No reverse, no drive, no overdrive

[hayhauler69]

OK, I just got this rig knowing it had tranny problems.
The guy I bought it from was driving, stopped long at a light, shoved it in reverse and clunk, no reverse. He then puts it in drive, goes forward only to find it doesn't get out of second. It also free wheels when letting off throttle.
I'm going to drop tranny pan and see if I find metal debris or what not (part numbers on chunks of metal.) But, if there's a chance that I don't have to drop tranny, if someone out there has an Idea of what may be up, PLEASE!! help me . I"m too fat and old to do this stuff anymore but then again I knew I'd have too when I bought the truck. It's a 1995 GMC 2500 auto with OD 6.5 diesel 4x4 with only 101000 miles on it.
Thanks, Buzz
So yes, I'm new to this site, please be gentle, I hope to be around for a while.

[Robyn]

Yes Yes

This truck would have the 4L80E gear box.

Reverse and manual low are provided by the low reverse band.
If this goes away as in Clunk you loose both manual low and reverse.

The auto start in low is from a sprag clutch.
As far as why it will not shift beyond 2 is anyones guess at this point but pulling the pan is a good starting spot.

Does the fluid smell bad???? SNIFFFFFFFFFFFFFFFF YEOOOOOWY

If it has chewed up some stuff its gonna have to come out and apart.
The 4L80 is very similar to a 400 except for the electronic controls and the OD. They use many of the same parts.

I personaly have not been into a 4L80 but the basics still apply

Good luck

Robyn

[dieseldummy]

It sounds like a broken band to me, had the exact same thing happen once. If it won't shift out of second it is most likely in "limp" mode and should have some stored codes. I'd start with pulling the codes and go from there.

[hayhauler69]

Pulled the tranny, transfer case driveshafts, let's see, rear drums, front rotors.
Anyways trans was wasted. Lot's of shinny brite particles and muddy from clutch material.
Rebuilt one is arriving Friday. New U-joints, calipers, slotted rotors and drums turned.
Getting a FSD cooler, some gauges, Bilstien shocks, and bodily fluids will be ALL Amzoil.
Oh, one more thing getting a 40HP chip. NOBODY around here has a 4" pipe mandrel for the exhaust. So one of these days I'll have to order up a 4" exhaust system.
Really looking forward to truck being down on all fours. This weekend I hope.
Thanks for the reply.
Buzz

[Robyn]

Flush the cooler out real good.
Pump solvent through the lines and the cooler and do so until it clean.
Then install an inline filter in the return line to the tranny.
All that crap that the box was chewing up has filled all the nooks and crannies in the cooler with junk.

Be sure to blow out the lines and the cooler with air and then squirt tranny oil in and blow it through.
You dont want solvent in there either.

Good luck

Robyn

[hayhauler69]

Thanks for the advice, but I'm putting in a heavy duty transmission cooler.
I thought about flushing, but when talking with the transmission shop guy he suggested a cooler. So the transmission lines and cooler under the radiator won't be hooked up.
I'll post more after this weekend. Hope to get it running, just depends on how much help I get. It may just be me and the Wife.
Thanks again, Buzz

[hayhauler69]

Just a quick update to tell all that the new transmission is in my truck. Transfer case is hooked up and all the wires and linkage are attached.
Funny thing though. I had new u-joints installed in front drive shaft and went to install but they won't clamp up. I have lot's of slop. Does anyone know if there are different size u-joints?
So today I'll be putting the aft cross beam in, along with aft mount. Brakes and exhaust. Then the wheels. UPS is bringing me some new stuff today but I want the truck on the ground so I'll install the new stuff.another weekend.

[Robyn]

There certainly can be different joints.

I am asuuming its the front joint thats the issue???

take it back to the party that installed the joints and get them to fix it.

The rear joint on the front shaft is a flange bolt up, does that seem OK??


Let us know.

Robyn

[mhagie]

you probably received the wrong u-joint, some joints come with all 4 caps the same size and some had two larger and two smaller ones.
GM had diferent u-joint configurations in those years so its not all that surprising to have this happen.
If i remember the driveshaft has the larger diameter and the axle yoke can be either size.
Ask me how I found this out.

Merle

[hayhauler69]

Thanks for all the replies,
I'm taking the drive shaft (front) back tomorrow.
Tried to take truck to work this morning but it came home on the back of a tow truck.
Battery cables were really bad. I just bought the truck, put a new transmission in and got over eager to drive it without 'checking' it completely out. So I've ordered new cables from the local Chevy dealership and bought two new batteries.
Anyways how did you come by finding out about the drive shaft difference?
Buzz

[mhagie]

Bought one with all big caps, noticed it wouldn't fit after assembly of course.
so had to go back to supply house and get the mixed size set.
Merle

[hayhauler69]

That's the way things go.
Some auto parts stores I'd walk right by if my truck broke down.
2 times Schuks auto parts. Once for the wrong part then gotta go back for the right one.
So the truck in the shop getting a few things done. She'll be a nice runner.
Going to have it for a long time.
Buzz