Suggestions with vibration...

[Teknik]

I have a 1979 Coupe with an entire 1986 conversion.
Swaped EVERYTHING. It has been fine and perfect for ever now.
Last week it started a strange vibration only when in gear giving
throttle. very noticable cruising in 5th. But absolutely nothing is
vibrating when in 4th gear. It runs perfect there. It doesn't matter the speed
or RPM. It's always there but not there in 4th. Driveshaft looks good and is
tight. engine is smooth, idles great. I can coast and it is fine.
Like I said, only in gear I get the vibration. Oh, and the efi system
was switched out for a carb setup. but that was done a long time ago
along with the motor swap.
Help and suggestions please !!!

 

[rigamaroles]

I've got the same problem. In 5th only. I'll stick around for this one.

 

[Teknik]

TTT Anyone?

 

[iwashmycar]

if the gear is the only variable i would guess its tranny related. Mine has a vibration from 65-75 in 5th, but it is NOT the tire balance (ive had them rebalanced many times). i was leaning to the DS, but then i thought maybe the A-arm bushings may be loose when cruising as the higher speeds. That probably doesnt help, but its all i got lol

 

[1fastsn95]

hmmm...only in 5th? Like "iwashmycar", my 94 had a vibration @ about 65-75 mph. Horrible. I tried a few different things but to make a long story short, I got an aluminum driveshaft and it stopped. Now, about a month later, i have some kind of grinding noise(sounds like DS rubbing bottom of floor) when there is a load in the car ei; someone in back seat, full tank of gas. I believe that is coming from the Trans, maybe the tailshaft. But back to the basic question, I would try an aluminum DS and see what happens. Also, check to see if your tailshaft is leaking. The bushing may be bad also(the bushing MIGHT fix it) Good luck!!

 

[Teknik]

Just FYI....

I fixed the problem. I had this wierd feeling that told me to pop the hood.
And sure enough, I had a spark plug wire fall out of the wire holder and was
arcing out lying on the exhaust manifold. Replaced the wire and got new
wire holders, and it's perfect again. So look under your hood first.
Thanks guys !!!

 

[1fastsn95]

youre kidding right?? Well at least it was a cheap fix!!