I had a vibration above 65 MPH in the drivetrain in my ’67 for years. I changed wheels and tires, had the driveshaft balanced, and even replaced the driveshaft but never got rid of the vibration.

The other day I was at Harbor Freight and picked up a cheap angle finder. When I checked the rear end I found it was pointing down 4º. The transmission was also pointing down 3½º. The way I understand it the transmission and the rear end should be parallel to each other or vibrations will result. In other words if the transmission is pointing down 3º the pinion on the rear end should be pointing up 3º.

I ordered some 4º leaf spring shims to raise the front of the rear end. I actually used two 4º shims on each side. I placed one shim on top of the spring and one facing the other way on the bottom so the shock plate would sit level. I also eliminated the rubber spring pads so I had to add a 3/8 inch thick spacer and a longer bolt to the spring pack.

I also made a ½ inch spacer for the transmission mount to raise the rear of the transmission. My pinion is now level or 0º, and the transmission is 2º down. The driveshaft is 1¼º down. The springs should wrap up a couple of degrees from the axle torque whish will hopefully put the pinion 2º up while running down the road.

It’s now smooth as glass. :hurray::hurray::hurray:

http://geocities.com/sdampier@sbcglobal.net/Team_Camaro/shims-005.jpg

http://geocities.com/sdampier@sbcglobal.net/Team_Camaro/shims-006.jpg

http://geocities.com/sdampier@sbcglobal.net/Team_Camaro/shims-007.jpg

Good deal, Steve. I'll bet it feels good to fix a problem that has been annoying you for years. Now you are wondering "Why didn't I do this sooner"! Congratulations!

Still trying to understand this, could be just too early. But if you used two equal ° shims, (4° forward & 4°rearward) pointing in opposite direction of each other, would you not be back to 0° and just make a thicker plate?
Like placing to pieces of 45° angles together to get back to a straight line?

I have had an issue like this since my car was new, I basically did what you did but bring both trans and pinion center lines , parallel. Still within a 1° differance of the two lines.

Did I understand correctly? Did you notice any differance in ride harshness with out the rubber insulator? I am using the poly material pads.

Still trying to understand this, could be just too early. But if you used two equal ° shims, (4° forward & 4°rearward) pointing in opposite direction of each other, would you not be back to 0° and just make a thicker plate?
Like placing to pieces of 45° angles together to get back to a straight line?
This would be the case if both shims were together but I placed the spring pack between the two shims. Think of the angle separating two 4° shims placed together, one on top of the other with one forward and one back. When the spring is sandwiched between the two shims it will be at the angle separating the two shims.

There was no difference is ride harshness or sound levels with the leaf springs mounted solid to the axle. I don’t know why GM chose to mount the Camaro axle to the springs with rubber. Most cars with leaf springs don’t use rubber spring pads.

This would be the case if both shims were together but I placed the spring pack between the two shims. Think of the angle separating two 4° shims placed together, one on top of the other with one forward and one back. When the spring is sandwiched between the two shims it will be at the angle separating the two shims.

There was no difference is ride harshness or sound levels with the leaf springs mounted solid to the axle. I don’t know why GM chose to mount the Camaro axle to the springs with rubber. Most cars with leaf springs don’t use rubber spring pads.

OK, I see what you are talking about, shim being on opposite side. Thanks for feed back on insulators.

i have a 67 with the same problem, i hope this is the solution for mine too. Thanks!!!

Glad to hear you finally got to teh bottom of it Steve... :thumbsup:

Was this problem there before you replaced the springs?

Roger

Good job!
Just be sure you have enough of the spring center bolt heads engaged to keep the housing from slipping. And any time you use a digital level, make sure it's zero'd before you start.
David

Steve, how many years did you suffer? I had blurry mirrors for 37 years. My rear took 6° shims. No more blur.

Steve
Where'd ya get the shims?

glad you found the problem and got rid of it!!

on a different note how would you fix a 72 chevelle type rear? i think this is the same problem I am having? was this a digital angle finder? im gonna buy one.
thx scott

I also have "blurry mirror syndrome"......I've tried everything that you did as well....except checking the relationship of the tranny and rear....I'll have to look into this .. Where did you get the shims?

It's amazing huh. I had a vibration for years too. When I installed my 9" rear I checked all the angles too and needed 4* also. Once I added the shims the vibration went away. Cool.

I also have "blurry mirror syndrome"......I've tried everything that you did as well....except checking the relationship of the tranny and rear....I'll have to look into this .. Where did you get the shims?

I got the shims at Summit.
Pro Comp 99-400B - Pro Comp Pinion Shims - summitracing.com (http://store.summitracing.com/partdetail.asp?autofilter=1&part=EXP-99-400B&N=700+0&autoview=sku)

I bet there are more than a few first gen Camaros are out there with bad pinion angles.

I'll fess up. I have one. But I think mine might be because of Motor mount perches. I had a 307. Swapped it with a 350 and inherited vibrations. I didnt change motor persches so I think the vibe will go away with changing those out....some day.

Where did you measure from on the rear end and trans… got any pics of the trans spacer installed? I need to do the same thing

Finally got the "Angle finder". Can you measure the angles when the car in up on jacks or does it it need to be on the ground?

Car should be on all 4-wheels and leveled... http://www.iedls.com/measure.html or this http://buickperformance.com/Pinion.htm

Where did you measure from on the rear end and trans… got any pics of the trans spacer installed? I need to do the same thing
I pulled the driveshaft and measured across the yoke on the rear end. On the transmission I took a reading on the machined end of the output shaft. I also stuck the angle finder on the starter and got a reading exactly 90º to the transmission output shaft reading.

I was really surprised to find how bad my angles were. If you have a vibration at speed, you should definitely check and correct your pinion angle.

Glad to hear you found the problem, did that link above help you.

How do you set the
pinion angle? On a single-
piece shaft you want to set it
up where a line drawn through
the center of the engine
crankshaft or output shaft of
the transmission and a line
drawn through the center of
the pinion are parallel to each
other but not the same line.

A simple way to do this is to
place a digital angle finder or
dial level on the front face of
the lower engine pulley or
harmonic balancer. This will
give you a reading that is 90
degrees to the crank or output
shaft unless you have real
problems with your balancer.
At the other end, you can
place the same level or angle
finder against the front face of
the pinion yoke that is also at
90 degrees to the centerline.
If you rotate the yoke up or
down so both angles match,
you have perfect alignment.

Road testing will tell you if
you have it right. If you
accelerate and you get or
increase a vibration, then the
pinion yoke is too HIGH.
Rotate it downward in small
increments of a degree or two
until the problem goes away.
If you get or increase a
vibration when decelerating,
then the pinion yoke is too
LOW. Rotate it upward to
correct it.

Well I bought an angle gauge and tried this on my 68 Chevelle. I am not sure I got it worked out because it’s pouring in Los Angeles and I just detailed the under side of the car so I am not about to take it out and find out if it’s still vibrating. It looked like the rear was at zero degrees (flat) and the trans was at -7 (pointing down) well actual numbers were (rear +2) and (trans -9) but I had the car on stands and it was higher in the front due to needing it under the A arms to simulate being on the ground. I measured the before and after on the degree gauge on the body line. It was a couple of degrees nose up from actual ride height. SO…I shimmed the trans up so it was only (-3 ish or -4). So here is what I am thinking. Actual numbers are now—(rear at zero) and (trans at -2) once off stands. So if I get this--- the rear will pick up a couple of positive degrees (AKA +2) and under load I will be at zero so no more vibration. Who knows? It will probably throw the driveline because its all messed up now. I will let you know. I did read where you can also oblong the holes in the upper arms in the direction needed to add positive or negative degrees to the rear and then weld a good washer on there to fix the hole. (This is a trick Just Suspensions uses). The leaf springs better be easier on the Camaro.

http://i279.photobucket.com/albums/kk153/cbrookss/IMG_2688.jpg?t=1233982032

The rear axle will wrap up on acceleration be more on a Camaro than a Chevelle because the Camaro axle is mounted on leaf springs. Good control arm bushings will keep the Chevelle rear end from rotating up much. Aftermarket adjustable rear control arms are also available for the Chevelle that will allow you to easily change your pinion angle.

...well dont shim the trans too much. Ask me how I know. I ordered udj upper control arms. better way to go anyhow.