a -3 line to the new throwout bearing.





I ordered a "Danny Popp Special" clutch yesterday from Dave at Quartermaster. I'm going to do a compression test and leakdown test on my engine before I pull it. Also, this tranny is leaking around the seals so I guess I need to pull it apart and install new gaskets at the least.

RAFTRACER

You'll be pleased with the clutch....PM me your phone #'s if you have questions about install.....or that pesky line .

sperkins

If you like crappy customer service and want a lot of practice at pulling your driveline, buy a Spec.

wallyman424

I know a lot of people don't like their spec.... I guess I've been lucky with my stg 3. No issues, pulled driveline once to install and thats it. Been 2-3 years or so since I put it in.