Differential vs U Joint help

[ADudeOnSkis]

Yo dudes.

I've been getting some shuttering on starting acceleration/deceleration in all gears. Only feel it when I'm beginning either. It feels like something (uhh, like, rear gears) is trying to engage/connect/stop slopping/something like that. It doesn't happen instantly, and sometimes I can drive for 10-15 miles before it's noticeable.
I do have a CEL for a bad IAC (which I'm planning on replacing tomorrow), and recently fixed the plenum gasket (should have done the IAC then but somehow ran out of cash ). I believe that this is causing my rough/slightly high idle (it does that "i want to die but wont" thing once within a minute of starting then just idles high).
When I crawled under her to check the U joints, I was able to rotate the shaft less than an inch, maybe 5-10 degrees, with no visible play/slop in the joints (but it was stupid dark and I didn't have a light) but I did hear a "clunk" coming from somewhere in the rear. I put the e-brake on, put the trans in neutral (5spd manual).

Any insight or ideas on how to eliminate something before I start throwing money at it? I know driveline gremlins can be a pain to diagnose, but maybe....


Thanks,
D

 

[MoparMagic'00]

I;ve been told all 9 1/4s have SOME clunk to them due to the crush sleeve failing and not holding correct pressure.. MAY be your issue.. someone else might chime in

 

[Merc225hp]

Pull the diff cover and see what's going on inside it. If it has an LSD good chance the retaining clips have broken and the clutch discs are broken letting the side gears clunk.

Next would be the stick tranny, does it have oil in it? Is it the right oil? NV3500 is what you have.

There is also the chance the clutch is going out, but more than likely it the rear diff.

A photo of the LSD in pieces (not all the parts are in this photo).

 

[ADudeOnSkis]

Clutch was done recently. Guess I'm opening up the pumpkin next day off I get. How much do you think I'll be out on this? I won't say I haven't been thinking about a Dana... would it be worth it to find a d60 and swap the whole thing?

 

[Merc225hp]

You can rebuild the lsd for about $200 in parts. If there is further damage it can get expensive fast, ring & pinion gear set $150+, new gear carrier $200-$800 depending on what you get, plus bearing's, gear oil $200+ and if you can't do the work yourself $300+ in labour.

Installing just the rear dana 60 (sans the 2500 leaf springs) is almost painless. Two 2.5 wide spring perchs $15, new wheels $$???. There is some welding that needs to be done but no more the 10 min work there, have to remove the old spring perches and move them and weld the new ones on.

If you install just the rear Dana 60 and want to use 4wd it has to have the same gear ratio as the front.

 

[ADudeOnSkis]

Hmm, seems less expensive, easier yet more effective to do the swap, especially since I have access (albeit 250 miles away) to a pretty well set up shop and welder. When you say new wheels, could I get away with 16s with greater offset or backspacing to clear the bigger drums? Or would I have to go to 17s? What did you pay for your 60s if you dont mind me asking?

I crawled under her again today, since its pouring rain and I hadnt gotten soaked enough yet. I feel like a *******, in my OP I said there was play when the trans was in 1st. I meant neutral. There is some play in the U joints when I put it in 1st, not a ton though. Still wondering how much their should be in the diff when in neutral.
I also drove around a little, and was really paying attention to how it shifted. Its a little stiff/hard going into 3rd from 2nd or 4th, and it actually sounds... dry? As if there isnt enough MTF, or its wrong or old or something. I'll try it in 4x4 later today if we get any snow on the ground. I also took a closer look at the rear pumpkin.... it almost looks as if there is a leak at the fill plug. Not becuase its wet, but because the lower 2/3rds of the thing is caked with oily dirt. Once I dry myself out I'm going to go poke around under her a little more. Either way I have an appointment at a shop in town for next week if I cant figure this out beforehand.

 

[Merc225hp]

I got my Dana 60's dirt cheap $300 at max for both. I could have just bolted them in and got going shy of needing new rear shoes and cutting the drums. You can use a 16" wheel just fine I do, it's the bolt pattern that causes the needing for different rim's 1500' are 5x5.5 and 2500 8x6.5.

You need to check the tranny oil level and change it out after you checked to see how much is in it.

Just use Black rtv for the rear cover, no gasket is needed.

Edit: Happen to be logged into PB so added these for you.

 

[ADudeOnSkis]

Oh, wicked dude! Thanks for those! Any advice on how to tell what is going on in the diff for when I do pull it apart? Obviously metal shavings are going to be a dead give away. Also still cant find any info on how much play there is supposed to be or just naturally is.

Also did you have to shorten your DS? Or did your lift eliminate the need?

 

[Merc225hp]

I forgot to mention that yes I did have to shorten the rear DS 58" weld to weld or just find one from the same wheelbase 2500. Forgot about the u-joints as well sorry. There are two opt for u-joints, one is to change the yoke on the 60 so it takes the 7290 joint or change the weld in yoke on the ds to take the 1410 u-joint.

Spec for DS rotation play is in the fsm.

 

[ADudeOnSkis]

So. Now it gets weird. I replaced the IAC because I need to smog it soon. Went out for a drive. No more lurching. What the ****.