forcefed1

I noticed a few days ago. When WOT in 2nd at about 6K RPM, I have a "vibration". The problem is load related not rpm related. I noticed It feels a bit like a miss though the power still feels real good there, It doesn't feel like a miss on a piston engine though. It's very mild. more like a vibration. Im thinking drive shaft wobbling or something. My exhaust is very loud so I don't hear a thing. It does it in 1,2,3gear for sure.
Nothing has changed on the car for several months. So I don't think it's related to something i changed incorrectly. Anyone have any insite on where to start looking, how to rule things out?
Im running 10-12PSi boost with mods in sig.

forcefed1

Don't know on the motor mounts but the PPF is good. I pulled it out about a month ago and looked it over.

any other ideas?
anyone?

Jim Calandrella

Try your diffierential mounts. I noticed the same symptoms while getting onto the highway one night. I put it up on the lift, and Dave and I at KD could move the dif back and forth. Watch your shift ****, or better yet, keep your eyes on the road and leave your hand on the shifter loosley.
My mounts are so bad right now, that the whole dif. basically vibrates back and forth at full throttle.
Good luck
Jim

forcefed1

so If the diff mounts are worn, the shifter will vibrate? I sort of figured that was more engine mounts. I suppose with a PPF they are the same. Ill take a look at them. To find worn diff mounts did you need to pry on teh diff with a pry bar to make it move? did it move pretty freely?

Jim Calandrella

The shifter will absolutely vibrate when the dif. mounts are gone. It's all connected. When I fixed my dif mounts last year, the shifter movement was cut down by at least 50%. The ones I replaced it with were fabricated by a friend, and didn't hold up. So now my shifter is moving a lot again.
The dif. mounts are nearly impossible to diagnose just by looking at them(unless they're totally gone, as mine are). Mine was able to be moved back and forth with a pry bar. Unfortunately, I didn't see what he used as a leverage point. It didn't seem like it moved that much, but the weight of the car will make it move much more than a person could.
I wish I could give you more info, but I'm not allowed near the car why'll they work on it. The mechanics that let me stay right there didn't find anything wrong. There is no easy way to diagnose dif mounts. Good luck
Jim

forcefed1

well Ill definatly take a look at them later. They have been suspect now for a while. I removed the PPF to rule it out a month a go. At that time I had a cluncking while say coming off a burn out. I thought maybe wheel hop but It wasn't as violent as wheelhop. The times it did it were more what people found to be cracked PPFs.

I suppose it's time to just find some diff bushings and replace them so I can rule them out.