musclecarfan87

Well, I just started driving my 'bird again today after two months of not driving it....I was quickly reminded of the vibration I spoke of earlier in this thread......Its not as bad until I get up around 60-70, which then its accompanied by a low bass kinda sound....kinda like the sound you hear when riding in a vehicle with big 'ol mud grip tires (the kind with wide tread).....so I'll check tires as soon as I can....could that also be wind noise? though it dies down to nothingness below 55....VERY CONFUSED

Dans87GTA

iTrader: (1)

Im sorry but im just checking but has anyone actually checked the tires to make sure they arent bad. I work in a tire shop and i see it all the time. If you really want to see if the tires are bad then take it to a shop that has a "Road Force balance machine". trust me that will find it. Or do you have any bent rims on the car, that will also cause a vibration 9 times out of 10 a vibration at high speeds is a balance or tire issue. As for the cooper tires being picky about pressure well thats because they are shitty and thats it. I wouldnt put those on my ex-girlfriends car that cheated on me. poor quality! get the tires checked and see what they say! my best advice. Later Daniel

joecautela

iTrader: (1)

Dans87GTA, I haven't read up on these particular Coopers as they were on the car when I bought it in January down in Florida. I had them set at 32lbs on the run up north. 1320mi in 21 hrs. And they were fine till I got on these rough washboards we call roads up here. At 80mph they cut thru deep water and I can crank a hairpin exit ramp pretty gd fast without breaking the rear loose or squealin the rubber. They are A, AA with a 360 treadwear, not bad. So I don't know about them being so shitty, but then again everyone's got their own ideas. And mine come from over 30yrs behind the wheel of just about every V-8 Chevy's ever put on the road. Up around here, NY, and LI and the north in general a lot of trick poly suspensions and super hard sidewall low profile tires can't handle the roads. They are potholed, washboarded, Heavy truck ribbed and just plain f-----g worn out! And that's why a lot of guys with lowered stiffened up cars are slower than **** up here because they're shakin and breakin. That's why I lowered the air pressure. That's also why I pulled all the poly crap out and went back to stock rubber bushings and I softened up the shocks. Now the suspension at least has some give and is more compliant. I've run those roads down south for years and they are sweet but each geographic area has it's own set of needs. When you want to go fast, and I mean real FAST on rough roads ya gotta have a soft/med to medium/firm suspension so everything can full range travel while the tires hold on for dear life!.

Dans87GTA

iTrader: (1)

Ya i understand roads down here arent to bad but we have our spots. i just dont like cooper as stated earlier i worked for goodyear for a year and i didnt like any tires they offered now i work for tire kingdom and they by far have better tires. Later Daniel

richm

I still have the vibration. It begins at 2300 to 2400 RPM. It will vibrate in "Park" I checked the flwheel bolts and two were loose and one was missing. I noticed the flywheel bolt holes were very egged. I replaced the bolt but still had the vibration.

I am going to disconnect the flywheel from the torque converter. If the vibration stops I am going to replace the flywheel and torque converter which I am guessing means I have to pull the transmission.

If the vibration still occures it means its coming from the engine which is bigger trouble.

Do you think I am on the right track?! Thought I had it when the bolts were loose.

Dans87GTA

iTrader: (1)

Its really not a good idea to run it without any thing hooked up to long a motor needs pressure. just to let you know i have heard it could mess something up. Later Daniel

Outlaw28

i have a vibration also from what ive been told the stock driveshafts are crap...i going to replace once i can afford...i also heard SFC's make a huge differnece so i got some of those will have them installed soon...unfortinitly my car was crashed by previous owner and i just recently found out the k-member is bent...so im assuming a big part of it...

Jproz1167

iTrader: (3)

I had started a thread about vibrations in my 1982 T/A. And my issue was resolved with a driveshaft from a true V-8 5speed 90'ish firebird.

to the guy who tried a 1 piece steel driveshaft from a 98 V-6 Camaro ... I have a good idea why that didn't cure your problem ... I've never seen a 93 up V-6 camaro that didn't have a two piece driveshaft. I'm using two piece meaning it's a true 2 piece shaft wih a carrier bearing mounted to the torque arm ... I have a 1997 3.8 V-6 Camaro and it has an aluminum two piece driveshaft. And have seen a 1998 with the identical setup. Think someone pulled a fast one on you here saying it was from a Later Camaro and thats why it didn't make a difference. And I believe LT-1/LS-1 cars had aluminum 1 piece driveshafts. So you really don't know what that steel driveshaft came from.

Also I have seen in some instances that the weight is missing. I've also heard since our steel junk has a inner driveshaft liner that these are the ultimate issue. not exactly why they are a problem but chrysler had issues with this inner liner that resulted in vibrations and noise that couldn't be traced.

richm

I separated the flywheel from the torque converter, rev'ed the engine and the vibration is there at 2300 RPM. Vibration is coming from the engine. I am going to change the engine mounts and harmonic balancer as that is the cheapest things to try. Anyone recommend a good harmonic balancer? liquid filled?

CBR1000RR

iTrader: (1)

Ok, so I think my vibration may be a pinion angle problem. No vibration when I'm on the throttle. As soon as I let off vibration go's nuts, get back on the throttle vibe. go's away. I'm thinking I may have a bad bushing some where that's allowing the pinion angle to change. Like maybe a torque arm mount. I haven't really take a good look at it in awhile. Well whenever I get some time I'll have to take a good look at everything.

novatuc

I hate to drag this one up again but I was reading a bunch of posts and someone mentioned everyone with a vibration complains about it but no one ever metions a cure. So here is the full list of what I have done to chase this vibration and what my outcome has been so far.

I have changed: Lower control arms, transmission mount, brake drums, totally different style of steel drive shaft, LS1 aluminum drive shaft, both u-joints twice, rear yoke, front yoke, axle bearings twice, shocks and struts and rear sway bar bushings. I rebuilt the rear end completely with different ring and pinions, new spider gears and all new bearings. I've checked the centering of the rear end. I had the rear axle tubes lasered for straightness and changed all four wheels and tires with a friends set. I have driven the car up to 60 mph and put it in neutral. I have driven the car up to 60 mph, put it in neutral and turned the engine off. None of the above things has made even the slightest difference in the vibration. Nada.

The only thing that has made the car vibrate less was putting in new Moog rear springs and using the 4th gen spring isolators. The vibration is now very good at speeds up to 50 mph.

The new thing I have noticed (and I don't think I'm imagining it) is at highway speeds around 60 mph, the longer I drive the worst the vibration gets. If I go for a short run, 30 minutes or so on the highway the vibration isn't too bad, but 2 or 3 hours and I start looking for secondary roads.

The way I see it, all I have left is a problem with the axles that I can't see or measure or something with the transmission that doesn't show up by putting it in neutral and turning the engine off.

The wife and I are both in our 40's. She said quit complaining and drive it, anything that is 23 years old is probably not going to ride that smooth. Do you think she meant the car?

RBob

iTrader: (1)

Fixing vibration problems can be difficult. What I do is to place the rear on jackstands with the tires a few inches off the ground. Then raise the front a few inches to match. This is so the vehicle is level. Note that the rear jackstands are under the rear axle assembly, out by the trailing arms under the spring seat.

Now start the engine, place the trans in drive (or gear for a stick), and gently run the MPH up to the point of vibration. Note how it feels, and remember it. If there isn't any vibration, let the car down and check the front tires, struts, and such. It isn't in the drive train. Also check the engine tune, a misfire will cause vibration issues. Sometimes this can be diagnosed by noting if the vibration occurs only when the TCC is locked.

If it still vibrates on the jackstands, remove the wheels/tires and place the lug nuts back onto the axles. Torque lightly.

Start the engine, place the trans in drive (or gear for a stick), and gently run the MPH up to the point of vibration.

If it doesn't vibrate anymore there is an issue with a/the wheel/tire assembly.

If it vibrates, remove the brakes drums or rear rotors (which ever it has).

(AT THIS POINT DO NOT DEPRESS THE BRAKE PEDAL).

Start the engine, place the trans in drive (or gear for a stick), and gently run the MPH up to the point of vibration.

If it doesn't vibrate anymore there is an issue with a/the brake drum/rotor assembly.

If it vibrates, pull the axles out. Note that 9-bolt and the 7.5/7.625" rears are different in how this is done.

Start the engine, place the trans in drive (or gear for a stick), and gently run the MPH up to the point of vibration.

And so on. . .

The next would be the carrier, then the driveshaft (need a yoke in the trans tailhousing for this). If it smooths out with the driveshaft removed, the issue can be one or more of three items. The driveshaft, yoke, or pinion gear.

Then diag the tans. If a stick pull it out. If an auto, disconnect the TC, then check again.

Once you find and correct the vibration, highway cruising is great. For me, once it was the differential carrier was out of balance (way out). The other was the driveshaft. The driveshaft was on the 3rd gen and started to occur sometime between 70K and 80K miles. A low miles steel shaft corrected the vibration. But not for long, it eventually came back. I also noticed that the greater the fuel load, the smoother the car was.

Eventually went to a 2000 V8 f-body shaft. Ended up being smoother cruising then I recall when the car was new. The other car got a new carrier which eliminated the vibration.

RBob.

Duratys

Well I can be added to the list as well. Same symptoms as everyone else Mine starts around 70 and gets worse the faster you go. Under load it smothes out somewhat but still noticable. I was hoping it was going to need a set of "U" joints but from what others have been saying its not going to be that easy. I need to get the rear seal changed ASAP and was going to tackle this issue then. Ill post results (if any) when the seal gets done.


Tys

RBob

iTrader: (1)

What is interesting about my '92 Camaro was that it was OK when new. From the factory highway cruising was smooth. Over time it started to vibrate, and finally got to the point where it shouldn't be driven on the highway.

The driveshaft was then replaced with another stock steel shaft with low miles on it. Again, no vibration. But after time it too started to vibrate on the highway.

What I noted is that the U-joints had grooved. What I mean is that where the roller needles ride on the u-joint arm there are divits. You can feel it by rotating the u-joint on the pivot. This I believe is what caused the driveshafts to eventually vibrate. Apparently there is little angle in the u-joints which has the bearing needles digging in at one location.

Not many folks have had much luck with replacing the u-joints. I've read here that when the shafts are factory assembled the u-joints are held in a fixture to align them. Then the plastic molding is injected to lock them to the driveshaft. This corrects for mis-alignment in the shaft yokes. This misalignment can't be corrected when the u-joints are replaced. As the wire clips are now used to hold the u-joint in place.


Posts from others that had vibration problems found other causes: a door skin that was loose at the front edge, others with the ES poly trans mount - the spacer plate raises the front of the driveshaft causing a misalignment of the angles. Removing the plate has the vibration ceasing.

My BIL had the rear differential yoke replaced to correct a vibration. That one took the dealer quite a while to find.

Younger brother had a '87, purchased new. Vibrated from day 1, was back to the dealer many times. Finally sold it as the vibration was never corrected and he got disgusted with it.

RBob.

camarorsssss

iTrader: (2)

Wow it seems a lot of people are having vibration issues with the third gens and there can be so many culprits that would cause vibration to the car. I noticed that you said you changed your transmission mount, what company makes the mount? I only ask because when i replaced my old worn mount with a poly mount, the mount was thicker than the original one and in the instructions it said to use the metal spacer plate which made the mount even thicker. My point is that after i replaced the mount i had developed a vibration that got worse as my speed went up. I went back and took out the metal spacer plate, which was throwing the driveshaft off, and put the new mount back on and the vibration was gone. I know it seems like such a stupid, simple solution, but a lot of the time its usually the stupid little things we overlook. I would just suggest you check the new mount and see if your driveshaft is being thrown off. good luck hope you find the problem.

novatuc

Well hi there Camaro RSSSS
It's kinda funny that you mention the spacer plate. If you are **** like me you feel every vibration even if it is the pavement. I've cursed this car so many times because I notice every little shake or rattle or vibration. It has really taken the enjoyment out of the car but hey that's me. I digress. The trans mount I put in is the Energy Suspension poly mount. Originally when I put it in, I did not put in the spacer plate and it didn't do anything to change the vibraton. When I put in the new Moog springs, things immediatley seemed better. So I ordered the 4th gen spring isolators which smoothed things a little more. So I figured the pinion angle must have been screwed up because of the old saggy springs. Suddenly the clouds parted. My problem was the pinion angle all along. So I put the spacer plate above the trans mount and things got worse. Like I said I'm **** and I didn't know what to believe any more. The spacer is still there, I may take it back out to see what happens. Thanks.

Rbob, thanks so much for your input. It has given me a lot to contemplate. At one point I did put the car up on jack stands under the rear axle. The vibration was still there with the wheels off which lead me to believe drive shaft, so I put the aluminum shaft on and vibration was the same. I put hose clamps back and forth and round and round on the aluminum shaft trying to balance out the problem, but all I could do was change it, never get rid of it. I know at some point someone exploded a rear end because there was damage to everything I changed inside. The only thing never changed was the axles themselves but I have measured them 10 ways from Sunday and I can't find a problem. As I mentioned before, I work in aerospace so I'm not a total newb and I have access to some pretty wild stuff. It would be pretty easy to put new axles in but in the back of my mind I'm thinking what if the axles ain't it. What's next?

RBob

iTrader: (1)

This is what I would do: remove the ES trans mount spacer plate. It is known to cause issues and is a 5 minute job and an easy task. If the vibration is still there I would proceed to placing the rear of the car on jackstands and raise the front to level.

Now pull the wheels and brake drums/rotors. Check for the vibration. Most likely it will still be there.

Then pull the axles out and check again for vibration. No need to replace them until you know they are the issue.

If the vibration goes away with the axles out then one or both have an issue. Can further diagnose it by re-installing one and checking for the vibration.

RBob.

CBR1000RR

iTrader: (1)

I still have not found the vibration, but then I haven't spent that much time looking for it. I still think it's pinion angle. I'll let everyone know if I ever fix it.

formula_pilot

novatuc,
Does your vibration change at all if you shift into neutral on the highway?

Your story of unsolved vibrations is way too familiar. Many hours of work and significant money spent, and I still have a vibration problem coming through the T5 shifter at faster highway speeds- 70-85 and higher. The vibration increases significantly (scary) if shifted into neutral or the clutch was pushed in when coasting at speed. No other noises, just bad vibration /sound through the shifter. Vibration still there if engine is shut down and coasting at 75+.

This first occurred after a large repair project where the car was apart and off the road for 4+ months. During that time I changed the pinion seal and the output shaft seal on the T5, among other things.

After talking to a few experts, the old steel driveshaft was replaced with an aluminum 2001 LS1 shaft. Unfortunately, the vibration was worse with the aluminum shaft! The aluminum shaft was checked at a driveline shop and the tech said the balance was great- better than most shafts when brand new, but he put a small weight on it to make it perfect. No luck. I bought a brand new custom aluminum shaft and the problem got only slightly better, but was very much there.

The 9 bolt rear was torn apart and even though all the bearings looked good, I installed new pinion bearings, carrier and wheel bearings with a new crush washer and set the bearing preload to spec. Pattern check looked good. Vibration still there.

When I rev up the car on jackstands at highway speeds, with the wheels off the car, it is apparent that the driveshaft is vibrating at the transmission end. The front yoke is following an elliptical orbit on the output shaft of the transmission, as if the yoke was sloppy from a worn output bushing. However, putting a dial indicator on the driveshaft did not show much run-out at the transmission end. The orbital path only occurs at speed, not when turning the drivetrain by hand. I put shims under the trans mount to adjust pinion angle – no change.

To summarize what I have thrown at the car trying to fix the vibration:

LS1 driveshaft
Balanced LS1 driveshaft
New Custom Aluminum Driveshaft
New transmission output bushing
New OEM style rubber trans mount
T5 Rebuilt, output shafted checked and less than .002” runout.
New clutch, pilot bearing, throwout bearing
9 bolt torn down and new bearings installed, bearing preloads set to spec
Removed tires and rev car on jackstands- vib still there at 75+
Hose clamps positioned on driveshaft trying to stop elliptical path of yoke- temporary moderate success, but problem is now back.
Adjusted pinion angle by placing shims under trans mount-no change
Axles appear to be straight and run true at wheel flange
New brake rotors

All that work and $ and the vib is still there.

I did measure 0.013” of runout on the driveshaft when measured near the rear end. Could 0.013” runout at the rear cause the other end of the driveshaft to flop around and vibrate? Is 0.013” within normal tolerance for driveshaft/rear yoke runout?

I am now getting ready to replace the ring and pinion in the 9 bolt, with the idea that somehow I may have bent the pinion shaft when I originally changed the pinion seal. I am not sure how that may have happened- I used a 2 jaw puller to remove the yoke from the rear end, I do not know if the puller could have bent the pinion, but I am out of other ideas at this point.

This vibration issue has driven me craze. After reading your post, I do not have much hope that the new gears will fix the vibration. What else is there that can be changed? I have had the car for 11 years, but this issue is making me want to get rid of it. I do not know what else can be done. I do not enjoy a car that I can not drive over 65mph. I also work in aerospace and the machine has to be right or it does not fly.

Any input from board members is appreciated
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novatuc

It's hard to believe that so many people have a vibration problem that seems to develop over time and no one can point to the problem.
I took the spacer out of the ES tranny mount and things did improve (I think). Reading back through the posts I noticed something in Duratys post # 63. I always take the same route after I have made an adjustment to see what it did. Up the road, merge onto the main highway for about 5 miles cut off and back home. Takes about 15 minutes. Every time I am going down the merge lane I get hopeful because there is no vibration at all. Then I settle in on the highway and the vibration comes back. Obviously in my case as in Duratys, when the drivetrain is under load from acceleration, something changes and the vibration disappears. Perhaps something to do with weight shift.

joecautela

iTrader: (1)

wierd thing happened recently. I always had a tiny vibe going at hgway speeds. Like I mentioned earlier I lowered the air pressure in the tires, 27all way 'round and it helped. Then I changed the rear out to a 10 bolt. Very slight vibe. I think maybe I imagined something. next time the car was in the air I pulled the d/shaft and rotated it 180 degrees and greased the u-joint needles and cups. no more vibes 0-100mph, rock steady. just my experience.

Azrael91966669

i have the same vibration around 70-90

ive changed all 4 tires and used differant rims also swapped in a balanced alloy drive shaft changed the rear end changed trans mounts

but i cant get rid of the problem but sometimes its not there its not rpm related its speed related as the problem happens regardless of drive shaft speed same mph with ether 2.73s or the 3.23s

4 new tires didnt fix it
a balanced drive shaft didnt fix it
no wheel bearings as the new rear was completely rebuilt all new bearings
what would cause this issue i really hate watching my dash shake from and its worse when i let off the gas it dosnt do it as much under full throttle
but will still vibrate even if i toss in netural and let it drop in rpms or if give it gas so i dont think its a mount

ahusted

Thank you so much for a very good diagnostic tree!!! That thing should be stickied!!!!!
I was a moron and didn't drive my car enough with a different set of tires and wheels and wasted 500 bucks on new tires….. My vibration is still there, 75mph and up.
I followed this diagnostic check list and found the problem must be with the pinion/bearings.
I'll let you know how I make out. I have to make a tool to assemble the pinion without using an impact wrench. (I must be screwing up the pinion bearings somehow?)
The weird thing is this is a spare rear and both rears have a vibration,(but I've had my hands in both) that's what threw me off. It must be my assembly technique that is messing something up.
I included RBobs list again!!!(I deviated a little,and included that in blue) It is a pain to do, but very conclusive.

j_dog454

Nah, I have an 87 that had a 2.8 and 5Spd, pulled em both, and dropped a 350 and another 5spd in, no change to rear end or d-shaft, and all of a sudden, shakes at over 80kph through the stick. I had that 2.8 wrapped around the speedo, ran 4 different sets of tires, ditched it once, and drove it out, ran it for years and no shake at any speed. Now, new u joints, steering components tranny and engine and it shakes like a bastard trhough the shifter.

It does it off the ground too, so it's not in the front end or an air flow problem. I will remove the tires and run it up to speed again jacked up, if it is still there, I will try the old hoseclamps on the d-shaft trick, and move them 1/2 inch at a time till i do a 360 with them. I'll keep you guys posted as to my findings. There seems to be too much of this problem and not a single reported fix that solves it completely.
Jason-OUT!

Auggie

I know this may sound stupid but I will get a real bad violent viberation at hwy speeds when I have the drivers side window down on a windy day. Has anyone else had that happen? Roll up the window and its golden. On another note I had all these same viberation proublems and cured all my viberations by going to a non-lockup torque converter. You can't belive how good you feel when you go down the road viberation free after chasing them viberations for two years.

Auggie

L69norm

Yes, had this one happen. I think there's an old TSB out for this too. The other solution for the wind noise problem is to crack down the passenger side window a bit.

j_dog454

I was talking with a mechanic this morning at my work who brought up something very interesting. I have heard TONS about this problem in OUR cars. F-bodies I mean. Im still a junior owner, but this could be something to look at.

A couple of people have mentioned that they have "heard" that Sub Frame Connectors make a big difference, but nobody has applied this theory and wrote about it. Is it possible that this vibration actually has to do with the cars being unified body contruction??

It's possible, but I personally don't think so, as most of these problems can be replicated off the ground with simply the wheels spinning. I am removing my tires this weekend, and going right down the line until the tranny is out to find where the vibe is coming from. I will let you guys know what I find.

Has anyone talked with guys that run drag 3rd gens, like guys in the really hard *** 8 and 7 sec brackets??

They pass 130mph easy most times, and if they had and killed a vibration with parts, I would love to know which ones.

-jason out.

sammaster

I can also be added to the list. I have a 83 camaro, just dropped in a 305 with a th-350 after removing the stock 173. It starts vibrating at 55 but it doesnt seem to get worse the faster i go it seems to vibrate the same, but its a pretty bad vibration. It seems like the vibration is worst around the dash area. Does anyone have any ideas that might help me solve it? I did have the front wheels balanced but that didnt do anything...

Firebird1984

Just my two cents worth... I never really seemed to have a bad vibration problem, just noticed that the car was never perfectly smooth. I had thought that was just the way these things felt on the road. Well, I happened to be at the tail end of my restoration work on this beast (1984 S/E Bird) and I had put a new aluminum driveshaft on my shopping list years ago as a possible upgrade. I finally got around to getting one from Inland Empire Driveline and boy did it ever make a difference. The car runs smoother and quieter than it ever has before. While this may sound nuts, it even seems to shift into overdrive several MPH earlier than it did before. Overall I am very pleased with the upgrade as it fixed a problem that I had just attributed to the characteristics of an older car.

j_dog454

Ok
Had a wicked bad day at the shop today. Decided to try the troubleshooting aproach where we jack the car up and systematically run it up to speed where it would normally vibrate, while removing more and morespinning components. ie. wheels, then hub assemblies, then axles, etc.

Before removing the axles however, I decided to try the old hose clamps on the driveshaft method. After moving them quite a few times, I found a spot where the vibration was very slight and didn't get worse as my speed increased. "At last" I thought, "progress". But then something really uncool happened, and I think I know where my problems are coming from.

I had a helper sit in the car and slowly run it up to 55 mph in 5th gear with me lying underneath looking around. 50/50 brave and stupid, but I REALLY wanted to know where that vibe was coming from. He hit 55, and it vibrated slightly, but I couldn't see where. He kept pulling it up until he was around 110mph THEN IT HAPPENED. The vibration went from passive to psycopathic and violent, shuddering the whole tranny and diff silmultaniously. I mean shaking the living daylights out of the works. He backed off, and it stopped, then revved it again, and wham, like a jackhammer.

We backed it all off, and turned the car off. I then got up and very gently pulled on the wheel studs with my hands, and body weight. "clunk". WTF??
I can actually pull and push the axle assembly in and out of the diff like 1/64th of an inch. Is this normal "play" ?? Both sides do it, but one worse than the other. Thinking that it may have been the hoseclamps I removed them and we tried it again, but still, at around 110mph, it shakes like a rocket trying to lift off. What the heck people. Someone give me something here. Is my rear end effed or what??

-jason OUT

joecautela

iTrader: (1)

j dog 454, I thought my rear was whacked too! Does the same thing. Mine's a 3:23 10bolt posi. It's been in about 3k mi. I talked to some folks and they said don't worry, but I'm not sure and am going to talk to some more experienced people. But in the meantime I've done a bunch of other things that have created and solved some vibes.
-one is I had the car changed over to the T5 setup.(It's an '88 Iroc) It's already got headers and I pulled the cat too so w/ the T5 the whole car lightened up quite a bit and was standing about an inch or so taller than stock. It was just floating over the bumps! I figure that the camber changed a bit too. but before messing with that..
-I changed the front brakes to the Ed Miller LS1 setup. While in there I cut 3/4 of a turn off the front springs. This lowered the car back down to just under where it was stock w/ the auto tranny. At the wheel wells the car is now 26 1/4" off the ground. About an inch lower than before. But now the car is just a hair lower in the front than the rear..and there's a slight vibe in the rear above 65. I'm thinking the fr to rear weight distribution is off just a bit leaving the *** just a little light. So I'm gonna whack a 1/4 turn off the rears to start with and get the rear settled down so that the ride height is even. I'm thinking this will cure it..I hope. Then an alignment just to dial in the camber..

syc0path

Add me to the list too... I've thrown lots of $$ and parts at it, but still no luck. Here's my post from the Suspension forum:

https://www.thirdgen.org/forums/susp...tion-88-a.html

syc0path

This got me thinking... is it possible that deteriorated subframe connectors could allow something to sag and change the pinion angle? If that was the case, u'd get the same vibration even if the car was up on jack stands. The fact that the vibe is better while we're on the gas and worse when we let off also would tend to indicate a pinion angle problem.

An ez way to test this would be to put the car on jack stands, but w/ the rear jack stands on the frame rather than on the rear axle. Then u could put a jack under the rear axle and raise it up and down while the rear tires spin. Maybe the vibe would get better or worse as the angle changes.

I'm really inclined to believe that it's a problem w/ something deteriorating, becuz it comes on gradually and worsens over time. I've also noticed that it seems to change depending on the weather or how long the car sat since the last time I drove it. If it was simply something out of balance, it should always be the same intensity.

I know a lot of people change the subframe connectors to improve handling... can we find out if any1 who has changed the subframe connectors has this vibration problem?

Auggie

Go to "Tranmissions & Drivetrain" and click on "Drivetrain Viberation! what could be causing " Read posts #11 and #34. I don't know if this is your problem but it sure worked for me.

Auggie

richm

I swapped my '99 TA DS into the '84 and put the new 3.5" alum DS in the '99 TA and the vibration was greatly reduced in the '84. It did not go totally away but you really have to be looking for it to hear it. A left the 3.5" in the '99 TA beacse it changed the feel of the car so much I really liked it. Many local guys feel I should try a good fluid based dampener

syc0path

Well this is exactly what I tried this weekend. The vibration remained at all levels thru-out the travel of the rear suspension. However, while the axle was moving up or down, the vibration temporarily went away. It seemed like moving it interrupted the vibration. So I don't know what that tells us, but that's what I found out anyway.

Guest

More likely is the driveline angle, reading all this and a few other posts tonight. Seems most of the people with a problem are running the Energy Suspension tranny mount, known to be taller than stock. Couple that with worn engine mounts and you've made it worse. I'd suggest getting a stock mount or running some spacers and maybe longer bolts on the trans x-member and see what happens then.

1tinindian

I have been reading this thread in hpes of finding a solution, but instead, I'm here to just add what I have done, without stopping the vibration.
I bought my 83, back in 1988, an she was pretty much stock at the time, other than the fact that the converter had been removed.
The viration is, and has been for years, like so many of you have described.
I start to notice it over 50 mph, and gets worse with speed.
70 is bad, but 75+ gets worse yet.

Now, my list of changes:

4 different sets of wheels and tires.
Stock steel d/s with new u-joints.
Custon replacememnt steel d/s.
2002 F-body aluminium d/s.
3 sets of ring and pinions
2 different sets of axle shafts.
new Auburn differencial
1997 F-body rear disc brakes
2 different trans mounts.
Entire engine swap.
New engine mounts
new flywheel
new pilot bushing
new clutch
new throw out bearing
new trans tailshaft bushing and seal
completely different torque arm and mount
new shocks and struts
new springs
new steering brace
new subframe connectors
new exhaust.

After all of these changes, the vibe is still there.
The car does it even on stands, and coasting at speed in neutral or with the clutch pushed in.
It vibes no matter what gear I'm in, either.
It is NOT rpm related.

The last hing I can think of is a possible problem within the transmission itself.
Ishits fine and makes no strange noices, but when it vibes at speed, the shifter buzzes something terrible, leading to think that the transmission is at fault, for one reason or another.

I just wish I had a known "good" transmission to swap in, to eliminate that as a possible cause.
Anybody have a spare T-5 they'd like to loan me?? LOL!

The search goes on, and an answer to our problem would be a godsend!

Leon

syc0path

I don't think it's the driveline angle -- see my post above. The vibe remains thru-out the entire range of suspension travel (and therefore over a wide range of angles).

But... I suppose a way to test that would be to run the car while up on jack stands and gently jack up the oil pan and see if it changes anything. Then the same thing could be done on the trans pan. My car is put away for the winter... any1 in a warmer climate wanna give it a shot??

royslsbry

I had a vibration in a 88 chevy truck i messed with the drive shaft trans mnt rear end changed shocks changed rims nothing helped and one a guy told your problem is in your harmonic balancer or flexplate I changed the flexplate no help changed the balancer and all my vibration went away I couldnt find anything wrong with the old one but when I changed it what a suprise no more vibration

Guest

You're not changing the relation of the two though, you're just moving the suspension through its normal travel but havent changed the relation of differential angle to drivetrain angle, just the driveshaft angle.

syc0path

I'm not following... can u explain that a bit more? Since the driveshaft connects the differential to the drivetrain, how can u change the driveshaft angle w/o changing the drivetrain angle?

northeaster79

novatuc I recently got my first 3gen car and I had the same kinda vinration in my car,being a mechanic I checked everything from joints to drum,alignment,rearend and mounts,then I tried a new exhaust.vibration/noise is now gone.sound crazy?I never figured it would work but it needed a better system anyways so I thought why not.

syc0path

Yeah we've already discounted the exhaust vibration theory.

Guest

Relative to each other. I'm attaching a couple pictures, exaggerated and not what you want your car to be but rather just to explain in general.

First pic, trans and diff parallel but not at same elevation from ground level, notice no matter where the diff is (ignoring arc motion of rear), the angle from the driveshaft to the rear and driveshaft to the trans is identical even though its angle relative to the ground has changed.

Second pic, trans and diff not parallel and not at same elevation from ground level, notice no matter where the diff is (ignoring arc motion of rear), the angle from the driveshaft to the rear and driveshaft to the trans is the same 5 degrees off even though its angle relative to the ground has changed. What I did here was rotate the engine/trans combination 5 degrees around the connection to the driveshaft... in other words where the front yoke u-joint is.

So while you've moved the rear up and down, the angle between the engine/trans and the rear differential has not changed. If they started parallel, they end parallel, if they started 10 degrees off, they end 10 degrees off... no matter where the rear is. I'm ignoring the arc motion of the rear but thats not relevant since in either case the motion is the same. If you have the engine/trans at a different angle because of something like an energy suspension trans mount its entirely possible you've thrown the alignment of the engine/trans to the diff out enough to cause problems. Its just a guess, but I've never had a car do this and I've never run that tranny mount. I can also think of quite a few complaints related to that particular mount and its known to raise the back of the trans fairly significantly so it may just be that drivetrain angle is the root of the problem.

syc0path

Thanx for the explanation -- that makes sense now! And my idea of jacking putting the car on jackstands and then gently jacking up the trans and engine should be able to test for that. So... any1 in a warmer climate wanna give it a try??

richm

Well I discovered a number of issues - thank goodness I found a guy that knew what he was doing. My 2000 RPM vibration - new tires, alum drive shaft replacement and other attempts - nothing worked. What I had was a weighted flywheel (not correct) one bolt attaching it to the torque converter (someone messed with it), a torque converted that had thrown its weight, clutches in the tranny about to go and a rear end rebuild that was botched badly (bad gear pattern and misaligned).

Its all fixed! quiet, smooth, and a joy to drive. This problem was two fold and expensive to fix but I am glad it is resolved.

syc0path

Well I finally got my car out this weekend, put her on jackstands, jacked up the engine/trans slightly and... no difference. At least when I raised and lowered the rear end w/ the jack, it interrupted the vibe temporarily. But jacking on the engine oil pan or the trans oil pan did nothing at all.

Hmmm... now that I've thought about it some more, I probably should have removed the rear trans mount so there would be some free play and I could have raised and lowered the trans more.

I also noticed a lot of gear noise coming from the rear axle... I didn't do that when it still had the original. Guess I'm gonna have to swap the original back in

syc0path

Well I tried this too... my dad had some spacers for the trans mount from my mom's old '72 Impala, and they fit! So I put a spacer in, tightened everything up, and tried it up on jackstands. Putting 1 spacer in made the vibration worse, and putting 2 spacers in made it a lot worse. Still, it didn't change in frequency or any other characteristic -- it was the same, just more intense.

So I figured I was in the right area, and I started thinking about going the other way -- instead of raising the trans w/ spacers, what about lowering it down? So I took out the crossmember bolts and put some washers between the crossmember and the body, thereby lowering the back of the trans. Lowering it a little or lowering it a lot didn't seem to make any difference -- the vibe was still there and it was the same intensity as always.

That was the last idea I had to try. So, I am officially stumped now and so is every1 I know and every1 I've talked to on the internet So if u have any ideas that haven't already been tried (and it's a LOOONG list, so please check it carefully before u suggest something else) or see any flaws in the way I tested something, please let me know. I love this car to death and I want her to run like she used to.

Auggie

See post #84.

Auggie