greggradwohl

Like many people here, I got a three inch lift (adjustable rear upper CAs .25” longer than stock), wheels/tires, and 1310 jereel shafts. Everything worked fine. Got my gears (5.13) and then there was a vibration. Took it back to the shop, and they found my jereel shafts were out of balance. I replaced those with the shops custom made 1310s. Much less vibration, but some. After several weeks of eliminating every other cause (including removing my front shaft), I decided to start screwing around with my rear pinion angle. After backing my rear uppers to just slightly longer than stock (somewhere between 1/16" and 1/8") that vibration is GONE. Not tolerable, not slight, it is freaking gone.

Dont know if this will help anyone else. But there is one happy camper over here.

Bodo

Glad you figured it out. Seems like I have heard that there should be a 2-3 degree difference between the angle of the shaft and the angle of the pinion. Did your JE Reels come with any installation instructions that mentioned the angles?

greggradwohl

Negative. I should have just started there instead of asking people how long to make the adjustable uppers.

It takes getting under the vehicle to get that angle, though. Something about the shape of the d44 produces an optical effect making the shaft angle "look" higher than it actually is. I just got a long piece of thin aluminum bar, made a 90 deg intersection with the dust cover at one end and see where the other end ends up. Right now, the shaft from the diff basically points straight at the TC output shaft. I dont know how to get precise enough for 2 degree increments... Bottom line, no vibe.

69thunderbird

guys at je reel said stock angle on the front was 5 degrees, and to eliminate vibration move to 6 degrees, and work up in 1 degree increments until the vibe is gone. also said do not go over 9 degrees or you will begin the death wobble. if that does not fix the problem then send it back for replacement.

mine vibrates around 50-55 but not enough that i'm going to start playing with the angle until someone lays out how to properly adjust in laymens terms so i don't hose things up worse than they are.

greggradwohl

My problem was with the rear. I have had no issues with the front 1310 shaft (stock CAs).

wayoflife

just out of curiosity, did you make sure that your pinion was in line with your driveshaft? the lenght of your control arms should be determined by it and should not be set by some arbitrary measuerment.

greggradwohl

That is what I have been trying say. I wish I would have started there - would have saved me a lot of hours of screwing around.

69thunderbird

crious - is there an easy way to determine proper pinion angle, and what is the proper control arm length?

wayoflife

just give it a look. with an aftermarket u-joint style shaft, the shaft itself should be directly in line with the pinion flange or yoke. an angle finder can help determine how accurately it is on but it's not really that necessary to be 100% on.

if you are installing a new drive shaft, these simple steps will help you get it on right:

1. with your tires on and your jeep on the ground, place an floor jack under your diff close to the pinion so that the two are making contact but not applying any lift.

2. remove your upper control arms

3. raise your jack until your pinion flange or yoke is in line with the drive shaft. you can use an angle finder to help determine this but being off a hair one way or another shouldn't make a difference.

4. take one of your adjustable upper control arms and set it so that it can be mounted up to the frame and axle mount without any additional adjustments.

5. take the set arm, measuer it eye to eye and then set the opposite arm accordingly.

6. install both arms, tighten up the bolts to 125 ft. lbs. of torque and you're done

69thunderbird

thanks WOL - there lies the problem - i went with a kit with no adjustable 'nuthin, so no adjustable end links or control arms.

this is probably a dumb question - but does anyone sell just the adjustable rear upper control arms? i over spent my budget about about $4K ago!