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 Post subject: powerglide pressures
 Post Posted: Thu Jun 18, 2009 3:43 pm 
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The trans was warm, since it consumes a lot of alcohol if I left it warm up the trans temp to 180. So these readings are around 110 degrees.

First gear pressure tested at servo housing is 255 psi @ 1800 rpm , with a calibrated gauge.( not the 195 psi I had with a old gauge that has to be bad.

Second Gear on the servo housing tap still has 255 psi

Reverse, at the pressure tap is 100 psi @ 1800 rpm.

I am using a reid pump and custom valve body by a shop here in Illinois, sloans racing transmissions. He uses alot of pressure in the valve body.

It is also a manual forward pattern valve body


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 Post subject: Re: powerglide pressures
 Post Posted: Thu Jun 18, 2009 4:20 pm 
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Is it a pro brake and was the solenoid engaged? 100 lbs won't cut it, it is leaking somewhere.


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 Post subject: Re: powerglide pressures
 Post Posted: Thu Jun 18, 2009 6:25 pm 
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The pressure was taken without the transbrake engaged. It is just a bracket trans. But If I continue to have problems with this modified stock valve body I am going to switch to something else.
They guy who originally setup the trans told me the pressures are good, I have no reference what it was last time it ran. It was getting hot because the pins in the output shaft were wearing into the drum, and caused alot of damage, mainly the pump. So fixed everything and put in a new pump,reid, and air checked it along the way. Reverse just seemed sluggish and So I put the gauges on it and cycled it a few times and it seems to be fine. Looking back maybe I just didn't cycle it enough.

But according to the tranny guy it is fine,the 100 psi, since I have no idea what they were. Friday I am going to take it out on the road and see what she does.
I am pretty sure that if anything is wrong with it it is in the valve body. I took lots of time to go though the internals and mic'd everything, rechecked measuremnts. Only thing I didn't look at was the valve body.

When the brake is engaged I would think that both gauges would have to be the same pressure...Correct?? Something to look at friday.


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 Post subject: Re: powerglide pressures
 Post Posted: Thu Jun 18, 2009 7:46 pm 
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Doug, If you apply the brake and matt the throttle it will creep forward with only 100 psi....

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 Post subject: Re: powerglide pressures
 Post Posted: Thu Jun 18, 2009 9:53 pm 
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Alot of this transmission theory is based on principles of hydraulics. It's all about PSIG applied to apply piston square inches of area. More piston square inches of area means more actual force applied to the clutches. If you look at the sq in of the high gear piston compared to the reverse piston it's easy to see how this works. One of these days I'm going to do the math on those two just to see how much difference the actual applied force is.

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 Post subject: Re: powerglide pressures
 Post Posted: Thu Jun 18, 2009 11:52 pm 
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On a non pro brake it is not uncommon to restrict the passage for reverse to slow the apply, but 100 lbs is low. Check it with the transbrake engaged in low and see what the pressure is. It should match low.


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 Post subject: Re: powerglide pressures
 Post Posted: Fri Jun 19, 2009 3:42 pm 
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Rain hampered my drive in the country, but I did get the pressures again. This time just started it and ran the gears, used the brake once and checked the pressures,

Rev is 100 psi @ 1600
Drive is 255 psi @ 1600
Low is @ 255 psi @ 1600

Trans brake engaged :

Low is 250 psi @ 1600
rev is 250 psi @ 1600

So I am happy with these numbers, I think I just didn't cycle it enough in the beginning and using a different fluid for the first time.


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 Post subject: Re: powerglide pressures
 Post Posted: Fri Jun 19, 2009 9:23 pm 
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That sounds more like it Doug. Mine was running at 235psig HOT tonight while we were testing. And what I mean by HOT is that I've seen that temp upwards of 300* at times.

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