Guys Im getting ready to order my driveshaft from tom woods andI need to know how much I need to raise the pinion angle in the rear due to the lift I put in (about 8-9") I know for a CV shaft the pinion has to be pointing directly at the rear output on the xcase, MY question is how can I find out how much i need ot lift the rear pionion angle, weather to use 4* 6* or 8* shims?

I can eyeball it but I dont think that going to work for long:D

there has to be a way to measure accurately, I do have a angle finder but I dont think this will help in my case.

any help would be good:)

thanks
john

The correct way would be to cut off the perches and weld on new perches at the correct angle. :flipoff2:

AFAIK a CV shaft you point a degree or two down from the output. A normal shaft you would point towards the output.

You could take an angle finder to figure out the differnce.

I got a Tom woods 1350 CV shaft if you want to buy it :flipoff2:

im not really up to the job of cutting of the old pearches and welding in new ones. wouldnt using shims be much easier? so how can I find the correct angle without eyeballing it:confused:

Well you could always just guess. Does it vibe on you now? Maybe just get a 2.5 degree shim and try that.

na.... the XJ im building (goto sig link for pics) was involved in a accident, wipped out most of the suspension (bent axles/arms bent links etc) so i went ahead and started from scratch.

I wouldnt know the answer to that question because I havent driven it yet. hopfully soon tho, I need to get this in order so I can order the damn shaft:D

Originally posted by KarmirXJ
there has to be a way to measure accurately, I do have a angle finder

So what's an angle finder do again? :flipoff2:




Measure your pinion angle, using that there "angle finder" contraption. :p

Get a wood stick or tube or something and hold it from about the center of the top end of the drive shaft to the center of the axle tube. Measure that angle.

Subtract that angle from 90 degrees (assuming your pinion angle measurement was was across the yoke, perpendicular to the actual pinion gear angle).

The difference between that angle and your pinion angle is about the size of shim you need.

Even if your measurements and angles are "perfect," you may still need to try some slightly different shims if you still have vibrations. Pointing the pinion at the t-case or 1-2 degrees below it should work though.

Originally posted by ErikB

Get a wood stick or tube or something and hold it from about the center of the top end of the drive shaft to the center of the axle tube. Measure that angle.



dont want to sound ignorant but why the axle tube?

I was thinking of getting those streight edge 90* (shaped like an 'L') rulers that you can buy from homedepot or something then put that on the face of the yoke, which would be perpendicular (sp?) to the pinon angle then face the other end of the ruler towards the rear of the xcase, then get the stock angle (which i have now, suptract the difference, add 1or 2* like said before and that would give me the shim I need. that a good idea? I hope it is:)

It's quite well explainde here:

http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html

even if I say so myself :flipoff2:

the Wiseman is pimping it again:flipoff2:

Tanks

Originally posted by KarmirXJ
im not really up to the job of cutting of the old pearches and welding in new ones. wouldnt using shims be much easier? so how can I find the correct angle without eyeballing it:confused:

I will help you out here even though your getting a limp woody shaft..

If you were running a single u-joint on each end you would just match the angles on the t-case and the pinion but with a CV you need have the pinion down about 2 degrees.

The best way I have found to do this is to cut a broomstick to run betwen both the yokes, the thing is the design of a CV makes the point where the full angle is acheived is about 2-3" back from the yoke so you will need to sorta hold the broomstick back a bit to get the point to measure from. Now take the angle of the broomstick and the angle of the pinion and add shims as necessary, but make sure they are STEEL shims, the aluminium ones ALWAYS seem to break.

This method is only going to get you in the ball park, you really should get a new set of perches that way you can rotate the axle exactly where you want it with the rig loaded and weld it up..

Oh and good luck with the limp woody shaft.. :rolleyes: :rolleyes: :shaking:

streight edge 90* (shaped like an 'L') rulers
that would be a framing square....

as for the shaft, a cv shaft you want to point right at or 1-2* below..the reason for pointing below is for axle wrap so that under acceleration, it rotates up and will be pointed right at the cv. with a normal shaft, you want the angles to match on both ends. cutting off perches is not hard at all...but shim if you would like, make sure you get STEEL shims and not aluminum, the AL cracks and that is not a good thing. I would recommend going with Jesse at HIGH ANGLE DRIVELINE, but to each his own....good luck
greg

Originally posted by TPIJeep


I will help you out here even though your getting a limp woody shaft..
Oh and good luck with the limp woody shaft.. :rolleyes: :rolleyes: :shaking:

Did I miss something:confused:

They're giving you a hard time about your Tom Woods shaft. Don't be fooled! High Angle Driveline is obviously very good and a supporter of the board, but Tom builds a top notch poduct as well.
Everyone need competators and choices, its what makes everyone honest and strive for improvement.
There is another way to figure out your shims and thats with a little math. If you know the distance your pinion yoke must RISE to get in line with your t-case, and you can measure the distance from the center of the axle tube to the end of the pinion yoke (RUN), you can use a little trig to solve for your shim angle. It would be sin(shim angle) = RISE/RUN
Example: your pinion needs to rise 3 inches, your RUN or distance from axle tube to pinion yoke is 14 inches,
then sin(shim)=3/14 which equals 12 degrees
Good luck, it will be worth it!

Billa answered but not directly (he typed it up so nice once already ;) ).

The reason you measure from the center of the axle tube is because the axle is axis. The housing would spin around the axle if you so wanted. You can also call it the "pivot point" or falcrum (sp?) depending on how you want to look at it in you noodle.

I think that in your case you should probably get an experianced friend to help you move the perches themselves and not use a shim. For three reasons: 1) just plain good old fashioned practice 2) Because that is going to be a thick shim with an 8" lift on an XJ. 3) If you have to adjust to reduce vibes, you are only going to be spending money on a shim or two instead of staring with an 8* shim then trying a 6* then a 10*. you get the idea.

Steps to move perches:

Imagine the rear suspension being together except for the u-bolts so you could pick the jeep up off the axle but the axle stays on ground. You want to be able to put the XJs weight on the axle like it would if it was driving around. That way you don't have to guess at how much the suspension will be dropping normally, how high the axle will be off the ground, etc.

Cut off old perches and clean axle tube smooth.
Put new purches on axle tubes (axle under vehicle with tires on).
Put jack under pinion yoke to help you raise and lower as needed.
Put high lift under rear bumper.
Block the front tires like you don't want it to move ever again.
Now pick the rear of the XJ enough to be able to adjust the purches by hand.
Now use the pinion jack to position the pinion to the correct angle.
Let the weight of the XJ down onto the axle.
Adjust as needed buy repeatingthe previous 3 steps.
Tack weld the purches when you have everything where you want it. Do this with the weight of the XJ on the purches.
EDIT: Don't forget to completely weld the purchs on after they are tacked. This is essetial for performacne ;) :flipoff2:

Cake!!!. Have fun. Leave the thick shims at home.

Tim :beer:

Originally posted by GED
They're giving you a hard time about your Tom Woods shaft. Don't be fooled! High Angle Driveline is obviously very good and a supporter of the board, but Tom builds a top notch poduct as well.
Everyone need competators and choices, its what makes everyone honest and strive for improvement.


Yes but when I talk to Jesse at High Angle he does not talk smack about his competators nor does he recommend a 1310 series CV for a 500hp Jeep on 40" boggers running at 24 degrees even after I tell him I constanly break the cross shafts on 1310 joints... :rolleyes:

well screw it then, I guess I'll go ahead and relocate the pearches. Thanks for advise, Im sure Ill come back with some more ???. I always change what I ORIGINALLY had planned after I visit POR. :D

JEEZ the original plans for my XJ was a 2.5" rancho lift and some 31s with a limited slip... now look what happen(click on sig) after I visited POR:rolleyes: