Driveline/u-joint angles…
 

So from what I read, you want the transmission/engine angle and rearend/pinion angle to be opposite but equal angles (essentially parellel lines if extended), and u-joint operating angles 3 degrees or less.

My question is, is the above even possible in these trucks? It would seem to be within the above “rules” your engine degree couldn’t be more then 3 degrees down. I have a SBC/Tremec Tko install that is 4.5 degrees down (stock drivestrain was even steeper) and driveshaft is 2 degrees down, which gives me an acceptable u-joint operating angle on the front-but if I put the rearend pinion up 4.5, I have an operating angle of 6.5 on the rear u-joint. If I put the rearend at up 1 degree, I’m at a better u-joint operating angle on the rear, but both angles (engine and rearend) aren’t opposite and equal?

There is no way I can lift the transmission enough to put it at only 3 degrees down- it would probably require cutting the stock floor to put a driveshaft tunnel in. Just wondering what happy medium I should shoot for? Is a 4 degree u-joint operating angle really that bad?!
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Re: Driveline/u-joint angles…
 

Here is a post I did on driveline angles. https://67-72chevytrucks.com/vboard/...6&postcount=14
Hope it can provide some help

Re: Driveline/u-joint angles…
 

I actually was thinking about this this morning and I think your post, if I'm reading it right, confirms this. Even though my pinion/rearend is pointed up the "angle" actually slopes down if viewed from front of the car to rear-just like the driveshaft and engine. So the 6.5 operating angle I thought I had in the rear (2 degree driveshaft downslope + 4.5 degree pinion pointing up, which is actually a downslope) is actually 2.5 degrees not 6.5. Correct?

Now when I lower it another inch or two and the driveshaft is level I may be in a worse situation but I think it looks okay now.

Re: Driveline/u-joint angles…
 

Correct. As I also mentioned. If you start at differential and say it points up, driveshaft is up and angle at trans is also up.

Re: Driveline/u-joint angles…
 

When you drop truck more. Say driveshaft is at 0 degrees. Will have a 4.5 degree operating angle. Not the end of the world. Just means less life for the u-joint. Have had a few 4x4 trucks with an operating angle more than that. Were my daily drivers and it was not a big deal.

Re: Driveline/u-joint angles…
 

Good to know. They make it sound like if the u-joint operating angle is 3.5 degrees, the u-joint is going to explode over 5K rpm.

This is one of those cases were not knowing may be better-was looking at my 2nd gen camaro I’ve had forever and the operating angles were greater than 3 degrees and that has seen 6K shifts on a drag strip with sticky tires hundreds of times.
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Re: Driveline/u-joint angles…
 

So I’m bringing this post back from the dead. What are you guys doing with lowered trucks and unjoint angles? I ended up lowering my truck a couple more inches- probably close to or a hair more than a 4/6 drop. The engine sits 4.7 degrees down and the driveshaft 1 degree down and as a result I have a 3.7 ujoint operating angle. Spicer says not to exceed 3 degrees. The tranny mount is already shimmed up and I don’t think I can go any higher without the driveshaft hitting the top of the trailing arm crossmember at full suspension travel.

Are you guys with dropped trucks just running the ujoints over these recommendations? Any vibration issues?
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Re: Driveline/u-joint angles…
 

I have used rear end shims on a slammed truck to successfully remove a driveshift vibration,
https://www.performanceonline.com/19...ar-Suspension/ since my tranny could only go so high due to floor clearance, I just tried to get the rear to cancel the front.

Re: Driveline/u-joint angles…
 

I'm currently fighting this. Stock C20 long bed with 2 piece driveshaft and 4.10 dana 60 gears. working angles after shimming the center carrier and rear end are all less than 2 degrees and still have vibration at about drive shaft speed of 2-3K rpm. Seems to get much better at higher speeds and at low speeds. It's not engine, trans, wheels, tires, brakes all have been changed out.

Re: Driveline/u-joint angles…
 

Very good video on drive shaft chit….

https://i.postimg.cc/dtVFGTPm/3857-E...-C4-A61-C7.png


https://youtu.be/gmV4qwLfOMY

Re: Driveline/u-joint angles…
 

For a two piece shaft there are three ujoints, so in theory one needs to go away so the other two can cancel each other out. You can set the carrier bearing up so the trans ujoint is 0 degrees (+ or - 1) then go about setting pinion operating angle so it matches center ujoint operating angle.

Other option is to raise or lower carrier to get center ujoint to match trans ujoint. In this case pinion would be turned so it's operating angle is 0 degress.
All operating angles can be + or - 1 degree to actual needed and operate fine in most cases. This second option is better for the lower vehicles.

For the post about operating angles exceeding 3 degrees. Have had two 4x4's with shafts that had twice that and were daily drivers. My current 72 will be around 6 degrees on rear shaft at ride height and axle drops about 8"-10" from there. 650 hp, 5.13 gears and 37" tires. Have no worries. Have you seen the 1000 hp rock bouncers?

Re: Driveline/u-joint angles…
 

One other option to make it easier for the piece shaft trucks is to install a CV in the place of the ujoint at trans or middle ujoint location. The CV will cancel itself out, leaving just two deal with. Granted this would take some $