yellow73bb

I recently rebuilt the 700R4 in my 73 corvette. Put in all the good stuff, including corvette servo, 9 clutch 3-4 clutches, hardened whatchamacallit, etc. I put it in the car, made a TV cable bracket and got it adjusted right, filled it with tranny fluid, and went for a drive. I was able to drive it several times, and the only problem I had was that it wouldn't shift down when I floor it. But it would shift into all four gears plus reverse and seemed to be fine. I probably put 25-30 miles on it total.

Today I went out to back it out of the garage, and it won't go backwards. I put it in reverse and it lurches like normal, but then even when I rev the engine, it won't go backwards. I put it in neutral, and it wants to creep forward a little bit. I checked the oil and it wasn't even on the dipstick so I put in some more fluid. I know that there are no leaks, so where the fluid went is a mystery. I re-adjusted the TV cable and it is set right. It still does the same thing. If I put it in neutral and turn off the engine, I can roll the car just fine.

It's hard to test forward gears in the garage, but it seems to pull in forward gears though I'm not 100% sure of that.

The cable appears to be attached properly although the car is low enough that I can't get under it. It is still hooked at the bracket and at the transmission lever.

Any ideas?????????

yellow73bb

Talked to my mechanic brother. He suggested that maybe a valve is sticking in the valve body. I'll get some tranny additive and see if that fixes it.

Still no clue why my fluid was low though. No sign of oil on the bottom of the car.

Dewey316

You did fill the converter before installing?

GASGZLR

Might sound dumb, but I would check the linkage to the shift selector and the shifter to make sure it has not come loose.

dukemushroom1

that happened to me when i put in my tranny. You've gotta take in to account that a completely bone dry tranny needs to fill up everything with fluid and it takes more to get it all back into the system...i ended up having to put in about twice as much in as normal when it was completely dry to get the fluid levels all abck up to spec.

yellow73bb

Yes, I did fill the torque converter before installing it. Then, I put in several quarts, started the engine, and put in more to bring up the level. Drove it a couple times, put in more fluid, drove it some more. I wouldn't think I would need to drive it more than a few minutes to get everything "filled" in the tranny.

I haven't checked it since I posted. I will put in some additive today or tomorrow, after I get the level right.

Can anyone recommend a good additive for the 700R4?

By the way, thanks for the posts, they have given me some things to think about.

I looked at the linkage, and it looks like it is hooked up, but the car is low enough that I can't reach it without raising the car. When I had the engine running, I would push the button on the shifter and slowly move it from park to reverse to neutral to drive and it would "lurch" a little bit at reverse (backwards) and drive (forwards). So, I think the linkage is OK, but will be checking that again.

John.

Precision Trans

You have a fwd clutch problem. Either due to cross-leaks allowing the clutch to be engaged all the time, or the plates being welded to one another due to slippage and/or oveheating.

This will cause a bind-up in reverse and the vehicle will want to move forward in neutral and park.

Your no downshift condition hints to me that your TV cable bracket may not be quite right, and since TV pressure also controls line-rise, you may have caused some low pressure related damage. Get yourself a 0-300 psi pressure gauge and hook it up to the pressure port near the shift linkage. Start the engine. Line pressure should be a minimum of 50-55 psi at 1000 rpm, and the TV cable at rest. Pull on the TV cable; line pressure should start to increase IMMEDIATELY, and rise smoothly to about 150 depending on valve body, boost valve, etc.

If you are using a Q-jet carb, use a factory bracket for a similarly equipped vehicle. If a Holley carb, contact Holley. They have the linkage kit you need.

If you have any other questions, please do not hesitate to contact us.

Don