3rdgenmaro

iTrader: (9)

Yes, another vibration issue thread. This one for a peace of mind, a little reassurance, additional ideas, and a place to document resolution.

My 88 Camaro has a pretty bad vibration. It is speed related. Comes on around 65 mph, peaks around 75 mph, then is almost gone near 85 mph. 4th gear or 3rd gear, no change. So that should rule out engine and atleast most of the transmission.

700r4, 3.73 gear, 275/40r17 tires.

Vibration shakes the car and has a hum to it. Don't feel it in the steering wheel, its more of a full car shutter. Dash pad rattles, passenger door rattles, driver seat, etc. All research I had done pointed to the driveshaft. I took it to a place and had it spin tested, they claimed it was good.

Car needed new tires, replaced them, had them balanced, no change in vibration. Also needed front wheel bearings, replaced them, no change.

Couple weeks ago I jacked the car up and listened to the bearings in the rear end, all were quiet. Checked the driveline angle. Its good. Double checked the U-joints at the same time. Everything is tight. Checked the rear axles while it was jacked up to see if one appeared bent. Both appeared to be fine.

Im starting to get lost on what to do. I have 2" wheel spacers up front, which I would think you would feel a balance issue with them closer to 50 mph and not 70.

Driveshaft shop could have BS'd me and never checked it.

Also read that a bad rotor could cause this? Not sure on that one though.

Any suggestions? At this point, I could swap to a different driveshaft, but if it is a natural frequency issue, another stock steel driveshaft may have the same problem and cause me to start looking elsewhere. Then again if I was to find a stock aluminum driveshaft and the vibration moved to a higher speed, I could confirm it was the stock driveshaft causing it. I could put new brakes on the rear, but they really don't need it yet and I don't want to throw parts at it. Do I bite the bullet and pick up an aluminum shaft and swap it in? That's what Im leaning towards.

Thanks

Bob88GTA

iTrader: (2)

Does it vibrate when you throw it in neutral at those speeds or continue?

3rdgenmaro

iTrader: (9)

It continues. Only difference is the exhaust note.

redneckjoe

i would try another tire shop and have them balance the tires again. if anything, for piece of mind. use a good reputable shop.

is it possible to take the wheel spacers off just for a straight line test?

3rdgenmaro

iTrader: (9)

At this point, no, but in a couple of weeks Im going to try that. Two tires off my dirt car should be able to go on without the spacers.

But you did make me think. Our suburban had a vibration at 65 that ended up being a misbalanced tire. I had forgot about that. Seems like people usually claim ~45-55 mph is usually tire related, and I had automatically jumped to driveshaft. Especially with as many threads on here with driveshaft vibration issues at the same speed. Maybe I shouldn't rule out the tires.

redneckjoe

if you got new tires, the red dot on the tire should line up with the valvestem. it has something to do with balancing that a tire tech should know about. there are some newer more advanced balancing machines out these days too.

a few years back i had a similar issue with brand new tires. i went to a different shop and the tech noticed a bent rim right away. he ended up using the older bang-on weights to help compensate because you can put the weights on different sides of the wheel, where most shops use the stick on weights inside the center of the wheel. eventually i changed the wheel. but glad i found an honest and knowledgeable shop.

i hope its something that simple for ya.

paulo57509

This. You might want to try moving the wheels to different locations on the car. This should tell you if there's an issue with the wheels/tires. Better yet, you can substitute the spare in each corner and road test.

Kind of off-topic...I just happened to see a BMW in the parking lot today. It had three rows of full lengths of stick on wheel weights in one location inside the stock wheels. No tire place worth a dang would ever mount and let tire that was that far out of balance out of the shop.

RBob

iTrader: (1)

It is probably the driveshaft. When they spin test them the u-joints are straight, not angled as they are in a car. The shaft is balanced but the u-joint bearings are knurled.

There is something not quite right with the stock drive line angles in these cars. When new my car rode smooth, even at high speeds. Over time a vibration developed. So I got a low miles steel shaft (stock) and swapped it in.

Car was now smooth again. But, as before over time it again started to vibrate. It was so bad that I didn't even want to drive the car over 45 MPH.

So purchased a new aluminum shaft from GM and installed it. Back to a smooth riding car.

The u-joints in the two steel shafts are rough feeling. Just rocking them a little back and forth shows the roughness.

RBob.

RBob

iTrader: (1)

The dot on the tire designates the lightest side of the tire. Placing it adjacent to the valve stem allows for using the lowest volume of balance weights. If the dot and valve stem aren't lined up the tire can still be balanced, just likely to use more weight to do so.

RBob.

P.S. for a bit of trivia, motorcycle tires are also marked. But they are marked as the heaviest side of the tire. So the dot goes opposite of the valve stem.

Abubaca

iTrader: (3)

I'm gonna throw some of my NON expert 2 cents into the mix.

I got a similar vibration around 65/70 mph when I lowered my car. I adjusted the torque arm/DS angle to the -3* that everyone discusses, measured it countless times, and no fix. 2 driveshafts, a 700r4 and T5, 2 set of tires, and 2 sets of axles for the 9 bolt through the years, same vibration.

Recently, while installing my new engine and Tremec TKO, I found a cool post showing driveshaft angles, and how (within reason) it wasn't the ANGLE that causes vibration/damage, but rather DIFFERENT angles between the rear and DS, and DS and transmission. The more angle you have, the more the rotation "pulses", and the same angle on the other end acts to compensate. ...a DIFFERENT angle...while still minor, can transmit that "pulse". I had NEVER checked the trans to DS angle over all the years. Now they were out of the car so I'll never know, BUT....I checked my current set up, and sure enough, when allowing for 3* of elevation under load, my angles were different. I spent about 2 hours of adjusting and checking, and now, when under load, both ends are "about" 1* from straight. Little less actually. ....and no vibration. silky smooth right through 60s and 70s, on up through 80s

Here's that vid.

https://www.youtube.com/watch?v=Idk3BVDVHq4

This wasn't a scientific experiment properly documented of course, and I can't be SURE...without ANY doubt that this caused my vibration, however through all the changes, I never check both angles. ....and once I DID check...no problem. I'm inclined to believe that was it. ...and while some posts about DS angles discuss trans to DS angle....by far, most do not. Even some "professional" shop videos on the subject don't discuss this.

akanitro

iTrader: (2)

I had the same problem. Replace the transmission mount. I went through the process of replacing the driveshaft with a brand new one. Adjusted pinion angle as the vehicle is lowered and does have rear lower control arm relocation brackets, replaced all tires and road force balanced all tires myself. When that was all done, still had the vibration. I replaced the transmission mount with a urethane mount and there was too much angle and did notice that my mount(even though only a year old was somewhat collapsed. Replaced the transmission mount and vibration was 99% gone. Other option is never go 65-75, only faster. LOL.

glouie99

I installed an rebuilt 700r4 at first no gears then drive worked and now all gears are like drive, except park, any ideas

paulo57509

Since your question is off-topic with respect to this thread, it would be best to start a new thread with your question.

3rdgenmaro

iTrader: (9)

I appreciate the additional responses.

Took my dad for a ride yesterday so I could get additional ears on it. He agreed it sounded more like a driveshaft then a wheel balance issue. Rbob and Abubaca may both be right. Trans mount is fairly new and looks good, but at this point I aint rulling anything out.

For anyone curious as to why I still lean towards driveshaft, its all due to the frequency. It just seems like a much higher frequency vibration then the slower tire vibrations Ive felt in the past.

I'll post up on down the road as I tinker with it. Ive got to get it fixed because its bad enough I don't want to drive it above 60.

damage31

I've gone through 2 transmission mounts in my weak little 3.1 V-6. Each time it went out, it was a bit different.

The first time it went out, it was like you say - anything above a certain speed ~50mph or so there was a 'seat of the pants' mild vibration that got worse as you went faster. at 65mph it was noticeable and by 70 or 75 you could hear the hum and feel the shake good. I figured for sure it was either my rear end or the driveshaft.

The 2nd time (just this past fall) when it went out, I had a clunk on acceleration like a hammer was hitting the tunnel. I figured for sure the torque arm bushing up front had finally let loose due to the cars age, but when the shop said it was the tranny mount again, I was in disbelief. There was no vibration this time, just a hard loud clunk under acceleration.

3rdgenmaro

iTrader: (9)

Mount is in good shape, but since it is Poly Im sure that is helping transmit the vibrations more, but since the angles are good, I don't think it is the problem.

I haven't done anything with it yet. Any normal driving I do is below 60 so it isn't that much of an issue. Been putting my free time into other things at the moment. I'll post up as it goes though. It is something that will be fixed. Just wont be within the next couple of weeks.

3rdgenmaro

iTrader: (9)

I came across a good deal in a factory aluminum driveshaft. It will end up in my dirt car eventually. However, I plan on swapping it in my 88 this weekend to see what it does to the vibration. I really hope it changes.

Tootie Pang

iTrader: (2)

That should do it. Had the exact same problem on a 5.0 Mustang with shorter gears. I went almost insane trying all the same things you did. Aluminum driveshaft solved it 100%.

3rdgenmaro

iTrader: (9)

Well I put the aluminum driveshaft in. Granted it is a used factory one. U-joints felt good.

Vibration started with the steel driveshaft at 65. Aluminum one it moved to 73 mph.

Feels alittle smoother under normal driving, but that could be placebo affect.

jmd

iTrader: (4)

you can put an app on your phone to tell roughly what frequency is occurring. Wheels/ tires are going to be a different freq. than a driveline. I wish I knew the app. and settings off the top of my head for you. But you're getting closer. . .

Tootie Pang

iTrader: (2)

Try re-indexing the driveshaft to the pinion flange. Just unbolt it and rotate it 180 degrees and reconnect. Take it for a ride.

You are bringing back all kinds of bad memories for me. I went through almost all the same steps you did. Except in my case, the aluminum driveshaft did it.

The driveshaft is the only high-speed unsecured item on these cars. The rear axles and gears are all running 3.73:1 slower and do not have universal joints.

The only other thing I think it could be is a tire.

A couple other questions:

1. Does it do it on all road surfaces?
2. Are you able to affect the virbration by feathering the throttle? (very light drivetrain load).

3rdgenmaro

iTrader: (9)

I'll try and re index it and see what happens.

Does it on all roads Ive been on at the same speed. Doesn't appear to be tied to road surface.

I'll check the feathering here in a little bit. I do remember putting the car in neutral and having the same vibration.

Tootie Pang

iTrader: (2)

GOTTA be that driveshaft. I'm in this until this gets resolved. It's personal- that's how nearly insane I went.

3rdgenmaro

iTrader: (9)

Yeah small changes to the pedal and on/off the gas only makes a small change in the pitch, but the overall shake/roar is there and stays similar overall.

It will be a long process, I dont have to drive that fast very often, so Its not a rush to fix. I'll keep this thread updated as it goes.

Abubaca

iTrader: (3)

Did you ever confirm you trans to DS angle, and your DS to pinion angle??? You acknowledged my mention of it, but you didn't say if you checked it.

3rdgenmaro

iTrader: (9)

I checked it, but honestly dont remember what it was right now. IIRC the tailshaft and pinion were within 1 degree of parallel. But I dont remember what the driveshaft itself was.

I'll check it all again next time Im under it. I had begin to question it myself. Im running the ES poly mount and a couple years back I removed the extra flat plate that comes with the mount. I remember at the time it was an attempt to stop the vibration, but I cant remember what changed when I did.

redneckjoe

if it was a driveshaft vibration, do you think it would occur at a different MPH if you stayed in 2nd or 3rd gear?

if it still stays at the same MPH in a different gear, i'm guessing tires.

sure hope you get it figured out.

Tootie Pang

iTrader: (2)

No. The driveshaft is tied to the wheels through the axle hence it is tied to roadspeed. Vibes will occur at the same roadspeed regardless of the gear.

3rdgenmaro

iTrader: (9)

Right, which it does.

Weather is going to be nice Friday. Im going to double check the angles on everything and clock the driveshaft.

Mikes86transam

Did you ever figure out what was causing the vibration? My 87 Camaro is doing the same thing.

NoEmissions84TA

iTrader: (1)

It is the wheel balance. You can test it for yourself. The vibration will have harmonics, meaning that you will feel a harmonic at about 35 mph, then again at 70 mph, then 105, 140, etc. The 70 mph one is the biggest PITA, because this is highway speed. So you have to try to drive in traffic at either above or below this speed. Not really possible.
Years ago I had a Chevy Monza with this problem. My father knew the owner at Firestone. So I asked him to give a call and ask what it would cost to balance a wheel (I had a good idea of what wheel was causing the problem). He said $20 for the set of 4 wheels. I marked each wheel for position and took them off the car, and brought just the wheels there. So I had all 4 done. Then I put them back on the car the same way that they came off.
The next morning I got on the highway on the way to college, and like 3rdgenmaro said, the dash was vibrating up & down, the door panels were going in & out, and it peaked at about 65-70 mph. Above and below that speed, it was less vibration. So now all 4 wheels were out of balance.
After weeks of having the wheels rebalanced and rotating 1 wheel off each day with another set I had, I had the vibration better but not gone. BTW, Firestone started claiming that the rims were bent. I was so pissed off with this that one afternoon I got out of class early and the traffic on the highway was light. I was trying to figure out the vibration yet again, but was driving like a maniac. About half way home, a gray Mazda MX6 GT Turbo with dark tinted windows was following me and mirroring my driving the rest of the way on the highway. I actually was impressed with his driving. Just before the last exit, I took it up beyond 105 mph, testing for that 3rd harmonic. As I was slowing down, I saw the gumballs and flashing lights. That Mazda turned out to be an unmarked statey with a German Shepard in the back. The officer said, "Pack up your stuff - you're coming with me!". I didn't even try to give him a story, I just said OK. He went back to his car and it was taking a while, so I realized he was writing a ticket instead. I walked up to his car and told him why I did what I did.
He did write the ticket, but in the end it got squashed because my uncle was an officer and he extended a professional courtesy. WHEW!

Mikes86transam

After reading through the posts I decided to re index the driveshaft by turning it 180deg. Took it for a ride and no more vibrations. Took it all the way up to 100mph and nothing. Still can't believe it. LOL

3rdgenmaro

iTrader: (9)

Glad that worked for you. I havent done much since. Car has had a steady increasing oil leak that I decided to finally fix. So right now I havent drove it in a while.

sofakingdom

iTrader: (1)

The simplest smartest thing to do, is to figure out up front, whether it's at wheel speed (wubbawubbawubbawubbawubba) or drive shaft speed (hmmmmmmmmmmmmmmmm).

The 2 speeds are something on the order of a factor of 3 to 4 apart. (3.23, 2.73, 3.42, 3.73, etc.) Not hard to put your finger on that. Drive down the road, find a pickup truck or something with wheels that aren't too vastly different size from yours and they have a blotch or patch or spot or whatever that you can see, compare it to your own vibe.

Obviously yours is/was a drive shaft problem. Glad you got it fixed without further $$$$. Gotta warn ya though; sooner or later, more likely sooner than later, it'll be back. Whenever whatever part that's loose, loosens up some more. I'd suspect either the extension housing bushing in the transmission (about $1) or pinion bearing in the rear (more $$$). If I was the guessing kind I'd be guessing the ext hsg bushing in the trans but that's just a guess. Frankly if it was mine, I'd go ahead and spend the $1 and fix that; I'd say there's a 60 - 70% chance that for $1 and about an hour of work, you can slay it forever. (well, for many many years, anyway...)

3rdgenmaro

iTrader: (9)

Yeah Sofa mine is in the driveshaft. When I put a stock aluminum ds in it changed speeds on me.

I didn't know about that bushing, but you are right, pretty cheap. Next time Im underneath it, I might swap it out anyways. Doubt it was replaced when the trans was rebuilt.

Tootie Pang

iTrader: (2)

I've been through all this. That bushing isn't going to help. Try flipping the driveshaft at the axle.

3rdgenmaro

iTrader: (9)

That's the plan. After I replace an oil pan and timing chain gasket.

Longshot08

I too have recently experienced this problem, except my vibration started at about 40mph and got worse up to 65-70mph. Whole car would shake including the steering wheel. I started with a whole set of worn out suspension components that I have steadily replaced which I'll list in order.


1.Transmission mount (was completely shot and would cause transmission to bang)
2.Shocks/struts (all completely shot, would not rebound at all when compressed)
3.End links (all completely shot... obviously)
4.Tires balanced (this FIXED the major part of VIBRATION)
5.Replaced differential fluid and added a oil additive (unrelated but I had catching/popping at low speed turns)


Now major vibrations are gone except a very slight (and I mean very slight) vibration at 75-80mph. Haven't been able to isolate it to road surface or go faster yet because fuel pump died before I could do more investigation. I suspect a problem similar to your car, 3rdgenmaro in the driveshaft. I experienced the same problem in the past with an 85 Z-28 but I can't remember exactly how I fixed it and don't want to post bad info.

3rdgenmaro

iTrader: (9)

Its been a long time since Ive put anything on this thread. Havent done anything to fix the vibration other then just drive it. (highway speeds, not interstate)

But this week I came across a good deal on an Inland Empire driveshaft. I was looking for another stock aluminum shaft for my dirt car, so I couldnt pass this one up. The inland empire one will be going in my street car. Im curious as to what changes to the vibration this does. Should find out next week.

RBob

iTrader: (1)

The poly trans mounts are a known problem. It would be worth it to get a stock rubber one of the new driveshaft doesn't work out.

RBob.

3rdgenmaro

iTrader: (9)

Actually have 3 on the shelf that I got a good deal in for my dirt car. That's the next thing I'll change after I get the DS in. Just taking me a while to get it.

I did learn one important thing. Just because a U-joint cross references to another brand, that doesn't mean the other brand will fit! Bodies were different and wouldn't go in. Delay after delay!

91Z28fan

Dealing with a vibration right now. My '91 Z/28 with manual trans has a vibration that feels like it is coming from the rear axle. Put to and two together and remembered both passenger side rims were bent/warped prior to my ownership. Replaced them with factory stock correct rims checked for warpage and none. Purchased new tires online and had shipped to my mechanic whose shop does tire mounting, balancing and alignments. The car could not be aligned as there is a discrepancy between sides. I did a little digging and ran across a website Dan's Driveline in NV and read where a big enough impact with a curb that warps a rim can also bend the rear axle housing which is not that uncommon and which can cause a vibration. That is where I am currently. Hoping a local axle shop can straighten it and if so with no heat applied.

zed-028

Did you ever figure it out?

91Z28fan

Hi and thanks for the interest. Well, not really. One front motor mount was cracked so replaced both. The transmission mount was separated too so replaced. I just picked the car up last week and when I asked the mechanic about the alignment again, he said the rear axle housing being bent was what he suspected early on, but it aligned fine, just the camber is out a little. So I am going to take it to a specialty shop that only works on front and rear axles here, in Chattanooga. I talked with the owner and he said they can put the car up and take some measurements to determine if the rear axle housing is bent. The guy I talked with said it's actually better to look at the rear axle with all the guts in rather than just a stripped housing. He said if it's s out, it can be straightened. At that point, I will want to know "how" that is done and how much heat is applied. An old drag racer told me it's not uncommon to tweak a rear axle housing in racing and he knows the owner on an old school frame shop that has straightened several for him over the years. This is my first experience with a T-5 too and even though the car only has 77K original miles, I think the transmission input bearing might be bad. It's always something, but the good news is I drove it yesterday when it was brutally hot with the AC on and it never reached 220.

3rdgenmaro

iTrader: (9)

I have had electrical issues and haven't swapped driveshafts yet. Whenever I solve mine I'll post up.

91Z28fan

Well sorry to hear about your electrical gremlins. Yes, I hope you will keep us updated as I think we all gain knowledge from each other. I forgot to mention that my driveshaft was bent so replaced with an aluminum driveshaft after a local driveline company attempted twice to make one so just went ahead and refunded the money.

3rdgenmaro

iTrader: (9)

Finally got the new driveshaft in. It made a big difference. There is still some vibrations in the car, but the big vibration that would shake the car at 75 is gone. Got a rubber trans mount that will be going in soon. Curious how much more that cuts out. I'll post up on the difference it makes.

Longshot08

Update on this problem. I still had the slight vibration at 70-80 MPH. It is now fixed as far as I can tell:

1) New tires (still had the same vibration at that speed range)
2) Indexed the driveshaft. This SOLVED the last of the vibration issue in that speed range.

I will probably replace all the wheel bearings sometime soon since I'm sure that has never happened during the life of this vehicle but the only thing I really "feel" at those speeds I think I can attribute to road feel transmitted through the steering wheel, which is so slight I think I'm imagining it. I'm completely used to driving my soft spongy Denali with no road noise, feedback, or creaks its hard trying to determine what sounds/feels wrong and what is just normal for this car. Calling it fixed for now until it breaks.

Javies86z28

no one cares about your story. We're simply trying to figure out what's causing this issue

Aaron R.

Lol. New guy who just joined this month and has a grand total of 4 posts tells the guy with over 4,000 posts that no one cares about his story and that "we" are simply trying to figure out the issue. Guess he didn't read the whole thread, or the part about how the OP fixed his problem (thanks to input from the forum members).

I'll save you the long read, it turned out to be largely driveshaft related but possibly something else unknown contributing.

(Also, this thread had been dead for about 3.5 years until today)