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Transmission lock up....

Tovar

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I have a'99 Chevy 6.5 turbodiesel. It has a 4L80E transmission. Started truck, slipped into drive gear, released foot from brake petal, started to roll forward, and then the back end locked up and the truck skidded to a stop. Transmission will shifted through all gears with no problem, just does not go into gear. Fluid is full and clean. I have not had an issue with the transmission until now. So, I have no back ground with this issue. Starting from scratch... Is seems that communication from the shift lever to the transmission is being interrupted. Has anybody had like symptoms, and what would be the remedy?
 

WarWagon

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Raise the rear wheels and turn em and turn the driveshaft seeing if anything is locked up. How does the rear end oil look and likewise for the trans oil? You could have had a brake shoe come off the backing and jam up the works.

Our 1988 6.2 1/2ton burb busted a chunk off a ring gear tooth. Only noticed it during a diff oil change, removed the broke off part, and ignored it. I had enough inertia on my 1993 to destroy the OD gears and keep going when a sprag or something failed and went through them with a great big "KABOOM!" crunch! crunch! OD never works again...
 

Tovar

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Raise the rear wheels and turn em and turn the driveshaft seeing if anything is locked up. How does the rear end oil look and likewise for the trans oil? You could have had a brake shoe come off the backing and jam up the works. Our 1988 6.2 1/2ton burb busted a chunk off a ring gear tooth. Only noticed it during a diff oil change, removed the broke off part, and ignored it. I had enough inertia on my 1993 to destroy the OD gears and keep going when a sprag or something failed and went through them with a great big "KABOOM!" crunch! crunch! OD never works again...
 

Tovar

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Trans. Fluid good. Rear diff. Fluid good. Rear end spins. Not familiar with the symptoms of a failing or broken automatic transmission. Before removing the transmission, is there something else that would create this situation? For instance, something with the shift lever? Does it need or have a need for adjustment? Does the parking brake have or need adjustment. Is there anything small and mysterious that has gone unnoticed, by me, that I could do first before I do something big like remove the transmission and get it rebuilt? All other owned vehicles have been manual trans, this is the first automatic I have ever owned...so, unfamiliar with signs of breakage.
 

WarWagon

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This is a rare and unusual failure. Generally failed automatics won't move but don't lock up.

You got a transbrake on this for the track? 🤪 Seriously pull codes. It's possible you have a wiring problem that shorted and locked the transmission up by selecting two gears at once.

Does the drive shaft turn in neutral with the rear wheels in the air? I assume you chalk the front wheels so it don't fall off the jacks and run ya over. Start the engine and go through the gears. Shut the engine off and stop the rear wheels before selecting park or you will get a racket as it tries to drop in when moving.

We are trying to find out what locked up - either the pinion in the diff or something in the transmission.

Manual transmissions lock up now and then - pushed a buddy out of an intersection with the rear wheels locked up when a loose bolt went through the gears on his POS Mazda pickup.

Looks like you are in AZ. I use Allstate Transmission and they haul the trans in and out, rebuild it, and shove it back in. Years ago it was $1100. Plus non standard rebuild hard parts like gears.

 
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Tovar

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Results:
No codes popped.
Transmission fluid is good.
Differential fluid is good.
Chalked front end, lifted rear end.
Started engine and cycled through all gears (did not accelerate)...no lock up...wheels and driveshaft turned through all gears.
Put transmission in neutral and turned both wheels by hand. Both sides turned, but the driveshaft did not. The driveshaft would turn with a pry bar only, but took effort. Also, when turning wheels by hand, it felt like excessive play before the wheel would spin.

What is this telling me...? What to do next...?
 

ak diesel driver

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So with the rear end in the air and the transmission in gear so the driveshaft and the wheels are turning what happens when you apply the brakes? Does the driveshaft keep turning?
 

WarWagon

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Drop the driveshaft and turn the yoke - is it stiff?
I wouldn't think a U-Joint would lockup and stop you - IMO it would bend the driveshaft.

I would seriously consider pulling the diff cover and inspect the differential innards.
 

Tovar

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AK: In gear, brakes applied, driveshaft stops...

War wagon: dropped driveshaft, yoke turns easily by hand. Opened up differential, gears look great...

Have an idea. This truck has an emergency brake located on the rear yoke of the transmission. It is shaped like a drum brake. After I ran the truck for a couple of minutes, I went under the truck. I accidentally hit that drum E-brake casing with my arm. It was hot. The exhaust pipes were not even hot, but that casing was too hot to touch. I think that E-brake is the trouble, and it is somehow locking up the back end, randomly. I have not torn into it yet... Anybody know anything about that E-brake, and what to look for...? It is definitely rubbing and getting very hot. I don't believe it should do that.
 

Will L.

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Yup. Drop shaft and it comes apart like a regular brake drum. If its that hot- you smoked those shoes and maybe the drum.
AK has it right- usually the cable or the linkage where the cable meets the drum gets seized.
 

THEFERMANATOR

FRANKENBURBAN
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I'm late to the party here, but it sounds like your ebrake locked up. 3500hd's have a trans mounted parking brake on them bolted onto the rear of the transmission. The 4l80e cannot get tied into 2 gears electrically and lockup, so that's not a concern.
 

Tovar

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Tore it down today. E-brake shoe came unglued, and locked up everything. What if this had happened at speed? I think the design is quite flawed. I'm not planning on repairing this. I'm planning on gutting it, and putting the casing back on with no innards. Is there any problem with doing this other than not having an E -brake? In other words, this will not affect some sensor which would cause something else to shut down. I am going to replace all three U-joints. Question: I have a 10 bolt differential. Is that a Dana 60 or an 80? And what would be my gears?

Thanks for all the help.
 

Will L.

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Loss of parking brake is your downfall, nothing else.
There is thousands of rigs that use those without issues. I would say figure rebuild cost before abandoning having it for the few times it is really needed could be worth it. I’ve seen enough parking pawl failures cause the vehicle to roll away to have me appreciate them things.

On your u joints, always smartest to do them as a full set. Remember to make a mark so you don’t get timing wrong and throw shaft out of balance. Also, if you are good about greasing the ujoints, then get them greaseable, but if you tend to forget then order the equivalent one that is sealed and just know they need replacement sooner than ones that get regular service.
 

THEFERMANATOR

FRANKENBURBAN
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The 93+ 3500HD truck's use a TRUE DANA 80 diff(not a hybrid like Dodge & Ford used in there 3500's). The 10 bolt cover throws people off and makes them think it's weak, but it is NOT weak. Make sure and check the slip yoke and splines CLOSELY in the middle of the shaft before doing u-joints. Locking up while moving can break those splines, not to mention high milage trucks normally have significant wear in the splines. It's normally best to take the shaft and have it balanced. And leaving the shoe out of the brake only loses your ebrake. If your truck has to pass a dot inspection, it will fail without it, other than that go for it.
 

WarWagon

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Tore it down today. E-brake shoe came unglued, and locked up everything. What if this had happened at speed? I think the design is quite flawed. I'm not planning on repairing this. I'm planning on gutting it, and putting the casing back on with no innards. Is there any problem with doing this other than not having an E -brake?

See if Raybestos or Wagner makes a shoe that's riveted. Check the ACDelco part at the GM dealer as well. I do not go cheap on brake parts and will not run the house brand of crap from local parts stores anymore. Learned the hard way. $35 for their shoe's and the Wagner/Raybestos is over $100. Worth every extra penny as they stop quicker and better quality. ;) Rock Auto for the brand stuff is a savings if you must.

I have a plan for using the e-brake (or suicide of the one use only "parking brake" cheap designs) if the main brakes fail. I had a AutoZone Duracrap pad come off the backing plate - a couple pumps of the pedal and the brakes came back. The 3rd pump was going to be to the "working" e-brake pedal going to the floor to reduce the impact to the little car ahead of me. 7 miles later the steel backing plate had trashed the rotor. Talk about a having to have the seat cushion surgically removed moment.

A half day's drive out of Phoenix the DOT targets 2500 / 3500 on up pickups with trailers to see if they are running "dirty" commercial. Your HD truck has a target on it. They catch you with an INOP Parking Brake: you get put out of service and fix it on the spot or get to tow it. Commercial or not is a grey area to them at this point.

Clearly I suggest you go ahead and fix it: for your safety and the safety of the pedistrians and drivers around you.
 
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Tovar

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Question: I already removed the driveshaft and replaced the u-joints before reading further replies...
Will L. I did not know to make any mark for timing. I've replace u- joints on my scout several times without any timing marks, and I, regretfully, assumed the same thing for this vehicle. How much trouble did I cause myself? I replaced all three u- joints, and I was going to reinstall, but not now. Should I go have it balanced, and if so, where do you take it, and do I take it as a full unit?
 
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