66 m-22

[Joe L.]

Re: 66 m-22

In the 45+yrs that I've been rebuilding 4spds (mainly Muncies), I've never seen a magnetic FILL plug. I've only seen magnetic Drain plugs.
And the T-10s that I've seen, BOTH plugs are NON magnetic.
Of all the 63-69 Muncies I've rebuilt (except ONE), I've always removed the magnetic donut and installed a magnetic drain plug.
In my opinion, the magnetic donut presents a serious potential disaster for total destruction of the internals------------------as seen below.

This destruction was caused when the magnetic donut came loose.



This is the remains of the donut that destroyed the above Muncie, compared to a removed donut and a magnetic plug.


In my opinion, REGARDLESS of NCRS correct or not, it's not worth the risk to leave the donut in the case when doing a rebuild.

Tom------


I agree. I regard the epoxied-in magnetic "do-nut" as an extreme threat to the life and health of a transmission. When I rebuild the original M-20 from my 1969 which is currently out of the car, one of the first things I've long-planned to do is to remove the magnet.

Believe it or not, GM used to supply these do-nuts in SERVICE as a kit with a tube of special adhesive. It was GM #369122. In fact, I have one. I NEVER plan to use it, though.

No one need be even slightly concerned about NCRS correctness. No one will ever know the magnet is not there.

[Patrick B.]

Re: 66 m-22

Patrick-------

1966-69 Muncie M-20 and M-21 were not originally manufactured with drain plugs. So, if you had some with drain plugs, someone added them. This is not difficult to do as the boss for the drain plug is present on all Muncie main cases.

All 661 main cases were originally manufactured with a drain plug.

Joe--- My apologies. The 66 and 67 transmissions had only one plug, the fill plug with no markings and no magnet. The 1970 transmissions with 661 cases had 2 plugs. The facts that were interesting were that the M-21 as well as the M-22 had magnetic plugs in BOTH positions, and that there was another manufacturer of OEM magnetic plugs besides Lisle which used a P as a trademark.

[Tom P.]

Re: 66 m-22

Tom------


I agree. I regard the epoxied-in magnetic "do-nut" as an extreme threat to the life and health of a transmission. When I rebuild the original M-20 from my 1969 which is currently out of the car, one of the first things I've long-planned to do is to remove the magnet.

Believe it or not, GM used to supply these do-nuts in SERVICE as a kit with a tube of special adhesive. It was GM #369122. In fact, I have one. I NEVER plan to use it, though.

No one need be even slightly concerned about NCRS correctness. No one will ever know the magnet is not there.

Joe,
Since you mention that, here is how I install a drain plug in main cases without the drain plug.