Ok, my caster is at about 10 degrees ( I know way to much) and my pinion is parallel to my transfer case, instead of pointing up toward the transfer case. I blew the cv joint in the stock drive shaft. So, I will be ordering a Tom Woods 1310 series drive shaft. To get my pinion angle corrected (pointing towards the transfer case) can I shorten my adjustable lower control arms?

Also, is about 6 or 7 degrees of caster what I need for good handling and for no driveline vibes with the Tom Woods drive shaft?
If it helps I have the teraflex 3" lift and 35's with front lower adjustable control arms.

I hope this is not confusing? Please be patient with me, my husband is currently deployed, so I'm trying to figure this out on my own.

TIA,
Brandi

 

6~8 degrees positive caster is good for the setup you have according to a lot of the write ups, so I believe you need to shorten your LCA's a little bit in order to get there. As for the pinion you want it pointing slightly downward...I will refer you to this write up on the project-jk website http://project-jk.com/jeep-jk-write-...-end-alignment

 

Hey, I have the same lift as you. Be sure when having your caster measured, have it measured professionally, you can not obtain accurate caster with an angle measurement devide, not with the new steering systems. My caster is 4.3 left, 4.5 right and drives like a champ. I originally had it at 5.3 both sides, and was not so good. I think I am at the sweet spot right now.

 

The figure below from the TW site shows the ideal geometry for a double Cardan driveshaft. Note how the differential is rotated to move up the pinion axis.



Many of us go with the double cardan driveshaft, but as you can see that puts more of restriction on the pinion angle, since it is designed to have the driveshaft aligned with pinion. In order to achieve this alignment the pinion needs to be rotated up which reduces Caster.

The double cardan driveshaft is considered to be smoother and stronger for a given operating angle, but it does require some compromise.

The solution is to find a good compromise between the two angles. This is where a good 4x shop can help because of their experience.

Did your CV joint (transfer case) or the Cardan joint (diff) fail?

 

The cv joint at the transfer case. I have looked for some 4wd shops around here and can't find any?

 

I had alot of driveline vibration that got worse as speeds went up. My pinion was just about horizontal which is bad. Gotta get that pinion pointed up towards the TC as much as you can with the adjustable lower CAs (right, make the lowers shorter and the uppers longer if you have adjustable uppers). True, you will be giving up castor angle, but I've gone from about 7 to less than 4 and cannot tell any difference. On the other hand, the vibration is gone. GL

 

If you go this route, get upper adjustable control arms. You can adjust your caster by lengthening or shortening both arms. It will still be a compromise, but it will be less of one.

 

I assume you are saying that using upper CAs instead of lower CA's is less of a compromise when it comes to the tradeoff between Caster and Pinion angles.

If so, why are the uppers CA better?

 

uppers aren't necessarily better and honestly, i like to recommend lower control arms to do the job instead as they are easier to install and setting them to about 23" eye to eye will give you what you want. depending on how much lift you have, getting both uppers and lowers is nice to have as you can use the lowers to reposition your axle to where it needs to be and use the uppers to set your caster.

 

I thought she said that adjustable LCAs were installed? So I believe that they would need to be shortened a little bit to bring the caster in to where it should be, so adjustable front upper control arms would help with the pinion angle. Whoever made the second post I believe is mistaken because you do not want the pinion pointing downward. YUP!