Rebuilt 700r4 high line pressures, Help!
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Rebuilt 700r4 high line pressures, Help!
Hi guys,
I've just popped over from the c3 section with a question on 700r4's
I've just rebuilt a 700r4 for my Dad's Studebaker and i've got 200PSI line pressures in all gears at idle.
Obviously this is way too high
, I got this info from hooking up a 0-300 pressure gauge.
I rebuilt the box with TCI 37600 universal lockup kit, a B and M 70237 upshift kit, a B and M 70239 shift improver kit and a vette servo.
This was my first rebuild.
My first thoughts are that the TV valve assembly is sticking leading the trans to think it's at WOT all the time? Before I start taking the valve body apart can anyone give any advice as to where to start?
I took the car out briefly before the gauge was hooked up and it didn't want to change out of first although it reluctantly did in the end.
Any help appreciated, cheers.
Oh and p.s this is a stock converter with a very mild (not stock) cam, we intend to change the converter when funds allow.
I've just popped over from the c3 section with a question on 700r4's
I've just rebuilt a 700r4 for my Dad's Studebaker and i've got 200PSI line pressures in all gears at idle.
Obviously this is way too high
, I got this info from hooking up a 0-300 pressure gauge.I rebuilt the box with TCI 37600 universal lockup kit, a B and M 70237 upshift kit, a B and M 70239 shift improver kit and a vette servo.
This was my first rebuild.
My first thoughts are that the TV valve assembly is sticking leading the trans to think it's at WOT all the time? Before I start taking the valve body apart can anyone give any advice as to where to start?
I took the car out briefly before the gauge was hooked up and it didn't want to change out of first although it reluctantly did in the end.
Any help appreciated, cheers.
Oh and p.s this is a stock converter with a very mild (not stock) cam, we intend to change the converter when funds allow.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The TV valve can be checked without taking the valve body off. It's got a spring on the linkage inside the trans so you can just push on it with your finger and see if it moves freely.
Do you have the TV cable adjusted correctly? Does your TV cable bracket have the correct geometry? See this link:
http://www.tvmadeez.com/article/index.php
What size pressure valve is in the pump?
Do you have the TV cable adjusted correctly? Does your TV cable bracket have the correct geometry? See this link:
http://www.tvmadeez.com/article/index.php
What size pressure valve is in the pump?
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Thanks Cliff, I do have the cable adjusted correctly as far as I know.
It has a standard pressure spring.
I'll check the governor first and then pull the pan.
Cheers, Aaron.
It has a standard pressure spring.
I'll check the governor first and then pull the pan.
Cheers, Aaron.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
It's not just the spring. The diameter of the boost valve affects the pressures in some gears. I assume from what you said that it's stock.
The pressures varied depending on what car the trans was installed in. Which version of the 700r4 do you have?
It's starting to sound more like your gauge is not accurate. 200 PSI is way too high.
These are the pressures I measured on my MD8 Corvette 700r4 with a 0.500" boost valve (stock is 0.472", as I recall):
The pressures varied depending on what car the trans was installed in. Which version of the 700r4 do you have?
It's starting to sound more like your gauge is not accurate. 200 PSI is way too high.
These are the pressures I measured on my MD8 Corvette 700r4 with a 0.500" boost valve (stock is 0.472", as I recall):
Code:
Idle or Min TV P 90 PSI R 130 N 90 OD 90 D 90 2 230 1 230
Last edited by Cliff Harris; Jun 16, 2013 at 03:38 AM.
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
It's not just the spring. The diameter of the boost valve affects the pressures in some gears. I assume from what you said that it's stock.
The pressures varied depending on what car the trans was installed in. Which version of the 700r4 do you have?
It's starting to sound more like your gauge is not accurate. 200 PSI is way too high.
These are the pressures I measured on my MD8 Corvette 700r4 with a 0.500" boost valve (stock is 0.472", as I recall):
The pressures varied depending on what car the trans was installed in. Which version of the 700r4 do you have?
It's starting to sound more like your gauge is not accurate. 200 PSI is way too high.
These are the pressures I measured on my MD8 Corvette 700r4 with a 0.500" boost valve (stock is 0.472", as I recall):
Code:
Idle or Min TV P 90 PSI R 130 N 90 OD 90 D 90 2 230 1 230
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Hi, i've just pulled the pan and found the tv lever needs nearly WOT before it even comes into contact with the TV valve, and at WOT on the carb it's only pushing the valve approx halfway.
Not correct....although it felt good when I was adjusting it at the time.
I'm in a bit of a quandary now because if I adjust the cable so that the valve is buried with WOT on the carb, then the TV lever is still not in contact with the valve until about 20% throttle position.
If I adjust the cable so that it's in contact with the TV valve at idle then the valve is buried way before WOT on the carb and is trying to bend the carb bracket at WOT carb position.
My question is.....Should the tv lever be in contact with the valve at idle or is slight gap before the lever contacts the valve ok?
Cheers
p.s - i've done everything by the book, I have the correct brackets etc
Not correct....although it felt good when I was adjusting it at the time.
I'm in a bit of a quandary now because if I adjust the cable so that the valve is buried with WOT on the carb, then the TV lever is still not in contact with the valve until about 20% throttle position.
If I adjust the cable so that it's in contact with the TV valve at idle then the valve is buried way before WOT on the carb and is trying to bend the carb bracket at WOT carb position.
My question is.....Should the tv lever be in contact with the valve at idle or is slight gap before the lever contacts the valve ok?
Cheers
p.s - i've done everything by the book, I have the correct brackets etc
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Update, i've just got the car back together after adjusting the cable so that the TV valve is buried at WOT on the carb linkage, this positions the lever approx 1/4" from the valve at idle and requires approx 25% throttle lever movement to make contact with the valve.
It's too late to fire her up now as the car is LOUD (louder than my side piped vette), but we'll start her up tomorrow after work and see how she's running.
EDIT - the valve was never stuck, I thought it was but it was fine
It's too late to fire her up now as the car is LOUD (louder than my side piped vette), but we'll start her up tomorrow after work and see how she's running.
EDIT - the valve was never stuck, I thought it was but it was fine
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Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Check out that TV made EZ link and read the WHOLE thing (though the last part was never posted). According to them the line pressure MUST go up INSTANTLY as soon as the gas pedal is depressed. Your setup doesn't meet that criterion. The cam on the lever should be touching the TV valve at idle.
You need to get this fixed immediately. You WILL burn up your 3-4 clutch pack with your current setup. Lots of torque and low line pressure is a BAD combination. You will be looking at THIS soon (burned steels and chunked out frictions):
You need to get this fixed immediately. You WILL burn up your 3-4 clutch pack with your current setup. Lots of torque and low line pressure is a BAD combination. You will be looking at THIS soon (burned steels and chunked out frictions):
Last edited by Cliff Harris; Jun 17, 2013 at 04:03 AM.
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Check out that TV made EZ link and read the WHOLE thing (though the last part was never posted). According to them the line pressure MUST go up INSTANTLY as soon as the gas pedal is depressed. Your setup doesn't meet that criterion. The cam on the lever should be touching the TV valve at idle.
You need to get this fixed immediately. You WILL burn up your 3-4 clutch pack with your current setup. Lots of torque and low line pressure is a BAD combination. You will be looking at THIS soon (burned steels and chunked out frictions):
You need to get this fixed immediately. You WILL burn up your 3-4 clutch pack with your current setup. Lots of torque and low line pressure is a BAD combination. You will be looking at THIS soon (burned steels and chunked out frictions):
Good news guys, just hooked up the pressure gauge and got this -
P - 85
R - 140
N - 85
4th - 85
3rd - 85
2nd - 200
1st - 200
Just took her out for a spin and she' awesome, very fast now
Basically the problem was a badly adjusted cable, my advice to anyone fitting a 200/700 is to connect the tv cable to the trans before you put it in the car ( it's hard to get to when installed), remove the trans pan and adjust the cable while keeping an eye on the lever/valve, what appeared to be adjusted well was far from it.
Thanks for all your help
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Hi guys
I thought i'd sorted it but no...
The car revs too high in 1st and appears to jump to 3rd, also there's no 4th...
So it appears to be a 2-4 issue, I took the servo cover off to check i've installed everything the right way round and the seal for the 2nd apply piston just fell out, it's the slash cut type seal and it's broken (although it was new)
I then checked the rest and found i've put the wrong seal on the 4th apply piston, I had the blue seal on there which is slightly too big.
My thinking is that the forth apply piston isn't sealing and has blown out the seal on the 2nd apply piston? Possible? Would this cause no 2nd and 4th?
Anyway, she's all back together now and ready for a test on the driveway. I'll report back shortly
I thought i'd sorted it but no...
The car revs too high in 1st and appears to jump to 3rd, also there's no 4th...
So it appears to be a 2-4 issue, I took the servo cover off to check i've installed everything the right way round and the seal for the 2nd apply piston just fell out, it's the slash cut type seal and it's broken (although it was new)
I then checked the rest and found i've put the wrong seal on the 4th apply piston, I had the blue seal on there which is slightly too big.
My thinking is that the forth apply piston isn't sealing and has blown out the seal on the 2nd apply piston? Possible? Would this cause no 2nd and 4th?
Anyway, she's all back together now and ready for a test on the driveway. I'll report back shortly
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland
Right guys, i've stripped the valve body out of the car and everything appears correct except -
The accumulators were not sitting flush with the vale body because I hadn't filed the tubes that came with the shift kit.
This made a gap both sides of the valve body where the accumulators meet it, I think this is the cause of my oil leak i've been having, I reckon the ATF is forcing it's way past the valve body gasket at high pressure and out through the sump gasket??
I have filed the tubes that come with the shift kit and i will continue to check stuff until I can't check no more.
I'll then reassemble and fire up the car, if there's still no 4th then i'll take the trans out.
My question is - how much pressure is in the accumulators and can it force it's way past the piston and out of the bottom where it's supposed to seal with the valve body.
...and if so could this be the reason i'm not getting 4th gear??
Thanks.
The accumulators were not sitting flush with the vale body because I hadn't filed the tubes that came with the shift kit.
This made a gap both sides of the valve body where the accumulators meet it, I think this is the cause of my oil leak i've been having, I reckon the ATF is forcing it's way past the valve body gasket at high pressure and out through the sump gasket??
I have filed the tubes that come with the shift kit and i will continue to check stuff until I can't check no more.
I'll then reassemble and fire up the car, if there's still no 4th then i'll take the trans out.
My question is - how much pressure is in the accumulators and can it force it's way past the piston and out of the bottom where it's supposed to seal with the valve body.
...and if so could this be the reason i'm not getting 4th gear??
Thanks.
Thread Starter
Burning Brakes
Joined: Jan 2009
Posts: 845
Likes: 54
From: Bangor, Northern Ireland