so im trying to dial in a few thing, does a angle of 16 sound about right for a 4" lift on a tj? the dshaft is 16 and the pinion is 16. do i need to bring the pinion down at all on the rear or is zeroed out ok? my upper arms are just a little less than 13.75" and the lowers are 15.75, also does anyone have issues with a rear adjustable trackbar hitting toward the frame side on the gas tank skid? i have a iro adj front and rear. on the back it looks as if it compresses a few inches its going to contact the top lip of the skid. i extended the bumpstop cup 3" but the distance between my skid and tbar are less then from the cup to the bottom of the spring perch.forgot to mention i also have a jks angled trackbar bracket thats bolted on.
The exact angle degree is not what you're looking for, that particular angle varies by the Jeep configuration... what is correct for one Jeep would not necessarily be correct for a different Jeep.
What is important is what driveshaft you have before trying to figure out what pinion angle is appropriate. If you're still running the stock OE driveshaft, and I hope you're not with a 4" lift, then the pinion angle has nothing to do with the driveshaft angle... the pinion angle must be the same as the t-case output shaft angle. In other words, the pinion shaft and transfer case output shaft must be exactly parallel to each other.
If you have an aftermarket CV driveshaft, the rear axle's pinion angle needs to be at the same exact angle as the driveshaft angle... pointing directly in line with the driveshaft in other words.
i forgot to add i have a tatton cv driveshaft with 1330 ujoints. i have been reading on setting angles and was wondering if i am doing it right, measured from the pinion and rolled the jeep then measure from the driveshaft at the ujoints. i used sockets and a craftsman angle finder if that helps.
i read some people set the pinion a few degrees low but is it really needed?
Start with it in line as has already been said. If you have vibes rotate it down a degree or two and see if they go away. In a coil spring TJ with good control arms I am very skeptical of axle wrap, but every jeep is different (or if you have worn control arm bushings). Don't worry about the exact numbers. In the ballpark you are talking they really don't matter. Orientation of driveshaft to pinion is what matters.
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You can throw the angle finder back into the junk box, you don't need it... your eyeball is good enough for this.
But if you really want to use it, measure the driveshaft angle. Then place it on the back of the axle on either of the two flat circle locations on either side of the differential cover. Those two flat circle surfaces on the back of the housing are perpendicular to the pinion angle... placing it on one of those two surfaces will cause the angle finder to show the precise pinion angle... stop trying to measure it from the u-joint or yoke.
Set the pinion angle so it is either exactly the same as the driveshaft, or as low as 1-2 degrees under that of the driveshaft. It's important that the pinion angle can't be so much as even 1 degree above the driveshaft though, that would cause the driveshaft to rotate.
You can place the pinion angle 1-2 degrees low, at the most, so when the axle rotates very slightly during acceleration so the pinion angle can't lift up too high which could cause vibrations during acceleration.
Measure the pinion angle like this...
The first pic shows the angle finder on the driveshaft. The second shows the two surface on the back of the axle that are there to give a precise pinion angle measurement point (precisely 90 degrees from the pinion angle), the third pic shows how the pinion angle is taken.
You can see both angles are about 17 degrees. The exact angle is not as important as it is that they are both the same when you have a CV driveshaft. Just make sure the pinion angle is never higher than the driveshaft angle when you have a CV driveshaft.
well looking at it, it looks perfect i was just throwing those out there. i have not driven it as im making a flange nut for my front trackbar and trying to figure out what else i can use with the rear axel end of the trackbar, a 7/16 seems to fit great inside the bushing on the front so i hope the back works out to. i need to check the front angle and adjust toe/center wheel before i drive it. anyway to post pics from a mobile phone on here?
whats the right way to make sure the rear axel is centered front to back? it seems good side to side but looks like when the suspension moves the front of the tire may rub a bit on the inner fender? also whats your guys take on using grade 5 7/16 bolts on the trackbar axel ends? i know the differences in grade 5 and 8 but want more opinions.
Grade 5 is more than strong enough for that particular bolt. For centering the axle, if I were to be off a tad fore or aft, I'd err on having the axle a tad forward of center because the axle moves aft as it moves upward into the wheel well.
thanks jerry! i should get my front tbar on tonight and drive it tomorrow for a shake down, its taken to long to install all of this it sucks not having a garage and using a lantern and work light outside in the cold. you guys have been a real help though i appriciate it.
well i drove it today it was about a 7 out of 10, feels a little loose. i set the toe at 1/8th of an inch but im going to get a lifetime alignment, its also a hour away. what are the effects of to much or to little caster? my wheelbase seems good and not really any vibs, it also tracks straight. not sure what i need to adjust?