I am hearing a light klanking sound that has gotten a bit worse over the last few weeks, it varies with the trucks speeds. I did have it on a lift in the shop (its getting a head gasket and ex-manifold) and the rear dif has a bit of play that produces the sound I am hearing when I spin the tires back and fourth a bit. Are my gears going out? BTW, I have 30" buckshots and its stock as far as I can tell 85 auto non sr5 2.4. As far as I can deduce from searching it has 4.30's in the 85 stock autos and I will go no bigger than 31's in the future if they need replaced. Has anyone had gears slowly go out on them?

 

So the sound comes from the diff or the rear u joints?

:wabbit2:

 

When I grabbed the drive shaft and checked for play in the u-joint there was a small bit of play, I don't know if any is normal, but the distinct sound that I heard came from inside the dif when I moved the tires clockwise then counter

 

Just because you can hear the gears klanking around in the diff when you do that, doesn't necessarily mean there's a problem. The only things you should really concern yourself with there is keeping it full of oil, changing the oil occasionally, and making sure the pinion nut stays tight. Do those things and your rear diff will last forever, under most circumstances. It's not that you can't bust one if you tried, but you'd have to neglect it and/or bang on it pretty severely.

It's probably the u-joints. Because you literally can't feel what little play the u-joints are allowed to have. Less than 5 hundredths of a millimeter is a very small amount. You'd need to use dial indicator to measure that accurately, even if you couldn't feel any play in it(which you shouldn't be able to). Meaning, if you can feel any play in the u-joint, replace it.

See page PR-8 from the FSM.

 

Cool. I'll double check the ujoint and update you guys. It's still in the shop and will be there for a bit as the hg is getting done thanks for the insight all

 

Sounds like what happened with mine. Is there a low humming/ slight vibrating that increases with speed?

My story: I bought my '85 around July/Aug last year. It has 322,000 miles but still runs like a champ. Well, when I got it, it had a hardly noticeable hum to it. I didn't pay much mind because I was going to deploy in Nov and just wanted it to last until then. Well, I decided to drive it from NY to IL on leave, beat the hell out of it off road, and then the rear end started clunking. I knew it was almost time to go, so I wasn't worried. I was nervouse to drive back, but it made the 800 mile trip back to NY just fine. Still a little clunky, got a little worse about half way back, but still made it. After being in NY for about a week, it finally grenaded. Deffinately the rear-end. And not even under load. It went as I pulled to a red light and put it in neutral. Still went forward for the 1/4 mile I had to go, but would just grind in reverse. Anyhow, I pulled the rear driveshaft, locked the hubs, and just drove it in front wheel drive back to post, then one more time to the storage place because I was ready to deploy the next day (about 3-4 days after it went out). It's been sitting in storage without a rear driveshaft since, but I have geared 3rd members waiting for me when I get back.

Anyhow, point of the whole story was to see if the symptoms are similar, and to give you a heads-up on what to expect if it's the same issue I had.

It took me about 2 mins to take the driveshaft out, so if this happens to you (and if you have 4wd) this should work to get you home so your not stranded somewhere. Just a tip.

 

No humming or vibrating just klank, klank, klank... Increase and decrease with speed. It's louder when coasting

 

Increased nose/vibration while coasting might point to something being loose or worn:
- http://www.4crawler.com/4x4/CheapTri...FixingProblems

Check for loose slip yoke, loose u-joints, loose pinion or t-case flanges for example.