1990 350 tpi. Okay well i bought my camero about a month ago and when i first had it on the road if i got over 3500-4000 rpms id get this massive vibration. At first it seemed like it was coming from infront of the dash....then it seemed more localized to from near the transmission like right beside my right leg but you can feel it through the shifter ****. My friend also said when he sat in the back he could feel the vibration too so ive had a tough time pin pointing it. The sort of vibration was similar to something turning over ie drive shaft it was like you get the heavy vibration for a half second and then off for a split second back on for a half second off for a split so the sort of vibration from something turning over (if you dont understand ill try to explain better)....the tranny mount bushing is still there and i replaced the u joints but that had no effect. Now the problem has gotten much worse to the point where i get the vibration during all acceleration and deceleration. Its really weird because it seems fine at first but as the car warms up it gets worse and worse and worse until the point where it becomes totally undriveable.

I took it to my mechanic and he took just a quick look at it and told me i wasnt getting the proper current coming off the alternator and that this would effect my computer and how it operates potentially causing the vibrations. Heres a couple of things.....one doesnt the computer just pull from the battery so even if the alternator isnt working at 100% shouldnt my battery just drain slowly i wouldnt think this could effect my computer. Second any way in hell the computer could cause this sort of problem because i really doubt it. Third my mechanic has been for a ride in it and knows what the problem feels like and im 99% sure it has to be drive train related.
Any chance it could be because of the alt.?

If youre still reading this thank you. Anyone have anything to check possibly towards the rear end of the car? i also hear a slight whirring coming out of the rear end but i think it just needs new gear lube. Any tips for things to check i am greatful for im at a loss and think my mechanic is a crazy man so hes not much help.

 

start with the u-joints. Sounds like a worn joint. If not look to the tranny mount. If it is poly, you "may" get more vibes than a stock rubber one. just some ideas

 

well it sounds like your mechanic has got some good stuff, but i wouldn't take his word for anything.. if it where me i'd check the ballance on all the tires and drive shaft if it isn't the u-joints like irocnroll was talking about

 

thanx for the tip i had that written down in my post but its buried somewhere in the middle. I have the stock rubber trans mount bushing and replacing the u joints turned out to be a big waste of time/money/effort. As far as the balancing i doubt it because the tires on the car are worn very evenly but anything is possible ill get that checked out. Anyone got any other tips?

 

Bent or warped driveshaft maybe.
Any whine coming from the diff? If so the rear is going.
How are your tires and rims , check the balance.
Also check the supension parts .
Check the harmonic balancer as well.

As for the alternator suggestion I suggest you find a new mechanic, stupidest thing I've ever heard(well almost).

 

i just pulled the driveshaft to do the u joints and there wasnt anything noticeable but i guess it could be slightly warped. Ill take my car in and get everything balanced/aligned.

what exactly does the harmonic balancer do?

 

Think it just needs gear lube...when i do swap the fluid how can i check to see if the rear end is going? i guess this could be my problem. How does a 10 bolt handle a 1990 tpi with headers/shift kit/3.73 gears? Could that give a 10 bolt some problems?

 

Sounds like you'll need to get the drive shaft balanced. I just got over this same thing myself....when you stated you replaced the U joints, that clenched it. Do a search. lots of info on this.

I'd try another mechanic. The guy you have now seems like he's on a wild goose chase!

 

yeah this guy seemed real good at first but im losing respect for him by the second. i want my car back asap. Ill get everything balanced and aligned and see what happens.

Im just going to ask again so it doesnt get lost how do i check for a rear end thats about to go. What should i be looking for internally or just shreds of metal everywhere. I ask because i get a slight whirring comming out of the back end but it is quiet, only at part throttle and doesnt sound too serious.

 

What is you mechs name and number? I need a hook up!

 

since your mechanic has actually looked at and done some trouble shooting i'd suspect he's right. even if he isn't right about the source of the vibration you would still need to take care of the problem he told you about and you can hope it takes care of the "vibration". posting on one board usually works too. in the future pick a board and post there and not everywhere.

 

I'm not sure if i trust the mechanic is the thing he was also saying oh my fuel pump might be going my car wasnt getting enough fuel pressure and my car was performing really well. I can take my car somewhere and get the alternator tested and see if my mechanic was being an idiot or not.

As far as posting on two different boards i actually went to delete the other one within about 10 minutes (there werent even any posts yet) but it said i wasnt allowed too. If you would like to please feel free to get rid of the other post.

 

reason you can only edit and not delete your threads is because people would or could get an answer to their question and delete it and not have anything for others if they did a search with simialr question or problem.

 

fair enough.

Anyways couple more questions. It was sugested to me that i run it until it gets hot and the problem acts up then put it in neutral and rev it up and see what happens. This way i can at least localize it to the front or back half of my car...i plan on doing this tommorow when i can get the car back.

Assuming i localize it to the back which i think i will where do i go from there. I will take it and make sure the drive shaft is balanced. I plan to change the gear lube in the rear end. What should i look for when i do that to see if the rear end is going.
Ill state again for anyone who missed it its not the u joints. What else can i check on the back of the car that might cause this kind of vibration?

 

Vibe causes I'd suspect: the slip yoke on the front of the drive shaft, the bushing in the trans that the yoks plugs into, loose pinion nut, trashed pinion bearings, or a damaged drive shaft.

Sounds to me like your mechanic needs to stop sodomizing himself with his head, and use it to think with instead. The alternator can't cause a drive line vibe. It wouldn't take much smarts to be driving down the road with the car doing its thing, and take it out of gear, and see if it goes away; that would pretty much rule out things like how the engine runs.

 

I have had such a problem in the past and it was my torque converter. It would act up anytime I the trans downshifted before I pulled up out of a curve or something like that (it was a couple of years back) but it all went away with a new converter.......

 

i guess it could be to do with the convertor but im thinking more and more its probably not transmission related....I am giving my mechanic a chance to redeem him self i told him to stay the hell away from the front of my car lol and told him to take a look into my rear end to see if he finds any damage in there. If he does ill check it out and decide what im going to do. If there is no damage then i start checking the tranny area.

 

A friend of mine has the exact same problem. He has gone through the trial and error crap, and balancing the tires helped but didnt fix the problem. Then he did some more stuff and nothing fixed it. He pretty much has it narrowed down to the tranny, which is a T5. It does it in all gears but is worse in 4th gear and it happens at about the same rpms as yours.

Could you possibly have any tranny problems?

Good luck

 

my car could most definitly have some tranny problems. The one thing i worried about was that the car has a shift kit in it and the previous owner just had someone do all of the work for him so he doesnt know what shift kit is in it. This worries me because the car has a B&M shifter and from what i have heard the B&M shift kit eats 700-r4's for lunch so if it is a b&m i might have a problem. The ****ty thing being that i dont plan to stay with an auto trany so i dont want to throw money away getting it rebuilt and i dont have the money right now for a t-56 so if it is the tranny i might end up having to garage the car until next summer...thatd make me cry...anyways ill know tommorow or wednesday if its a problem with my rear end and if its not then i have to move on to the tranny.

 

So, does the vibe go away when you're driving down the road and put it in neutral, or not?

If it doesn't, then it definitely isn't the converter, or anything else in front of the trans. A shift kit pretty much can't be responsible for any kind of vibe, without the trans being so trashed otherwise that the vibe would be about the least of its problems.

 

Why do you think it's not the U joints??? Because they're new?
That doesn't mean squat. If you did a search, you'd already know that the way the factory installed the original u joints, as compared to the C-clip replacements you installed, are totally different. Get it balanced.

 

i dont think you mentioned if it was an aluminum drive shaft or not....the front and rear u-joints are not the same size, at least their not on my 88 gta...hope this helps........

 

I havent had my car back yet its still at my mechanics so ill not know until tuesday or wednesday. The question about the shift kit is that the harder shifts would put higher strain on the rear end and i was wondering if this could account for possible damage in the rear but if it is my rear end my mechanic will let me know by the end of the day.

I highly highly doubt its an unbalanced drive shaft because it gets worse as the car warms up. When the car is cold i can drive normally and have no problem but after a few minutes when everything gets warm it gets really bad where under breaking and acceleration its really noticeable. The heat issue made me think that it was the u joints at first because its bearings. The heat factor is now whats making making me think it could be the rear end where things are spinning and getting warm and the heat would only make it worse if there was a problem.

EDIT: and how are they any different. My drive shaft had u joints that were the exact same as the ones as i put in but i dont think they were stock ones. I'm thinking that my drive shaft is probably aftermarket because my rpo codes dont have the aluminum drive shaft option.

 

hehe that was a fun experience. Yes they are different from aluminum to steel and let me explain how i know this. My friend was convinced that the drive shaft was steel because it had some rust on it (must be an aluminum alloy) so we ordered u joints for a steel one. The ones for steel are both the same and the front one for steel is bigger the the front one for aluminum so it straight out doesnt fit. I couldnt figure out for the life of me why they were the wrong parts until i realized the fact that my drive shaft was aluminum.

 

lol......my friendly auto parts guy asked me if it was alunimum and i looked at him like a cow looking at a new gate..[country humor] ...i had no idea they were different, i heard this driveshaft didnt come with all gta`s. but im glad mine did...

 

OK...If it's only a warm engine problem then I guess U joints won't fix it.

What I meant was not just the diff between aluminum and steel drive shafts, but the difference in the factory installed U joints vs. what you're replacing them with. Check this out...but again, doesn't sound like what I had...https://www.thirdgen.org/techbb2/sho...hreadid=189254

 

This thread has gone on for a LONG time with only ONE person actually starting to hit on the correct issues, and that would be RB83L69.

You need to get the car back, drive it until it vibrates, throw it in neutral, and idle the engine. Does it vibrate? If so, it's the slip yoke, u-joints (I know you replaced them), drive shaft, or pinion yoke/shaft.

If NOT, stop the car, and rev the engine. Does it vibrate? If so, it's an engine problem or trans/converter problem.

I think your description of the character of the vibration is good, but now we need to pin point the specific condition that causes the vibe. Otherwise, it's a guessing crap-shoot. Can you do the above mentioned test.

And please don't listen to anyone who recommends following your mechanics advise. I think your mechanic has issues. Your computer should opperate fine down to 6-7 volts. Your FUEL pump may not but the computer should be fine. And you're right, the computer gets it's power from the battery.

 

cool ill be able to do the tests tommorow (so no one else bother giving sugestions unless you have something really different then shats been sugested). Im going to call my mechanic first thing tommorow morning and he should be able to tell me if it is because of my rear end tommorow. Either it will be...problem solved. It wont be....i start problem solving. Or he hasnt gotten to it yet and i go give him a kick in the *** and get my car back. Either way ill have some new info tommorow morning. Thanx so far for everyone whos tried to help me and as well to the ones that have actually been helpful. Ill update in the morning.

 

UPDATE
Well i got my car back from my mechanic (will tell about that after) and ran the tests that were sugested. Drove the car around for a while until the problem started. Got it in my drive way and put it in neutral. Revved the engine up and around 3500 rpms i started getting the vibration. It was a little different unstead of it pulsing it was a solid vibration but that should just be attributed to the fact that my drive train was not turning over so i have basically pin pointed the problem to my engine.

The problem is a bit worse now. When the engine is at idle it rocks back and forth pretty good. I dont think there is anything wrong with the engine mounts i just think its just because i have a 350. When you get on the gas the engine stops shaking and goes pretty normal so i think all is well there.

As far as the problem with the engine im thinking one of the problems is i might have a leak on the intake side of my engine. When you get on the gas it feels like there is a slight sputtering and the car doesnt feel like it has all of its power. I had pulled off the plenum and egr and i think there is a chance the leak would be coming from the plenum due to some issues putting the plenum back on.

However that i know has nothing to do with my vibration problem because i had the vibration problem before i took anything off the car it just wasnt as bad.

My mechanic couldnt figure out what was wrong and said to take it to a gm dealership repair place because they have some scope? that he doesnt and some other stuff so they could better evaluate the problem. Any tips for things to check for the reason of my problem? What could cause a large vibration coming from the engine at over 3500 rpms?

(the problem i had when i put on the plenum is me and my friend are idiots and tightened it from front to back not from the middle out. Had some other problems but nothing that could be attributed to a vacuum leak.)

 

ttt

 

is your mecahnic a "real mechanic" or some guy with a little knowledge and a few tools? i'd run compression, vacuum, and cylinder balance test to start with.

 

Not to disagree with our illustrious moderator...... I think I would go after the vacuum leak first. In a feedback engine management scheme, a vacuum leak can have some rather serious side effects. It is possible that the leak "developes" as the engine warms and parts expand. Causing the condition he is seeing. It is a simple enough check, just spray with WD40, brake cleaner/carb cleaner, or some such chemilcal at every available gasket surface. (and there certainly are a lot of 'em on TPI) If a scan tool is available for use, it will also provide a wealth of info, the data will change as the problem gets worse.

Good luck, and let us know how it turns out.....

 

allright thanks for your help guys. The guy is a real mechanic. The thing is i have a feeling that the problem is something internal and that it might be something you can only truly get to the bottom of by tearing apart the engine. I am also not completly sure about the vacuum leak the engine just sounds a little weird....the mechanic who the car was with b4 said he did a compression test but never told me the results hes kind of sketchy some times....nice guy....but not the best mechanic. Right now the car is at a mechanics where my friend actually is a mechanic (although he really just mostly does simple jobs ie replacing lights, oil changes etc but he can still keep an eye on my car for me) and he says the guys there are pretty good so theyre going to take a look i think on monday didnt have time today and tell me what they come up with....hopefully something cheap to replace but ive noticed with the third gens it never is =( oh well hopefully itll all be figured out soon....thanx again for everyones input.

 

Doug, good job on the test. Now we're learning some specific things and like you said, we can stop waisting our time speculating about the driveline, and now concentrate on the engine.

The vibe could be mechanical, or it could be cause by a malfunction such as a bad plug wire, vacuum leak, clogged injector, etc. But again, before everyone goes off on time waisting speculations, lests narrow it down a step further.

If I were you, and I wanted to know if my vibration was originating from a drivability problem, or from a mechanical problem inside the engine, I would again, warm the engine up to the point were it is vibrating, rev it up to say, 4000 RPM, and kill the ignition. If the vibration persists as the RPM's fall past 3500, then I would say that we have a mechanical problem. If it is now as silky smooth as a decent V-8 should be, then we more than likely, have a misfire that we need to diagnose. So that is the test I would do next. You may have to repeat it several times. to get a good feel as it sweeps down past 3500. The other thin you could do is to get it warm and vibrating, find a good down hill stretch, get the car going 3500 RPM down hill (probably in second gear, or you'll be speeding), and kill the ignition. JUST ONE CLICK!! so as not to lock the steering column! Letting off the accelorator should kill teh fuel supply compleely and achieve the same results, but jsut to be sure, cut the ignition...one click. Then get back to us!

Sorry I tookk so long to respond. I was out of town. Good luck with your next "session".
-Tom