I think my transmission has died.
 

Right now I can barely go 10mph.

It makes a weird rattling sound as I drive.
It shudders and pulses as it does drive. Then hits hard if I go to fast.
If I rev the engine in gear to go faster. It makes just more noise.

The trans is a TH700r4.

Any ideas of what maybe wrong, and any external things I could check?

Re: I think my transmission has died.
 

"The trans is a TH700r4. ''





sorry, couldn't resist

Re: I think my transmission has died.
 

Check in this order

1. Engine idling warm, park brake on, trans in Drive, check trans oil is at correct level

2. Check if the noise is present if the engine is running but the truck is stationary.

3. Does the noise increase if the engine speed increases?

4. Check the parking brake is not jammed on.

It sounds like the trans has broken some internal components ....if the above points dont yield a result, drop the pan and inspect for shrapnel....

TH700R4 trans are renowned for failure....however, if they are built correctly they can be made to last.

Good luck

kwmech....hahahaha....

Re: I think my transmission has died.
 

That was the first thing I checked.

It always makes noises like rattling exhaust.

Sort of, but after 2000 rpm it's to much noise to hear more.

No parking brakes. Still relocating them.

I will drop the pan after I talk to the shop. I may still have a warranty so I have to leave it intact for now.

If it is really broken. I have a 4L60e I may use instead.

Re: I think my transmission has died.
 

To use the 4L6e you will need an aftermarket trans controller unit....

Be careful that the convertor you use is correct for the engine trans unit....

Is this behind an LS or a small block or big block ?

Re: I think my transmission has died.
 

I have the factory converter for a 4L60e.

But I could also clean my th700's up, and install a non lock up plunger. Or what ever it is. Plus my corvette servos. That way everything works the way I like it.

Will be at trans shop first thing in the morning to see what I can do.

It will be behind a 350 LT1 reverse cooled with about 425hp. As if I have to do work the fresher motor is going in.

I am aware of the controllers. Trying to decide which one is better or more flexible for me.

Re: I think my transmission has died.
 

Do you have the super rare and hard to find TV cable brackets for the LT1 and 700r4?

Re: I think my transmission has died.
 

If this transmission was built and installed by the "shop" it should be covered by their warranty.

The brackets are super hard to find as they were only on a few model variants....

If the wrong bracket was used, the transmission will fail.

The correct relationship between the TV cable / valve position and the throttle position is critical for long term performance.

:chevy::chevy::chevy:

Re: I think my transmission has died.
 

Yes I do, but I am using a Holley 750 with there bracket.

I kept the intake just in case there was a kit to use the fuel injection

Re: I think my transmission has died.
 

The trans is 5 years old, and was pulled out of a stalled project.

The TV cable was adjusted by the shop, but right now it looks like a hard part broke due to the engine.

Yesterday I was on the overnight shift to cover, and doing research. My issue maybe the torque converter has failed instead of the pump.

Either way I will have the engine on the ground Sunday maybe, but definitely Monday. Then I can start the diagnosis for certain. I have had my kid all week, and besides work. I have just talked to a few people to see what I could do.

The trans guy can do a rush job if he can bench rebuild it for me. Since it can fit into his schedule easier.

My machinists can do a quicky valve job. So next weekend I can slide the engine back in. If all goes well enough for me. Hopefully. Possibly. Maybe.

Re: I think my transmission has died.
 

I believe I've had those transmissions in three different Astro vans with 4.3's for a total of well over 300k miles and although they never failed they never struck me as being a really strong transmission. Putting it behind a strong engine I can see why yours is failing prematurely and you're going to be spending the big bucks to keep it going. I guess I am just one of those old guys who drives them easy to get as many miles out of them as possible. Each to his own though, enjoy your hobby.

Re: I think my transmission has died.
 

I know there weak, but I thought I took enough precautions. I want a 4L80, but they are a bit out of budget right now.

Depending on what went wrong. I may just do the 4L80. Just have to see what I broke first. Or if it was a bad part, and not my combo killing weak items.