bensbaby

I have a 1988 GTA Trans am . 5 speed 5.0L tpi
225000kms in it .
My parents bought this car brand new and im a mechanic and im lost i need help.

Its been well maintained. I grew up with the car and ive inherited it.

It had the trans rebuit back at 200000kms ish.
It has a few new clutchs.
A new used rear end off of a automatic gta with the crappy 3.32 ratio. I think the 5 speed ratio was 3.53 or something like that.

It has lots of mods. bolt ons.

it was runing mint...smooth right up to 200+kmh

zero vibrating.

I tried to race this nice red non turbo porche and he rapped me lol and i was in 3 gear flooring it and the rpms are climbing and at 4000 ish rpm the car just started shaking violently....
no bang...no grinds
it shakes worse 80kmh up 120 its so bad that the dash and rearview are shaking like crazy

i thought right away i blew the new clutch.

so i took it to the local gm dealer and they said it could be the cluth or the driveshaft u joints...
so 450 later they put 2 new u joints in it and re balanced the whole driveshaft. made nooooo difference...so they told us it was the clutch.
then the car went into storage for 2 years.
i got it out this spring....it needs calipers and stuff...
new battery etc.
i got it runing it passed etest lol.
and still vibrating like crazy tho 80 up.
in neutral doesnt shake at all...clutch in or our no shaking.
only under load
and we had all the tires balanced up to at the dealer so its not tires.

could it be the rear end????

could it be a motor mount????

i have the energy suspension trans mount and the bar mount that goes to the rear end.

I just spent the last 3 days taking the tranny off the car and replacing the clutch with a brand new one.
i also had to change the clutch master cylinder which was a pain in the *** LOL
but i got it all back together....shifts mint...drives mint...but still vibrating like crazy ...
im sooooo mad at myself...im getting soooo frusterated....
i did what the gm mechanics told me to do and not fixed...

If its a broken gear in the rear end would it cause vibrating?? why is it not grinding.??
or maybe a blown bearing or a bent axel or something.
god its making me crazy.
please gimme some advice.

I love this car. I will never get rid of it.

Im rebuilding both cylinder heads in 1 week to fix the oil buring issue the PUFF when you start it

could it be the rear end??

the car has red tubular rear control arms. with the prothane bushings.
panard bar too... it was a kit.

and new tires..
ads super chip.
cat back exhaust.

intake ...
tps air foil thing..
new struts and springs.
we had a new floor put in it at a body shop a few years ago....super expensive.

it has a ton of new parts. tons

and it starts right up and runs mint.. except this crazy vibrating issue....

as soon as i hit 120kmh i start slwoing down because something is wrong its shaking like crazy.
and i tried 4th gear and 5th gear same vibrating.

thanxs !!!!!

bensbaby

shocking i figured there would be a ton of posts on this.

here is what i know so far.

i pulled the rear axels out of the rear end and i have a 3.23 posi 9 bolt rear end.
the used one we bought for the car a few years ago replaced the broken gears inside the 3.55 10 bolt rear end.

i had no idea it was a 9 bolt.

apperently its bigger ring gears so and 28 splines wich make it stonger.

anyways...both rear axel bearings had a ton of up and down play like crazy....im in the middle of changing then in the driveway.
Its pretty big job...

but i got them both out and confirmed 28 splines.

and both bearings were gone lol
i have to order the seals...i get then tommrorw am.

ill let you all know how it goes.
I hope this was it.

i did the motor mount test this am and it barly flexed at all.

hellz_wings

iTrader: (2)

28 spline axles were the better type that came with the 9 bolt differentials.

As for your vibrations, it could very well be the driveshaft. I had that problem and I just bought an aluminum driveshaft (you can get an LS1 camaro aluminum one for cheap and it'll do the trick) and the vibs went away more or less. Then I changed the tranny mount to a prothane one (NOT energy suspension poly one, this raises the tranny height and vibrates, trust me I've went down that road). The prothane one eliminated any vibs as well.

Also check to see that your tires are in good condition and VERY importantly your alignment must be up to spec. The stock alignments on these cars are just crap, these specs are good if you can it adjusted this far:

Camber: -0.75* on both sides
Caster: 5.0* on the driver side, and 5.5* on the passenger side
Toe: 3/32 is good for the street which equals to 0.09* of total toe (this is toe IN, NOT toe out!)

I listed the things in the order that my car was affected the most, so driveshaft (around 100$ used) then tranny mount (cheap at like 25$), and then alignment (not too expensive, around 80$). Should cost around 205$.

Good luck!

EDIT: Just read that you tried to balance your driveshaft and it didn't fix the problem. The fact is that aluminum weighs much less than steel so either way the aluminum ones vibrate way less anyway, it's a good upgrade if you can get a good used one. I'm still putting money on tranny mount or alignment or a combination of both.

jmd

iTrader: (4)

I'm glad you found the problem. Your post could be helpful to others in the future.

If a compression check is good on the engine, consider just replacing the valve guide seals. Those regularly go out after about 100,000km and do exactly the start-up smoke that you describe.

bensbaby

I bought the sold tranny mount and the torque arm mount but i think it was energy suspension...but after i installed it it didnt vibrate at all....i drove it for 2yrs untill i was racing the porche and broke something wot in 3rd gear...no grinding no smashing just crazy dash shaking vibrating....
anyways heres what happened so far lol.

I ordered the rear axel bearings for the 9 bolt...more money than 10 bolt...and the seals to 2 x the price... and the 9 bolt diff cover gasket...
i had to borrow slide hammer...

i was under the impression that i had to take the diff cover housing off to take out clips so i took it apart to find no clips lol...then i relized i had a 9 bolt.
so the all you have to do it get the rear discs off and 4 bolt take the caliper holer thing on the axel tube...easy part...
i smashed 5 studs with the huge sledege hammer lol... and i had to buy new ones and replace them...
then i slide hammered them out it worked mint...the just come right out.

Then i grinded very very carefully all the old bearing race of the axels. pain.
Then i took them into midas here for 20 $ they pressed on the seal then the bearing then the bearing retainer thing on both mint !!!... i was happy took them home reinstalled everything...
was putting the diff cover back on with the new gasket and letting the silicone stuff dry a bit before i put all new oil in and the guy from partsource comes to my house and tells me that the driverside rear seal is the worng one. LOL.....

OMGGGGGGG

they had a mix up and ordered me 2 passeger rear axel seals...

the issue is the seal is under the pressed on bearing and the pressed on new coller.

arghhhhh....

i will have the proper seal tommorw, but geez... can midas unpress that bearing and collar without destroying a 35$ bearing????

im sooo mad...

it was just one of those days...but the passenger side is all back together rim on and the diff cover gasket can cure over night...but i was dying to see if this cured the issue....
any ideas?

bensbaby

also i have a 5 speed trans...are you saying i can swap in a alum driveshaft bolt in from a 6 speed manual ls1??? is it better??

bensbaby

also this car did the puff smoking thing since it was 2 years old...my dad took it back under warrenty and gm dealer told him it was normal. LOL...i woulda made them fix it .
im gonna do the heads....225000kms im sure there cakedddddddd in carbon and crap.
do you think i can get away with doing them myself...or will i need new valve guides....
i got a head set and it came with the 16 valve stem seals...
i can clean the valves and lap them with the compund and the lapper tool i have
do you think i can save the money...?

bensbaby

something also worth mentioning .... i jacked up the car on the rear end and blocked of the front wheels and got a friend to let it out in 5 th gear... the whole car started doing the crazy vibrating thing 120kmh with the front blocked off not even moving...so at least i know it has nothing to do with the front wheels....
i think the rear axel bearings will solve the issue but ill let you know hopefully this time tommrow

hellz_wings

iTrader: (2)

If you have an energy suspension tranny mount it could very well be that, or part of it as I mentioned above. It raises the tranny height which changes the pinion angle and could cause vibrations. Tranny mounts are cheap, if what you're doing now doesn't fix it i'd try that next.

bensbaby

so i changed all the axel bearings and put new oil and everything.
jacked up still got friend to put in 5th gear and get it up to 120 again and still vibrating like crazy...but all the noise in the rear end is gone....the bearings were gone...just not the issue causing vibrating.
i got under it and held the rear end....its not the rear end making the vibrating.

i got under and the tourque arm is vibrating like crazy where the tranny mount is....bad.

im 99% sure i got a energy suspension tranny mount in there si i ordered a stock tranny mount from partsource 9 $ lol...here this afternoon.

im gonna change it like you said...its worth a shot.....

i know i have a energy wavy bushing in the torque arm thing to...but partsource cant get it...ill try the 9 $ mount its easy to change.

otherwise....wth could it be.?? engine mounts maybe still???
im kinda getting irratated LOL

hellz_wings

iTrader: (2)

ah don't worry you will find this problem soon.. It has to be something. The stock tranny mount should fix it if it's that, although rubber tranny mounts aren't that strong, it should last if you don't have too much TQ.

TQ arm is vibrating? Is the torque arm loose? Could be a bushing where it connects to the tranny tailshaft, or could be the tailshaft itself, also check the bolts that connect it to the rear end. Also check your driveshaft for play as well (up and down and side to side movement, it shouldn't move at all).

bensbaby

ill check for play in the driveshaft...but like i said i think its vibrating most right where the trans mount is.

i just did the clutch becuase thats what gm dealer told me was next on the list.
they said the disc was blown casuing vibration
but it wasnt and i put a new clutch kit in it anyways a week ago...so everything is tight as hellll....
im gonna try the tranny mount this aft and when im underthere im gonna see if there is play like you said.

i think it might be the pinion angle or whatever you said. could i not use 4 big washers under the tranny bracket where it bolts to the frame...to act as shims and shim the pinion angle a bit to see if it helps.??

i lowered the car 1" in the front new springs...i cut half a coil.
new non cut springs in the back...
so it sits a bit lower in the front than rear and i was told it could affect pinion angle .

i guess i will let you know how it goes this afternoon.
im just getting so frusterated...im getting a migrane LOL

bensbaby

i just look at all my old pics and i found the pic of when i bought the stuff.

its a prothane trans mount.

and energy suspension torque arm mount .

so what does that mean?

hellz_wings

iTrader: (2)

The prothane worked for me but I am not lowered, so you could have had different results. I've had an energy suspension one and that vibrated alot for me. Try installing the rubber mount that could make a diff and it's not a big job.

bensbaby

i got a new stock tranny mount made no differene (((

the i checked for up and down play in the driveshaft where it goes in the rear end no play....
then i cecked for up and down play in the driveshaft where it goes into the tranny and im shocked...there is a tiny bit of up and down movement.
what does this mean??? output shaft bearing for the tranny is gone??

it was rebuilt 20000kms ago, and there is a tiny bit of tranny fluid leaking out of the driveshaft seal prob because the bearing is gone in there????

xX89RSXx

iTrader: (1)

There is supposed to be some movement of the yoke in and out of the tranny. This is so when the rear is moving up and down over bumps. Hold the yoke and move the driveshaft, see if there is play now, may just need new u-joints. As for the leaking, it may be the seal.

bensbaby

There is no play in the u joints there all new and the whole driveshaft was prof ballanced....by gm dealer tosole this issue and did nothing. they told me next clutch..which i did but was fine and did nothing...
but the tranny input shaft and output shaft has some up and down play in it....considering it got rebuilt 25000kms ago i dismaissed it figuring it wasnt a issue.
there is up and down play at the output of the tranny where the seal is leaking...and when i drianed the tranny oil to do the clutch it looked murky but i fugured it was from being in stogage for 2 years.
god im pissed off LOL...mannnn i swear .
i love this car but im getting mad.
and

on the driveway i put it in 5th gear and held it to 170kmh and the vibrating was so bad i was under neath it and the whole tranny is vibing so hard right near the output shaft..... i got a new stock mount there didnt do anything.

It has to be the friggn tranny....

Im mad. i wish i could takeit back and throw it in that rebuilder guys face.

25000kms is pathetic.

im gonna tear it out again and take the tranny apart....
there is some bearing kits on ebay for 100$ shipped.
im pretty sure i just will need the input and output shaft bearings.
but when i open it up i can tell.
the rear axel bearings didnt change anythiing except there is no noise coming from the rear end now...and no play up and down.
but grrrrrrrrrrrrr

WhiteKnight1990

I have been having the same issue. my my car was smooth as glass up to 120 mph untill I had the tranny replaced with a rebuilt unit and had the rear rebuilt. Thought it was the driveshaft. went through 3 steel and one aluminum. vibration was less with the aluminum. tried different mounts w/ no change. adjustable torque arm. no change. changed clutch 3 times, no change. I think my trans is messed up as well after reading this. Mine is a t5 as well. when in neutral it sounds worse than the one I replaced. I also hear chatter from the tailshaft when I go in reverse. Mine vibrates the worst at about 70 to 75 mph and up. can really feel it in the shifter. Let us know what you find out.

bensbaby

ive been rebuilding the heads to fix the oil smoking issue .... did you all know that all 16 exhaust valve stem seals were missing like completly gone???? the 16 intake ones were tere but hard and brittle and falling apart...
i have rebuilt tons on motors and i have never seen seals missing?? whats up with that i took pics for god sakes..
as far as the tranny goes...i still have to take it all apart..i just so pissed at it right now...maybe there is a bent shaft inside the tranny like maybe the shaft bent slightly who knows.....all i know is theres up and down play in the output shaft where the tranny meets the driveshaft...thats bad apperently.

Alex83z28

I have a 83 z28 and i put a rebuilt t5 in it and its vibrating bad I've checked wheel bearings drive shaft u joints diff etc and still shakes I was wondering you found out what was wrong with your car