LS199CAMAROZ28

iTrader: (32)

You need to have a working angle for the u-joint or it will cause brinelling. Not saying that with the measurements you have it will happen but it's good to check. Awesome you got the vibration issue under control, just don't want you to trade off to another problem.

lees02WS6

iTrader: (5)

U-Joint needle bearings only need a small angle to avoid brinelling. He's well past the necessary amount. Driveshaft operating angle is more about ensuring that during full suspension droop, or compression, the u-joints won't bind against the shaft they are mounted in - highly unlikely in an f-body, especially if it's lowered.

lees02WS6

iTrader: (5)

It's also a stick axle, so one yoke is always moving.

LS199CAMAROZ28

iTrader: (32)

Can you explain this a bit further?

lees02WS6

iTrader: (5)

Notice the axle yoke always has an angle, by extension so does the joint at the trans. Even if the trans and pinion were set parallel with planet earth (represented by the black line) the axle movement by its suspension travel puts varying angles on the driveshaft.

As you increase the operating angle (meaning the components, the shaft, trans, and diff are not level with each other) the more difficult it becomes to cancel vibration, even with equal angles.

The fact of the matter is the less angle on the u-joint the more efficient they are. They transmit more power, last longer, and vibrate less the closer they are to perfect inline (not really possible with solid axle, the components can have center lines that are parallel though, which is what you want).

There are two reasons to measure driveshaft angle. One is when stick axles have to articulate a great deal, its possible the trunnion bearing caps could bind up against the shaft.

The other is that as stated previously when you get too far away from a good working angle for the u-joint, matching angles just don't produce effective vibration canceling.

LS199CAMAROZ28

iTrader: (32)

I was more curious to your definition of a stick axle, never heard the term before or if I have I don't remember. I take it you mean a solid axle, no offense.

The reason I mentioned measuring the working angle of the u-joint is because I have personally found more failures from lack of driveline angles than from excess driveline angles. I have yet to see any instance of the caps contacting the driveshaft and / or the yoke. Although it is possible.

I've seen the videos you posted before in previous training classes I've had and even got to play around with some "mock" drivelines with angle finders and certain manufacturers software. Pretty cool videos. Unfortunately these are not common problems I work with so a lot of the information is forgotten over time.

LS199CAMAROZ28

iTrader: (32)

I'm not sure if you have seen this or not but it's a video about differentials, made in 1937. I know it doesn't directly relate to driveline angles but kinda sorta.

lees02WS6

iTrader: (5)

Stick, solid, live axle, all the same thing. Bearing caps binding against the shaft in a car would be uncommon, but in a lifted jeep that's still using standard single cardan joints, has happend.

LS199CAMAROZ28

iTrader: (32)

I know how you guys in PA like to say things different than we do in VA.

Never really got into the whole aftermarket 4x4 thing. Good point though.

01ssreda4

iTrader: (96)

My trans was pointing down also, about 3 degrees. I set the rear end up 3 and it got a little better. Went up to 4 with no change. Went to the track and popped the front tires off the ground and nothing broke. Slight vibe from 90-110. I'm gonna try to fine tune it though.

ThoR294

iTrader: (6)

try setting it to like 2.65-2.75 like I did

Kevin97ss

Both these pix represent correct phasing of the joint. The bottom image is what these cars like. The top image is what you would see in a pick up truck for instance.

lees02WS6

iTrader: (5)

The bottom is the "broken back" driveline. Either configuration could work, but apparently the broken back is better with lower RPM applications.

Kevin97ss

I will politely disagree that either could work "well" in these particular cars. The issue with aiming for a set up like the top image is the shaft angles in these cars especially when lowered are not steep enough. I know many will argue that shaft angel does not matter...problem is that there is very little shaft angle, in this case it needs to be taken into account. Trying to compensate for axle wrap using equal but opposite angles and shallow shaft angles poses the problems of 1: not having the joints phased at rest which is what the joint sees cruising down the high way. 2: assuming anywhere between .25 and 1.5 degrees of compensation the pinion is either pointed up or level to the shaft angle.

The "broke back" configuration works because of the design of the car, with factory components the flex of the torque arm and the stretch of the trans mount keeps the phase correct even during WOT. Once an after market T/A and relocation bracket are used the flex is severely limited in the T/A and upward trans mount stretch is non existent. There is enough joint angle to prevent brinelling and assuming these components are in a properly set up drag car the small amount of T/A flex and resulting pinion angle change is countered by anti-squat effectively dropping the rear end down(actually pushing the rear body up) which lessens the angle at the tail shaft joint...again keeping the phase...close anyway.

When setting up your "broke back" configuration the vehicle must be fully loaded on its suspension, preferably with someone of similar weight in the driver seat and on a drive on rack or pit. Unlike the equal but opposite configuration that can actually be done just by jacking the rear.

ThoR294

iTrader: (6)

I assume that is why when I cranked the rear down (it was pointing down almost 3degrees), the vibration wasn't too bad, but it wasn't perfect. Now that I did the 3degree down for trans and 2.65-2.75 up for rear... its perfect... :\

slow01z

Old thread but....
Could this pinion angle thing be my issue? My car has a vibration from about 65-75 under throttle. My suspension is stock aside from bilsteins at all four corners???!

slow01z

And my drive shaft is steel???

ThoR294

iTrader: (6)

So if my Trans is pointing down 2.6* I should have my rear pointing down 2.6*?

Driveshaft Shop

The angles they spoke about in the previous posts are with in range, the only thing i would caution is to also check the Driveshaft angle. when you talk in terms of the U-joint angles is the difference between the two parts not what each is set at. SAE states that there are 3 angles under a single shaft system you have the Trans, the shaft and the diff. these 3 will create 2 "operating angles" or what the joint is going to and from. the rule here is no greater than 3 degrees and no more then .5 off from one end to another.

so as long as the driveshaft is at Zero yes this would be correct.

Kevin97ss

Yes, this will correctly phase the joint at rest (suspension loaded). Joint phase is critical for reducing vibrations.

The SAE "rules" are good to know if you are custom building something but I think most here are using factory mounting points for their rear suspension. Short TA's don't count for this equation as the arc angle of the rear is dictated by the lower control arms. The biggest variable we need be concerned with is ride height.