U Joint Angle
 

Hi Guys
My 36 Ford has a 350 chevy engine with a chevy turbo transmission. My question is......i have a slight vibration in 2nd gear at 20 MPH. The front universal joint has about a 20 degree angle. I believe thats my problem. Is there a u joint on the market that will handle that kind of angle?

Bob

20* angle :eek: :eek: none that I know of, that's CV joint territory.
http://www.rosslertrans.com/Pinion%20angle.htm

The only one I know of will only get you 10* more angle.But... It's made for the offroad guys and you still could have a vibration. You may be better off to try and get your angles better.

It shouldn't matter what gear you are in- it's the driveshaft RPM that would create the harmonics if it's the driveshaft causing it, I believe.

You were on a level surface when this was measured? 20º is a lot of angle... :pain:

Thanks for the info , I'll start looking to see if i can change the angle some way.


Bob

You could have the driveshaft double checked for balance. If its out of balance,It may help a little getting that taken care of.

Your fighting a uphill battle with that much angle.

I gotta agree with Cobalt and Prostreet. 20 degrees is too much to ask from a typical u-joint. I think they are designed to handle angles between 2-5 degrees, and while that may not be the cause of your vibration (only in second gear?) you'd be smart to try to do something to reduce the angle; its too severe dude! :evil:

hard to believe a 20* angle... can you post photos? What is the down angle of the trans? Was this a mistype, do you mean 2 degrees?

Yes I will post angle tomorrow.


Bob

How do i post a picture of the U Joint?

When you are typing a reply, scroll down the page to ATTACH FILES and click on MANAGE ATTACHMENTS, then click BROWSE and find the photo in your computer and click OPEN (or SAVE), then click UPLOAD.....then close that window, it is attached to your post. Then click SUBMIT REPLY.

Average angle down (looking from the side of the engine/trans combo with the trans to the right) is usually in the 3-4 degree angle. Center-line of crank thru the center-line of the trans mainshaft. At that angle the carb base of the intake manifold will be level from front to rear and should also be level from side to side.

The average angle up for a street driven vehicle of the pinion shaft center-line of the rear end should also be in the 3-4 degree range.

The two angles should be parallel to each other looking from the side and looking from above. They do not have to be inline with each other but must be parallel.

A problem could come about if you have a very short driveshaft and/or the engine/trans is mounted very high. This would cause a steep u-joint angle even when the engine and pinion shaft are set at the correct 3-4 degrees and are parallel.

The 'fix' is to lower the engine mounting position to decrease the driveshaft angle. The third member is pretty much at a fixed height because of overall tire diameter. Changing the tire diameter can alter the height of the pinion shaft but it would be more correct to change the engine height. Keep in mind that the 3-4 degree down angle of the engine must still be maintained.

There are a few exceptions to the engine angle. They pertain to boats and drag race only vehicles primarily. The above info pertains to street driven vehicles.

Maybe I'm missing something (wouldn't be the first time...), but I don't see tire diameter effecting the driveline angle.

u joint angle
 

Incorrect u joint angle

That would be correct. :)