darguy

Hey Gang!

Got the '99FRC on track for season opener practice session and am having clutch issues. Background: car was DD, got new clutch/slave/master/DOT4 back in 2010 and was used for Time Attack and DD until 2012 when it was converted into dedicated race car. Since then it's got about 17 hours of track time spread over 3 years.

Symptoms:

During the last several sessions I'd "miss the 2-3 upshift" at just under the redline resulting in gear grinding. I had been thinking that either I'd not pushed the clutch in far enough, or that my 2-3 synchro was going. This would generally happen only after about 10-15 min on the track and everything was hot.

Yesterday, during a practice day this again happened a few times, then I wasn't able to physically get the shifter into the gear position despite the pedal being fully depressed and many seconds elapsing. I think I double clutched and it went in - this was on the front stretch at speed.

Then, the pedal stuck to the floor and after stabbing at it several times, I pulled it up with my toe and it felt reasonably normal. I did another lap and the same symptoms - not being able to get into gear and pedal sticking to the floor. After it had cooled off in the paddock it felt totally normal getting it onto the trailer.

I've read up on the issue: fatbillybob posted on a similar discussion that it sounded like air in the clutch hydraulics - this seems very plausible to me. Also, froggy47 has a discussion elsewhere about the Lingenfelter clutch return spring.

Putting the two together, here are my thoughts: air in the system causing my poor upshift scenario and not forcing the pedal back (hasn't been bled since 2010 - yes, I'm very bad but it doesn't look that dirty). The return spring would combat this and pull the master piston back, drawing fluid back from the slave.

So, my questions are these:

1. Is this a reasonable assumption, and if I flush/bleed the clutch and install the return spring will I be good for race day? Or, am I going to have do replace the slave (I really don't want to do this unless I have to - the logistics are a nightmare as I don't have a shop and the car is in storage 1.5 hrs away near the track).

2. I have a Tick Performance clutch speed bleeder line - is there any way I can install this on jack stands at the track, or on a hoist without dropping the driveline? Again - the logistics are a nightmare.

3. Am I fooling myself, and I need to tear everything apart and replace the slave.

froggy47

I would flush it a few times (Ranger method) AND put in a return spring (both very easy) and drive it hard & see how it goes. IIWM I'd also put D4ATF (Redline) or a more racy Redline (those need some warming up) and do a shifter alignment (both of these also pretty easy).

If all that does not work a new slave & master (ask around for some better than stock) next and last the syncros are getting bad enough so that they are really not up to the forceful shifts.

Hope that helps.

Vettechris996

I had somewhat related issues with the clutch pedal sticking to the floor that began when I ran a pass at the drag strip. After that I noticed that the pedal would feel funny if I free rev'd the car at all while driving (clutch in to throw a rev at a buddy in passing kinda thing). Never had issues going into gear though. Anyway I drove it like that, shifting fairly hard at times until one day a hard shift into 4th got it stuck in fourth. That was basically the beginning of the end for the synchro keys. This was all with the stock clutch with no remote bleeder and doing the Ranger fluid swap method regularly. I was able to get it out of fourth and drive it carefully for a few weeks there after then one day is jammed in fourth an that was it. I had Rick at RKT rebuild it and by that point I had done a good bit of damage. Wound up replacing a few synchros and going to all billet keys, etc. Had I dealt with the issue properly (likely a slipping clutch and/or bad hydraulics or both self-propagating together) it probably would have been a cheaper rebuild but hindsight is 20-20. Needless to say my take away from all that was if it doesn't feel right in the shifter or the pedal its likely a sign to take it apart and deal with the clutch and hydraulics before it starts damaging the trans. That said i'm not sure you have time for that but keep that in mind if you chose to drive it with some strange symptoms.

darguy

Thanks for the feedback, folks.

I asked Tick Performance, and they're saying I'll need to drop the driveline to get the speed bleeder in. And, I have my doubts about complete flushing using the Ranger method. If anyone has experience getting a speed bleeder into a slave cylinder without dropping the driveline - I'd love to hear it!

Also, the only way I can test the car under 'hot' conditions is on the track, and I can't get onto the track until the first race weekend. And, if it doesn't work I'll miss 1/5 of the season and still have to fix the car.

It looks like the only way I'm going to give myself a reasonable chance of eliminating this problem is to open Pandora's Box. If I drop the drivline, I'm going to want to open the tranny and diff. So that leads me to my next set of questions:

1. Is there a recommended 'race' slave/throwout assy?

2. The car is a '99 FRC - I understand that the later cars switched seals & fluid in the tranny. Anyone have any insight into that, and recommendations?

3. If I open the tranny, what should I be upgrading beyond a std rebuild?

4. Same question for the diff?

Thanks in advance - now to see if I can line up a friendly shop...

darguy

A field service Tech at work came up with a novel suggestion, which I should have thought of myself:

Drill a hole in the tranny tunnel to access the slave to install the speed bleeder. If a guy lined it up properly and used a reasonable sized hole-saw, it should be fairly accessible - plug the hole afterwards. This is a gutted race car, after all - form follows function.

Thoughts?

UstaB-GS549

Can you insulate the line or fit a heat shield to protect line from header heat. I going to assume that your car has tubular headers?

My friend & I both have 02 Z06's. His has headers etc & my motor is bone stock. He frequently has problems at track with clutch not disengaging (boiling clutch fluid?) & I never have. Once his fluid cools down the problem goes away. We fix his car by sucking out all the clutch MC fluid and refilling with fresh fluid. Pump pedal a few times and repeat. It's usually good for the rest of the day.

I believe that there was a post about having the black stuff in brake fluid analyzed by a lab and it turned out to be clutch lining material. That would indicate that when hot the seals on the release bearing are allowing material the get by on the return stroke.

aaronc7

I'm pretty sure it's stock pressure plate related issue. I ported my stock heads and swapped in a cam and started having this issue (2003 Z06). I was hopeful that I could fix this issue by getting the Tick master cylinder (move more fluid, the line has heat insulation on it)..... no joy. In my case the issue isn't terrible or really affect me, but it does get soft after a few high rpm shifts. I also religiously change/flush the clutch fluid, has had no effect for me... I use ATE type 200 fluid.

darguy

Thanks for the input - the car has a stock LS1 and stock exhaust. Headers and such are on the list, but I haven't gotten that far.

It did get ferocious hot under there last year during the last couple race weekends due to insufficient cooling, that's been addressed and is no longer an issue, but I hadn't been able to bleed the clutch since.

Clutch is a stock type - will have to dig up my records to see exactly which brand, it was several years ago.

darguy

Dropped the car off at my friendly local driveline shop on Sunday. We're opening up Pandora's Box again (first time was the suspension & brakes). I don't want to suffer a breakdown on one of 5 race weekends this year...

1. Suggestions on clutch hydraulics: Tick Pfm clutch master? Aftermarket or GM slave/throwout? Speed Bleeder will be installed

2. Clutch recommendations? Do I replace necessarily, even if not worn? Basically, T1 rules apply for CACC IP racing.

3. I bought the parts to rebuild the TT last time, but it didn't need it then. Do it now, I'm guessing.

4. Transmission: upgrades to stock '99 FRC 6-spd?

5. Diff: upgrades to stock '99 FRC?

Wish me luck, first race weekend is in 7 work weeks...

braknl8

I think you'd end up messing around with it longer than just unbolting the UCA's, upper shock mounts, popping the axles to clear the brake lines and unbolting the cradle. The method above is going to be a heck of a working angle and getting the lines off then tq'd back properly will be a huge pain, imho. It would suck to do it all just to have to pull it out a second time (the correct way) because of a leaky line.

Chris Edwards

I do recommend the Tick master and new GM slave (since you're in there for the speed bleeder). I had similar shifting issue into 4th that the Ranger method simply would not resolve. The Tick master has surprisingly transformed the shift engagements. All gears were stiffer prior to the Tick, now I feel it could powershift if I cared to. For sure put a new GM slave in when the torque tube is lowered for the speed bleeder. I would absolutely not drill into the torque tube, that sounds like a jack job. You can always add the Tick master at a later date, since driveline removal is obviously not necessary to install.

Socko

ls1 forums i seen a number of holes cut to access the bleeder. It isnt new ground, just hunt around to find the right spot if you dont want to pull it apart.

That said, best bet is likely to just replace the slave, as its likely pretty beat to hell. I would move away from an auto adjusting stock pressure plate if you can, based on your rules. As they cause some issues at high rpm the way it is.
New stock slave. New master, a tilton master is prefered. If you are staying single disk I would probably consider the smaller bore one as it wont make the pedal too much harder. The 7/8" bore is noticeable, though honestly its not bad to drive if you buy a decent clutch.
I don't recall why but in looking at them the ecs bleed hose looked like the best one so i have that one and it does work well.

EDIT: Oh yeah, assume you will have to shim your new slave as they new ones are different then the original one but may be the same as the current one that will come out which could have something to do with your issue if it isn't shimmed. In theory it shouldnt be an issue if it needs shimming, but there is enough talk about it and shims are cheap enough its worth doing imo. So buy a shim kit from tick when you buy the master. You will need new longer bolts for it possibly as well. They are a normal size i bought some 10.9 hardness ones at ace.

Supercharged111

New (used aftermarket) clutch (COA #2) made my pedal worse! It overwhelmed the stock hydraulics worse than the stock clutch. I really though the stock self adjusting PP was to blame after replacing the master/slave with new GM parts.

With the new GM master/slave (COA #1), I also installed a remote bleeder. This kept my fluid clean and made bleeding a snap, but still a POS pedal.

With the new to me clutch, I checked clearance and I had a whopping .050" which is less than half of what is recommended. I twitched and worried for a bit, then came to the conclusion that it's nothing more than a brake caliper, and they're self adjusting until they run out of travel. Plus my clutch was broken in, so it's not like I stood to lose a bunch of clearance. Finally, I installed the Tick MC and my troubles are solved. I hate to be a nutswinger here, but I suspected that this would be the end all solution. Having tried everything else first, I now have peace of mind that the stock PP won't fail me and neither will a busted *** old GM slave. They wear out quick! I changed one with a good 10,000 miles and the nub that prevents the throwout bearing from rotating had worn halfway through the plastic deal it rides on! It can spin around and hit the other nub, but after that I imagine that plastic piece would just start to kill itself.

darguy

Thanks for all the input, guys!

I just placed my order for the Tilton/Tick Pfm master cylinder kit and slave/throwout shim kit. I'll get the slave locally from GM.

Rule on clutch is:

Any clutch disc and pressure plate of stock diameter may be used, provided that they shall be bolted directly to an unmodified stock flywheel. Balancing of the flywheel/clutch/pressure plate assembly is permitted. Lightening of the flywheel beyond the minimum material removal necessary to balance is prohibited.

Not sure what options that leaves me for a 'stock diameter' clutch and pressure plate on a stock flywheel. Any suggestions?

They should have the driveline out and apart early next week...

trackboss

for rules like that 10,000rpm is the place to go to. They make stock appearing light clutch setups.

Supercharged111

Let's consider the aspect of policing this rule. Are they gonna remove the clutch? And if not, are they gonna stand around for the eon it take you to remove it (because I'd make it suck for them if it were me)? I'm not saying you should cheat, but maybe it's not worth sweating it to be dead nuts on the clutch weight.

trackboss

That is another thing to consider. If the rules are not enforced then why follow them. I've heard of complete engine teardowns in scca to the opposite. NASA on the other hand swears by the dyno which is most easily defeated.