I have a ’69 Camaro 396, Muncie 4spd, 12-bolt Posi. I purchased the Camaro about 80% restored. I have some serious clutch chatter, occasional throw out bearing squealing and heavy vibration after speeds above 65 MPH. The throwout bearing squeals when cold and the clutch pedal vibrates. The clutch disk likely was contaminated with oil in the past. The vibration is not engine RPM related. It occurs at speed and is present when in neutral coasting at 65 MPH or above. Drives me nuts.

I have recently rebuilt the 12-bolt rear end (Mark Williams Enterprises), purchased a new/balanced drive shaft, new u-joints (upgraded to larger 1550 u-joints), new trans mount and had the M21 transmission rebuilt. I have verified that my pinion angles are correct. Tires and Rims are new and balanced. I have verified that the engine frame mounts are correct for a big block. I can't tell if there is a problem with the stock engine mounts but they physically look ok. I recently replaced the wrong SB trans crossframe with a correct BB trans crossframe. The BB trans crossframe is offset a little to the passenger side and it was a real bear getting the M21 to lign up with the bolt holes.

What could be causing this vibration?! Any recommendations??

Thanks,

Joe
Littleton, CO

Have you balanced the tires yet? Also make sure the rearend is up and tight to the frame.

check brake drums lol i had a long affair with my camaro years ago.

same problem and found a chunk out of the rear drum.

Is this vibration happening in all gears or just in neutral? If it's not engine rpm related, is it speed related? Does it do it when accellerating, coasting and deaccellerating?

I am still guessing driveshaft issues here but stranger things have happened such as a bent axle (which would be felt all the time at speed in all gears). Could be an output bearing on the Muncie even tho rebuilt because they do that when not under load and bad.

The best way to isolate this is jack the back up and run it up to speed where it does it and then look and FEEL for the component that is doing the vibrating.

One other point. Why is the BB mount offset? And...how much in degrees?

BBC were installed closer to the pass side of the car to avoid the steering box. The pass engine mount is thinner in height than the driver side frame mount. The crossmember moves the trans over to the pass side by 3/4(?) inch to keep the centerlines parallel with the car.

Vibrating clutch pedal means the diaphram in the pressure plate is warped do to heat or abuse. like you suggested, the clutch disk may be oil soaked. anyway, your post reads like a clutch system replacement is in ordr. Don't forget the Z-bar ball studs, and throwout fork.

Is the vibration felt in the steering wheel? Front axle problem.
Is the vibration felt in the seat of your pants? Rear axle problem.
Is the vibration felt in the gas/clutch pedals? Engine/trans problem.

Good ideas given here. Mine is this: Jack up the car on stands. At the rear axle, remove one wheel and replace all the lug nuts to keep the drum on the axle. Doing all five nuts will keep the balance on that side, plus since you have posi, this next ebent will keep the clutches from burning out. Now, spin the remaining tire up to speed, make mental note for later use, and notice the balance of the tire/wheel combo.

Substitute another tire/wheel combo and check balance. Do all four tires this way. This experiment will show if any tire/wheel combo is out of balance. You suggested you have a balanced set, this will tell.

While spinning the rear tire, look at the driveshaft to make sure its spinning on-center.

And Welcome to the Club!! I hope you enjoy your membership here.

I hope you have better luck than I did. It only took me 20 years and then it was indirectly. It had an annoying vibe around 70. When the tires and brakes wore out, I replaced them. A couple years latter I decided to go with new rims. Then I put in a new engine and tranny. In the process The drive shaft was shortened and balanced. You'd think after all this, it would be gone...nope. So after leaving half the rearend on the street one night I replaced it. Wallaa... gone. It'll now cruise with the speedo buried smooth as can be. Now I'll have to go after the bump steer... indirectly of course.
Good Luck!!

Thanks all for the input. I forgot to mention I have new tires and rims and I had both the tires and the drive shaft double checked for a good balance. Rotating the tires makes no change. I bought the Camaro with a Moser 3:73 12-bolt in it. I had an original '69 Camaro 12-bolt housing (correct stamped numbers) powder coated, rebuilt, new brakes and components and new drums. So with a newly rebuilt original equipment replacement rear, I had the same problem.

The vibration happens at speed only. I can get going down a hill at 65 MPH and pop it into neutral and feel it in the seat of my pants. Feels like in the transmission. Also, when at 65 MPH (or above) if I feather the throttle up and down slightly I can feel a vibration come and go if feather the gas right at the point between the transition between coasting and accellerating.

Yes, I know I am due to the clutch replacement so as soon as I have saved up enough I will get that done right. I am sure it is in pretty bad shape.

Reds69camaro, man, your story is bumming me out... :(

She is a pretty beast though. I'd like to post a picture but looks like I don't have permission to post any attachments.

Joe
Littleton, CO

Could be as simple as a pilot bearing in the crank for the tranny input shaft,or out of balance clutch assembly.

Doug G,

That sounds encouraging! I have been trying to find out and I have been told that anything forward of the transmission input shaft is always spinning with the engine. So I have always thought that since the problem is not RPM related, that the problem had to be from the M21 trans and back (which has ALL been replaced now). If in neutral and at speed, what is spinning forward of the M21 input shaft?...Sorry for my ignorance here. I have never worked on this part of the drive line.

Joe

If in neutral and at speed, what is spinning forward of the M21 input shaft?...


The front wheels... Any chance you're picking up a front end vibe? Maybe a slight wobble in a rotor (or drum)?

When you replaced the rear end, did you change the drums?

You mention the motor mounts look ok..but are they the '69 style interlock mounts? 67-68 motor mounts will fit on '69 frame brackets. They are wider and thinner than correct '69 mounts and are a sloppy fit. This allows the engine to move around, vibrate and cause clutch chatter.

It is not easy to detect but if the balancer is quite close to the sway bar or there is any gap between the mount and the frame bracket I'd say you have the wrong motor mounts. The correct mount is a very tight fit on the bracket.

I am sure it is not in the front end. I had the front end looked over and the bearings packed when I had the transmission put in last year and the shop indicated that all was well. Yes, new drums on the rear end.

I recently purchased new motor mounts from Rick's for the engine and they do match what is installed now. I am intending to have them replaced when I do the clutch. One thing that your comment about the balancer and the sway bar reminded me of was that the Camaro came with that triple pully (water pump, AC, PS). I don't have AC or PS but the outer pully (larger diameter) was so close to the sway bar that there was no way you could change the belt. I have since replaced this pully with a standard double pulley. But I thought it odd that it was so close. I am sure the frame mounts and engine mounts are correct for the BB so I am not sure why this would be like that...

Joe

There is a difference between the SBC & BBC sway bar. The SBC bar is straight across whereas the BBC has a formed "dip" underneath the harmonic balancer.

I thought the BBC bar was located underneath the h/balancer and not the pulley, I could be mistaken.

Balancing is only part of the solution for wheel-induced vibration (think about it - you can perfectly balance a square wheel both statically and dynamically, but it won't run smooth on the road). The culprit in many of these situations is wheel and/or tire radial runout, and/or loaded radial force variation due to tire construction.

The cure for this is to have your wheels balanced on a Hunter GSP9700 machine, which also checks radial and lateral runout, plus LOADED radial force variation, and shows the tech how to re-orient the tire on the rim to minimize the effects. Go to www.GSP9700.com and use the locator there to find the shop/dealership closest to you that has one, and have it done. You'll be amazed at the difference between the results from the Hunter machine and just ordinary spin-balancing.

If that doesn't cure it, then you know it's between the diff and the tranny. :)

I've been fighting a vibration issue in my GTO for a little over a year now. Is it a shake, or a "buzz"? Mines a buzz. Also there in neutral and parked, and comes and goes depending on rpm. But more so under a load at highway speed/rpm.

I did like you, and started from the rear forward. Axles checked okay. Friend of mine had some that were way off and still had no vibration. Went throught the trans/clutch/flywheel, still there. You mentioned it had a lot of clutch chatter. Mine did too, and it turned out that automatic flexplate bolts with a 4spd flywheel dont mix at all. They were making contact, but the correct lower profile bolts fixed that.

If its there in neutral, with the clutch and trans disengaged, then it sounds like its probably in the engine. I'm in the same boat as you. I've been told its a balance, crank, or (possibly) a bearing issue. The engine in my car was balanced with a auto flexplate, but the flywheel is supposed to be zero balanced. In theory, it should be fine, but I still have questions.

Man, I know how frustrating it can be. It can be real tough to find, and will make you "pucker" and hold your breath at certain speeds. At least in my case, it could get expensive.

dave

The flywheel and pressure plate are always turning with motor running,Clutch disc disingages (peddle in) and tranny isn't turning is the vibration still there?

If your not real sure on what it looks like and how its assembled,watch Horsepower TV on Spike channel, although a ford, its simular.

Doug G,

The vibration is not present when parked in neutral and RPMs up. It only occurs at speed. I have always popped it into neutral when at 65 MPH to still experience the vibration. Haven't tried it with just the clutch in at speed but can do tomorrow. I'll check out the channel...Looks like I need a better basic understanding. Thanks...

Joe

If the vibration is not there in neutral with the rpm's up its not the clutch/motor. Its has to be at speed tells me its in the drive line. U-joint off center or going bad,bent drive shaft,bent axel,bent wheel,broken cord in tire,or something along those lines.

Just a thought, I had a 78 Trans-am that had a bent pinon yoke. I was young and a few to many beers after changing a u-joint I forgot to put the c clips on the new joint that keep it centered in the yoke. Well the joint moved and bent the drive shaft. I replaced the driveshaft and still had some vibration and found that the yoke was bent also.

The vibration happens at speed only. I can get going down a hill at 65 MPH and pop it into neutral and feel it in the seat of my pants. Feels like in the transmission. Also, when at 65 MPH (or above) if I feather the throttle up and down slightly I can feel a vibration come and go if feather the gas right at the point between the transition between coasting and accellerating.
This statement, to me, eliminates the front wheels.

If the vibration is not there in neutral with the rpm's up its not the clutch/motor. Its has to be at speed tells me its in the drive line. U-joint off center or going bad,bent drive shaft,bent axel,bent wheel,broken cord in tire,or something along those lines.
I agree with this, but since you mentioned the vib did not change with tire rotation, it is not a tire/wheel issue. That leaves the driveline from the rear of the trans back. Up to the drums. Got a good driveshaft shop around you? I might start there.

I hear what you guys are saying but the bad news here is that I have literally replaced or had rebuilt from the transmission nearly every component from the tran back to the tires: M21 rebuilt, New drive shaft, new u-joints, 12-bolt housing rebuilt by Mark Williams Enterprises, new brakes and drums, new wheels and tires. I had had the rear end axle runout checked, I have had the tires balanced twice and the drive shaft checked by another company for balance. I'm pretty bummed.

It sounds like your problem is very similar if not the same as mine. I have noted that if I change out the bushing in the tail of the tranny it helps a lot but the problem stedily comes back after a couple thousand miles. I had no vibration until I built a 9" rear and lowered the car. I have done everything people have suggested above and more, including changing rear end yokes. I am starting to think this may be a spring related issue. I am going to eventually pull the springs and inspect for cracks or bind. I am currently runing blocks to lower the car but I may go with a pair of 3" drop springs. Good luck and let me know if you discover anything.

i have the same vibration seems to be definitly rotational.ive too have changed almost everything still there.i,am running a powerglide trans could this be in the sun gears of the tranny??,the only thing my fellow hotrodders can think of.vibration seems to pause every couple of seconds definitly patternized,any input also needed Thanks George,

I've also have a driveline vibration for 10 years I've owned my '69 Camaro. I need to know if anyone can perform an excorcism. I'm sure the car is cursed. The vibration feels like a rumble starting above 55 mph, felt in the seats and vibrating the mirrors. It is also there when I depress the clutch and release the gas. When I restored the car 7 years ago, I thought I would fix it after rebuilding the Muncie, getting a new driveshaft and lots of new parts. NOPE! About 3 years ago I started changing the car from stock to a "Pro-touring" look. Over a 2 year period I put in a Tremec 5 spd, a rebuilt 12 bolt w/ new axles, bearings, gears, rear disc brake package, bought new 17" wheels, 2" lowered springs. I've put in leaf spring shims to get the rearend angle perfectly parallel to the trans. I've checked runout on the driveshaft. I've checked the rearend is installed perpendicular to the crankshaft. Nothing has made it go away. I've spent $25K and untold hours on the car and can't drive it at highway speeds! Any help would be greatly appreciated!

Gary

I have a 69 camaro and I have the same vibration, my buddy has a72 nova and he also has the same vibration weve been trying to find it for years. STILL LOOKING!!!!!!!!!

I wonder if my wife has a little Voodoo doll of mycar? That might be the only explanation!

Gary, thanks for the uplifting story. I wonder how much play there is of the motor on the motor mounts in a side to side direction. In other words I wonder if the crankshaft centerline can be made to not point straight back towards the pinion. This would cause bind of the u-joints in the lateral demension as opposed to the usual verticle demension. You can change every part in the car and it would not make a difference.
Just a theory anyway!

Josh

Josh,
Good idea! I will have to figure a way to check the engine lateral position. I know that there is enough flex in the motor mounts to loosen up the trans mount bolts and push the trans over some with my foot. I wonder how much lateral position is out of spec??????

Gary

I would measure the angle between the rear of the trans and the front of the drive shaft. I would push the trans as far as possible to the drivers side and measure, then push the trans all the way to the pass. side and measure. Then put the trans right in the middle of these two measurements to start. I am not sure what tool you could use since a gravity based inclinometer would not work on the horizontal. There may be some fine tuning you could do with road testing. If you do this please let me know what you find as I would be learing from you! Thanks.
Josh

I am going to be replacing the clutch, resurfacing the flywheel and replacing the throwout and pilot bearings in a couple of months to fix my major chatter problem. When I do, I am going to replace the motor mounts also. I will re-post when this is all done and we can see if the problem is still happening. I have a feeling my engine is floating on a bad mount. One of the mounts looks like it could have a crack along where it adheres to the metal mount but it is very hard to tell.

Joe

Thanks Joe.

I'm experiencing the same type vibration in my car. I've replaced u-joints(still greaseable). I've replaced rear brake drums(one had chunk of metal missing). I've even borrowed a set of vibration free wheels/tires and the vibration persists. I've been suspecting the rear bushing is worn-out in the muncie. Also, the yoke has a groove worn I believe near where the seal makes contact. From another thread in the Transmission Section, GMJim mentioned possible problems caused by greaseable u-joints and the "out of phase" camaro driveshafts. Please post your solutions! Thanks!!

I replaced the tranny mount and the front u-joint just to cover all the baics... and the vibration got worse?? I am down to rebalancing a driveshaft that was previously balanced and good, transmission problem or some issue with my springs. I even swapped my center differential section (Ford 9") and there was no change. I would like to know more about this phasing of the driveshaft. Mine joints are offset a 90 degrees but I know my driveshaft was set more like 45 degrees before I had it shortened.

Many years ago I had a mystery vibration in a '69 SS 350 Coupe that turned out to be a problem with the U-joint yoke on the differential- just a tiny amount of wear or mis-shapened original machining on the face of one of the U-joint mounting cradles. Almost imperceptable- but when replaced with a used yoke all the troubles went away.

This has been a fascinating thread to follow. Best wishes to all of you on your quests.

Great news guys! After 10 long frustrating years, hours of work and tons of money, I finally have fixed the vibration problems with my '69 Camaro. I just got back from a 100 mph run down the interstate (the first time ever) and no vibration at all. I feel like I deserve a masters degree in vibration analysis!

I cannot possibly cover all the things I have tried. I have a 5 page word document I used to gather info from all the websites I could find!

After 2 complete drivetrain swaps, I had run out of things to fix the problem. Tonight I just installed a new quality driveshaft from Denny's Driveshaft with greaseless U-joints and a new forged rearend yoke all balanced to 10000 rpm . It cost $400 but well worth it. It seems the local shops can only build a drive shaft good enough for a slow truck and they only balance to 2000 rpm. Since I had 3.73 gears and had lowered the car, the requirement for a precision driveshsaft is increased. I had lately installed shims to get the pinion angle correct, but the "working angle" of the driveshaft was 6 deg. because of the lowering. (A stock Camaro is about 2 deg.) I also recently discovered that the "local built" unit had a runout 0f .013".

So, it was a long battle and I don't have to put a "For Sale" sign on the car!!

Gary

Gary,

I am happy for you!
I have very similar news. While on Power Tour in Indy I had the car in to Pattersons driveline to take a look at the shaft because my vibration kept getting worse and allowing me to drive 60MPH or slower...not good on Power Tour. They checked the shaft and found the production place that spun it before did a crappy job at best. It must have been good enough for the car as it sat stock at that time, but with lowering the suspension and tightening everything up the shaft runnout became an issue. Pattersons fixed the shaft and rebalanced it and NO vibration! I cruised 65-70 MPH after that and passed people with no problem.

Moral of the story..Never assume the driveshaft is good and take it to somebody who knows what they are doing!!

Josh

..........................

I cannot possibly cover all the things I have tried. I have a 5 page word document I used to gather info from all the websites I could find!
............................

Gary,

Any chance you can email me a copy of your document? I have been chasing a vibration for years in my '68 Camaro.

Kindly email to: davefra@hotmail.com


thanks

Dave,
It's on the way! Good Luck!

Gary

Got it! thanks, it looks great....................


gracias