First I am running new style BFG DR 315 18's. My best with stock clutch was 1.653. My last time out with stock clutch I ran: 1.75, 1.76, 1.77, 1.79, 1.70, 1.71, 1.76.

Installed new Textralia clutch, and installer didn't change f-body bleeder on slave to Z06 bleeder (shorter) and had pedal stick on sec launch and complete failure on 3rd launch from bleeder snapping off. When repairing I noticed heat bluing from slipping inbetween complete failure.

With that said, after shop replaced slave, here are 60's so far: 2.05, 1.93, 1.92,1.89, 1.86, 1.75, 1.83, 1.94, 1.80, 1.83, 1.96, 1.97, 1.94, 2.07, 1.77, 1.93, 1.91, 1.84, 1.76, 1.84, 1.92, 1.94, 2.00, 1.96, 1.86, 1.93, 1.91, 1.87 in order 1st to last.

I get pretty bad spin and wheel hop 90% of the time (nun before new clutch). I have 78 runs on these tires. I have tried different pressures, different launch rpms, 3000/3200/3500/3600/3800/4000, n2o, no n2o. Seems now I have to burn the crap out of them to get anything on launch, and my traps are down. I also notice more chirpping when changing gears, even when hitting 4th. Are these tires just worn out? They still look good and are no where near bald.

Any advice or insight would certainly be welcomed, as this is driving me nuts.
Thanks in advance.
Robert

 

So where is the bluing, on the Flywheel/pressure plate? That would explain most of your troubles.

 

Yes, flywheel, on the outer edges of where the pucks were seating. I only had 200+ miles when it first started slipping on launch before complete fluid lose. I figured it wasn't bad enough, and had guys put it back together? Thaey did take pictures at my request, and I'll try to get them and post. Don't remember if pressure plate was blued also?
Robert

 

I don't have much technical knowledge, but if the new clutch is in good working order now, maybe the new "bite" of the new clutch is too much for the tires to hold...
That might be causing the extra spinning. What PSI are you running them? It may be time for some 15 or 16" ET Streets...
Ron

 

Yea, kinda my thoughts also. Time for ET Streets. What about pass life on the BFGs. At 78 launches/runs and hard burn outs, also driving back and forth to the track, do think they still have life? They look good, but don't want to sell them to someone if they are shot.
Robert

Edit: I tried from 15psi to 19psi and found no combo that worked along with diff rpms.

 

I've heard many times of guys running them until cords are showing...That is a lot of passes on your DR's though. How much tread/grooves is left? Can you measure anything?
Ron

 

Sounds like your drs are shot.................I got 64 passes and about 2K miles out of my 345/30/18 drs..........they now have "0" tread showing, basically a slick and no side wall to give on launch.
Top of the picture........

Mine is an A4 and the 60's started to go up to 1.77 vs 1.52 and I started to get wheel hop. Took a good 15 sec burn out and 15 psi hot to get a 1.56..I have a slightly used set to put on

 

Robert,

Get some new tread and use that clutch…. It’s a shame about your install issue, but you get that some days! Blue is still good… (350°C) is actually nothing to worry about!

All the best….

Pete.

 

Hi Robert,

Heat striations (blue black dapple marks) on the flywheel are a normal by-product of launches. Not indicative of an issue.

The older style BFG (Comp TA) that I ran, were very consistent even when the tread was completely worn away. At that point, I usually got new ones for safety reasons, but not because of any fall off in performance.

I'd suggest checking your burnout procedure to ensure that no water is thrown in the wheel wells and subseqyently drips onto the tires while staging.

During the slower 60' was the psi in the range of 16-18?

Ranger

 

Dr.Ron and Phil, you are correct as was Ranger, and here is my reply from a duplicate post in perf section:

(Ranger, at first I agreed with everyone that tires may be shot. However, after checking, I found wear bars are not even being touched yet. I now have 87 passes on these tires.

All passes sited have been n/a, as was checking n2o last night and have wiring problem and it is not working at all, even when I thought I was using. This is also backed up by my mph, as with spray I get mid 120's usually, and haven't broke 114mph in sited 60's.

I think now I agree with what you say about clamping force. I was in such a habit of quick releasing at about 3500, just doesn't work for new set-up. Last night towards end, I started doing heaver burn-outs and launching at 4500rpm, results: 1.73, 1.74 and 1.75 (earler was all 1.8x's) and gained back 2-tenths in ET. Even at that rpm some slight bogging was happening, so I believe I still need to up rpm at launch.

Conclusion, just needed to adjust my launch/burn-out for new clutch, and tires are still fine even with many passes. There is definately some more time to be knocked off 60'er with a little more seat time. It's amazing how one change can through your whole launch off to point of a relearn/adjustment factor. I may have to slow my shifting down a tad also, as a slight spin is being had all the way into 4th, at least until I change over to ET streets. I'm sure this may be taking a bit off my ET as well, the best last night was 12.1x.

Thanks Ranger, once again you've hit the nail on the head, first time.
Robert)

Thanks everyone for helping me sort this thing out. Clutch is great and tires are ok, border line holding power though, just needed to adjust my driving tech.
Robert

 

Hi Robert, glad you found the problem. I hope it's an easy fix.
If you're bogging now, just up your launch RPMs. The bogging may be due to a combo of your new burnout technique which is getting the tires hotter & stickier, as well as the new clutch clamping harder (not slipping at all like the stock clutch) & the tires hooking better...
Ron