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theprez
02-01-2016, 06:06 PM
Hey All -

So I did some additional suspension work (front upper and lower adjustable control arms, front and rear adjustable trackbar) and needed to get the vehicle aligned - also wanted to check my own DIY alignment work for piece of mind.

My JK has stock drive shafts and a Teraflex 2.5 inch lift (so far stock wheels and tires as well).

So here is where the conflict begins -

Went to a local auto repair place and they indicated the jeep was at 5.5 degrees caster and 6 or 7 would be more appropriate with my 2.5" lift. I indicated that I thought +4.2 degrees would be ideal and given the adjustable nature of my JK it should be able to get in that range. Auto tech disagreed and said the 5.5 was already technically in spec and he would road test it and adjust to 6 or 7 degrees, not 4.2. In his words, +4.2 would create vibrations. Naturally, I declined and left.

Went to a more specialized 4x4 place in Dallas and they had no problem adjusting things and didn't ask any questions. Alignment took over 2 hours tho lol.

My question is who is right? I'd assume the goal would always be to get it close to stock specs (otherwise why buy adjustable components) but thought I'd check around since i've never encountered any pushback like that before from an alignment shop.


New Alignment Specs:

Left | Right

Camber -.5 -.5
Caster 4.3 4.5
Toe .09 .10

Thanks

WJCO
02-01-2016, 06:10 PM
Hey All -

So I did some additional suspension work (front upper and lower adjustable control arms, front and rear adjustable trackbar) and needed to get the vehicle aligned - also wanted to check my own DIY alignment work for piece of mind.

My JK has stock drive shafts and a Teraflex 2.5 inch lift (so far stock wheels and tires as well).

So here is where the conflict begins -

Went to a local auto repair place and they indicated the jeep was at 5.5 degrees caster and 6 or 7 would be more appropriate with my 2.5" lift. I indicated that I thought +4.2 degrees would be ideal and given the adjustable nature of my JK it should be able to get in that range. Auto tech disagreed and said the 5.5 was already technically in spec and he would road test it and adjust to 6 or 7 degrees, not 4.2. In his words, +4.2 would create vibrations. Naturally, I declined and left.

Went to a more specialized 4x4 place in Dallas and they had no problem adjusting things and didn't ask any questions. Alignment took over 2 hours tho lol.

My question is who is right? I'd assume the goal would always be to get it close to stock specs (otherwise why buy adjustable components) but thought I'd check around since i've never encountered any pushback like that before from an alignment shop.


New Alignment Specs:

Left | Right

Camber -.5 -.5
Caster 4.3 4.5
Toe .09 .10

Thanks

4.2 is spec. The more positive your caster, the more your steering wheel will return to center and handle better. However as caster gets more positive, your front axle pinion angle gets less ideal and can cause vibrations. So by lowering caster, your pinion angle is better for less driveline vibrations. Glad you got it back to stock, but you would have been fine at 5.5 too.

zimm
02-01-2016, 10:13 PM
After my RK 2.5 install I had the dealership check the alignment. The caster was way off, but the tech wouldn't touch the adjustable arms. He incorrectly told me I had to lengthen the arms (they needed to shortened) and it would cost me $100 to have them re-check castor after I adjusted the arms. I left and emailed rockkrawler. Their idea worked perfectly. I downloaded "angle finder" app on my iPhone and laid the iPhone on top of the kingpin. It showed exactly what the alignment shop showed for castor. So I shortened the arms up as much as they could go and got 4.2! Bingo, fixed for free. Bottom line, angle finder app and put phone on top of the upper ball joint. Done.