bad idea?

im just thinking out loud..im a rookie with the suspension stuff. i have been reading like crazy and i just wanted to ask this question thats been bugging me.

ok first im starting off with frame stiffners. im wanting to build my lower arms(mid arms). im just thinking about welding these on the chassis like the stock ones sit obviously farther back., and run my arms, keeping my RE adj uppers. how would this work out?

not sure if that makes sense..i have been reading way too much.

that link bracket is just an example..im still searching..

i believe further back on the framerails then the stock mounts, the metal is thinner and not reinforced like where the stock mounts are. you would need to make a saddle(for the lack of a better term) that intigrated the stock mount to weld those brackets to or if you cut the stock mounts off, the saddle would have to be longer to spread out the load. i would sleave and bolt the saddle/mount to the framerail along with welding. this is just one option as there are many, many ways to do this.


if the xj had a thicker full frame, then you could just weld those brackets to the frame.

You don't want to use longer lower arms with the stock length upper arms. The suspension geometry will be off and cause drivability issues. I suggest you look at some mid or long arm kits from some vendors.

I'd weld mounts like that to the bottom of the frame, since the mount itself has plenty of surface area against the frame and quite a bit of weld bead length. I'd also add a reinforcing plate up the inside of the frame, however it fits. If you use a different bracket, like a U shaped, then plate the bottom of the frame in that area and weld the bracket to the plate.

Whether you can safely use the stock upper arms depends on how long you're going with the lowers. Tera uses short uppers with long arms, and while it has extreme pinion angle change, it's being done (but not recommended). How much pinion angle change depends on how much different the arm lengths are, and what angles they're at. If the uppers are shorter but close to level, then you can get away with longer lowers because the arm is in the center of it's arc of movement and so won't have so much fore and aft movement.

Draw it on the garage floor to duplicate the arcs of movement at various arm lengths to see what kind of pinion rotation you'll get. Pinion rotation all by itself isn't bad, you just don't want too much, mostly because you don't want the pinion joint to bind.

jeeperjohn said:

You don't want to use longer lower arms with the stock length upper arms. The suspension geometry will be off and cause drivability issues. I suggest you look at some mid or long arm kits from some vendors.

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John, unfortunately, no one makes a bolt on mid-arm suspension. Well, I guess Skyjacker does, but not too many use it. Unless something has come out that I haven't seen.

thanks for the input! it sounds like itsa 50/50 deal here, yes its possible ..but....

im thinking of making my arms in the 27" range.....

Richard im planning on running RE adj uppers not stock.

Goatman said:

I'd weld mounts like that to the bottom of the frame, since the mount itself has plenty of surface area against the frame and quite a bit of weld bead length. I'd also add a reinforcing plate up the inside of the frame, however it fits.
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im thinking this is how im goin. i already have enough 1/4" plate left over to plate it in.

even though the RE arms will be adjustable, they will still be in the stock location, thus not allowing correct suspension geometry. DON'T do it. You have to move BOTH mounting points back proportionately. When you go to flex this thing will bind, and it'll prob drive quite a bit harsher on the road as well. Think of it this way. When the axle cycles through it's suspension range. The upper axle mounts need to remain the same distance from the upper frame mounts (as links aren't suposed to stretch or compress), while still allowing the lower axle mounts to remain the same distance from the lower frame mounts (same reason) If they aren't somewhat proportional, then the axle housing will have to rotate to compensate. A distance like what you're designing will cause the axle to have to rotate quite a bit for even little a suspension movement. This will cause serious vibrations, u-joint failures, all around bad ju-ju. Good luck.

my .02

arctycfox said:

even though the RE arms will be adjustable, they will still be in the stock location, thus not allowing correct suspension geometry. DON'T do it. You have to move BOTH mounting points back proportionately. When you go to flex this thing will bind, and it'll prob drive quite a bit harsher on the road as well. Think of it this way. When the axle cycles through it's suspension range. The upper axle mounts need to remain the same distance from the upper frame mounts (as links aren't suposed to stretch or compress), while still allowing the lower axle mounts to remain the same distance from the lower frame mounts (same reason) If they aren't somewhat proportional, then the axle housing will have to rotate to compensate. A distance like what you're designing will cause the axle to have to rotate quite a bit for even little a suspension movement. This will cause serious vibrations, u-joint failures, all around bad ju-ju. Good luck.

my .02

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While you're trying, you're not hitting the nail on the head. The issue with a big difference in upper and lower arm lengths is mostly when the whole axle is dropped out, not when articulated. And the danger because of the possible excessive pinion rotation is binding the pinion u-joint at full droop. If the pinion u-joint doesn't bind, really nothing else bad will happen. If the lower arms are longer, then the ride will most likely be better, as the lower arm mostly locates the axle and controls it's overall arc of movement. There's nothing wrong with the arms being different lengths, just don't make it excessive.