I've got Atomic's front coilovers (with QA1 18-way adjustable shocks), Calvert (Rancho) 9-way adjustable rear shocks, Cal-Tracs, and Belltech shackles. Truck is 3/4" higher in the rear than in the front so it has some rake but not much. Tires are older Bridgestone Dueler 265/60/18 at 35psi. I've tried maxing out the front and rear shock stiffness and twisting the Cal Tracs as much as I can by hand, but the front still wants to spin. Putting the Calvert rear shocks at 9/9 stiff, the fronts at 18/18 stiff, and twisting the Caltracs by hand did help a lot, no doubt. Now the truck hooks a little better and goes straighter. Before, it would spin worse and torque steer. Maybe I just need a decent surface with some rubber on the ground? Should I shim the pinion down a little more? Maybe the old Craigslist tires are hurting me, but I don't think new tires would help much. Feels like the driver's side front just wants to spin no matter what when I footbrake launch at ~ 5psi.

 

Get some good tires before you start over thinking stuff.

Trying to grip the road with sub par tires is just shooting yourself in the foot.

 

Do you have a video of it launching? How much downtravel in the rear do you have before you hit the bumpstop? How much preload on the caltracs?

How much does your truck weigh and whats your best 60ft so far?

At some point, those terrible race tires will spin no matter how good your setup is, get a real tire on there or at least a radial.

 

Atomic thanks for the post and sorry I didn't reply quicker, but I knew I was gonna head to the track on Saturday and then I'd have some real data. I ended up basically answering my own question, or at least in terms of my current power levels. Earlier last week I had been noticing my front tires were really worn on the insides from breaking them loose on test launches. Visually I could see I had a fair amount of camber in it so on Saturday morning before the track I installed some Belltech cams I had laying around, as a while back the alignment shop had said my stock cams were max'd out and he couldn't do any better than 1.5* negative on each side if I wanted them equal. So I used my level on the wheel face to get them as close to 0* as possible. Then I zero'd out the toe, which was actually about 1/8" toe'd out. So I think doing the home alignment and launching on a prepped surface allowed me to have zero traction issues at the track. I only mustered a 1.72 60ft, but I didn't think the truck would hook as well as it did, so I was going really conservative at first, and only started trying to build boost the last 2 passes and by then the truck was so heatsoaked it was pulling a lot of timing.

I haven't weighed the truck in race trim, but it weighed 4835 with the spare, hitch, and tailgate still on. I removed the tailgate at the track and ditched the spare and hitch a while ago so I would say it probably weighed 4850 with me in it and a 1/4 tank.

 

Drop the tire pressure. Mine does better on about 20-22psi in the rear on street tires. At 32 psi it spins ALOT!

 

So when you 4wd launch on street tires you'll drop rears to the low 20s? I'll definitely try that once I can build enough boost to overpower the current setup.

 

i am 2wd.. but if my tire pressures are way up they spin soooo easily. when i drop the pressures it does better. You being 4wd it might be better. give it a shot and see what it does.

 

I drop mine to low 20's also for AWD launches and it helps. At full pressure mine spin pretty easy, actually on the street they do period but at the track I drop pressure. On the street I don't care enough to drop it.

 

you drop all four tires or just the rears?

What are you guys doing for tires? like using All terrains or more of a performance SUV tire like nitto 420s?