extending short arms

I have those adjustable JKS short arms, love them and their freedom of movement. I am thinking about converting them into long arms by extending the tube. What kind of problems am I looking at?

At that point is it not just easier to build new ones?

Not with the same performance -- rubber bushings and unrestricted rotational movement

You would be better off to sell them and buy proper arms or material to build new ones rather than hacking up and patching something together that was once of decent value. If you want rubber bushings there are options available, and many flex joints out there to choose from. Or just buy a known well working kit.
I was considering building mine, but once time and materials was factored in I realized I was better off just buying a kit with all the geometry figured out already.

ehall said:

I have those adjustable JKS short arms, love them and their freedom of movement. I am thinking about converting them into long arms by extending the tube. What kind of problems am I looking at?

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First off, you simply can't put long arms in the same place as short arms because it would move the wheels too far forward. You will have to deal with the mounting as well. You are far better getting a full kit if you aren't a fully equipped experienced fabricator. Yes you can extend the tube, but that is only small part of the battle.

ehall said:

I have those adjustable JKS short arms, love them and their freedom of movement. I am thinking about converting them into long arms by extending the tube. What kind of problems am I looking at?

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The haters have a point but to answer your question just slug your arms. I would cut the arm right at the bushing at the axle and extend from there. Just find DOM that can slide over your current tube size. Nothing less than 1/4" thick of course. That could make your control arm excessively large in diameter which isn't long arm friendly.

Or go hardcore and make new arms with heim joints and have all the freedom you'll need. Get the arms flat enough and you won't be bother by the heim joint.


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not that your welds should be the failure mode, but i dont like the idea of having a piece of bung welded to a tube welded to a slug welded to a tube welded to a slug, welded to a tube, wended to another bung... just build new arms. your options for rod ends are almost limitless. i run heims from barnes for maintenance free operation, but they have both poly joints and their enduro joint is a hybrid of sorts.

for what its worth, when i built my long arms, i really didnt come out ahead cost wise compared to simply buying new arms. and i got a deal on everything, including material. especially when you factor in my time... id have just been better off buying something nice. the only satisfaction i have is that my 3 link is as close to my CAD models as i can measure.

You'd be time, money, and safety ahead just making new long arms.

This presupposes you're a certified and/or experienced welder. If not, just buy some- Clayton's comes to mind.

I disagree with the 'sell them and build all new or buy a kit' philosophy.

I'm re-using a lot of tube adapters and pieces from my XJ on my pro-mod build, and have sleeved short arms into longer (but still short) arms with success in various stages.

The concerning thing is that 'long arms' (as pointed out by Tom[old-man]) require a place to mount the back of the arm. If "how do I extend my short arms" is the question you have, then I'll answer with "where are you going to mount them, and how is that going to be attached?"

I'd wager that once you got through cutting / griding / fabricating / welding your new mounting points on your chassis side, and actually had a measurement for how long your formerly short, now long arms need to be, then you will have the knowledge required to extend them.

It really is: grind the weld that holds the threaded piece in out to the fusion line, beat on it to get it out of the press or slip fit, clean it up, find a new piece of tube the same that you just cut the threaded piece out, cut that to length, weld them together. :compwork:

Agreed. My comment was in case the OP thought you could simply lengthen the arms without changing up the mounting. Arms are easy, mounting is harder and more expensive.

XJ_ranger said:

It really is: grind the weld that holds the threaded piece in out to the fusion line, beat on it to get it out of the press or slip fit, clean it up, find a new piece of tube the same that you just cut the threaded piece out, cut that to length, weld them together. :compwork:

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that sounds terrible.

this is my gripe with extending the arms. i agree it is plenty safe to cut out and reuse threaded tube adapters. and its not super techinical, just labor intensive. considering my time investment as money... id sell my arms and make new ones with the joints i want (and did just that) simply to save myself the hassle of dismantlement them. grinding welds is not my idea of fun. and having built my own arms... even with a reasonable discount on rod ends, and a very good deal on material... i still didnt come out much further ahead than a kit. but did lose a lot of time (admittedly on the crossmember fab more than the arms themselves).