88GT vibrating! --> not the usural deal..

[Danish88GT]

When i drive faster then 30mph she starts vibrating a bit, not much but enough for it to bother me.. we have tried changing the wheels with no change.
last night we tried to change the driveshaft to an aluminium one - no change.
We checked the U joints and they looked fine. - also looked at the engine & trans mounts they also look nice..
Does anyone have an idea of what could be wrong? Engine is purring like a cat! - should i check the trans? (auto AOD) or am i looking the wrong places?
could it be the 8.8 rear end?
any thoughts are apreciated!
thx
Jonathan

 

[FrdMustangCpe]

the driveshaft could be outta balance. do you have gears?

 

[Danish88GT]

hmm

the driveshaft could be outta balance. do you have gears?

We already tried a whole other driveshaft.. made no difference.. !

what do you mean - do i have gears?

Sorry, i'm danish not that well up to date with all english terms..

 

[wrathchild]

I just finished tracking down a vibration/shudder in my car. Had the rear end gone over, put in new ujoint, rebuilt the tranny. Finally when i was replacing the clutch i pulled off the pressure plate and out fell my pilot bearing. Must be my problem.

 

[tmoss]

Cehck the harmonic balancer to see if the outer ring has shifted or the elastomer rubber is comming out from betwen the inner and outer ring..

 

[HISSIN50]

We already tried a whole other driveshaft.. made no difference.. !

what do you mean - do i have gears?

Sorry, i'm danish not that well up to date with all english terms..

what he means about gears: people often replace the stock ring and pinion gears in the rear end (differential) with numerically higher gear ratios. doing this often exacerbates previously unfelt vibration problems.

i might try rotating the aluminum driveshaft 90* to see if it helps. though the driveshaft is probably balanced, the entire drivetrain needs to be balanced - so if the DS is slightly out of balance, rotating it can help with vibes.

good luck - and your English is great.

 

[Danish88GT]

good luck - and your English is great.

Thx! much apreciated!

Well the car i'm talking about isent mine yet, ive talked to the dealer and he's promised to make the vibrating go away.. but here its very hard to find people who know about Mustang's since only 1% of the cars on the roads here are from the us!
I've sent him an email to check the harmonic balancer.. i hope it turns out to be it..
regarding gears i dont think they have been replaced, but since i have only driven it once - and never a model like it before i dont know how the 5.0 preforms with stock gears.. i'll have to count the DS/wheels and find out what the gear ratio is..
I'll keep you posted.. also throw some pic's in here when i get it..