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Old 08-19-2020, 01:26 PM   #1
Jrappl
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Default Mile-o-matic servo piston seal question

I have a 1959 Edsel Ranger 292 with the aluminum case Mile-o-matic 2 speed. I'm restoring the car and am cleaning and resealing the transmission.

I got a seal kit for the transmission and everything in it looks right except for one of the servo piston seals. The front servo piston is 3 5/8" in diameter and the rear is bigger at about 3 7/8" but both piston seals in the kit are the same size. Matching the old seals all other seals in the kit are much bigger or smaller.

The new seal size is slightly smaller than the original one I removed from the front piston - the old one could have stretched a little in 61 years and I'm not concerned about this fit. The problem I'm having is using that same size seal on the bigger rear piston. I can stretch it and it's not hard to get it on the bigger piston but I'm worried that being stretched out it might get thinner and not seal.

I called the the kit seller but after looking through all the books they had on hand they said it came in a kit and they don't have a separate listing for the 2 piston seals so couldn't tell me if the seals in the kit would work.

Does anybody have any experience with these servo piston seals? Can I just use the same size seal on both pistons?
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Old 08-20-2020, 05:59 PM   #2
rotorwrench
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Default Re: Mile-o-matic servo piston seal question

I've not seen too many Edsel 2-speeds but I have seen the Ford equivalent. The aluminum case 2-speeds came out for the 1959 model year and were used for several years with the 332/352 & 292 V8s and the 223 I6. They gravitated toward the Falcons & Comet cars in 1960 for use behind the small I6 like the 140 and the first of the small block V8 engines. They didn't get vacuum modulation till 1962 like most other Ford transmissions.

I looked up the servo piston seal sets for the Ford-O-Matic 2-speed of 1959 and believe it or not, there are three different part numbers of these sets depending on what the engine application is. The 292 used the B9AZ7A294-B with dimensions 3.689" OD - 3.286" ID - 0.86" thickness and it also shows the same seal for the rear which makes me wonder if the applications might be different. The I6 application is the only one of the three with a smaller size front seal. I wonder if the transmission was ever changed in the past. That application uses the B9AZ7A294-C which has dimensions 3.108" OD - 2.684" ID - .086" thick.

Whether you can cross these over to some other seal or not is unknown to me. At least you can tell that not all of them had the same size servo pistons. It just depended on the application. I just hope you can find some to fit. It would likely have to come from a supplier that knows these transmissions really well.

If Edsel applications are different then a person would need an Edsel specific parts catalog to find numbers.

Last edited by rotorwrench; 08-20-2020 at 06:27 PM.
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Old 09-20-2020, 10:43 AM   #3
Jrappl
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Default Re: Mile-o-matic servo piston seal question

The kit I got had the same size seals for both servo pistons even though the pistons are different diameters.

I took the pistons and the seals to a local transmission shop and they were very helpful. The desk guy pulled their top tech out to look. He said the seal looked a little tight on the bigger piston but should be find - just go with it!

I did and we will see shortly, just getting it running now and finding a few problems (hopefully minor) to work through before driving it
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Old 09-20-2020, 02:44 PM   #4
dmsfrr
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Default Re: Mile-o-matic servo piston seal question

Are they seals with a more 3D shape, or O-rings?
If there's a shop near you that sells and makes hydraulic and pneumatic equipment hoses they should have selection of O-rings in lots of sizes.
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Old 09-20-2020, 02:54 PM   #5
Jrappl
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Default Re: Mile-o-matic servo piston seal question

No, these are square cut o-rings just like the originals. They are supported better than a round o-rings would be and give a bigger sealing surface.
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Old 09-20-2020, 04:40 PM   #6
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Default Re: Mile-o-matic servo piston seal question

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I believe they are called quad rings. square seconded O rings.
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Old 09-20-2020, 06:10 PM   #7
rotorwrench
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Default Re: Mile-o-matic servo piston seal question

My guess is that they are selling a kit that is one size fits all or at least the end user hopes it will be. Square cross section o-rings are not common like round cross section types are. Hopefully they will last a good bit without splitting due to any extra tension that may be imposed on them.
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Old 09-20-2020, 07:00 PM   #8
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Default Re: Mile-o-matic servo piston seal question

There is a trans shop named Fatsco in Pine Brook, NJ that services and sells parts for older transmissions. They may be able to help you.


email - FATSCO@FATSCO.net 973-227-5414
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Old 09-21-2020, 10:22 AM   #9
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Default Re: Mile-o-matic servo piston seal question

If Fatsco don't have it; it did not exist....................
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