rear tire pressures ?

We run tubes and liners, 40 lbs in tube, 7 lbs (at first) 6 lbs now, in tire. Seem to be getting a lot of tire spin, you can hear it in latest video, can I go lower like 5.5 lbs ? What about longer burnouts, hoosier said just a little scrub is all they need ? Suggestions ?? video is at: http://www.BackMotor.com it's the newest one, thanks

 

5.5 is still to high. i changed to the hoosier this year and run 5lbs and seem to be pleased with them..

 

Back in the mid 80's we used to run between 4.5 & 5.0 lbs

 

Hi ! hey i saw the video, Are those 33.5 or 34? What engine and rear end? stall?

Well to tell you the truth the car is NOT spining the tires, I joust moves out 5 or 7 foot and can't get on the tire. Either get smaller 16*33 or make a little more HP. Nitrous? ect


My opinion only!

 

Hey JP, tires are 34.5x17x16, one video shows burnout procedure, and tire spin right off the line. Newest vid, eased off line and then spins tires from half track to finish line, even with pedal job. We run a lenco 2 spd and a clutch, launch at 3400 RPM, alky injected, no blower, with a BBC. Thanks for your help, guys

 

thats too big of a tire with no blower or nitrous. all you should be using is a 16x33 tire on a car like you are running. alky cars that are making 2500-3000 horsepower are using the 34.5x17 tire . how old are your tires and how many runs are on them. too big of a tire can cause you as many problems if not more than too small of a tire.

 

Tire Pressure

We run the hoosier inner/outer combination as well. We started with 40 inner and 6 outer. We have been bumping it up every run and it seems to like 7 or so. I run a blown alcohol funny car with 33.5's and a crowerglide nitro slider clutch. We leave off idle because of the clutch and don't have any trouble hooking up. You may want to soften up your clutch so it can slide a little bit more on the hit and then lock up down track. Have your video person stand behind the car, slightly offset so you can just see the front wheel. I'm not sure with a rear engined car, but ours will carry the front wheels for a while. It seems like yours just spins because the clutch is locking up right on hit. Good Luck.

Chris Bennett
www.b2motorsports.com

 

I have made may way from bracket racing to top alcohol fc so I can honestly tell you that all those handling troubles are from, not having enought power to get up on the tires .

The least expensive move will be a 33*16*16 with no liners this will reduce the tire weight and help get up on the tire . If you want to keep those big tires put a nitrous system on it , to help it move.

Also I have no idea how that mid mounted spoiler would help or hurt your car.

You say its a 2 speed and cluth ? what ratios? what rear gear?

 

Forgot to give rear gear ratio 4.30, trans is 1.68 in first gear, looks like two different problems, clutch too aggressive off line (adjusting now) and spins tires from 1/2 track to lights in 1/8th mile, thats the area I'd like to work on. Spoiler has very little attack angle, big side plates and shark fin help it go straight in the lights, but has room for wickerbill/gurney flap. Pretty sure it spins tires, was seeing shift lite near finish, which is rear wheel speed of 133 mph (in first gear), but only clocked 105 mph, got my basic tire pressures from an alky dragster, cause of motor location, but kinda felt they should be lower, didn't want to try it without some feedback first

 

1.68 Gear Ratio

More years ago than I like to think about, I asked the folks at Lenco about changing our 1.56 two speed to a 1.68 ratio. This was with a 426 inch 5/8ths stroker 354 early model Chrysler, 8-71 on alcohol in what is now a TAD. The car ran 7.01 in 1976, so it wasn't a total slug for the time, about .14 off the ET record. The Lenco guys said we couldn't pull that gear, there was too big a split between the gears. We ran a 33.3 M&H tire and two disc spring clutch, 4.57 gear. At the time the hitters were running three speeds, and thats' what I'd reccomend for you. We also tried 34.5 Goodyears, and couldn't pull 'em.

 

We wanted 1.92 first gear with our 36" Goodyears, lenco said won't fit in the case, 1.68 max, so got that and went to hoosier 34.5", much better. There is NO space for 3 speed or torque converter set-up. Think I got the launch prob under control with clutch adj., want to work on top end tire spin problem, wanted to drop air pressure to help traction but did not want to make it unstable at speed, actually goes pretty straight (when not blazing tires) we test at Lakeland on JULY 29, try 5.5 lbs in rears, go from there, let ya know

 

With all due respect,guys watch his video .
It is not spining tires!

best bet on that combo is a 300hp fogger nitrous.
Also check on a set of 14*32 tires and a 4.86 gear.

I owned a rear engine bracket dragster and with a 509 bbc had 33*16 a 4.86 gear a lenco 2.15-1.45-1.00 and ran 7.29 in the quarter. Just to give you an idea.

 

Lakeland Dragstrip

Try another track, I don't want to rag on a track but.....it looks like they are useing highway barriers for the wall, I went out helped a buddy with his VW at an import race there and downtrack was "real loose" watching the cars from the line, and they are slow cars, relatively speaking.

 

oops

Just looked at the video, I agree it isn't spinning.

 

silly question

hi silly question but with the two way valve which is for setting the inner pressure and which is for the outer?

 

Turn the valve all the way out, that is for the outer. Turn the valve all the way in and that is for the inner.
Sorry to ask a question in this thread but going on from the previous post, I have been told that the valve should always been turned all the way in before the run. Is this true and why? Does it stop air leaking from the inner to the outer?
Thanks, John

 

We run the new Hoosier tires, tubes and liners. They have separate valves for each. 40 lbs in tube thru conventional location, then, on back of rim (near caliper) is the tubeless fill point. Always fill higher pressure first, any air that seeps thru natural rubber tube, winds up in the tubeless portion, and you have to let them down to 6 or 5.5 lbs (for us anyway) edit: OOPS forgot this, we used to run the goodyear ones, had inner leak to outer on one side, took valve core assy out and replaced the o-rings, that fixed it. The same o-rings seal off passages whether in or out, but whole the stem is shorter (when turned in) and less likely to get hit or damaged from debris or cleaning