QIK59

Alright Tom, JohnZ and other guru's :

What is your preference and rationale on the installation order for Muncie input oil slinger AND shim ?

I saw pictures on here somewhere showing the slinger going against the gear and then the shim.

Elsewhere I saw a recommendation to install the shim first (against the gear) and then the oil slinger.

I would think the oil slinger is more effective in keeping excess oil away from the input bearing by being closer to the bearing and also shielding it.
This would also maintain the original as installed spacing and configuration.

What do you guys say ?

Avispa

The tapered face of the oil slinger should always face outward, away from the bearing and there should never be any shim or other piece between that surface of the oil slinger and the front bearing retainer. The oil slinger works by running a small clearance on a similarly tapered surface on the inside of the bearing retainer. The oil is literally
"slung" away from the tapered surfaces of the oil slinger and the bearing retainer by centrifugal force - so none leaks out. The inner surface of the bearing retainer has an oil drain channel that feeds into a hole through the front of the transmission case to return the slung oil into the transmission case.

That's my story and I'm sticking to it. Good luck with the reassembly.

QIK59

Thank you for your response but you are getting the input nut mixed up with the oil slinger that goes on the other side of the bearing

midstyle

I believe the extra shim (in addition to the slinger) was a rebuilder trick to improve 1st gear synchro engagement or something. Chevrolet/Muncie never added a shim, only the slinger. Looking at my Chevy parts catalogs, seems the slinger was introduced for '68 and up, in both M21 M22 and M20, and was available as a separate part (Gr 4.374 #3925692). The front input/clutch gears for M20/21/22 changed part #s at this time. I don't know whether this was just to signal the addition of the slinger (catalog description of gear says "w/slinger"), or whether the gear itself was modified in any way to accomodate said slinger. Picture immediately below is an NOS M21 gear with the post-'68 part #. The slinger is 0.020" thick. The other pic shows an M22 gear, circa 1971, with slinger, and someone added another shim ink-stamped 0.037". The M21 gear on the right is from a pre-slinger era '66 trans, assy. P0308, and some previous rebuilder (not me... I just take them apart ) added a brass shim that measures 0.048".






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QIK59

Thank you Mid,

I checked my tranny's end play's before I pulled it apart and also how much the input could be shimmed back.

The input had .055" clearance with the GM slinger (.021") installed.
The aftermarket slinger I'm going to use is .027".

I made a bunch of shims today out of .027 and .030 stainless to nest nicely with the slingers.
Just need to machine the ID's for a nice fit on the input.

Have a bunch of Muncie's to "tune-up" - ran out of spares and also want to change inputs on some to suit the fine spline L88 clutch disc's I have in 'stock".

DZAUTO

MANY, MANY years ago, Larry Fischer (of D&L Transmission), as well as my uncle, who was a factory trained Chevy mechanic, taught me to ADD a .030-.032 shim between the input gear and the front bearing. This shim is added in addition to the oil slinger (a factory slinger is shown above). The factory slingers are no longer available, but Larry includes them in his rebuild kits (I buy ALL my parts from Larry and have been doing exclusive 4sp business with him for about 35yrs.
The purpose of adding a shim between the input gear and the front bearing is to shove the input gear deeper into the synchronizer (which produces a more secure engagement of 4th gear (NOT 1st gear).
So for about 30yrs, I've been adding a .030-.032 shim to the input gear of Muncies (can't do this with early T-10s that use a snap ring in front of the bearing).
Adding the shim to a Muncie is one of the best little rebuild tricks that can------------------and should be done.

Auto Gear

GM really dropped the ball with this one. Generally speaking you need (2) shim/slingers as DZ says. If you want to check this on an assembled unit; you can put the sliding clutch in the neutral position and see that the input side (4th gear) has a larger 'gap'. the slinger pushes the head of the gear closer to the synchro. You should NEVER need 3 slingers. If you do; something is wrong.

QIK59

Here are some photo's of the shims I made - they index off the groove between the bearing mtg surface and the gear.

First picture shows a partially completed shim.
2nd picture is the partially completed shim with a completed shim.
3rd picture is the slinger and shim installed.