Kids are scared of the clunk.....

[WarWagon]

Seriously, I have to get rid of my unwanted house guest. Spent time and money today replacing the u-joints and guess what......CLUNK

I was hoping against hope this would do it, but nope. So I'm back to square one

I know there are tons of threads on this and I'm sifting through them. But I'd really like to hear from those that have not settled to live with their clunk and have actually tackled it!!!

'91 FJ80 and I love it so far.

I love the thought of getting rid of this clunk even more

 

[nukegoat]

There is way more accumulated slack in the drivetrain than there would be in u-joints... you could re-do your diff gears to reduce backlash, replace axle drive flanges, get a new transfer case, etc... and it'll probably still clunk.

Give up

 

[Corbet]

have you checked the slip joints on the drive shaft/s

 

[SUMMIT CRUISERS]

Check the tension on the transmission cable. If it is too tight it will cause hard shifts and will amplify the clunk. The other thing to check is the grease in the yokes/slip joints. I fill mine until they move first move outward/inward then remove the grease zerk to release the excess grease. This has helped on the clunk on our 92.

 

[WarWagon]

Jealous of those that replaced the u-joints and solved their problem.

Not ready to give up though. This isn't normal and there has to be a fix.

On gas clunk.....off gas clunk again. But if I'm easy on it sometimes no clunk.

I'm clunktified.

 

[ElPolloBlanco]

I clink to. It showed up when I pulled my seized up VC. After I installed my Aussie in the rear it got a little worse. My play was at the high end of tolerance when putting the third back together but I couldn't get it any better.

Fat-fingered on my iPhone using IH8MUD

 

[NLXTACY]

Hate to state the obvious but did you keep track of the phasing of the shafts when reinstalling?

Also when is the clunk happening? When stopping? When driving only? When shifting? When off the line???

 

[WarWagon]

Had a shop do the swap.

Only starts doing it when the truck is warmed up.

Then when you press the pedal to accelerate and when you let off the gas. Cruising.....gas clunk, off gas clunk. Repeat.

 

[inkpot]

Had a shop do the swap.

Only starts doing it when the truck is warmed up.

Then when you press the pedal to accelerate and when you let off the gas. Cruising.....gas clunk, off gas clunk. Repeat.

So you have fresh new rubber bushings in all 8 positions on the upper and lower rear control arms?

 

[WarWagon]

I do not inkpot......please tell me more!!

 

[inkpot]

I do not inkpot......please tell me more!!

AFAIK, the rear suspension on the FJ 80 is very similar to the later FZJ80s. The rear axle is held in place by 4 control arms. The uppers are about a foot long and the lowers are about 2 foot. They have a rubber bushing in each end of them, and if those are worn out, cracked, split, etc, then they allow a lot of extra movement that can make a lot of noise, especially when you are going back and forth between on/off throttle. I have seen folks try several aftermarket bands, but the OEM parts from the dealer are much better and will last much longer: worth the $30 ish each price. They have to be pressed in, so you may need to find a good press for the job.

Get under the rig with a good flashlight. Look into the sides of the big steel rings on the ends of the control arms. If you see cracks, tears, splits, chunks, etc, then they need to be replaced. Search on the 80s forum for LCA bushings, or control arm bushings, and you should find lots of info. John

 

[DARKNESS]

Loose caliper bolts? Spare tire not pulled up all the way? I've read the baffles in the gas tank can come loose and clunk, maybe check that?

 

[Aggiesdm]

Jeeper...I have a '91 with the exact same issue. I've taken it to a shop and they told me that the U-Joints were fine. The only thing that seems to make a difference to me is making sure all of your fluids are topped off. I have a slow leak in the tranny and if it gets a little low, the cluck seems to get worse. This is not a fix, but just a PM suggestion. I would also make sure that all of your Zerk fittings are greased properly. If you just had it serviced, I'm sure they're fine.

I'll be interested to see what you find. I've unfortunately learned to live with it to an extent, but it still bugs me almost every day.

I've not read about the control arm bushings before, so I'll have to check them out. I'm sure after 23 years, they are shot like every other rubber piece on the truck!

 

[Motleyone]

Times 2 on making sure your kick down cable is adjusted properly. Mine will clunk like crazy if the cable is adjusted to have firmer and quicker shifts. It happens on acceleration and deceleration. You have to play with the adjustment until you find a happy medium. Make sure you use some type of gauge that you can accurately record the distance from the red stopper. Write down each adjustment until you get it right. The clunk was common in most 91-92's. Let the kids look under the truck to assure them that there is no clunk monster hiding under there.

 

[Stevesnj]

Could be as simple as a loose or broken exhaust bracket or front sway bar bushings are worn

 

[WarWagon]

Had all fluids changed out yesterday while we replaced the u-joints.

Looks like I'm going to track the transmission cable adjustment and control arm bushings.....both of those seem plausible.

I hate just throwing parts at it but the clunk has to go. One thing is for sure, something is loose or worn out......just a matter of finding it.

Thanks for all the opinions......if I can solve it this will make driving our 3FE's much more enjoyable!

 

[CJF]

I hate just throwing parts at it but the clunk has to go. One thing is for sure, something is loose or worn out......just a matter of finding it.

Lol...

Sorry, but no.

Most 91-92's clunk exactly as you've described, period.

 

[Brentbba]

Check the torque specs on your control arm bolts! Three on each arm and as I recall, specs are somewhere around 150 ft/lbs. Had a clunk and that's all it was!

 

[WarWagon]

I don't understand all the people that say all 91-92's clunk and that's just the way it is. If that's the case then why didn't they come from the factory clunking? Why does the clunk begin when they get on up there in mileage? And what about the people that had a clunk and fixed it?

They didn't come factory like that.....that I do know.

 

[WarWagon]

Well I think I just got my answer from a different shop than the one I had do my u-joints. I've used these guys before and I trust them. He crawled up under and put the Cruiser in gear. The rear locks But the front is sloppy and doesn't lock with it. Too much play in the pinion. Front diff rebuild basically.

Calling ACC today.