How long are extended radius arms supposed to be?

[tweakedlogic]

I'm getting help from a welding buddy to cut and turn my beams for a 4" spring.
I've been looking for weeks now trying to find out how long to extend the radius arms. I see a lot of guys push their ttb forward about an inch or so. So with 4" springs, do I extend them 5" or 4" or what?
The extended radius arms are supposed to increase (or at least not hinder) travel right?

 

[little x]

Most kits extend them all the way to the trans support and replace the stock piece with one that pulls double duty as trans cross member and RA mounts. Longer is better, up until they are the same length as the axle arms. I think that's around 12-13" or so.

 

[tweakedlogic]

Wow! really. I didn't know about extending them that far and using the trany cross member.
That helps out a lot. Thank you.

 

[94Gexplorer]

i saw a sas'd explorer with radius arms back to the transfercase skidplate bolts would that be a good idea with the ttb?

 

[rhauf]

The longer the better on the radius arms. just put them as far back as is convenient and reasonable. The most important thing is to get the caster correct.

 

[4x4junkie]

That's not necessarily true. After about 15", the only thing you're really doing is eating up more of your ground clearance behind the front tires.

12-15" is the typical range for extended arms.

If you wish to incorporate your arms into the transmission member, 15" extended works well.
If you want to mount them on separate brackets, 12" works better.

 

[tweakedlogic]

would 15" @ the crossmember push the wheels forward a little? I understand you get better tire clearance that way. i'm only going with a 4" lift.

 

[4x4junkie]

Sure. You can push the frontend forward about 1.5" before there's an interference issue between the passengerside axle beam and the pivot bracket for the driverside.