A little driveline angle help

[Buuushman]

Compared to the diagrams of the way it should be, my drive shaft angles are all goofed up. Got some crappy pics from my phone- drive shaft to Transfer Case , drive shaft to diff., and homebrew -Transfer Case drop. There are degree shims in the rear spring pack and the Transfer Case drop is about 2". The drive shaft is 16 1/2" long and I am getting very slight vibration under hard acceleration, nothing when cruising or at high speed. The pinion angle seems to be a few deg. above a straight line with the drive shaft, I know it needs to be fixed but not sure how to go about it.

Thanks,
Bush

 

[Old Dog]

Buuush, it sounds like you either have a joint going bad or with thoes
new soft wrangler springs your pinion is rotating up to far under power.
Heres a couple good links for driveshaft angles.
Pirate4x4.Com - Extreme Four Wheel Drive
Tom Wood's Custom Drive Shafts - Tom Woods Custom Drive Shafts Custom Driveshafts Specialist

 

[fzsk4p]

Buuush, it sounds like you either have a joint going bad or with thoes
new soft wrangler springs your pinion is rotating up to far under power.
Heres a couple good links for driveshaft angles.
Pirate4x4.Com - Extreme Four Wheel Drive
Tom Wood's Custom Drive Shafts - Tom Woods Custom Drive Shafts Custom Driveshafts Specialist

X 2 on axle wrap

 

[fzsk4p]

YouTube - ‪Jeep Axle Wrap‬‏

YouTube - ‪Axle wrap‬‏

 

[BusaDave9]

YouTube - ‪Jeep Axle Wrap‬‏

YouTube - ‪Axle wrap‬‏

Now there's a cool demonstration on axle wrap. Makes me wish I could rig up a camera under my CJ to see what's going on down there. If you have ladder bars they have to allow the axle to manoeuvre. A single ladder-bar is good. Two is bad. I remember in the '80s when people would lift 4x4s sky high (some still think that's cool). They would use 2 ladder bars that would prevent articulation.

 

[BusaDave9]

I am getting very slight vibration under hard acceleration, nothing when cruising or at high speed. The pinion angle seems to be a few deg. above a straight line with the drive shaft, I know it needs to be fixed but not sure how to go about it.

Even sitting still it looks like your pinion is too high. If there are shims at your rear leafs I would remove them.

 

[Buuushman]

Won't removing the shims increase the angle at the Transfer Case ? it's pretty steep already and the Transfer Case drop is as far as I want to go. Can you get just the center section of a double cardan joint and use your existing flange/driveshaft end?

Thanks,

Bush

 

[BusaDave9]

A lot of suspension lifts will have you install angled shims at the springs to turn the front of the axle upward pointing to the TCase. Do you have shims like that? Look at how they are angled. It looks like your pinion is too high.

 

[Buuushman]

A lot of suspension lifts will have you install angled shims at the springs to turn the front of the axle upward pointing to the TCase. Do you have shims like that? Look at how they are angled. It looks like your pinion is too high.

Totally understand about the functionality of the shims, and yes I have them in the rear, and I agree the pinion is to high, but by removing the shims and lowering the pinion, the angle between the driveshaft and the Transfer Case will become steeper than I am comfortable with. I have lowered the t- case as far as I am comfortable with also. This is why I asked if you could use the center section of a double cardan joint with your existing flange / driveshaft end rather than spending the bucks on a new shaft.

Thanks,
Bush

 

[BusaDave9]

Totally understand about the functionality of the shims, and yes I have them in the rear, and I agree the pinion is to high, but by removing the shims and lowering the pinion, the angle between the driveshaft and the Transfer Case will become steeper than I am comfortable with. I have lowered the t- case as far as I am comfortable with also. This is why I asked if you could use the center section of a double cardan joint with your existing flange / driveshaft end rather than spending the bucks on a new shaft.

Thanks,
Bush

Yes you can get a double cardan joint. That's what I did on my CJ. It looks like your rear pinion is already pointing to your TCase.
I got mine at Tom Wood's Custom Drive Shafts - Tom Woods Custom Drive Shafts Custom Driveshafts Specialist

 

[BusaDave9]

The point I was trying to make is you don't want to decrease the angle at the pinion just to make the TCase angle smaller. Both UJoints should have close to the same angle. If those angles are too much then yes you need to get a double cardan joint.

Good advice.

Adding more oil helps and you have a good idea to prevent loosing oil out the vent.
Let me add a couple notes on drive line angles.
If the U Joint angles on a drive shaft are not strait (they never are on an off road vehicle) then they actually speed up and slow down on each rotation. This can produce a bad vibration. But a drive shaft is made so the vibration of the front U Joint cancels the vibration of the rear U Joint. This works great if the the angle of the front U Joint to match the rear. This is how every manufacture makes vehicles.

But this only works at small drive line angles. The UJoints don't like too much angle so when you lift your jeep you may have to angle the rear differential upward. This can be done with angled shims at the leaf springs. Then to keep both u Joint angles the same you can lower your TCase. If the drive line angles get to be too much you should then go to double cardan joint or a CV joint at the front of the drive shaft. A double cardan joint is 2 U Joints together.

These 2 U Joints cancel each others vibrations. In that case the U Joint at the differential should not have any angle. To keep it from vibrating it should be strait like this.

Now you can see how the pinion is much higher than the manufacturer intended.

I think you are on the right track in getting a double cardan joint.

 

[Buuushman]

Thank you Dave, I appreciate your responses, but what I want to know is can you get just the center part of the double cardan joint and use your stock t.c. flange and driveshaft end to make it work or do you have to get the whole works from Tom Woods? The site wants you to buy a whole shaft and I am on a Limited budget, so if i can get just the center part that holds the two U-joints and shorten the shaft to make up for the extra length myself, I will go that way. If I just remove my shims, the angle at the Transfer Case will be too steep, and it will most likely bind. I do not believe it is axle wrap that is my problem, stock flat Y.J. springs lend themselves to that type of distortion, but the 2 1/2" lift springs that I have have enough positive arch that unless pinned solid, under heavy acceleration, they should not distort enough to bind the driveshaft. I can fabricate an anti-wrap bar if necessary, but I think it is driveshaft geometry that is the issue, and I want to know if there is a less expensive way to remedy this than taking $500 from my daughter's colledge fund for a custom shaft.

Many Mahalos,
Bush

 

[BusaDave9]

Bush, I got my driveshaft for $334 including the flange for the TCase. I don't know if Tom Wood would sell you just the CV Joint. I doubt it but you could ask.

 

[Old Dog]

You should be able to buy the double joint. If not a trip to the junk yard should get you one. Alot of guys get the front shaft out of the mid to late 90's ford explorer and shorten it. it has a double joint on it already.

 

[Buuushman]

Thanks Old Dog, that's what I was looking for. I know the guy at the local wrecking yard and I'm pretty sure they have a pile of exploders over there, so grabbing a shaft and chopping it sounds like a plan.

Mahalo,
Bush