control arm length

[jared]

i just bought adjustable controls arms upper and lowers for my xj. i was told a length of 15.5'' upper and 17'' lower. this is with rustys 6.5'' springs.

 

now i have the arms bolted to the axle with no springs installed. with these measurements i have 0 degrees pinion angle from the axle which probably isn't great and it should be pointed up a little bit at least.

 

so my questions are-

 

How long are the stock control arms upper and lower

 

how many degrees shouldi have of pinion angle

 

how long should my adjustable control arms be.

 

thanks you very much for any help you can provide

[CWLONGSHOT]

Try here..

 

www.yuccaman.com

 

OR, more specfically: HERE http://www.yuccaman.com/jeep/re_db.html

 

 

Down to the bottom of the page is a chart with suuggested CA legnths!!

 

CW

[jared]

that site gives the same measurements i used for 6''. it just doesn't seem right to me. there is no upward angle on the pinion. i never payed any attention if there was stock either.

[87manche]

the front shaft has a cardan joint, so the pinion needs to point at the t-case output.

You're going to have to make a compromise between pinion angle and caster.

[JOMJ87]

I would go by the caster on the axle and put it stock. All you need is a angle finder and then you need to adjust your control arms to whatever the setting needs to be.

 

Cole

[jared]

what is the caster angle of the front stock?

 

and how do i measure it

[87manche]

everything you need to know for a home alignment:

http://gojeep.willyshotrod.com/HowtoAlignment.htm

 

good luck.

[jared]

^^ i just goolged it and found that exact same site. definatly need to figure this out now.

 

so basically i need to make my differnetial cover read 87.5 degrees which will make my caster +6.5 degrees which is factory specs.

 

now i just need an angle finder.back to harbor frieght i guess

[jared]

so i just got my angle finder. i know how to use it, and the angle for stock caster is 87.5 degrees. but the angle finder i bought goes up to 90 then back down

 

like

 

----------------90

 

 

 

0-----------------------------------0

 

so which side of the 90 should it be on? i think it should be to the right side of the picture(front of vehcile) but i am not sure. that would give it some angle toward the tcase so i think that is right.

[comancheman]

i just put in adjustable UCAs and LCAs with 5.5.inch springs. i initially set my arms so my driveshaft angle was non existent. when i set the truck down from the jack stands my coils arched like a backward C in the wheel well because where the coil mounts in the wheel well wasnt lining up with where it mounts in the axle. i had to sacrifice a little extra u-joint longevity so my coils sit right on there perch. it took a few trys of adjusting the control arms to get it right but hopefully itll work out

[comancheman]

o yeah...

if antidisestablishmentarianism i did was wrong someone correct me please ^^^

[jared]

what were your final lengths? and how does it ride. does it have any angle on the pinion or is it flat.

[DirtyComanche]

that would give it some angle toward the tcase so i think that is right.

 

 

The ball-joint centre line points back towards the tcase. At least, it should.

 

 

 

Raising the pinion up makes them vertical, and then pointing forwards. Vertical can be lived with (it won't WANT to recentre), pointing forwards is BAD (it'll want to not centre).

 

 

 

As far as what comancheman did, it may or may not be alright. Drive it and see how it handles. The pinion angle should NOT be favoured over caster beyond the 0* (vertical) point. But, curving over the coils isn't a bad thing - it's just bad form.

[jared]

i readjusted my arms to 15.5 upper and 16.75 lower. this gave me a caster angle of +6 degrees which is good considering stock is 6.5. but the pinion is also angled up a little bit, which is better imo than it was.

 

i did notice on the sight i learned the info from he ran 5.5 degrees caster, so i hope mine will ride alright i don't want to pull it all back apart.

 

i hate working on cars.

[Bounty Hunter]

IIRC, I ran 5.5" coils and 17" LCA's, and built my UCA's to 15.5" for about 5º caster. The MJ worked well with that setup.

 

With 17" or even 17.5" LCA's, I would recommend setting the jeep on the axle with the UCA's removed and a large 2" ratchet strap from the top of the inner C's to the rear axle, holding the top of the axle from flipping forward. Then adjust the ratchet straps for the proper caster, and finally adjust the UCA's.

[Stumpy]

IIRC, I ran 5.5" coils and 17" LCA's, and built my UCA's to 15.5" for about 5º caster. The MJ worked well with that setup.

 

 

here is what i have mine set at..LCA's are 17" and the UCA's are 16.25" with 5.5" coils. This is waht Bounty sent me

[jared]

what is your caster setting with those lengths?

[jared]

well i set it up fianlly (hopefully) to 17.75 lowers and 16.75 uppers. i have it on the groung now. looks really good. its almost level with the back now.

 

befoe i installed the spring i used the jack to cycle the suspension to check for binding and it it is hanging up on anything. sure enough the uppers were hitting a little bit of the upper/lower/frame mount. so out came the cutoff wheel and i took care of that.

 

my final caster with it on the ground is about 5-5.5 degrees which is a little less than stock, but it should be enough.

 

now at full axle droop my front driveshaft bottoms out, but i don't think it will be a problem because the shocks should limit that somewhat, and i don't really think it will flex that far.