Toyota FJ Cruiser Forum banner

1 - 20 of 41 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter #1
I installed 2” taller springs on the rear of my 2014 FJ. I have Bilstein 5100 shocks, which should be okay in this application. The problem is, I get a very loud banging sound from the right rear, when I go over even smallish obstacles, at anything but the slowest of speed. This commonly occurs when the right rear wheel drops into a pothole, off a small ledge, or even on parking lot speed bumps, unless I go very deliberately in these situations. It’s not during the compression stroke, but as the wheel drops. It sounds like the rear end is going to fall off. It’s fine during normal around town/highway driving. I’ve checked everything for proper connection and torque. All seems okay. Any ideas much appreciated.
Thanks
 

·
Mean Time Moderator
Joined
·
5,523 Posts
Check the alighment of the spring. They seat in the axle cup but need to be rotated to do so correctly. I had someone do mine and he didn’t do this and my left one wasn’t seated and clunked/banged
 

·
Premium Member
Joined
·
415 Posts
I would look at the top shock mounts and make shure all hardware is in the correct order and tight, the shock bushings.
 

·
Premium Member
Joined
·
1,712 Posts
I hope you figure it out. Mine has been doing the exact same thing since I put my lift on. I can't find the problem either. The right Bilstein shock broke and I thought the new shock would fix it but no luck. I'm keeping my eye on this thread for sure.
 

·
Registered
Joined
·
21 Posts
Discussion Starter #9
I was thinking there might be an issue with the shock being defective and losing dampening at the top of the stroke. I even contemplated swapping the right shock with the left to see what happens. After reading your post about getting a new shock, I’m thinking it’s probably something else ☹
 

·
Registered
Joined
·
21 Posts
Discussion Starter #10
BTW, I seem to remember seeing a post quite a while back that related a similar problem to the upper control arm. Not sure how that could be. I tried to find that post, but didn’t. Might have to search a little harder.
 

·
Premium Member
Joined
·
1,712 Posts
I've been through all the rear axle components and didn't see any problems. All the bushings looked good, all parts are in correct order, and all bolts and nuts are tight. I'm not sure where to go from there so I just live with it. I'm still running all the factory rear links and trac bar, if you are also maybe its something to do with these items, I'm not planning on upgrading these any time soon unless necessary.I've travelled thousands of miles and have off roaded it pretty hard and nothing has happened. I really hope you come up with a solution.
 

·
Registered
Joined
·
21 Posts
Discussion Starter #13
All my components are stock, with the exceptions of the shock and spring. When I get a chance, weather permitting, I’m going to go back in, loosen everything up, check the spring seating, lube whatever I can, retorque everything, and hope for the best. I don’t know what I’m missing, but something is not right.
 

·
Registered
Joined
·
6,184 Posts
I am in a similar place. This started a while ago. I get a solid pop or thunk when articulating. Mine too seems to happen on extension and mine seems to be from the left rear. After this started I looked and didn't find anything. I replaced all 4 shocks as they had >100k miles.
I am going to remove the rear sway bar and try it on a dirt trail where I take the pooch. Trying to eliminate possibilities one step at a time.

I am also considering replacing all of the bushings in the rear control links and panhard rod.
 

·
Registered
Joined
·
29 Posts
Possible that the spring is unseating then reseating if it happens on extnesion off road? Are your shocks longer than stock?
 

·
Registered
Joined
·
21 Posts
Discussion Starter #17
Yes, it does seem to happen on extension. Shocks are Bilstein 5100’s and rated for my 2” lift. However, I haven’t ruled them out. I may try switching my shocks - left to right, just see what happens. The spring is still a possibility.

I want to emphasize - I am not talking about a little thud. It is a very loud bang, to the point you can almost feel it from the drivers seat. It sounds like someone is hitting the undercarriage with a sledge hammer or like a very heavy object was dropped onto the right rear, interior bed of the FJ, transmitting the impact directly into the body of the vehicle, as opposed to a sound one might hear coming from outside - if that makes sense. This is why it doesn’t seem to me to be a mere control arm bushing. I have searched underneath the vehicle to see if there was anywhere that showed evidence of a suspension part contacting with the frame, but found nothing.
 

·
Registered
Joined
·
1,969 Posts
Just throwing out potential ideas and this is based on daughters 99 4runner, which has an almost identical suspension to the FJ.

Check to make sure that the rear sway bar links are not hitting the lower control arms as they are cycling through their range of motion. Second thing is to ensure that the zerks on the rear driveshaft/ or the rear driveshaft is not hitting against the side of the fuel tank/fuel tank skid. You can also check to make sure the rear trackbar is not somehow contacting the back of the rear differential. The other thing that I would do is put the FJ up on jack stands on the frame rails and then use a floor jack to cycle the rear axle up and down on on each side (imitating the drop where you are hearing the bang) and see what if anything you can discover. I would also check the tightness and bushing wear on the upper reaer control arms, lower rear control arms and both ends of track bar and watch what happens as your cycle them through movement with your floor jack by raising the axle in the middle and both sides.

For about two years I kept hearing a clank on daughters 4Runner when she would wheel it.....turned out that the upper control arm mount to the rear axle was slowly flexing and fatiguing the metal...eventually she sheared off the upper control arm mount from the rear diff. I discovered that after she had driven back 7 hours from Telluride to Denver.
 

·
Registered
Joined
·
21 Posts
Discussion Starter #19
Thanks, SilvFx, for adding to my list of things to check out ? Cycling the axle through its range, with a floor jack, is a great idea!
 

·
Registered
Joined
·
18 Posts
Did you replace lower and upper bushings on the struts? Had the same symptoms but with the front end. Took apart, installed the lower bushing I forgot the first time around. Now it’s perfect.
 
1 - 20 of 41 Posts
Top