How to remove shifter rails from 420s ???

[DoubleO7]

This is for a 1957 and it does not have the gated shift tower.

I have the five speed shifter on the work bench.
The right hand rail moves like it should.
But the center and left rail do not move linearly, just partial rotation.

I see there appears to be a steel pin thru each fork casting going into the rail shaft.
Does that pin have to be drilled out to pull the shaft out??


I suspect the detent springs and/or ball bearing hidden in the rails are rusted up or damaged resulting in them not allowing the rails to move.

 

[wore out]

Yes, to take it apart the pins will have to come out.

The parts catalog calls them "groovpins", they originally were made (by the design of the grooves) larger at one end, and were driven in from that end.

If you can drive them out from the opposite end they will come out easier.

On some transmissions I have inserted a long punch through the gearshift opening to drive one or more from the back side.

Once you get the middle rail out that will free up the interlocks, allowing the remaining two rails to be rotated more which POSSIBLY will allow better access to the remaining groovpins.

Speaking of the "interlocks", I assume you are aware of the interlock balls and pin that prevent movement of a second shift rail once one has been moved from the "neutral" position, these are the parts that MAY be causing your problem.

Are you SURE all three rails are in neutral when two of them can't be shifted?

As I touched on before, the action of the interlocks even prevents the rails which are in "neutral" when the third is shifted from having much of an "arc" through which they can be rotated.

If you DO take it apart the interlock balls and pin will have to be installed first and held with heavy grease while you insert the rails one at a time and deal with the individual detent springs and balls.

Perhaps some analysis of how this all works and penetrating oil and wiggling and TIME might loosen t up without having to take it apart?

 

[drew p]

you might have to throw a wrench across the shop to get it

 

[DoubleO7]

Thank you wore out, very helpful info! Had no idea of those lock out balls.
So I moved the right rail more to center and that allowed the other two to move with some help from a
hammer. Looking down thru shifter hole, the three (dogs?) are inline so that the shifter, when installed
can be moved from left dog to right dog with center dog inline. With all three dogs slots lined up, that
would be the neutral arrangement of the rails??.
But the three rails (in unison) might not be in right position forward and backward?
Time ran out to fiddle with it further. Been soaking it all in PB blaster for a week everytime I pass by.

I think the shift lever is okay as far as the dog end being worn. The slot might be worn a bit too much??

 

[DoubleO7]

Looking down thru the shifter hole I punched out the pin coming up into the right rail and actuating block.
That allowed the rail to be tapped out of the mother casting.
Then the same for the center rail.
The left rail pin has to be punched out from the bottom side.
The right rail has to come out first in order to rotate the middle rail enough to get it's pin punched out.
With the right side and middle rails out then the left rail can be rotated enough to punch it's pin out.

Started polishing the rails and dressing the edges of the detent ball scallops(?). will rifle brush the rail bores and hone them out to polish those.
Springs look good, most of the balls are black. I think I will order up new shiny ones. They mic at 0.373 to 0.3745 diameters.
I counted seven balls but diagram shows eight, I better count again, maybe one is hidding somewhere.

 

[wore out]

(quoted from post at 16:57:30 03/15/22) Looking down thru the shifter hole I punched out the pin coming up into the right rail and actuating block.
That allowed the rail to be tapped out of the mother casting.
Then the same for the center rail.
The left rail pin has to be punched out from the bottom side.
The right rail has to come out first in order to rotate the middle rail enough to get it's pin punched out.
With the right side and middle rails out then the left rail can be rotated enough to punch it's pin out.

Started polishing the rails and dressing the edges of the detent ball scallops(?). will rifle brush the rail bores and hone them out to polish those.
Springs look good, most of the balls are black. I think I will order up new shiny ones. They mic at 0.373 to 0.3745 diameters.
I counted seven balls but diagram shows eight, I better count again, maybe one is hidding somewhere.

Good for you for sticking with it and getting it apart!

Sounds like my generic advice on getting it apart was fairly correct!

 

[DoubleO7]

Yep! Your insite helped A LOT.
Replaced all the balls reused springs.
Polished the shafts and knocked down the sharp edges on the shafts where the detent balls roll in and out.
Had two shafts reinstalled and was putt one of the interlock balls in but it rolled into the detent spring
hole instead.
Uh-oh, had grease on it so it would stay in the interlock hole so now it want to stay in the detent spring
hole instead. I turned the assembly upright and used a propane torch to induce enough heat to melt the
grease in the spring hole. It dropped right out.
So before trying again I put the spring in first!
Got it all back together after that hickup.
Used motorcycle chain spray on sticky grease all up in and on the shafts.
Made a new gasket out of a cherrios box as the previous owner had only used blue silicone.
Put oil back in tranny.
Drove it till up to thermostat open plus some.

Thanks again!