Axle shims- how much is too much

[Bucks86Renegade]

Hello,
In process of building a CJ7 :
I've installed a 4.0L I6, an AW4 tranny, a 2.5" lift w/ a 1" body lift. Dana 44 rear, Dana 30 front, 4.10 gears.

I know there are others who have the AW4 tranny in their CJ- what degree shims did you use on the rear axles?

It's looking like I'll need 6 to 8 degrees and I'll need to shorten my rear driveshaft as well. What are the cons to using shims?

Anybody recommend a maker of custom driveshafts for the front?

Thanks a lot.

 

[BusaDave9]

You want to keep the u-joint angle at the axle close to the angle at the TCase end of the drive shaft. Here's what I posted in another thread:

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 matches the rear. This is how every manufacture makes vehicles.

But this only works at small drive line angles. The U-Joints 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.
That vent reservoir is a good idea. Thanks for the tip.

 

[BusaDave9]

Anybody recommend a maker of custom driveshafts for the front?

Tom Wood's Custom Drive Shafts - Tom Woods Custom Drive Shafts Custom Driveshafts Specialist
Very low prices but very heavy duty drive shafts. I have wasted my money elsewhere but now I will only go back to Tom Wood.

 

[BajaEdition]

great answer Busa, I was wondering if I would have to explain all that, but those pictures did it perfectly

 

[Bucks86Renegade]

Thanks for the information, Dave. Great forum too.

 

[AussieCJ7]

Hello,
In process of building a CJ7 :
I've installed a 4.0L I6, an AW4 tranny, a 2.5" lift w/ a 1" body lift. Dana 44 rear, Dana 30 front, 4.10 gears.

I know there are others who have the AW4 tranny in their CJ- what degree shims did you use on the rear axles?

It's looking like I'll need 6 to 8 degrees and I'll need to shorten my rear driveshaft as well. What are the cons to using shims?

Anybody recommend a maker of custom driveshafts for the front?

Thanks a lot.

Exact same swap for me except I was 4.5" lift and I used 8* wedges make sure you get steel ones not alloy I have not just swapped in a Dana 44 and welded my spring perches at the right angle the angle is as per posts above

just make sure you check out your oil level with so much pinion angle

 

[AussieCJ7]

BTW with the AW4 it must have the brake light switch connected to the TCU if not you will get weird shifting and Torque Converter will not lock

Can go into full explanation in another thread if you need it but it took me months and hours of reading the manuals to sort out

 

[Bucks86Renegade]

Thanks, Aussie. I'll keep those tips in mind. I might ask you some questions on it later if I get stuck. The plan is to have it running in the next couple of weeks.