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Discussion Starter · #1 ·
I built this myself with all good parts, mainly BTE and JW
I had around 80 passes and my reverse clutches started to burn causing my transbrake to jump at the line. The reverse clutches had well over 100 passes on them.
Tore the trans down. The band had a slight burn but really looked ok, I replaced it anyway. The clutches in the 10 clutch drum looked brand new and they had 70+ passes on them.
Replaced the reverse clutches, air checked them, OK.
Replaced the band and slammed it back together.
2nd pass the band let go on the t-brake and backed up at the line.
I figured I adjusted it too loose.
Tore it out the next day and in 3 hours threw another band in it to make a race that afternoon.
Next pass I lost 1st and 2nd gear. Smoked the clutches so bad the piston popped out. Found I had no end play from the previous rebuild. I had relpaced the output shaft carrier and did not recheck the end play. Set end play to .010, new clutches and band and went to another race. I figured now the problem was the pump gasket was not seating properly from no end play causing a pressure loss.
1st pass launched nice and held through 1st gear, right after hitting 2nd the hi clutches started slipping and burned up in 2 seconds
Car has now been sitting for 3 weeks because I needed a break. Now ready to find the problem.
Could I have a valve body problem. I have never touched this valve body, just bolted it on every time.
I have a pressure guage and can access the rear pressure port which is reverse. How much pressure shopuld I see. I want to check this before I tear it back down. I have to have a pressure problem.
The pump and valve body are BTE and before the 70 pass freshen up this trans was perfect.
What am I missing?
I have been building stock (dealership technician) transmissions for over 20 years and never have had a problem like this on a powerglide before.
My car has ran 7.82 at 181 MPH on 2 kits and it is burning up right away on just one nitrous kit.
Help
Thanks
Martin Keefer
 

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Discussion Starter · #3 ·
what sealing rings are on pump and how are you checking end play. {h-gauge] OR daila indicator
Scarf cut seals that came with BTE seal kit and I used a dial indicator.
 

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from across the pond...
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Have you checked wether the stator support has turned in the pump?
Also with all the debris that has gone through the trans you will need to strip and check the valvebody....
 

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I like to see at least 200 psi on a bracket brake. Take the valvebody apart and clean it. Dual ring servo piston. 3.5 to 4 on the band adjustment, around .100 on the rear clutch clearance, and as mentioned check the stator tube. Check everything.
 

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you want to access the pressure port also in the cover for band piston. does the break hold at the line if so your pump is probably good if not you have a pressure prob check the case for cracks at the back where the low rev clutches get fed.
 

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If you have an O ring servo piston , you may have nicked the rings. Other than that , check line pressure, check the stator tube and take the valve body apart and check the regulator valve,spring and booster.

Hutch
 

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Discussion Starter · #9 ·
I have 2 new seals on the servo piston and they looked good before also. I had time to install a pressure guage on the rear pressure port for reverse last night and saw what I thought I would.
I only have 100lbs max line pressure on the trans brake at the rear port. The pressure built to 100lbs at less than 2000RPM and stayed there. I remember hooking up at this port before about a year ago and remember seeing 225 lbs using the same pressure guage. I will pull my collector tonight so I can access the servo cover port and test pressure in 1st and 2nd gear then pull the trans out.

This is a JW case also if that makes any difference.
Anyone have a pic of the valve body pressure regulator spring and valve?
 

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Discussion Starter · #10 ·
Ok I hooked the pressure guage to the servo port. I have 225 to 240lbs in 1st gear. That blows my theory that the pressure regulator valve stuck or spring broken.
As soon as I shift into 2nd gear I only have 90 lbs of pressure. It never goes over 90 lbs.
The clutches are burned but it will still pull the car in 2nd gear so I don't believe the piston has come all the way out.
The last time it smoked 2nd, the piston came out and I completely lost 2nd gear.
I was told I should see a drop of pressure for a fraction of a second when the shift occurs and then I should see full line pressure again because the pressure equalizes on both sides of the servo piston.
So these pressures show why my trans is burning up, I just don't know where to look for the problem.


Rear port in reverse or on the brake I have only 100lbs
Front port 1st gear I have 225 lbs or more pressure
Front port 2nd gear 90 lbs max pressure.
Someone here has to know WTF is wrong with my trans. I really want to go racing again but I am not going to burn up 1st pass and pull this trans a 4th time in a row.
Thanks again
Martin
 

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LOOK AT THE STATOR TUBE TO SEE IF IT HAS TURNED.... just thought i'd put it in capitals incase you missed it first time around....:-D
 

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Discussion Starter · #12 ·
LOOK AT THE STATOR TUBE TO SEE IF IT HAS TURNED.... just thought i'd put it in capitals incase you missed it first time around....:-D
I will check it but mine is bolted in, not pressed like a stock powerglide pump. I have a BTE pump. How would the stator tube being loose cause good pressure in 1st and low pressure in 2nd?
What are the symptoms of a loose stator tube?
 

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We know now what the system pressure is. 225psi should be enough to make the trans work properly. Now you need to pull the trans apart and find the leak in high gear and the leak in reverse/transbrake.
For high gear , look at sealing rings, servo return circuit , pump gasket , pump half flatness, valve body gaskets blown out etc. It sounds like you are testing a wrecked trans so the pressure readings may be due to damage not yet seen.

For the reverse/transbrake leak , check the valve body for a checkball leak if it has one , or an improperly indexed transbrake spool valve.

Let me know what you see when its apart.

Hutch
 

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Discussion Starter · #15 ·
We'll I gave up and carried it over to a performance builder.
I will have it back this week. They are making several changes. Hopefully this problem will be fixed so I can race.
They are going to cover it so if it burns up right away I can cuss someone else instead of looking in the mirror LOL.
 
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