GMC 4L60-E - Help

[my$100project]

Yea, yea. I know this is a "mustang" forum for "Mustang" enthusiests. I usually don't post about my other vehicle here, but am asking if I can make this exception just this one time, This forum is the most active that I know of and am trying to gather as much help as possible. It is, after all still an American vehicle, and we are all here to help are we not?...... Yea Yea, Should have bought a Ford, go blue oval, I know all the "Chevy" jokes too, bla bla bla.. Thanks in advance for not deleting my thread. :SNSign: Rules.

Ok here's the deal.
99 GMC Denali.
4l60-E Transmission
Electronically controlled 4 wheel drive
168,XXX miles.
History of problems : Vehicle has always had a slight shudder at complete stop and take off. According to tsbs - lubed slip yoke, then tried to replace slip yoke with Nickel played slip yoke when lube was only temporary.
This is probably irrevelent and not affilated with my current, but worth mentioning.

Recent problems: The transmission would sound/feel like it was "binding" slghtly when taking right turns for the last few miles... odd, eh.
I got the truck home, not thinking much of the problem, except maybe a suspension problem.
Pulled it out of the garage today, and less than 100 feet from home you could hear and feel a "clunk", it would be really loud. The transmission would engage then "clunk", then slippage, Then a really loud and vibrating "clunk" then engagement. back and forth. It'll do this in all gears including reverse, and is so frequent it'll do this 5-6 times within 15 feet. It's not a smooth movement at all.
Being that I have taken a 4L60-e and 4T60-E (Transaxle version) both apart and back together, the only thing I can think of is that the bands on the planetary gear set and engaging and disengaging spuratically. Then I think, that wouldn't make since since it is such a harsh and very loudengagement, disengagement.
SO I thought I would try manual 1.---Same problem. In D- R and Man 1
This is my Winter and "reliable" vehicle. I couldn't possible risk driving my son around in the mustang even short-term with it's rear-end shudder and can't seem to find any good repair info on the 4L60-E, Searched the crappy GM forums, TSBS, all usual places. I know the stangnet guys are always a good place for some help.

 

[my$100project]

I just went out and check my 4 wheel drive engagement. Auto 4 wheel, 4 hi, and 4 low and 2 wheel drive all seem to work fine. I did notice a rather harsh transition when pushing the buttons. (you could feel a "movement" of what sounds like the driveshaft slightly binding."Also double checked the operating to make sure I had all symptoms. The TCC seems fine. When I'm at a dead stop and put it in "r" and push the gas with foot on the brake the truck seems to raise, and there is no problem. When bscking up its' more like clunk clunk clunk clunk clunk, then the real loud and harsh "clunk" then disengagement. Maybe it's a transfer case issue?

 

[90mustangGT]

Don't forget the one way clutches. One could have broken teeth allowing it to slip some then catch. Transmission mounts, motor mounts and U-joints are good, right? I would be sure the mounts and u-joints are good first. A broken mount would expalin a clunk and the binding.

 

[my$100project]

Don't forget the one way clutches. One could have broken teeth allowing it to slip some then catch. Transmission mounts, motor mounts and U-joints are good, right? I would be sure the mounts and u-joints are good first. A broken mount would expalin a clunk and the binding.

Nope, U-joints, mounts, all exterior items are in good shape. I replaced the gear box last year, and with the high mileage decided to do the u-joints, dif/tranny/transfer fluid change with all gm fluids, idler arm, pitman arm, etc. That's why I was a little hesistant in my original suspension thought. The U-joints where greased about 2000 miles ago, but I suppose anythings possible. I think they are Moog or Spicer - I usually demand Moog if the part is available.
As far as the one way clutches are concerned, I do beleive they are O/R in first gear.
I may have to copy and paste this in the automotiveforums.com section forum. (I hate that freaking place, it's full of idiots.)

 

[my$100project]

oh yea, I forgot to add that if I leave it in park and rev the engine to help heat it in the morning, the MPH gauge moves to about 5-6 MPH. I just assumed this was a problem with the wiring in the dash and that the vss wasn't actually moving. being electronically controlled could this pose a problem? ---Couldn't imagine the vss is turning and giving the pcm false information??????

 

[90mustangGT]

I don't know what to tell you without seeing it, so maby take it to a good shop and have a tech look at it. They usually charge little or nothing to check it out. Throwing parts at it won't be a good idea.

 

[notchback]

i would guess converter.....my lt1 had some similar problems w/ a bad converter.

 

[FORCED2DV8]

I wouold check your axles also, make sure the spider gears and everything is turning smoothly, If it feels like its binding something has to be holding it, maybe the 4 wheel drive isnt disengaging all the way. I have had the seal inside the trans go bad pump seal i believe, and it gives uneven line pressure to the clutches and bands which made a very rough transistion between gears and when you drove it, good luck with it,

 

[MYSTICSVT]

I can't help much with your diag, but since I work in a GMC parts dept. I can tell you some things we repair very frequently on Denali's:

Instrument clusters and front differentials(especially the all-wheel-drive models).

 

[rd]

Outside chance it is the 4wd. I'd say the axle disconnect, but I don't think you have that.

If it was just shudder when driving, or harsh engagement, it may be the famous torque converter shudder, which, in an F150 can be fixed by changing to Mercon 5.

Otherwise it sounds like rebuild time. My brother in law's van with that trans needed it at about 100k.

 

[5.0tbirdguy]

Most likely it's the transfer case. There is a snap ring on the rear output gear that weakens and lets the output gear flop around. The way to test that problem is put it in 4wd and see if you can floor it without the chatter. Harsh, but that's how I tested the last one

The "updated" stronger snap ring is from a c-6 output shaft I believe. The guy at the transmission parts place said it's a common problem had a handful of those snap rings. Just can't remember for sure what the snap ring came from. People who rebuild transfer cases every day would know.



edit: almost every late GM truck I have ever seen makes the speedo move when you rev it.