MCR 85 928

What are you guys using for the brake booster gasket?
AutoZone has a make your own gasket made out of cork. Which looks useable.
I didn't see anything on 928sRus.
It's the gasket that goes over the 4 bolts and the body.
Thanks

icsamerica

I've never seen cork used in that application. I would recommend the heavier gray paper gasket like the Cometic paper also availabe at AZ.

The Forgotten On

People have used manila folders with great success shockingly.

I would personally source some paper gasket material to use. I'm sure someone has made them somewhere out there.

Petza914

I used my wife's craft silhouette machine to cut one out of adhesive silicone gasket material. Took a new original, scanned it in, and cut the silicone one. Did the same thing for my water bridge gaskets. Don't think I took any photos of the booster one, but here's the water bridge one. Due to a welding that had been done on the motor I was installing one side has a little defect.so I needed thicker gaskets what would better conform to the shape. Scanned them in normal and reversed and stick the two adhesive sides together to make a thicker gasket.

Mrmerlin

For the booster gasket a manila folder works great,
as thats just about what was in the their from the start.

Pete if you have a mismatch on the WB legs to head .
Then I suggest you do a fit check without any O ring or gaskets,

use a flash light and feeler gauge to see how close the mating surfaces are ,
If you find the legs dont sit flush then use some grit paper on a flat surface and work the face of each leg till you get them flush.
then you should be good with the factory gaskets.


.
NOTE the reason the legs are not flush is due to the head surface being cut, this puts the legs out of mating.

NOTE in the picture on my 84 Ruby, the water bridge was damaged at the flange groove and was leaking,
I filled it in with JB weld so i could use gaskets instead of the silicone seals

Petza914

Thanks Stan, but this one is all wrapped up. It's the engine in the Spyder back when I was replacing it before the Atlanta Rendezvous - no leaks since then.

I did do as you suggest and here are the before & after pictures with the light so you can see how large the original gap was and how close I got it with a glass sanding block and sandpaper before putting things back together.


This weld near the passageway was the cause of the deformation



This is the gap that was causing the leak



After glass block sanding to get the surfaces more flush



Held vacuum with the AirLift tool prior to refilling and hasn't leaked since

Mrmerlin

Perfect Pete !

GregBBRD

The required seal thickness varies a bit, from year to year.
9" boosters needed 4mm of gasket.
10" boosters needed 2mm of gasket
From 1985 onward, the correct gasket is 1mm think.
....All of those are thicker than a "manila folder"...

Mrmerlin

Based on what I pried off the firewall it pretty much matches the thickness of a manila folder.
Atleast the crushed part,
I used glue to hold it in place
I replaced boosters in a 80 , 82, 84, 87, 88,
That said if you can get the factory gasket,
get it.
Thanks for the info Greg

GregBBRD

I'm only repeating what the factory did and calls for.
Doesn't make much sense why different booster would need thicker/thinner gaskets.
I haven't been able to buy a factory gasket, for years.
I've been making them out of 1mm gasket material, for about the same amount of time.

MCR 85 928

What Greg said.
Why would it matter which thickness you use?
The gasket is going between the firewall and the booster. It's not holding any fluid or anything else as far as I can tell.
I always defer to @GregBBRD . What ever he says to do... I do.

GregBBRD

I'm sorry.

MCR 85 928

My 1 year of experience vs a semi retired expert.

GregBBRD

"Semi retired" simply means that I'm not at the shop every single Saturday and Sunday....

No other changes.

MCR 85 928

You have to make time to take the dog to the park.