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"A" Type Overdrive Fun

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Tinkerman

Tinkerman

Darth Vader
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"A" Type Overdrive Fun

Afternoon:
Disassenbling my a type overdrive and when I pulled the accumulator spring and the spacing tube I found these two washers under the tube and the spring. They are 1/4 " flat washers but are now, about 1/2 the thickness of the ones in my flat washer drawer.

Anyone have any idea why anyone would do that? It is apparent that someone else has been in the unit. Also it sure does kind of stink also like burnt lining.

Anyhow any thoughts would be appreciated.

Thanks, Tinkerman
 

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Re: "A" Type Overdrive Fun

A desparate attempt to raise the operating pressure by increasing the spring pressure against the accumulator?? Or possibly just shimming the spring to the correct pressure (like a valve spring shim to correct seat pressure)
 
Re: "A" Type Overdrive Fun

jessebogan said:
Or possibly just shimming the spring to the correct pressure (like a valve spring shim to correct seat pressure)
Click to expand...
I vote for the latter. Although not certain, it appears that even the factory did that as needed (sometimes). And it's common practice when rebuilding. There are limits, of course, but check out
https://www.buckeyetriumphs.org/technical/AOD/AOD4/AOD4.htm
for Nelson's experiments.
 
Re: "A" Type Overdrive Fun

Thanks Randall. Looks like I will haave to do some reading, studying and testing before, during and after the rebuild. By the way I sent you a PM.

Thanks, tinkerman
 
Re: "A" Type Overdrive Fun

Nelson Reidel, in his great article on the dissasembly of the A type overdrive states "Putting a washer behind the spring is the accepted way to increase the accumulator presure." I have read that article a couple of times, made notes and underlined stuff. Missed that part though :-(.

So thats the answer, he uses fender washeers though, because they are bigger and fit the piston better.

Learn something every day!

Cheers, Tinkerman
 
Re: "A" Type Overdrive Fun

It is common practice to increase spring pressure by installing washers. The increased spring pressure raises the hydraulic pressure. It is done on any hydraulic system that uses spring resistance to regulate pressure. Why would the increased pressure be required? Who knows.

Tinkerman, I have the gauge that is used to check pressure through the ball and rod valve. Let me know if you need it and I'll lend it to you.
 
Re: "A" Type Overdrive Fun

Guys I met the O/D hydraulic gauge wizard this weekend , at the Glen. Jay is from Indiana and told us the story about how he got started making these. Nice setup and reasonable money.

fja
 
Re: "A" Type Overdrive Fun

Larry, Great! I certainly will take you up on it, I will call you this evening.

Frank, I don't know about anybody else but I sure would love to hear the story.

Thanks, Tinkerman
 
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