Tires are not hooking any more.

[Thomas W]

Went to the drags in Medford last weekend. Had horrible traction problems. Wasn't sure if the problem was the track, my tires, or a combination of both. My tires are 3 yr old MT ET Street Radials. These were my last 3 passes with me being in and out of the throttle more times then I can count:
60 ft....ET....MPH
2.02 10.91 144.60 (15 lbs boost)
2.06 10.87 144.21 (15 lbs boost)
2.02 10.97 144.47 (17 lbs boost)

I realized on the last pass above that I had been hitting my 6000 rpm rev limiter (which limited my mph). I had forgetten to change out the module for a higher rpm for racing.

Last night I took my car to PIR, which is normally a better prepped track then Medford. PIR will kick me off the track if I go over 135 mph. I decided to turn my boost way down to see what would happen. These are my last 4 passes:
60 ft....ET....MPH
1.72 10.71 128.93 (9 lbs boost)
1.78 10.80 129.29 (9 lbs boost)
1.73 10.82 125.92 (9 lbs boost) I lifted off throttle before finish line by accident.
1.74 12.44 122.61 (10 lb boost) went sideways on track at about 80 mph.

I was surprised that the last pass with 1 more lb boost made me lose traction at about 80 mph, but the turbos seemed to really like that extra lb of boost pressure. My tires didn't like it though.
Overall I was amazed I could run consistent 10's with only 9 lbs boost, but that seems to be the edge of traction for these worn tires. Time for new tires and then I'll post the results next time out. Cheers.
Thomas

[keezling]

Thomas, what about a spare pair of wheels with full tilt drag slicks just for the strip?

[Butch B]

Thomas,
Gerald may have a good idea. Have a pair of race only tires & wheels, and a set of road tires and wheels? That is what I'm doing this season, my MT/Ets for racing only, and my BFG/TAs(yuck) for street/trips. Mel & I plan on doing a lot more road trips this season & I think/feel BFGs will hold up better for the longer trips?
hth
Butch

[Thomas W]

Gerald and Butch, thanks for the suggestion. For some reason I feel like running slicks is cheating. I want to be able to say how I drive it on the street is how I drive it on the strip or go around a track. Besides, I'd have to buy 4 new tires and wheels since it has to be non-radial fronts to go with the slicks. Once I make a 9 second pass I'll be cut off and the tires and wheels will just gather dust.

On a side note, I really had fun racing my car run after run on Saturday without a worry of being kicked off since I added the full width roll bar with side bars. I had a lot of people asking about my car and the whole Cobra replica industry. At 9 lbs boost my car was reasonably well mannered and controllable, but I could tell the tires were at the end of their life cycle at 7,000 + miles. Cheers.
Thomas

[Butch B]

Thomas,
Quit talking & just call Summit up!lol. Your "new" tires will be on your front porch by this Friday, and you can go racing this Saturday nite!
Butch

PS
7000 miles!?
I got only 6000ish miles before mine went south?

[No Tread TommyG]

Hey Thomas!

Great to hear you got your roll bar in. Sure feels great not having to worry about getting booted off.

I was surprised to hear about such a difference in traction.

Any chance something got moved that might have changed your pinion angle?

What is yours set at?

Tom

[Thomas W]

Tom, good question, I've never checked it. I'll look at that and make sure everythings ok underneath in the next day or two.
Thomas