Vibration starting @ 58 mph

[diggerbob]

Originally Posted by boostedc10

Actually road force has nothing to do with a speed it has to do with loading a tire to ensure uniformity. The balancer applies about 1200 lbs of force to contact surface of the tire with a drum to simulate how it would react on the road. This can detect issues in a tire that normal balancing cant detect.

I bought the new Wheels Vintique wheels and tires after I finished my frame off restoration/700R swap and the vibration appeared. I had hoped new wheels and tires would fix it. That was a long ways back....

[boostedc10]

So are you saying it was there before the wheels and tires were swapped? Sorry if I am rail roading your diagnosis but I can't tell you how many times I have seen tires ruled out and a ton of other diagnosis is done only to end up a wheel/tire problem.

[diggerbob]

I checked my rear coil springs today to see if they were clamped down properly after I saw a post on here about how to position them properly within the notch in the clamps...one of them doesn't have the pig tail on the bottom clamp set in the clamp notch...my next weekend project. Maybe that will prove to be the culprit. I am gonna get this damned thing running vibration free one day!

[boostedc10]

Make sure you let us know when you find it. These types of problems just take time to sort them out.

[diggerbob]

Originally Posted by boostedc10

Make sure you let us know when you find it. These types of problems just take time to sort them out.

Time and $$$$.... thrown at useless "solutions". I just want to put this old girl on the road and enjoy her. Sooooo close....

[real69ss]

Check your transmission bell housing for cracks. I had a similar problem, thought it was my driveshaft. then torque converter and flex plate. My starter started to chirp a little after starting. Decided to see if a shim would help found the bell housing cracked over half way around.

[austinstocker]

It sounds to me like you definitely have a driveline angle issue... Which seems to be what you're thinking also. With the fact that you installed a one piece aluminum driveshaft in place of the original two piece, I would bet that is the entire reason for your vibration. I'm assuming that the working angles of the new driveline are a lesser angle than the two piece (since the driveline begins to angle downward closer to the rear end with a two piece). I know you have been shimming to try to find a fix.. But you could be close. It doesn't take a very thick shim to make a world of difference. I have dealt with a vibration on a truck before around the same speed and ended up shimming the t-case up only a fraction of an inch. Obviously this is a different scenario, but I think you just need to figure out what the original angles normally are and get as close to that value as you can.

[austinstocker]

Another thing: are you sure that this nice new aluminum driveline is balanced correctly? Might be worth your time to take it back to the shop who made it and have them check the balancing.

[diggerbob]

Since I am running out of things to try, I guess I'll try to shim my pinion down by 4.5 degrees in place of the 4 degree pinion angle shims. This would give me 3.5 degrees pinion angle and 3.6 degrees at the transmission output shaft. The net result would be working angles of 2.6 degrees for the universal joint by the pinion and 2.5 degrees for the universal joint by the output shaft.

I am gonna go broke buying all these billet aluminum shim combinations! They are pretty nice looking though. The ones that I don't use will look nice on my desk as paper weights.

[geezer#99]

Did you measure where your tranny output shaft sits in the frame?

Some more info.
http://www2.dana.com/pdf/J3311-1-DSSP.pdf

[Lee H]

Are those shims from Stock Car Products? They are nice, I've bought a few. Not many options out there for trailing arm shims. Can't help with your problem and I'm sure you will get it worked out. I've always heard and read the transmission and pinion angle should be "very" close to each other and as close to 3 degrees as possible. I got my trans right at 3 and pinion at 4, vibration is all but eliminated. Still shakes a bit at about 70+. I'm going add another degree to the pinion and see if that helps me out. Don't get to those speeds very often so no big deal for me.

[diggerbob]

Originally Posted by Lee H

Are those shims from Stock Car Products? They are nice, I've bought a few. Not many options out there for trailing arm shims. Can't help with your problem and I'm sure you will get it worked out. I've always heard and read the transmission and pinion angle should be "very" close to each other and as close to 3 degrees as possible. I got my trans right at 3 and pinion at 4, vibration is all but eliminated. Still shakes a bit at about 70+. I'm going add another degree to the pinion and see if that helps me out. Don't get to those speeds very often so no big deal for me.

I got the shims from Carl's Racing.

[diggerbob]

Originally Posted by geezer#99

Did you measure where your tranny output shaft sits in the frame?

Some more info.
http://www2.dana.com/pdf/J3311-1-DSSP.pdf

Do you mean the distance from the frame rail on each side to the output shaft?

[Lee H]

Originally Posted by diggerbob

I got the shims from Carl's Racing.

Just looked them up, same company, $45 plus shipping for a pair.

[geezer#99]

Originally Posted by diggerbob

Do you mean the distance from the frame rail on each side to the output shaft?

Yes!!

[diggerbob]

if that is off, how in the heck would I correct it?

[geezer#99]

Move the mount over by slotting the bolt holes in the crossmember (if you have room)or move the whole crossmember over by drilling new holes.
The motor will swivel on the motor mounts a liitle bit. Your exhaust might need to be loosened and then tightened after.
Measure the front of the motor too. Make the motor/tranny parallel to the frame.

[diggerbob]

Originally Posted by geezer#99

Move the mount over by slotting the bolt holes in the crossmember (if you have room)or move the whole crossmember over by drilling new holes.
The motor will swivel on the motor mounts a liitle bit. Your exhaust might need to be loosened and then tightened after.
Measure the front of the motor too. Make the motor/tranny parallel to the frame.

I might just have to build myself a laser alignment tool like this to help me get lined up in both planes. Anyone here tried this method?
http://www.yellowbullet.com/forum/sh...d.php?t=447131

[geezer#99]

You could, but how much more accurate can you be than a simple tape measure.

[diggerbob]

Using a laser distance meter that reads to the closest 16th inch, I get 15.125" from frame rail to output shaft from both sides.

[geezer#99]

So your tranny is centered.
Not good maybe!
Now measure the front of the motor.

[67 chevelle]

did you check your pinion for up and down movement

tires for flat spot

bad shocks

trany mounts , engine mounts

any of these can cause your issue




the top picture works well for 4 link , laderbar , truck arms
if you have leafs your pinion angle should be 1-2 degrees greater than the transmissions angle {in the opposite direction} toward the ground , all angles checked with vehicle on the ground , check those,, set them and if thats not it , its something else , ie , trany , driveshaft , diferential . Sounds like you have been all over the place on driveline angles , set it and move on

So as an example your tailshaft angle is 3 degrees towards the sky , if you have a fixed rear [not leafs] you pinion should be 3 -4 degrees toward the ground , with leafs 4 -6 degrees toward the ground

[diggerbob]

Originally Posted by geezer#99

So your tranny is centered.
Not good maybe!
Now measure the front of the motor.

9.875" frame to harmonic balancer on both sides

[geezer#99]

So your motor/ tranny is parallel to the frame.
Now you need to find out how much your pinion is offset.

[diggerbob]

Originally Posted by geezer#99

So your motor/ tranny is parallel to the frame.
Now you need to find out how much your pinion is offset.

It's difficult measure distance from pinion to frame since the frame is higher than the pinion. It doesn't appear that there is any offset of the pinion from the transmission though since the distances from both frame rails to the drive shaft is the same as you go toward the back of the truck.