Control Arm Length

HOOP · Oct 1, 2005

just wandering if ya'll can help a ol HOOP out,in process of install lift and was wandering what approximately should length on upper and lower arms be ,putting on 6 in. coils

thanks
HOOP

GirlScout1 · Oct 1, 2005

Here you go...it's a good guide:
http://www.lunghd.com/Tech_Articles/Suspension_Steering_Axles_and_Brakes/Control_Arm_Chart.htm

HOOP · Oct 1, 2005

Thanks Gs1

Hoop

Bounty Hunter · Oct 2, 2005

I just installed RE 5.5" coils, LCA's were 17" and UCA's needed to be 16" for correct caster.

Ramsey · Oct 2, 2005

http://yuccaman.com/jeep/re_db.html#arms

GirlScout1 · Oct 2, 2005

Bounty Hunter said:
I just installed RE 5.5" coils, LCA's were 17" and UCA's needed to be 16" for correct caster.

Yeah thats about what I'm running except I have short arms. My lengths are about that thoug. I think My UCAs might only be 15 7/8" though.

Bounty Hunter · Oct 2, 2005

GirlScout1 said:
Yeah thats about what I'm running except I have short arms. My lengths are about that thoug. I think My UCAs might only be 15 7/8" though.

Mine are short arms too, no drop brackets either. Had I used the above chart I would have had way too much caster.

Fergie · Oct 3, 2005

At 6", your LCAs need to be adjusted out to 16 3/4" and your UCAs need to be set to correct your pinion angle.

Fergie

PS-Those charts are wrong.

GirlScout1 · Oct 3, 2005

Fergie said:
At 6", your LCAs need to be adjusted out to 16 3/4" and your UCAs need to be set to correct your pinion angle.

Fergie

PS-Those charts are wrong.

I agree Fergie but it is a good starting referance. Mine LCAs are set at about 17" and my uppers are about 16". I used a protractor after against the pinion output to get it about 94( can't remember exactly but I know my pinion is pointing at my TC out put yoke now)

Yucca-Man · Oct 3, 2005

Fergie said:
PS-Those charts are wrong.

Then feel free to priovide constructive numbers. I even say in the writeup that these are typical numbers that may vary on yours...if you have other numbers then feel free to let me know what they are instead of always claiming that these are wrong.

Bounty Hunter · Oct 3, 2005

Fergie said:
At 6", your LCAs need to be adjusted out to 16 3/4" and your UCAs need to be set to correct your pinion angle.

Fergie

PS-Those charts are wrong.

I'd give a little more attention to caster when determining the length of the uppers.

I used ratchet staps on top of the C's on each end of the axle, to the rear of the jeep. Use these without the uppers installed to determine proper caster, then measure for UCA lenght.

Fergie · Oct 3, 2005

Yucca-Man said:
Then feel free to priovide constructive numbers. I even say in the writeup that these are typical numbers that may vary on yours...if you have other numbers then feel free to let me know what they are instead of always claiming that these are wrong.

Ummm...did you not see the numbers I DID provide?

It is real simple. You take 248.0625 and add the square of your lift height. Then you take the resulting number, and root it. This will give you the decimal value for your LCA length. Convert as needed.

For RE DBs, you use 232.5625 and subtract 3" from your lift height before squaring it.

As far as caster, I have no clue, and just set my pinion angle accordingly. I know there is a more accurate relationsip than that, but can't find it, or what the acster should be, but remember it being around 7*.

Here is something more....to find your lift height in the front, you measure from the top of the axle tube to the bottom of the frame rail. Stock measurement is 6.75"(7.75 for HD/Up Country).

For the rear, measure the same way, and it should be 6"(7") and both front and rear can vary by .5".

Good enough for you?

Fergie

Gridikal · Oct 3, 2005

Hmmm...

Copy/ Save

Ramsey · Oct 3, 2005

very interesting, where did those numbers come from

Fergie · Oct 3, 2005

Ramsey said:
very interesting, where did those numbers come from

The numbers I used were from the stock LCA length of 15.75", and from the RE site which states that the DBs move the stock location forward by .5" and down by 3", so the length would be 15.25". Square those and you get the number I used.

The stock height measurements I got from a post by Eagle from a while ago..."Measuring lift...the dirty way."

All the math is just a^2+b^2=c^2 and making sure to maintain stock geometry.

Fergie

AZ DESERT RAT · Oct 4, 2005

Fergie said:
The numbers I used were from the stock LCA length of 15.75", and from the RE site which states that the DBs move the stock location forward by .5" and down by 3", so the length would be 15.25". Square those and you get the number I used.

The stock height measurements I got from a post by Eagle from a while ago..."Measuring lift...the dirty way."

All the math is just a^2+b^2=c^2 and making sure to maintain stock geometry.

Fergie

My brain hurts!!!!! LOL

Ramsey · Oct 4, 2005

wow, never would have thought of that

Control Arm Length

HOOP

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