When i put it in reverse w/brake on the truck lunges back and makes a load clunk sound, same as putting it in Drive. I was told i needed to set my backlash...???

What is backlash?
And what do i to set it?
Could it be the T-Case?
Any other thoughts on what it might be?

C6/Np205 Divorced.

 

Check your trans fluid if it's low it may cause this or you may have bad u-joints

 

fluid is good all u-joints where replaced not to long ago.

 

check your engine idle, bob

 

she idles at 700Rpm give or take 200Rpm depending on where the choke is set.

 

loose chain , bob

 

There is no chain on this transfer case. I doubt it's your tranny or your t-case. Backlash is the amount of play between gears and it's more likely that the backlash in your rear axle is the issue here. If you have your rear wheels chocked so the truck can't roll put the tranny or t-case in neutral and try rotating your driveshaft back and forth. There shouldn't be much play in it at all. If you have a lot of play, enough to where you can visualize that rear end making the "clunk" noise when you put it in gear, then the backlash on the ring and pinion is too great and will need to be adjusted. Another symptom of this is if you're cruising down the road and you can hear that "clunk" if you step on the throttle and then let it off all together, between acceleration and deceleration. Check this out and let me know what you come up with.

 

I tried the tranny/t-case in neutral and theres some play in the drive shaft, if i turn it hard enough it makes a clunk! Whats next?

 

Your rear ring and pinion my be going out, my 76 Highboy's rear Dana60 did the same thing when I bought it, and the rear end lasted 2 months before the ring and pinion came apart and locked the rear end up. I'd suggest rebuilding the rear differential before it causes any more problems to the rear end.

 

If you do some searching in this forum you'll find info on rebuilding the rear end but it's a job that a lot of people prefer to take to a shop. If you do it yourself you'll need a dial indicator, dial calipers, an inch/lb torque wrench, a shim pack for the D60, and a little patience. You'll also need to remove the bearings from the carrier to change shims. There's a special tool that allow you to remove the bearings in tact but it's a lot of $$, a cheap one will pull them but destroy them, in which case you'll want a rebuild kit with bearings and shims. You'll also want to pull the cover and inspect the ring gear for wear. Too much backlash can wear the gears badly and it may need to be replaced.

Okay, all that being said, call around and check with local shops on what they charge for a job like this. A lot of times, by the time you buy the tools to do it, you're not a whole lot ahead to mess with it if you're only doing one axle. If the ring gear is okay I would imagine labor on a job like this will run you about $250-$300. You might also have a shop check your backlash to make sure that's the problem or you can check it yourself if you have a dial indicator.

Btw, my D60 rear that I pulled out of the truck had the same problem. I don't know how or why it happens. Backlash on those axles should be within a few thousandths (.005-.010 if I remember right, in that neighborhood anyway) but they seem to open up over time and get a lot of slop in there.

 

A rear ring and pinion kit costs near $200, not including installation. A used, complete rear Dana60 can be found for $100-$200. A used axle in decent shape to replace yours may be the way to go. When my rear 60 blew I replaced it with a Dana70U I aquired for free.

 

Just make sure if you get a used axle to swap in that you check it too. This seems to be a common problem with the D60 rears. It would suck to put in another axle and have the same problems.

 

I know this is a older post. But thanks for sharing that test procedure to diagnose the rear end. My 89 F150 is thunking pretty good. u Joints looked fine.
Did the chock the wheels in neutral test. I have about a 1/3rd of a inch of slop in the rear end.
Time to shop for a used rear end.
Any ideas what year ranges fit? its a 4wd.

 

Arg. Disregard.