To cut a long story short after my last transmission service I feel as if the transmission is shifting much softer.

About a year before that I had a vette servo fitted and I could really feel the difference. But now after my last trans service it seems like the vette servo is not there anymore.

Things I have checked:

TV cable adjusted many times no difference
The temperature stays around the 150 mark, I do have a trans cooler installed.

I also performed a pressure test on the transmission here is a table of the readings I got they all look pretty good to me?



I went out in the car to do some tests and the only problem I found was that the transmission will not downshift into 1st when I am travelling at the minimum speed when it shifts into 2nd.

So basically if I am gong about 10mph-15mph and hammer the gas it will not downshift into 1st but just accelerate in 2nd. That is my biggest problem and I don't know what is causing this. I also think that is causing my soft shifts from 1-2.

Downshift from 3-2 is very firm.

But downshift from 2-1 does not exsist like I said.

Anyone have any ideas? Could it be the governor?

 

First, auto-adjust the TV cable and then leave it alone. Make sure there is still travel in the mechanism. If it's maxed the cable is stretched and should be repalced. I only use GM OEM cables, because I feel the quality is a little better than even the best local parts store cables.

Second, the governor only controls WOT upshifts. If the trans upshifts fine at WOT then the governor is fine.

Third, have you tried shifting it manually? If it shifts fine when shifting manually I would say that the problem is accumulator or valvebody related. I've seen several 700R4s with broken accumulator springs. This could cause a situation similar to what you're describing.

Fourth, I'm not sure about the pressure readings. I would check a Haynes or AGC manual to see what is normal. If the line pressure is low this could be part of the problem too. Maybe the pressure valve spring is weak or broken (assuming the pressure is low).

 

Yep the TV cable is good, nothing wrong with it. I checked the travel with it. I also checked if there was slight movement with the TV cable there was instant pressure readings.

With the upshifts. The only time I would say I have problems upshifting is at WOT. When I hit the end of 2nd I really have a feeling that I have to let off the gas for the trans to make the shift into 3rd.

If I manualy shift the gears I don't seem to have the same problem it goes into gear right away.

So going by that I would say it looks like the vavle body or accumulator springs as you say. I don't know heaps about the transmission, all I know is that the valve body requires some knowledge to remove or replace? What about the accumulator springs are they easy to get to?

The pressures seemed to be okay by the readings I got. This is a 1986 transmission so it did not have the auxiliary valve body.

Going by what I just said do you think it is the springs and valve body? How are these items replaced both a PITA?

Thanks for your help.

 

I have a simular problem,my car shifts 4500 to 4800 from 1st to 2nd WOT then it short shifts on me,it wont shift pass 3800 rpms at WOT after 2nd and 3rd.I took the car to 2 transmission shops, and still nothing changed.I was told their nothing wrong with it?????? OK

 

I love it when they tell you nothing wrong with, when there is.

 

I guess its not just the tranny shops around here that tell us that.

 

I would see how things go manually shifting it Like TKO said.

 

I tried that, the tranny holds the gears but the car dont move,its seems like all the power is blowing rt out the tranny,It revs but the car dont move like it should???

 

Having to let off the gas to get the trans to shift is almost certainly a sign that the trans is starting to slip. Usually this problem starts in the 3/4 clutch pack because it's the weakest one in the trans. Eventually the problem will migrate to all the clutches, and it won't shift at WOT at all. That's the problem I had with the 700R4 in my '86. I wasn't thrilled with the auto, so I swapped in a T56. I'm still running the 700R4 in my '87 Blazer though, but I completely rebuilt it with Pro-Built's road race kit. In that truck I flat love the trans.

The valvebody isn't that hard to remove. The accumulator springs are between the valvebody and the seperator plate, and the seperator plate and the case. I would check them first. If they're broken replace them with good new springs. Then check all of the valves in the valvebody. Use a small screwdriver or pick to push in the valves and check for sticking or a lack of movement. If a valve sticks pull the roll pin and check to see it the components are damaged or the spring is broken. Replace any broken springs. Get a Haynes or AGC manual so you know what valve you are working with. They both have pictures of the valvebody with descriptions.

Based on what you said it wouldn't suprise me if the trans is just starting to show its age and slip. If that's the case then a rebuild is the only way to cure it for good. Check out the valvebody and accumulator springs first though. The worst that's going to happen is that it won't fix the problem, and you'll learn a lot about the trans in the process.

 

Based on what you said it wouldn't suprise me if the trans is just starting to show its age and slip. If that's the case then a rebuild is the only way to cure it for good. Check out the valvebody and accumulator springs first though. The worst that's going to happen is that it won't fix the problem, and you'll learn a lot about the trans in the process. [/B][/QUOTE] The transmission only has 4000 mile on it, its did this from the begining, i never drove the car when i bought it i had it towed, i did the engine and trans at the same time,becauce i was restoring the car,The car was in pretty bad shape to drive when i bought it.

 

No offense, but I wasn't talking to you. I was talking to the guy that started the thread.

As for your problem, depending on what engine your car has in it from the factory the trans shop may be 100% correct. This is not uncommon. Call Dana at Pro-Built and ask him. He'll tell you he's seen this same situation a lot. It was mentioned on another thread not too long ago.

 

Thanks for the detailed description. I'll save this thread for future reference. When the time comes to service the transmission again, I'll print his information out and give it a go and see if I can find anything.

Thanks for your help.

Mike