[64-3Deuces]

Has anyone seen or used a master cylinder shim plate like the one shown?

This is listed as from a 64+ Chevelle but would fit other GM A-bodies. Never seen one on a car and don’t know if this is a GM part that was used to resolve a problem noted later. Based on the design of the brake pedal bracket I would guess this goes between the firewall and the master. Many years back Ames had these in their catalog advertised as used to reduce firewall flex at the master.

[remy30006]

My car has one. its a manual brake car.

[64-3Deuces]

remy,
As this is a Pontiac site I would guess your car is a Poncho; however, I have visited/posted on non-Pontiac forums. What year is your car? Any idea the reason for the plate? I tore my 64 GTO apart years ago (a manual brake car) but have all the parts and don't see the shim plate, and I don't see it referenced in the service manual.

[remy30006]

my car is a 64 GTO built in Pontiac 5th week of January. It did have the spacer/reinforcement plate on it behind the master when I took it apart.. Someone can correct me if I'm wrong but I think they came on non power brake cars to reinforce the firewall. Here is a link to one
http://www.ebay.com/itm/64-74-GM-A-F...lZdkAc&vxp=mtr

[Rich-Tripower]

Both my Chevelles have one or had one. On the 64-65 Chevelles they are used as a spacer when you have manual brakes and the fancy 2-speed wipers with washer, part of the Comfort and Convenience Group in my case. Without the spacer the master cylinder cap bumps into the washer nozzles. The spacer is used to push the master cylinder out just a bit for the needed extra clearance. The wiper/washer involved looks like this (first photo), not sure if Pontiacs used the same motor. Our GTO has a much different wiper motor, the square one with a washer pump. I don't recall if it used the spacer or not, I think it did, maybe for the same reason even with a different wiper motor (see second photo). You can see in the Chevelle photo the close clearance between the cap and the nozzles and this is with the spacer in place.





I don't think it would do much work as a firewall reinforcement as it is on the outside/engine side of the firewall. To be useful as a reinforcement, it would need to be on the inside.

Here is a wider shot of the Chevelle application.

[64-3Deuces]

Hey guys thanks for the info.

remy:

My car is a Pontiac plant build, third week of June, manual brake so I’m pretty sure it had the plate. If it did I must have misplaced it over the years. I also thought the plate was to add strength at the firewall but as Rich indicated below it was for clearance. But you confirmed what I needed to know.

Rich:

Good info and the pictures helpful-BTW nice rides My 64 GTO has manual brakes and the two speed wiper/washer which is basically set up like the one shown. This has been an on/off again project over the years and maybe I don’t remember the plate. I converted to a dual master but never got to the point of installing the wiper so not sure of any clearance issues. At least I know the reason for the plate.

[Rich-Tripower]

Originally Posted by 64-3Deuces

Hey guys thanks for the info.

remy:

My car is a Pontiac plant build, third week of June, manual brake so I’m pretty sure it had the plate. If it did I must have misplaced it over the years. I also thought the plate was to add strength at the firewall but as Rich indicated below it was for clearance. But you confirmed what I needed to know.

Rich:

Good info and the pictures helpful-BTW nice rides My 64 GTO has manual brakes and the two speed wiper/washer which is basically set up like the one shown. This has been an on/off again project over the years and maybe I don’t remember the plate. I converted to a dual master but never got to the point of installing the wiper so not sure of any clearance issues. At least I know the reason for the plate.

I might have a spare plate around here somewhere if you need one.

[remy30006]

That does make sense because my car has the 2 speed wiper/washer.

[64-3Deuces]

Rich,
If you happen to come across a spare shim plate let me know the details. Would be good to have one on hand if needed. Thanks, Mark......

[bill ryder]

That part does not appear in my Pontiac MPC's or the illustrated break down.. "Bill"!

[64-3Deuces]

Originally Posted by bill ryder

That part does not appear in my Pontiac MPC's or the illustrated break down.. "Bill"!

Bill,
I don't have the MPC but I don't see it either in the illustrated breakdown, that's why I asked. Have seen a few of these on E-Bay in the past with various reasons for their use. It looks like also available aftermarket. Wonder if this piece was a quick fix to cure clearance problems and never made it into the parts book.