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new flex joints

M

matthagey

NAXJA Forum User
Location
Valley Forge,PA
So I recently installed Rustys control arms. Rubber bushing on axle end and flex joint on frame end. Heard a clunking coming from them so I called Rustys, they said tighten them more and it should go away. Did that, still, clunking coming from them. Buddy said after having old stock control arms in there as long as I did and might have created oblong holes. Checked for signs of the control arms rubbing up and down in the holes, nothing, snug as can be. I saw something on jeepforums that the threads might not stay snug but wondered how that can be if the set screw is in. They have been in just about 2 weeks and they shouldn't be making noise already. I am getting very frustrated and am looking for any kind of advice/tips to fix the problem. Oh, in case it matters, I have the 3 inch lift from rustys with 31's.
 
ummm... the flex joints go on the axle end and the rubber bushing goes on the frame end. sounds like you have them on backwards. yep... you definitely have them on backwards.
 
post pics too just to know for sure.
 
I just got rid of the clunk and rattle that showed up after I put in a set of Rusty's control arms using the flex joints. I have been putting up with it for months and finally got around to fixing it today. It rattled and clunked on big bumps and sounded like the front end was about to fall off when on rocky roads. Your post is very timely.

The flex joints bolt holes are larger in diameter than the factory bolts.
The fix is pretty simple: Put 9/16ths bolts in the lowers. Put 7/16ths in the uppers.

You will have to drill out the control arm mounts on the chassis and the upper flex joint. This is tricky on the upper bushings that are in axle housing. Start with a 7/16th bit. Make sure it doesnt catch on the nubs in side bushing and pull the bit through. Step up to 29/64ths. You may be able to put the bolt through. If thats not enough step up to 15/32nds, but dont go any bigger.

John
 
nosigma said:
I just got rid of the clunk and rattle that showed up after I put in a set of Rusty's control arms using the flex joints. I have been putting up with it for months and finally got around to fixing it today. It rattled and clunked on big bumps and sounded like the front end was about to fall off when on rocky roads. Your post is very timely.

The flex joints bolt holes are larger in diameter than the factory bolts.
The fix is pretty simple: Put 9/16ths bolts in the lowers. Put 7/16ths in the uppers.

You will have to drill out the control arm mounts on the chassis and the upper flex joint. This is tricky on the upper bushings that are in axle housing. Start with a 7/16th bit. Make sure it doesnt catch on the nubs in side bushing and pull the bit through. Step up to 29/64ths. You may be able to put the bolt through. If thats not enough step up to 15/32nds, but dont go any bigger.

John
Click to expand...

or he could just put them on the correct way.
 
Last edited:
i have the same noise on my re lift... u guys thinks its a bolt size problem?
 
Only way to tell is to pull your links and check for clearance between the bolts and frame mounts and the bolts and bushings/rod ends/joints.

John
 
nosigma said:
Oh and the adjustable end goes to the Frame, NOT the axle. Read the instructions or see the Rusty's web site

http://rustysoffroad.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=rustys&Category_Code=faq


John
Click to expand...

The adjustable end is the flex joint end. Who in their right mind puts the flex joint end on the frame?
RC-CA411_01.jpg

Which end goes to the axle side and which end goes to the frame side?
 
I am the original poster, my account wont let me reply for some reason. 1. bosco, chill, I talked to Rustys personally and asked how to install them. They are installed correctly and they recommended flex joints on the frame end and rubber on the axle end. nosigma, thank you so much for the help, it makes sense thinking about the noise now. I took off the control arms real quick just to see if there's play from in between the bolt and the flex joint, there is. Again thank you so much for your information, this has been driving me crazy.
 
controlarmdiagram.gif


Bosco01XJ,
Apparently me and the manufacturer.


xjkraut,

glad to hear you found the problem, Its a pretty easy fix if you decide to put in larger bolts. Try to avoid drilling out the axle bushings if you can. Fix the frame end first and its still bad do the axle end..

John.
 
Last edited:
ok... so what's the benefit of the flex joint on the frame end rather than the axle end?
 
so this is wrong?

IMG_7424.jpg
 
so do i need to swap mine? i've got the adjustable end at the axle. will this hurt anything?
 
As the axle droops and compresses... do your axle mount bolts stay in the same plane... yup they do

You "should" run bushings at the axle and the flex at the subframe
 
Following up with Rusty's on this over the last few days. There were real prompt in getting back to me (less than 3 hours). Rusty's did a bunch of checking with new bolts and used bolts off older XJ's. They tell met that there is clearance problem with older used bolts on the lowers at the frame end. Sounds like they will be including new bolts for the frame ends with future shipments of control arms. I was really impressed that they responded to my email inquiries, read the threads and put the time into looking a the problem and coming up with a fix. I have beat on Rusty's pretty hard in the past but I have been very pleased with these new arms and their customer service over the last year.

John
 
J-Roc said:
As the axle droops and compresses... do your axle mount bolts stay in the same plane... yup they do

You "should" run bushings at the axle and the flex at the subframe
Click to expand...

This.

Bosco, the flex joint needs to be on the "frame" side. Your axle is what flexes not the other way around. When I had short arms I thought like you did and installed the flex on the axle side but once you go flex it you will see that it is wrong.
 
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