AT9T/A

I have an 89 TPI 305 with a 700R4. The car has 85k. I have noticed a slight vibration that begins at around 1500 rpm. It becomes more noticeable as the revs increase to about 2100. It will do this in Park or neutral so it's not driveline or balancing issues. I am swapping plugs and wires in the morning and I am hoping that this cures it, but I doubt it! The only thing I can think that it would be is a motor mount that is separated. I have replaced my trans mount twice because of breakage, but never any motor mounts. What do you guys think this could be? Any help would be greatly appreciated!!

19doug90

ahh hearing that problem scares me i had/have a very similar problem that ive been chasing for months.... for me engine vibe above 3500 rpms....eventually got so bad i couldnt drive it...took it to a couple dif mechanics with no conrete answers. Finally traced my problem to a dead injector...thought i did at least....took the car out and the problem was sooooo much better but not still completly gone....I think my tq converter might be going out but im not going to replace it because im going to do a t-56 swap in the summer and right now i can still drive it hard but i get a slight vibe. Sounds an awful lot like youre dropping a cylinder....happy hunting.

iroctpis

I've had a slight vibe in my car since I got it, I've done a lot of stuff to fix it and it was still there even in park etc.. etc.. So I read about the mounts and decided to look at mine and sure enough the pass. side was sagging to the bottom, so it was metal on metal. I replaced it today, here is my post about it. The other mount is fine but I will replace it anyways since it is original. After I fixed it I started the iroc up and reved it to 3k and it felt smooth unlike the past 6 years where you could feel the vibe around 2500rpm's. I'll test drive it tommorrow and hopefully no more vibes! I've only replaced and done pretty much everything you can do to solve the vibration so hopefully its smooth now.

Here is a side by side pic of the bad and the new mount.

http://images.cardomain.com/member_i...280_1_full.jpg

https://www.thirdgen.org/techbb2/sho...hreadid=200855

iroctpis

well after changing the mounts I still have a vibration around 2500rpms. The mounts made a little difference but they needed to be done. Im going to test my flexplate next then check compression. My harmonic balancer looks fine while its spinning but I won't rest untill get rid of the d@mn viberation.

SpeedyGeek

iTrader: (2)

Did you ever get rid of the vibration?

SpeedyGeek

iTrader: (2)

I had my torque converter replaced with a stock replacement for a vette, the vibration is now gone.

skinny z

I've been chasing this problem for a couple of seasons. Still no solution.
Checks my posts under vibration. Let me know if anything helps or you have any other possible solutions.
Next up is a new driveshaft ( not the problem because of the vibration in park or neutral ) and a new exhaust. Maybe a new set of LT headers and an exhaust (Hand crafted by a true fabrication artist. You have to see this guys work!) will make a difference.

SteelTownMadDog

iTrader: (2)

I also have a sort of "harmonic" vibration at 2000 RPM. I installed a new harmonic balancer without any change. I also have the flywheel machined, and checked, and everything was OK. Also added a new cluch...still a vibration. It happens in neutral or with the clutch pushed in. Very annoying.

I've conceded that the engine was probably not balanced when it was rebuilt (before I bought the car).

skinny z

Here's my list. All parts that had to be upgraded anyway but still no solution.
Fluidampr balancer
SFI approved flexplate
new OEM engine mounts
polyurethane trans mount
torque converter
another torque converter
complete engine balancing
replacement trans
went over every possible point of contact with chassis, bodywork etc.
Car is heading to the shop for different headers and exhaust as well as an upgraded driveshaft.
Here's hoping!