Went drag racing for the first time yesterday

Went to a local NHRA 1/8 mile track for a test and tune. Ended up running 9 times in about a 3 hour period. I had MAJOR problems on the launch all day. Tried about everything but couldn't find any sort of a sweet spot. My 60' ranged from 1.832-2.025. Over half the runs I had to get total out of the throttle twice cuz the rear tires were trying to leave the track. Towards the end of the day, I just stayed in it and it would kinda-sorta recover but would end up with a lot of wheel spin. I included 3 videos that all have different launches.

This pass was leaving off of the foot brake at about 3000 rpms. Converter flashes to 5000, so it hits pretty hard. Ran a 1.903 60', 8.029 @ 89.85. 1.5 turns preload on both sides for Caltracs, 7/7 on Rancho 9000's, 14 psi in the 325/50r15 M/T ET Streets. Seemed to kinda initially spin and then hook and bounce.


This was the quickest ET pass. Ran a 1.881 60', 7.976 @ 89.90 mph. Foot brake to about 3500, 2 turns preload on right, 1.5 turns left, 4/4 on shocks, and 14 psi in tires. Just seemed to hook really hard on this pass and bounced hard twice before I got out of it.


Should've left parts on the track on this pass. Looks like the rear end drops down a foot and the left rear comes right off the track. Went off the transbrake with the 2 step set @ 4200 rpms. Had a 1.961 60' time, 8.033 @ 90.07 mph. Had 2 turns preload on right, 1.5 turns left, 4/4 on shocks, 12 psi in tires.


The best MPH I ran was a 90.18 and according to Chris Kelly's calculator, it takes about 470 rwhp to push my 4200# truck that fast in the 1/8. But, since its a truck, I'm assuming it takes a little more cuz of the added wind resistance. That equates to about a 12.4 quarter.

As for the Caltracs, the front mount is in the bottom hole and the rear mount is in the bottom hole too. I tried adjustments from zero preload to 2 turns and seemed to be the worse at about the zero preload. I didn't have my springs clamped, so not sure if that caused these problems. Tried air pressure in the ET Streets from 12-16 psi. Also tried the shocks from 4/4, 4 left/5 right, 5/5, 7/7. Seemed the worse on 7/7. I'm thinking a set of real slicks would help me too. Not sure if I'm shocking the tires so hard that they can't recover? Would a set of dedicated drag slicks be able to handle this shock better, hence the wrinkle sidewalls? I think there is a lot more in the truck if I can just get it to hook and not bounce. I appreciate any help on rear suspension solutions.

Have you considered a four link?

What is yer rearend gear ratio ? btw, that was awesome-

His rear gear ratio is a 4.86. I was with and can say it was impressive, would love to see what it'll run with the launch figured out.

Too tight of a shock setting defeats the functioning of the Caltracs. As you figure out on you own, run the shocks loose (maybe even 2 or 3.)

You will need some preload and Calvert recommends starting at 1/4 turn. You will probably need to increase it some to make up for the softer shock setting, but 2 turns seems excessive. Top setting on the front of the Caltracs hit the hardest. Not sure what the rear setting that you mentioned is though.

What happens if you launch from just above idle ??I have never seen a car turn a faster time when you must lean on the converter so hard. The lower you stage, the more torque multipacation you will get. The trans brake leave has NO torque multipacation at all. Most cars I have worked with run much better when they foot brake it on the starting line. The transbrake is only to get a better reaction time when bracket racing.
JOE SHERMAN RACING ENGINES

Originally Posted by BIGJOE

The trans brake leave has NO torque multipacation at all. Most cars I have worked with run much better when they foot brake it on the starting line. The transbrake is only to get a better reaction time when bracket racing.
JOE SHERMAN RACING ENGINES

I have a 3300 (actual) stall and a transbrake. so you are saying that i would be have a faster 60ft (and possibly overall et) if i kept foot braking instead of using my stall? i plan on stepping up to a 4000 stall, would this still hold true or is there a point where it no longer makes a difference? curious to know as i have previously footbraked to a 12.22, then last year after a few "improvements" i managed a 12.29 with a 10tnth slower 60ft after trying out the transbrake. interesting......

Originally Posted by 1 Bad 88 GT

Have you considered a four link?

Actually, the new rear suspension is almost done. I went with a S&W Race Cars ladder bar kit. I jumped onto a Ford Lightning forum and guys either run the 56" bars that mount under the axle and go up to the frame, just below the seats, or a few guys ran the ladder bar setup. We should have mine done this weekend. Too bad the tracks are closed now and won't be able to see how much it helped or hurt it.

Originally Posted by BIGJOE

What happens if you launch from just above idle ??I have never seen a car turn a faster time when you must lean on the converter so hard. The lower you stage, the more torque multipacation you will get. The trans brake leave has NO torque multipacation at all. Most cars I have worked with run much better when they foot brake it on the starting line. The transbrake is only to get a better reaction time when bracket racing.
JOE SHERMAN RACING ENGINES

Joe, after reading that, it makes more sense. I was looking at my time slips and the ones that I footbraked at the lowest RPMS had the best 60', but due to the terrible bounce I got from the better launch, I had to get out of it more so the ET or MPH wasn't as good. I'll be sure to try the right off of idle launch this next spring.

Originally Posted by dennis111

Too tight of a shock setting defeats the functioning of the Caltracs. As you figure out on you own, run the shocks loose (maybe even 2 or 3.)

You will need some preload and Calvert recommends starting at 1/4 turn. You will probably need to increase it some to make up for the softer shock setting, but 2 turns seems excessive. Top setting on the front of the Caltracs hit the hardest. Not sure what the rear setting that you mentioned is though.

The two turns was excessive and just made me spin. I talked to Calvert a couple different times about this and never got any real definate answers. I got on a Lightning board and only a couple guys had had any luck with the Caltracs on a truck like mine. The guys that did were pure drag trucks with 6500 rpm converters leaving off the 'brake. So, I'm trying my luck with a ladder bar setup.