700r4 Issues
 

The backstory...bought a 1976 K5 Chalet and showed up pretty much a wreck. Got the rust taken care of and started on the drivetrain. Built a 350 SBC with an RV Cam, nothing fancy just a nice, new SBC. I also picked up a 700r4 and a NP241. Got those off CL, guy said they worked, rolled the dice. So I got it all in the truck and hooked up and took it for a drive. If I am on the gas I get a hard shift at around 20-23 MPH and the truck keeps pulling. Only driving around my neighborhood for now so 2nd is all I've gotten to so far. The issue I'm having is if I get off the throttle before the shift the truck seems like it has no gears...RPM goes up but the truck doesn't really move any faster. If I come to a stop and take off again it pulls hard and I get a shift and keep pulling. Any ideas? Transmissions are not my strongest area. Thanks in advance.

Re: 700r4 Issues
 

Check simple things first:

Oil level in transmission is correct,,,parking brake applied, engine running, trans in Drive (have someone hold their foot on the brake) and check oil level

Throttle valve cable is correctly adjusted....700R4 trans MUST have the TV cable connected and correctly adjusted....

All engine and trans mounts are intact...

Did you check / change the trans oil filter before installing the trans?
Are the trans cooler lines in place, not blocked off....

:chevy::chevy::chevy:

Re: 700r4 Issues
 

Yup...did the simple things. Oil level is good, new oil, new filter, new engine and trans mounts, new TV cable that I set according to several write ups. Also put the TV corrector plates on the Carb.

If I stay on the gas and keep a steady RPM it shifts around 20-23 mph and keeps pulling. If I get up to say 15 mph and let off the gas and get back on it, RPM's goes up but the truck stops pulling...until I stop or manually shift down to first.

Re: 700r4 Issues
 

Do you have reverse? Third gear clutch is likely out, this is the most likely scenario. Could be the sun shell has the hub broken out. And there is a one way sprag that may have failed.... In any case it's a tear-down.

Re: 700r4 Issues
 

Sounds like 3rd clutch failure to me....

what residue was in the pan when you opened it up?

700R4's are renowned for 3-4 cutch failure....

:chevy::chevy::chevy:

Re: 700r4 Issues
 

I do have reverse. Its strong too. There was some metallic dust I guess I would call it, in the pan when I dropped it for the filter. Is there a way I can tell if it's clutches using a pressure gauge? I just ordered one. Should be here in a few days.

Re: 700r4 Issues
 

Suggested good pressures for 700R4

Thanks to Clinebarger.....

Also check out

http://67-72chevytrucks.com/vboard/s...d.php?t=526152

Re: 700r4 Issues
 

Thank you for that...the gauge should get here soon. Seems I should also order a rebuild kit and a book. Any suggestions?

Re: 700r4 Issues
 

[QUOTE= I should also order a rebuild kit and a book. Any suggestions?[/QUOTE]
I would use Youtube as there are some excellent videos on rebuilding.

This guy is one of the best.
https://www.youtube.com/watch?v=mcUo3rDHaLU

You have pressure as it goes into gear and shifts to second. The pressure gauge will not help much. It may give you a clue to why it failed but litttle else.

Re: 700r4 Issues
 

Could the tv valve be sticking on you? What did the pan look like inside? Did it look like it may have been pulled off recent ,just thinking outloud but I hear of guys cleaning the pan and putting it back on :devil:

Re: 700r4 Issues
 

Well I don't think the TV valve is sticking. It moves freely when I pull it by hand or with the throttle. The inside of the pan had super fine metal in it. I'm not sure what is considered a lot. It was all on the magnet but it wasn't like a huge pile on it.

Re: 700r4 Issues
 

If the shift is late and hard I would think the TV is sticking in the valve body (somewhat common)

If the 1-2 shift timing changes with throttle opening and not always late and hard it could be 3-4 clutches.

Can you accelerate hard to 40-45 mph and let off the gas pedal and see if it shifts?

Re: 700r4 Issues
 

I'll give the hard acceleration a go and see what happens, haven't tried to drive the truck over maybe 25-30 mph yet. The shift timing isn't changing I don't think. I mean its always shifting to 2nd at around 20-23 as long as I stay on the gas, and by that I mean just accelerating, not having my foot in it. But if I take my foot off the gas and let the rpms drop a little before the shift to 2nd, I get no upshift and rpms go up but the truck barely moves along. Then I either stop all the way or manually downshift to 1st and its good. Thank you guys for the help. I really appreciate it.

Re: 700r4 Issues
 

Third and fourth use the same clutch. The sun shell breaks, you lose reverse, second and fourth

Re: 700r4 Issues
 

Got the pressure gauge and ran the following test: All gears at Idle with TV connected and all gears at idle with TV disconnected. Here's what I got

With TV- P:70, R:115, N:70, OD:70, D:70, 2:180, 1:185
Without TV- P:120, R:180, N:110, OD:115, D:120, 2:180, 1:180

Seems as these should not be the numbers I got but they are. From what I've read I should get slightly less PSI with the TV disconnected but I'm very far from knowing what's up with these transmissions. Any ideas?

Re: 700r4 Issues
 

Also forgot the mention that I tried to pull the TV cable while at idle and I did get a rise in pressure on the gauge but it was not an instant rise.

Re: 700r4 Issues
 

Not from the factory. The OE transmission has a check ball in the valve body (under the TV linkage) so that if the TV cable breaks or becomes disconnected the transmission goes full pressure.

A lot of times a rebuilder leaves that check ball out eliminating the protection.

It looks like yours is working

Re: 700r4 Issues
 

So I've been messing with the truck and watching the pressure gauge...it was mentioned before that maybe the TV is sticking in the valve body. I really think this is what is happening. I've been reading more about this and was able to get the TV unstuck, which I'm sure happened because I was watching the gauge at the moment. In my ignorance earlier I thought it was referring to the TV cable being stuck. Anyways...it moved freely and a bunch of pulls with my hand so I went out and drove the truck. It drove great...until it didn't and the TV is stuck again. Any recommendations? A kit? A new valve body? Thanks guys.

Re: 700r4 Issues
 

Transgo JR

edit: the roll pin that holds the throttle valve in the valve body can be a pain (especially 92-93 models). They make a pin puller but some sharp small diagonal cutters usually works ok

Re: 700r4 Issues
 

Is the Transgo JR kit truly installable with the trans still in the vehicle?

Re: 700r4 Issues
 

These JR kits do not need the trans removed for installation....

However....

They will not correct worn bushes, clutches and bands or worn pump housings.

You must follow all instructions and perform all steps....then tune the TV system as directed in the installation instructions ....

The kit includes a paper install instruction set, but here is a link to the online PDF file you can review prior to purchase...

https://res.cloudinary.com/transgo/wbiss/sk/SK700JR.pdf

Re: 700r4 Issues
 

I was able to spend some time tinkering more with the truck, here's what I learned. Hopefully it'll help someone down the road, also I have one more question. So I dropped the pan and was looking at the TV assembly...it seemed to grab a little in the rotation of it. In looking more and more at it and taking it off the valve body, it seemed as if it was the new TV cable I had put on the truck. Turns out the one I bought was about few inches too long. I saw reference to it here on this site as being the correct length for a 700r4 on a carbed motor. Thing was that the 5 or so inches of extra length made the cable sheath kind of bend in not so good ways making the cable not pull smooth. That made the cable adjust too far out. A chain reaction of bad stuff. Anyways I marked the cable where I thought it would be good and went to the store to match it up. All works great now. I've got good pressures at idle and instant rise with the throttle. Truck shifts good and it was cool to actually be able to drive it. So here's the question...I've seen several places say that pressures should be recorded with the tv cable unhooked as well...when I do that on this truck the pressures will spike to 150 and stay there like the TV valve was doing before. Only way to remedy that is to shut off the truck and rehook the TV cable up and its all back to normal and shifts great. Is this normal? It's almost like a "limp mode" it seems so as not to burn up the trans in the event the cable snaps or comes unhooked.

Re: 700r4 Issues
 

Transmissions direct from the factory have a check ball in the valve body that locks off the TV circuit if the cable ever breaks....yours obviously has the ball still in place....

Many rebuilders leave this ball out ....never really figured out why they would...

Your trans has obviously never been apart....

A pressure rise when cable disconnected is correct...

:chevy::chevy::chevy: