Lathe turned aluminum shift rod plugs for m5r1 transmissions, see pics

[corerftech]

So I have delayed addressing a leak on Frankentruck, the triple rubber shift rod seals on the transmission top plate for the M5R1 trans. I have been avoiding driving long haul so I don’t deplete a second fill of oil. Bleeds pretty good when topped off for sure!

Today I did a fuel pump hanger so my fuel gauge would behave at all temps (old/tired) and had the bed off. Figured I’d tackle the transmission leak as well.

I didn’t have a solution planned and I wanted to verify that it indeed was the three seals on the top plate.
Once I viewed the situation, it became obvious that I wanted a proper repair and one I could trust, service, reuse.
The bores are about .628 in diameter, I only have pin gauges to .501 so that was close enough. The bore is about .500 deep. It has a chamfer at the entrance.
I turned a plug from 6061 to .625, added a simple o-ring groove to an OD uncompressed of .630. That ring rides about half into the bore so there is trans case meat to both sides. There is a .700 diameter flange on the plug. For extraction and seal breaker, I d/t a 10/32 stainless cap screw into it.
I had some AC system o-rings handy and just used them, 12mmx 2mm

The middle plug has a caveat. The tail shaft to main case rib is tall enough to prevent a direct entrance of a rigid plug. So I shortened that plug to .500, thinned the flange and removed the flange on one side so that it would just barely make it over the case seam and go straight in. Once seated, the section with flange removed was clocked to 12 o’clock so that gravity isn’t going to allow oil past it.

Ultimately the o-ring plug snaps in quite tightly. The plug is coated with black permatex silicone and the middle plug is rotated as mentioned. The ring is a seal in and of itself, it’s also keeping silicone trapped on both sides of the ring so there won’t be any oil passing the plug even if it developed modest pressure.
The 10-32 screws are sealed with blue something, a gasket treatment. They are driven in finger tight. The middle plug is turned 180 degrees using it and an Allen wrench to keep the relief cut on top as mentioned before.

For service, put a good Allen wrench in head, turn as to tighten screw, this will break the silicone seal and also allow extraction.

Pics below.

If anyone is interested in them, let me know. I have not found a patent method for curing the leaks and doing it right. It took me 90 minutes to make all 3 with trial fitment, freehand on the lathe. I can make them rather quickly now that I have a dimensional spec and a work around for the center plug.


I’ll be keeping the carpet out of the truck for the winter as my floor needs some patchwork and carpet is just keeping moisture in contact. I’ll take a few pics in a month and verify seal quality/integrity. I expect it to be as solid as a freeze plug but removed easily and installed even easier.

I’ll be inspecting my M5R2 tomorrow and measuring for a set for it in my V8 application. Unsure if they are the same or not.

 

[85_Ranger4x4]

I just used steel expansion plugs on my R2

 

[Josh B]

What happen to the originals ?

 

[85_Ranger4x4]

What happen to the originals ?

Rubber does rubber things, fall apart and the trans spits oil out the holes and bleeds to death.

Shift Rail Plug Maintenance - The Ranger Station

There are (2) ways to approach this job: 1) Grab the plugs with needle nose pliers, but this only works if you have small hands. 2) Remove the driveshaft(s) and transmission crossmember, lower the transmission slowly with a jack, and … Continued

www.therangerstation.com

 

[alwaysFlOoReD]

So I have delayed addressing a leak on Frankentruck, the triple rubber shift rod seals on the transmission top plate for the M5R1 trans. I have been avoiding driving long haul so I don’t deplete a second fill of oil. Bleeds pretty good when topped off for sure!

Today I did a fuel pump hanger so my fuel gauge would behave at all temps (old/tired) and had the bed off. Figured I’d tackle the transmission leak as well.

I didn’t have a solution planned and I wanted to verify that it indeed was the three seals on the top plate.
Once I viewed the situation, it became obvious that I wanted a proper repair and one I could trust, service, reuse.
The bores are about .628 in diameter, I only have pin gauges to .501 so that was close enough. The bore is about .500 deep. It has a chamfer at the entrance.
I turned a plug from 6061 to .625, added a simple o-ring groove to an OD uncompressed of .630. That ring rides about half into the bore so there is trans case meat to both sides. There is a .700 diameter flange on the plug. For extraction and seal breaker, I d/t a 10/32 stainless cap screw into it.
I had some AC system o-rings handy and just used them, 12mmx 2mm

The middle plug has a caveat. The tail shaft to main case rib is tall enough to prevent a direct entrance of a rigid plug. So I shortened that plug to .500, thinned the flange and removed the flange on one side so that it would just barely make it over the case seam and go straight in. Once seated, the section with flange removed was clocked to 12 o’clock so that gravity isn’t going to allow oil past it.

Ultimately the o-ring plug snaps in quite tightly. The plug is coated with black permatex silicone and the middle plug is rotated as mentioned. The ring is a seal in and of itself, it’s also keeping silicone trapped on both sides of the ring so there won’t be any oil passing the plug even if it developed modest pressure.
The 10-32 screws are sealed with blue something, a gasket treatment. They are driven in finger tight. The middle plug is turned 180 degrees using it and an Allen wrench to keep the relief cut on top as mentioned before.

For service, put a good Allen wrench in head, turn as to tighten screw, this will break the silicone seal and also allow extraction.

Pics below.

If anyone is interested in them, let me know. I have not found a patent method for curing the leaks and doing it right. It took me 90 minutes to make all 3 with trial fitment, freehand on the lathe. I can make them rather quickly now that I have a dimensional spec and a work around for the center plug.


I’ll be keeping the carpet out of the truck for the winter as my floor needs some patchwork and carpet is just keeping moisture in contact. I’ll take a few pics in a month and verify seal quality/integrity. I expect it to be as solid as a freeze plug but removed easily and installed even easier.

I’ll be inspecting my M5R2 tomorrow and measuring for a set for it in my V8 application. Unsure if they are the same or not.


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I'm interested in a couple sets.

 

[scotts90ranger]

That's a neat fix, for over 20 years I've heard of this issue but in 23 years of having an M5OD I've never had an issue that I've noticed... haven't checked fluid level in a while but no drips in the transmission area of either of my Rangers... (no drips on the '97 at all somehow and only engine related on the '90).

That said, if I have issues I might have to do something similar...

 

[corerftech]

It becomes very obvious when the plugs fail. It’s not drips, it’s puddles. Especially after a hard run at 70 down interstate. It doesn’t pour out, it just gets flung everywhere and when you stop, it drips off the tail shaft (and everything else in vicinity) housing till the next drive.

Update: I tested the silicone and plug seating 12 hours in. I wasn’t happy with the 10-32 sealant, it hadn’t set yet. I had never used that sealant which was for gaskets. But the plugs are definitely only coming out if you intend them to. I mean they are really really tight and well seated.

My next set will not have a hole through. My bar stock had been used for other things before and had a center already drilled on the first plug experiment. Drilling the 10-32 in, I broke through and now had a hole in the middle. It was nice for tapping with a taper tap, I just tapped right on through without fear of bottoming. I did all 3 same way just because.

I didn’t intend to drill through. I won’t on the next set. I had called my wife And asked her to pick up the 10-32 at the local machine hardware store and she brought 3/4 inchers.

The next iteration will have a short screw boss at 3/8 inch. Plug will not have a hole to seal. Also a comparably shorter 10-32 screw.
With only .003-.005 clearance on the plug and the o-ring slightly compressed, there is zero chance of the plug leaking, ever. Ford should have done this. The silicone film before and after the o-ring make 3 separate seals for oily to get past.

This is a case where cheap didn’t even factor in at the factory. It’s like it was designed to be a service issue.

5.4l triton has a coolant line behind the intake manifold. It’s steel. It notoriously gets a pinhole leak at 15-20 years. Tube otherwise is mint upon inspection.
Why steel? Why not stainless? It’s small, very small, low cost to produce. To service you must rip the whole top end off engine, for a minor coolant leak.

It sells gaskets and labor! $1.00 in rubber plugs produces transmission replacements like clockwork and at least, a trans service including removal, for the average vehicle owner.

I hate that- that’s not American Exceptionalism. In 1950 it would have been an oversight. In 1990, it was intentional. Oh well.

 

[gearfather]

before retirement (again) my company supplied approx 25-35 m5r1 and m5r2 reman units a week to fomoco plus many shops in us and canada, so we just purchased bulk boxes expansion plugs from pioneer for years. never had an issue..

 

[PlumCrazy]

You can run a 3/8 NPT tap in through the holes and just put pipe plugs in. Bonus feature if you have a Hurst that causes pressure build up, because you can put a barb fitting in one to make a breather setup.