TR2/3/3A OD cover plate gasket sealer.

[DavidApp]

Having filled my rebuilt TR3A OD transmission with Red Line MT-90 as advised I has a small leak from the cover plate that the solenoid mounts on. The guy that did the rebuild sent me a replacement gasket.

Any thoughts on the best gasket sealant. Either a thin smear of Form.A.Gasket 1B Fast drying hard setting or Form .A.Gasket 2 Non.hardening.

David

 

[TR3driver]

Gasket leaks are almost always a sign that the surfaces are not flat; and that solenoid plate is particularly easy to distort because it holds a big spring behind it. So check both it and the surface of the main housing carefully while you've got it apart.

Hylomar is what I use on that gasket. So if I had to chose Permatex #1 or #2, I'd probably go with #2.

 

[Tybalt]

I had a similar problem in the same area on an A-type OD in my TR6. I made a gasket from rubberized cork and in the true spirit of belt and suspenders, used non-hardening gray Yamabond sealant, no more leak (at least from there). From what I understand an outfit called Threebond makes both the gray Yamabond and Hondabond and that their own Threebond 1184 is the same stuff. A local bike shop (Honda & Yamaha dealer) told me that even though it is the same stuff and same size tubes, as a general rule the Yamabond sells for a bit less than the Hondabond and as a result despite being a Honda dealer, only stocks Hondabond for their own use on warranty work and sells Yamabond at the parts counter and uses Yamabond in their shop for most work.

 

[DavidApp]

Hello Randall.

I did check the plate and there was a very slight gap between the lower 2 bolt holes. About 0.002" in the center. I managed to sand out most of it using 600 grit we and dry on a surface plate. The pin in the center made it a bit difficult.
I did go with the #2 as I thought that with that large spring pushing against the cover there was the possibility of movement in the cover. Also I cleaned both surfaces with lacquer thinner before I applied the gasket with a thin smear of #2 sealant on both surfaces.

I will see how it is in the morning.

David

 

[DavidApp]

Thank you

How thick was the rubberized cork material? Is the setting distance on that cover critical for the accumulator pressure?

I will have to try the local bike shops if it still leaks.

David

I had a similar problem in the same area on an A-type OD in my TR6. I made a gasket from rubberized cork and in the true spirit of belt and suspenders, used non-hardening gray Yamabond sealant, no more leak (at least from there). From what I understand an outfit called Threebond makes both the gray Yamabond and Hondabond and that their own Threebond 1184 is the same stuff. A local bike shop (Honda & Yamaha dealer) told me that even though it is the same stuff and same size tubes, as a general rule the Yamabond sells for a bit less than the Hondabond and as a result despite being a Honda dealer, only stocks Hondabond for their own use on warranty work and sells Yamabond at the parts counter and uses Yamabond in their shop for most work.

 

[Graham H]

David, I found the steel tube that holds the accumulator piston in the cylinder tends to droop if you fit the end plate with the box sitting in its normal upright position. I tend to lay the box on it's side to make sure the tube is sitting upright and not holding the cover plate off the gasket, just a thought.

Graham

 

[CJD]

This plate is my only "current" leak. I think over time the extreme spring pressure warps the cover. Definitely a non-hardening sealer is in order for it.

 

[Tybalt]

Thank you

How thick was the rubberized cork material? Is the setting distance on that cover critical for the accumulator pressure?

I will have to try the local bike shops if it still leaks.

David

It was either .025" or .032" thick. OD operation was not impacted so I have to think that at least in my case it was close enough to not be considered critical.

 

[DavidApp]

Thank you.

There was a single drip on the cover his morning. I think I am going to have to live with it.

The brass plug also has a small leak but I gather that an "O" ring makes a better seal there. I have made a tool to fit the plug.

David

 

[CJD]

When mine started leaking I thought it was my simple “O-ring” fix on the OD drain. That was so dry I re-used the o-ring for a 3rd time! All the drips are from the side cover.

 

[Graham H]

That steel peg in the cover plate should come out if you want to resurface it, or you could try two gaskets.

Graham

 

[DavidApp]

Making a replacement cover out of stronger material and a little thicker would be a good project for someone with a mill.

Are the replacement covers from Moss any good? If they are I may get one and put it on at the first oil change.

How warm will the solenoid get when it is activated. I know it should switch one coil off as it activates.

David

 

[CJD]

Hmmm...a thought since I have a mill now?!? It is kinda complicated though, as it includes the solenoid mount and through shaft.

When I first rebuilt the OD I installed the shaft seal on the wrong side of the plate. The parts diagram shows it on the outside...but it belongs on the inside. I remember the pain was that the entire tranny cover has to come off to reach all the bolts. I tried for hours with the tranny cover installed, but the top are just too tight to reach with the solenoid blocking them.

The end result is that it is a very simple fix to change the gasket and shaft seal...but a bear to get to it.

 

[DavidApp]

I noticed that on the older version of the cover plate there it has a box type structure around the lower part of the solenoid and lever. Could this be adding to the strength of the cover and reducing the chance of leaks?

Are the covers from Moss thicker so less likely to leak?

David

 

[Graham H]

Hello David,

I don't think the spring tension is strong enough to bend the plate but as I mentioned before the steel tube that holds the accumulator cylinder in the housing can be loose and drop down and stop the plate from fitting flat on the gasket. I put a row of centre punch holes in the end of the tube so it was a tight fit in the cylinder which keeps it straight while you fit the cover. It is a bit of a fiddle to get the plate off with the box in the car you may need to jack it up to get it off, good luck.

Graham

 

[TR3driver]

Graham, I think you may be thinking of the later IRS-style OD. The earlier units had a much larger accumulator piston (and stronger springs), with no tube involved. Just a short distance piece on the inner spring.

The smaller piston lets the pressure drop more when shifting into OD, which slows down the engagement and puts less shock into the differential.

The original box probably did reinforce the plate to some extent, but I think it's purpose was only to keep dirt away.

I don't recall hearing of any stronger side plates, but you might talk to John Esposito. He had some thicker adapter plates made up some years ago, so he might have done some solenoid brackets too.

 

[CJD]

And I don't think the box lasted long. Mine, car 5248, did not have the box, so it had disappeared by 1954.

 

[DavidApp]

Hello Graham

I do recall having to fiddle the spring over the steel peg as I tightened the bolts but don't remember seeing the tube sticking up that far.

I have a drip tray under the car and will keep an eye on the OD oil level. Having an inspection pit helps getting under there to check it. May get a turkey baster if I have to add oil.

At the first oil change I will try the "O" ring seal on the brass plug.

David