Troubleshooting Driveline Vibration
in my 69' Camaro I replaced my 10-bolt 3.08:1 rearend with a new Moder 12-bolt 3.73.1. I have a terrible vibration at 55 MPH+ in the drive line and I can feel a "whir, whir, whir" at lower speeds. I had a new driveshaft built and balanced and still experienced the same problem. I just had the pinion angle and the transmission output shaft angle checked. The transmission shaft is at 4* down. The rearend was 1* down. I shimmed the rearend to 4* up to cancel them out. The vibration is better but it is still there. So I had the rear end and drive shaft runouts checked and they are all within proper tolerances.
I think that the 3:08 ratio was spinning the drive shaft much slower so I never noticed a vibration at that lower driveshaft RPM. Now that I have the proper 3:73 ratio, the vibration problems that were probably always there at much higher speed are now at a lower RPM and noticable.
My question is, 4* seems like a lot of angle. Would it be recommended to try and shim the transmission up a degree or two (to 2* down) and shim the rearend down to match at 2* up? Do you think this would make any difference?
I am currently looking at replacing the transmission mount. I believe there may be some metal to metal contact. I should have an answer today.
If I still have a vibration I am thinking of having my Munci M21 rebuilt. It is pretty worn out and 2nd gear is whining like no other. I do not believe the tail bushing is worn out though.
Any more advice???
I have always heard to use 3* on the rearend, but here's a part of a post from anothe forum I belong too........joe
This information was taken from a website that provides information to people like up, Drivetrain Specialists of Las Vegas - Las Vegas NV, 89102, www.drivetrain.com/main.html
High angles combined with high RPM is the worst combination, resulting in reduced u-joint life. Too large and unequal u-joint angles can cause vibrations and contribute to u-joint, transmission and differential problems. The improper u-joint angles must be corrected.
Ideally, the operating angles on each end of the driveshaft should be equal to or within 1 degree of each other, have a 3 degree maximum operating angle and have at least 1/2 of a degree continuous operating angle.
RPM is the main factor though in determining maximum allowable operating angles. As a guide to maximum normal operating angles, refer to the following chart:
DRIVESHAFT RPM . . MAX. OPERATING ANGLE
5000 . . . . . . . . . . . . . . 3.25º
4500 . . . . . . . . . . . . . . 3.67º
4000 . . . . . . . . . . . . . . 4.25º
3500 . . . . . . . . . . . . . . 5.00º
3000 . . . . . . . . . . . . . . 5.83º
2500 . . . . . . . . . . . . . . 7.00º
2000 . . . . . . . . . . . . . . 8.67º
1500 . . . . . . . . . . . . . . 11.5º
When the transmission output shaft centerline and axle input shaft centerline are parallel, the u-joint operating angle permissible is length of driveshaft divided by five. Example: A short coupled driveshaft with a 15" length would be limited to 3 degrees maximum operating angle. A 30" shaft would be limited to 6 degrees.
When the transmission output shaft centerline and axle input shaft centerline intersect midway of the driveshaft, the joint angles are equal. However, due to the change to unequal joint angles during up and down axle movement, this is a more undesirable condition than parallel centerlines. In this case, the maximum u-joint operating angle is determined by dividing length of driveshaft by ten. Example: A 30" driveshaft with intersecting angles would have a 3 degree permissible operating angle.
I thought I'd give credit where credit is due. I remembered someone here posted something like this in the past. The important thing is to keep the difference between both angles as close to zero as possible. And now that the chart shows danger levels for increased joint angles, please keep rpms in mind when setting up to race.
Even with a resulting angle of zero, you can still exceed the allowable angles based on rpms. Like they say, you should have at least 1/2 degree working angle, even in a straight line shot, to keep the bearings rolling withing the trunion caps.
DUDE CHECK YOUR BEARINGS!!
I had a vibration problem couldnt figure it out. I took it to shops someone said it was the driveshaft, another dimwit said it was the freakin tire. I changed the deiveshaft, nothing.
So one night after i was driving home from work i feel this big thump and jolt. Still couldnt figure it. So im driving home on Valentines day, i hear that thump again but two more thumps than i heard before.
I feel the driver side rear fall and see all sparks in the rearview. Just like the 4th of July. I look in my side mirror and something catches my eye, its my damn tire passing me up with the axle still attached.
Man, if that tire wouldnt have taken a short hop right before hitting the concrete highway divider, someone in oncoming traffic would of taken it right in the windshield.
needless to say my date didnt "up" any that night.
Check the bearings just to keep you and others safe.
Thanks for the advice. The rear end is a brand new complete Moser 12-bolt/eaton posi. The drive shaft is new and balanced.
I got the new transmission mount in and it moved the transmission angle to 2* down (from 4* down). So, I am going to shim the rear at 2* up to compensate. Then I am going to verify that the pinion angle is less than 3*. If I still have vibration then I suppose I will need to have the transmission looked at and possibly rebuilt. I read that a tranmission bearing could also cause vibration and my Muncie M-21 2nd gear is a major whiner. The vibration has much worse in 4th than in 3rd (although still there) so I am figuring the bearings may be the problem if the angle changes don't resolve the problem.
Does anyone with a 1st Gen camaro have any specs on transmission angle and pinion angle relative to ground? I am wondering if my setup is abnormal somehow from stock.
I had a similar viberation that I couldn't find. Being that the newly aquired '70 Chevelle wagon was for the wife's daily driver I decided to replace the entire front end..new bushings, tie rods, idler arm, everything. Then I replaced the front and rear wheel bearings. Still viberated :mad: . I went out bought new tires and rims..balanced of course. Then had the drive shaft balanced..yep, still viberated. I gave up and said I'll have to live with it.
Last week I decided to put a new crate engine in and when I went to unbolt the motor mounts..they were finger tight!
I just finished up with the engine install, drove it on the highway and guess what?...No more viberation. Could have been the engine but I think it was the motor mounts not being tight.
Just my .02 cents.
I hope that you get this Email.
I have the same problem. I have a 1985 IROC 5 Speed, 3:73. @ 60 mph +, I have a vibration. I rebiult the trans, new engine mount, and last light I just pulled apart the rear to replace the gears and bearings. I'm thinking about replacing the axel's also. I just put in a new drive shaft last week. I changed the engine mounts, trans mount, balencer, flywheel, clutch plate, balanced the tires...
I'm really lost with this... :confused: Reading your Email reminded me that when I put a lot of weight in the rear of the car, the vibration gets better. I changed the trans mount also. ON my IROC, there is rubber bushings under the transmount on the trans cross member. I'm going to order those Monday.
I try to think back when this vibration started. (if I was a girl, I might like it...) I blew the original rear and I think that it started after that. I'm thinking maybe I bent the trans cross member.
I just want you to know that you are not alone in this. I have spent about 3 to 5 thousands dollars on this vibration. It just makes me so mad!
I don't see when everthing is stock and the same that I would have a vibration like this. Well I did change the rear lower arms in the rear. It did push the rear back a little. I called Hotchinks and they said it wasn't a problem. I don't know...
Let me know what you came up with...
this is gonna sound lame..... but, I installed new ujoints in an old f150 i had, test drove it, haD a vibration that started @ 50 lasted to 65 and settled down, but it was still there. long story short. the parts place sold me the wrong ujoints.... not off by much, as i couldn't tell looking at them but it was enough...... does your new rearend use the same ujoints? or is it a different ujoint? just looking at the obvious.......... good luck.
Just curious if you have checked the tires for slipped/broken belts. I know from experience that a slipped belt can cause vibration in the 55-60 mph range.
Thanks for the input. At least I am not alone. I am pretty bummed out that I can't drive my car.
I am reading a lot about pinion angle and I am still working changes to see what happens. While the rear is on the ground (not hanging) I am sure that you need to ensure that the transmission angle and the rearend pinion are parallel. Then you have to ensure that the pinion angle, the angle between the drive shaft and the pinion yoke is less than 3*. I am still fighting it and I ain't giving up.
The new Moser rearend uses the larger 1530 u-joints and they fit perfectly. I have new rims and tires too so that's not the problem.
What I really need to know and can't find is what is the stock angle of the transmission output shaft on a 69' camaro.
I will keep you informed.
I too am having a real bad vibration problem in my 76 Camaro RS.
The vibration appears at around 65 and gets more violent as the speed increases.
It is impossible to see through the rear view mirror at highway speeds.
The car has been in storage for the past 3 years.
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