I experienced this at the track this past weekend and I was wondering if anyone had any ideas...while coasting in the staging lanes with the truck in neutral, I hear and feel two clunk noises right under my feet/front drive shaft area. I don't feel anything in the wheel. No biggie, I discount it as a bump and I go on with my run. On the next pass while accelerating down track right around the 2-3 shift, I hear it and feel it again...just one this time. After the finish line, I pop it into neutral and I coast through the shut-down area...I hear and feel 3-4 clunks then it goes away. I go up for my next pass and no clunking through acceleration but this time, past the finish line I leave it in 3 and just coast off the gas and I hear and feel multiple clunking and clanking, then it goes away. I turn off track and drive to the pit with no clunks at all.

The question? WTF is going on here? Could it be the steering shaft thing even though it happened when I was going straight? I checked the u-joints for the front drive shaft and they appear fine. Any ideas?

Some info...

AWD, 3200 PI Converter, Transgo Kit, Vette/Billet Servos, and I had just installed new 16 inch wheels. They are not hub-centric but I felt no movement or vibration in the steering wheel.

 

Anyone???

 

Have you greased the slip yoke that goes into the tranny?

 

Thanks for the reply. I haven't done any work yet, just trying to get some ideas before I begin.

 

Can't find the clunk!!! I got under the truck to day with the intention of changing the t-case fluid but I couldn't get the drain and fill plugs loose (is there some kind of friggin secret to this?). So, while I was under there I changed the front diff fluid and checked all of the u-joints and stuff. Went for a drive and boom, CLUNK very loud when I was OFF the gas. I even felt it in the steering wheel. I was going straight at the time. Turned around, felt no clunk in the wheel )maybe some minor little pops) started down the road again and CLUNK, felt it in the wheel again. Could this be as simple as the steering shaft clunk? The truck drives fine and has no loss of power when the clunk occurs but so far I have only felt it when going straight which I would think would rule out the steering shaft. Any ideas would be appreciated.

 

Cant help you with the clunk but "13.784 @ 95.55" DAMN....13.7s with a 95.5 trap?? You must be launching like a ****

 

Anyone have any ideas at all, please?

 

That may be why he's clunking...lol

 

Lower control arm bushings?
I only mention this because I had to replace these control arms on 2 of my cars. They will make a loud clunk as you describe and usually when coasting. (No torque being applied) Hope you figure it out.

 

I had both of the NBS "clunks". The steering shaft was more toward the front and when it was twisting. Like turning on bumps. The driveshaft clunk was on decel and accel kind of middle to rear sound. Both fixed by greasing the **** out of them. Had the grease so I guess a free fix.