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Discussion Starter #1
Need recommendations for a slow full tree powerglide transbrake. I have areas to speed up reaction times if need be.

Tired of the spool valve problems that I am experiencing with my current valve body.

Thanks,
Greg
 

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Discussion Starter #3
Hard to beat the old ATI pilot circuit valve body, nice and slow. A lot of them sitting around because of that.
That sounds like exactly what I need. Is this old technology that's no longer available from ATI?

If so I guess the search begins.

Thanks,
Greg
 

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They called it compuflow. Can be id'd by the little gold solenoid where the brake valve normally fits. Call ATI, they probably have one laying around, however verify it's the pilot circuit type. On the other hand spool valve problems can sometimes be traced to debris in excess. If ATI can't help, email Charley @ ATD, he'll probably be able to help out.
 

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Discussion Starter #6 (Edited)
Why are you looking to do this in the valve body? Can you not use an adjustable button?


Hutch
Not looking to slow it down with the valve body. Just don't want to speed it up any.

My current valve body uses an aluminum spool valve and has failed several times both not releasing and not engaging. Most recently in our Div 6 ROC with three cars left.

My thinking is that the aluminum spool valve and cast iron valve body may be the issue being that material expansion rates differ. Please correct me if I am wrong.

Thanks
Greg
 

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Discussion Starter #12 (Edited)
I missed #6
I’ve never seen a problem with it being an aluminum valve.
Not that it couldn’t happen.
Yes a steel one would work if it were the problem
I would ream it first then make the spool to fit.

Is it not going in or coming out?
And it could be for other reasons.
Brand of T/Brake?
It is a TCI full tree brake with the spring.
It has had issues with both engage and release. Currently engage.
It only happens when turn around gets short. Trans temp is not showing over 210. But my thinking is more heat sink with the short turn around.
Has happened with different solenoids and is grounded direct to battery negative and electrical connections have been checked.
Could be debris related but the issue never appears with ample time between rounds.

Maybe shrinking clearance and debris combined?

I am running out of ideas and the above is what got me thinking about expansion rates and going to a TB with a steel spool valve.

Thanks,
Greg
 

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You can easily make a steel valve and lap it to the bore, don't need much clearance. Cost of racing what it is I sure as Hell would have been into a different V/B by now. The piece you are working with is probably older and far from the best quality machine work. Long ago I puttered with aluminum hard coated valves and had the same kind of experience you describe.
 

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Discussion Starter #14
You can easily make a steel valve and lap it to the bore, don't need much clearance. Cost of racing what it is I sure as Hell would have been into a different V/B by now. The piece you are working with is probably older and far from the best quality machine work. Long ago I puttered with aluminum hard coated valves and had the same kind of experience you describe.
So sounds like my prognosis is on target.

For clearance are we talking thousand's or tenth's? Not much in my mind is .0015 or less.

Thanks everyone for your input.
Greg
 

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Discussion Starter #16
Go with .001" on the small diameter land and .003" on the large. You can make it from some 4140ht and it will be just fine.


Hutch
Thanks, I will go with those dimension -0 +.0005

Again thanks to all that chimed in.

Greg
 
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