[31rdster]

Hi,
I have searched through the threads have been unable to find an answer to my question. I hope one of you will be able to help me out with a problem I'm having with a 700R4 transmission installed in a 66 Chevy pickup behind a 350 engine.

I recently bought the truck with the 700R4 installed in it. The shifting was rather late and hard (It had a home made TV bracket and a cheap universal cable). I purchased a TV kit and a converter lockup kit from Bowtie Overdrives. I installed the TV cable etc. per instructions and all went smoothly. Before test driving I hooked up a pressure gauge and got the readings. From what I can gather my readings are rather low. I test drove the truck and it seems to be shifting, locking up etc. perfectly. Up shifts, down shifts, kick down into passing gear all seem to be fine. I get instantaneous increase in pressure at the slightest movement of the TV cable. I think the trans is an 89 model. It is extremely clean inside and out so I suspect it may have been recently rebuilt but I'm not positive of this. The fluid was nice and clean and the pan did not have any trash in the bottom. I was wondering if something could be done to remedy the low pressures, could something have been possibly installed wrong, or is it just worn out?
My pressures are as follows:
--------At Idle---------- At 1500 RPM
Park------63----------------130
Reverse-105---------------220
Neutral---65----------------130
OD---------62----------------140
3rd---------60----------------130
2nd--------95-----------------100
1st---------95-----------------100

I hope someone can shed some light on this subject. I also hope for an easy fix, but if not, is rebuilding one of these transmissions something I could do myself? Are there any good manuals available covering a rebuild. Sorry the post is so long. I wanted to give as much info as possible. Thanks for any advice you can provide.
Mike

[OneMoreTime]

Located at http://www.hotrodders.com/t44407.html

And line pressure:

The transmission fluid pressure readings should be in the ranges of the following numbers (psi):
Range----Minimum--Maximum
Park.........90-110...190-230
Reverse....95-120...200-300
Neutral.....90-110...190-230
Overdrive..90-110...190-230
Drive........90-110...190-230
Second...185-230...185-230
Low........185-230...185-230


Yours do seem to be on the low side..of course cannot be sure of just what the cause is..

There are some good manuals on rebuilding one of these and you will need some special tools to do so tho they can be improvised or found at some of the online tool suppliers..

Any morre questions come ask and some of the more skilled tranny experts can chime in on this thread..

OMT

[31rdster]

Hi,
Thanks for the info. I am hoping to get some idea what might be causing the low pressures, especially since the trans seems to be functioning properly. It is so clean inside and out that I suspect it has been rebuilt recently. I am hoping that there may be an easy fix or solution to the low pressures. When I installed the lock up kit I found the 4th gear pressure switch installed in the wrong place (switched with the one next to it), plus there was no internal wiring so I know it has been gone into, but what could have been done I have no idea. Is there a possibility that something could be installed wrong in the valve body or a check ball missing etc? I appreciate your input.
Thanks again,
Mike

[OneMoreTime]

Murphy's law being what it is anything that can go wrong will go wrong..you may want to replace the spring at the check ball to raise the pressure..those can be had from anyone of the high performance tranny suppliers..

other than that I dunno..could be the pump is worn..sometimes guys will just replace the bands and call it good on a rebuild..and I have no idea what might have or have not been done..

Myself since it seems to be working fine just go with what you have until it breaks or starts sliping and then go into it..

MY thoughts..

OMT

[stu]

Your pressures aren't that bad. In fact they are within specs.
I am not sure where those other readings came from but according to the information I have you are ok.
I base my response on pressures taken from a GMC shop manual.
If the pressures you recorded were too low for the actual performance of the transmission it would have burnt up long before now.

[Crosley]

as stu points out the pressures do not look out of line.


there are many variables in the size of the main & low/reverse boost valves

[31rdster]

Hi stu & Crosley,
Thanks for the info. I was basing my low pressure concerns on the info from this board (as seen in OMT's post). If they fit the guidelines in the GMC manual I should be alright. As I said the trans seems to perform fine. Is there any benefit to be gained by replacing the boost valve to raise the pressure (ie- longer trans life, firmer shifts) ,as this is inexpensive and easy to do, or would it be not worth the effort? Thanks again for your input, it has helped me feel alot better about my transmission.
Regards,
Mike

[stu]

If it ain't broke, don't fix it.

[31rdster]

Hi stu,
Yeah, your probably right. I sometimes have to stop myself from trying to make "improvements" to things. In this case I'd probably be better off to leave well enough alone. Especially since its working good. Thanks again to all for your input on this subject.
Mike