Need a quick answer, please. . .servo?

[JR1964]

'84 GN 'BQ' transmission

I've got the thing apart right now. My question is with the intermediate servo INNER and OUTER pistons.

If you change the intermediate servo to an 86/87 GN servo, as many do, is the 'INNER piston'
changed as well as the outer piston and cover?

The original INNER piston is too small to seal the inside of the GN OUTER piston, like 1/16" all around.
This doesn't seem right to me since the INNER piston seal would serve no purpose.

Should I have been given the cover, outer piston AND inner piston, or has
the inside of the outer piston (inner sealing surface) been enlarged/machined
larger for some reason?

PLEASE HELP!


________________________________________

Jim

 

[petesgn]

Yep the cover and the piston should be changed together

 

[JR1964]

I understand the cover and the 'outer piston' (the one with two seals large/small), but what
about the 'INNER' piston, looks like a disc with a seal on the outer edge that goes inside the 'outer piston'
and pushes against the large spring?

Sorry I can't post a picture. . .

I could email you a pic though

________________________________

Jim

 

[petesgn]

#21

 

[petesgn]

I think its used to cushion 1-2 on downshift .
It should fit a little snug , maybe a new teflon seal would help.

 

[JR1964]

Yes, #21.

#21 fits inside #19 and you'd expect it be just snug to allow the oil seal to seal.

On mine, #21 (original part) measures 2.136" OD,

The GN #19 measures 2.282" ID. That's about .150" clearance!

My original servo #19 measures 2.144" ID which would give about .008" or so for the seal of #21.

So my question, when changing to the GN servo, do you replace #16, #19 AND #21,
or has the inside of #19 been modified on the servo I received?


_______________________________________

Jim

 

[JR1964]

Got it handled,

Thanks!

__________________________________

Jim