I am losing 70lbs of unsprung weight and about 6lbs of rotating weight(smaller slicks) on my 10.9 drag coupe (10.91@123mph) I wonder how much e.t. I will lose?
Jim Forbes is much more knowledgeable than I am so he is probably correct but I wonder if smaller slicks will limit traction enough to even give you that much.
I'm assuming the car still launches the way it did before. That's unknown with the information given.
3300 lbs. Going from 39 Ford drum brakes in front/57 Olds in back to Wilwood Disc front and rear. 14-32s down to 29.5-13.5.The slicks seem about 3lbs lighter per tire.
I am slipping the clutch with the 14-32s and will be doing so with the 29.5-13.5s also. I expect the car to 60' at least where it did before and hope for quicker ets as well.Current best 60' is 1.483
I will make a wild guess that you will run 10:[email protected] ,, if that is all you changed. It takes at least 550HP to run 10:90@123
The pressure plate is adjustable,there are allen screws that you can turn to vary pressure. At the meltdown 2 years ago,I ran 5 runs (100 degree and HUMID!!!) of 11.1 in a row(Sat and Sun.) and that was changing shift points and launch rpm every pass!
So you slip the clutch instead of spinning the tires? Is that the same as a fueler? Stops slipping as the rpm's come up or stops slipping as the weight of the cars starts rolling? Sorry for the kinda off the subject question, I have been away from the pit side of the track for years. How many runs on that clutch setup, and do you adjust every run?
I was just getting a handle on the clutch at the end of last year.The trick is to slip the clutch enough to keep the rpm up where ya want it AND not hit so hard ya bust things...(see my albums for some of it) also the levers are counterweighted so when the rpm goes up the centrifical force applies more clutch.I went to alot smaller tire this year to get the trap rpm I want but with my 14-32s I had the clutch set at 860 lbs. and I dont remember how many grams of counter weight on my billet clutch levers. I know when ya get close to the sweet spot the adjustments get touchy! I went from about perfect slippage ( I gave it 1 more turn) to hitting so hard the car put the front end 4' in the air and drug the wheelie bar(battery box) busted the tranny case and shut me down for the year! Launch rpm?7500!!!car? 3300lbs.!!! I drive the car ALOT on the street,the clutch is set with shims(more to it...) at the beginning of the year and I pull the trans. and check the disc for cracks around the rivets when I have 30 HARD dragstrip passes on it. I have exploded 1 disc already before I learned ya gotta keep a close eye on it! VERY COSTLY lesson!
I for one would like to know what kind of clutch that you are using and wheer did you get it? Thanks! N.N.
Tis a Ram 471 I had Tim Hyatt 440-254-1311 (Clutch guy follows NHRA circuit) rework for me and install the billet levers etc. ( oh and 8 grams of weight on levers) and I run a sintered iron disc with a solid hub.This setup works very well on the street ( I turn the pressure up) although it does get dust build up and starts squeekin after a thousand miles but just launch it on slicks a couple times and yer as good as new! Just gives ya an excuse to drop the hammer.....
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