700r4 Pressures

[blwn31]

I rebuilt my 700r4 last year. Before the rebuild all the pressures were fine. After rebuild, full pull on the TV cable I don't get steady pressures and they are low. Especially in L1, L2 and Rev. The pressures indicate between 120psi to 190psi, just cycling. These pressures should be in the area of 290psi. Has anyone had this happen to them. I contacted a trans shop they suggest replacing the pump. Don't want to spend gobs of cold hard cash shotgunning this. I've thought about changing the press reg vlv spring and slide springs agian.?Any suggestions welcome.

[blwn31]

DennyW, that's the kit I used. The good part is I have a transmission that has all the gears now and a good stall converter, I just can't let it hang until I get it sorted out. This motor will kill the trans right now. I want to get the pressures up to snuff so I can install the Torque Drive Kit, Billet Servo and upgrade the Boost Valve and Reverse Boost Valve to the largest on the market. Thanks. Any other info would be appreciated.

[lt1s10]

Originally posted by blwn31
DennyW, that's the kit I used. The good part is I have a transmission that has all the gears now and a good stall converter, I just can't let it hang until I get it sorted out. This motor will kill the trans right now. I want to get the pressures up to snuff so I can install the Torque Drive Kit, Billet Servo and upgrade the Boost Valve and Reverse Boost Valve to the largest on the market. Thanks. Any other info would be appreciated.

are you driving the car?

[blwn31]

Yeah, but only really light on the pedal. I know what will happen if I don't baby it.

[lt1s10]

Originally posted by blwn31
Yeah, but only really light on the pedal. I know what will happen if I don't baby it.

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just wondern where you got those # from, just checked mine not long ago and i think they were the same yours. the tv cable pressure has to be set with a certain amount of pessure on it. cant just add pressure and expect it to shift at the right time. have you got the instruckens on what pressure you need at the tv valve in each gear. tell me what they are. if youer running a blower then i dont know if that 700r4 is the trick.

[lt1s10]

Originally posted by DennyW
Mike, check this out ? This may help him.
http://www.transmissioncenter.net/subject.htm

i wont to know what the tv pressure is sitting still, motor running. tv cable pulled wide open in all the dif gears. i found it the other day some where and now i cant find it , but i know you can denny. the pressure he has sounds to high.

[lt1s10]

Originally posted by DennyW
Is this what you want?
http://www.tciauto.com/tech_info/lin...e.htm#TH200700

yes what took you so long? look like his pressures are ok to me. you cant just increase you puessure to what ever you wont them. if they are to high it wont shift plus it will blow seals. blwn31 what do you think is wrong with the pressure. you cant have 300 lb. in drive.

[blwn31]

The pressures are normal in all gears with the tv cable unhooked, the boost system seems to be working as required. I think the pressure was 90 psi in P, N, D, 3, 160 PSI in R & 2 and 120 PSI to 180 PSI (Cycling not Steady) in 1 @ 1000rpm . Now this is where it gets more weird. Pulling on the TV cable to full pull if the engine is not Fully Warmed up, the pressures are much lower than they should be for full pull. After warm up, at full pull on the TV Cable, 150 PSI in P, 120 PSI to 190 PSI (Cycling not Steady) in R & 1, 240 PSI in N, 210 PSI in D, 190 PSI in 3, 180 PSI in 2. OK, one last thing, pressures are different for many different transmissions. I took reading before I tore this monster down and they were very good and steady. And yes, with a Huffed motor I am going to run on the high side of the pressure scale. What the heck is going to make the trans give me different readings everytime I do a test. This thing is driving me crazy. If the pressures are not up to snuff in 1 and 2 say bye-bye to the clutches and band!... Maybe it is the Pump? Hope that's not to much info. Oh yeah

[lt1s10]

Originally posted by blwn31
The pressures are normal in all gears with the tv cable unhooked, the boost system seems to be working as required. I think the pressure was 90 psi in P, N, D, 3, 160 PSI in R & 2 and 120 PSI to 180 PSI (Cycling not Steady) in 1 @ 1000rpm . Now this is where it gets more weird. Pulling on the TV cable to full pull if the engine is not Fully Warmed up, the pressures are much lower than they should be for full pull. After warm up, at full pull on the TV Cable, 150 PSI in P, 120 PSI to 190 PSI (Cycling not Steady) in R & 1, 240 PSI in N, 210 PSI in D, 190 PSI in 3, 180 PSI in 2. OK, one last thing, pressures are different for many different transmissions. I took reading before I tore this monster down and they were very good and steady. And yes, with a Huffed motor I am going to run on the high side of the pressure scale. What the heck is going to make the trans give me different readings everytime I do a test. This thing is driving me crazy. If the pressures are not up to snuff in 1 and 2 say bye-bye to the clutches and band!... Maybe it is the Pump? Hope that's not to much info. Oh yeah

blwn31 i dont know why your tv pressure is cycling but i think you are looking at this pressure thing wrong. the tv cable pressure only change the shift points, so you cant change it to some pressure you may like. thats pre set at the factory. if your tv pressure is to low the trans shift to quick, if the tv pressure is to high then the trans wont shift or shift late. if the trans is shifting like it should then the tv pressure is ok. now if you wont to put some extra pressure on the clutches and bands then you have to go into the valve body and change the springes and valves to each clutch pack that you wont to make stronger. putting a shift kit in. you can change the pump pressure reg. pressure in the trans and that dont have anything to do with the tv pressure or if it change it youll have to go back and readjest it to the fact. setting. go back and read the pressure reading link that denny gave me. all trans work on about the same pressure range. if you are pulling on the tv cable with your hands, then the least bit movement will cause the pressure to change , lock the cable down when you check the pressure.

[MadMax]

Hi blwn31,
I have exactly the same problem: newly rebuilt trans, pressures aren't OK. Yours seem to be just about high enough, but mine are still lower and not constant either. Even if I bolt the TV down at some stage I still get pressure flutter. I haven't had the time to take it apart yet, will do so probably next week or the following, just got a lot of exams coming on
Have you found something out yet?
I thought it would probably be the pump, because it's similar in all gears, that wouldn't be an internal seal inside the trans. I've just bought an old trans in need of a rebuild, gonna take that pump and see if it works.
My guesses as to what it might be:
- pump seal between the housing halves
- rough pump surface (my rotor broke last time so I guess that might have damaged the flanges)
- pump screws not torqued up to specs
I don't think that putting in stronger boost valves is going to help, because the flutter will probably stay (and BTW: I have a 13 vane rotor and stronger boost valve and a TV-style shift kit and my pressures are lower than yours...).
Just my guesses. We'll see. please let me know as soon as you find anything out, I'll let you hear once I've pulled my pump.
Best of luck,
Mad

[blwn31]

Hey MadMax, I will try this again. I've typed this twice, hopefully the computer won't #@%^&!@) out on me agian. I feel your pain, I've been driving aroud like this for about 3 years. Now, I better fix it before I do some real damage. My pressures are still a bit on the low side & fluttery. I called Performance Transmission, they sell the transmission by the name of Raptor. They were almost positive it is the pump. They said the pumps are real sensitve to being rebuit. I guess not being extremely flat. If you get good numbers with a different pump let me know. I guess I will have to buy a new one of those 13 vane jobs. I have ATSG Rebuild manuals from 82-93 if you need any pressure info.