['31Vette]

I bought a previously built '31 Ford 5 window street rod (350 sb w/ 350 TH) with four link / coilover rear suspension. I am experiencing a vibration at hiway speed (55 - 60) that appears to be coming from the driveline. I suspect that the pinion angle is drastically different from that of the transmission output shaft. What is the correct angle relationship between the pinion and output shaft? Is the adjustment as simple as adjusting the link lengths on the rear suspension? What is the best place to measure each of the angles?

[Jason]

It could be the pinion angle. Basically the centerline of the engine and trans should be equal to but opposite of the pinion gear center line. For example 2* negative on the engine and 2* positive on the pinion gear c/l would be 0* pinion angle. Check the discussion I started at Chevy Talk
There are a lot of links that I posted but the replies toward the end really helped me understand how to measure to check pinion angle. The links are good to read to figure out what your pinion angle should be set at.

[Jon]

'31Vette -- welcome to the Hotrodders Bulletin Board .

You might want to have a look at the <a href="http://hotrodders.com/kb/" target="_blank">Hotrodders Knowledge Base</a>. Type "pinion angle" into the search box, and you should see some good info come up.

Also, if you haven't yet had a chance to look at the board guidelines, <a href="http://hotrodders.com/guidelines" target="_blank">click here to give 'em a look-see</a>.

[Jon]

Or try a search on "vibration" too. There is an article from FordMuscle.com in there, entitled "Vibration Diagnosis Guide" that might be useful. Hope this helps .

['31Vette]

Thanks a bunch for the references. I read them and now have a bunch of operations to do. You guys are great!!!

[Lloyd Topping Jr]

Your best bet would be to get in contact with Moroso Performance Chassis Shop. They have some terrific guy's there that really know there business.I am sure they would be glad to help you. Telephone # 860-453-6571 ask for the Chassis Shop & ask for either Paul,Bruce,or Rick.

['31Vette]

Well, I finally got rid of my vibration. I adjusted the rear suspension links to allow the pinion angle to drop 4 degrees which brought it into "alignment". 3 degrees negative on the trans output shaft and 3 degrees positive on the pinion. I learned the hard way not to do this on a ramp lift. Next time I will suspend the car on a frame lift. Other than that it was easy with the help of the knowlege base and all of you fellow hotrodders. Thanks again!