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Discussion Starter #1
I am getting ready to install a new booster on my '70. I have included pics of the old and new booster.

The old one had a clevis type pin on it just inside the plastic boot. I can't tell if it is just in a groove on the rod or if there's two lenghts of rods coming out of the back of the booster making up the overall length.

The new one definately has one long rod sticking out of the back of the booster. The new one came with the clevis, pin and cotter pin for the brake pedal. It also came with an extra 4" long rod. This rod has a groove in it with what appears to be a rubber 0-ring sitting in the groove.

I think I can adjust the rod that came in the booster to match the length of the old one. My question is what is the short extra rod for and do I need it?

Thx, Chris.
 

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Discussion Starter #3
I’m feeling pretty stupid right now. The rod goes between the MC and booster? I pulled this car apart 10 years ago and have the old MC and booster but not the little rod. Thx
 

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1970 SS 396 25-C, 1966 SS R-R
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I believe a 70SS with an original BB master cylinder uses the short rod. If you look at the end of the master cylinder one that has a shallow recess in the piston takes the short rod. The piston that has a much deeper recess uses the long rod.
 

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Discussion Starter #7
My MC has the shallow recess. Does that mean that I use the rod that came on the new booster shown in the pic above? With different MC's requiring different length rods I need some help understanding the rod going thru the booster. How does the rod sticking out of the front of the booster attach to the rod sticking out of the back of the booster that goes to the pedal?

Another question I have is how the plastic lip on the back of the booster fits against the firewall. My original booster plastic lip was in line with the mounting flanges. The new one sticks off the flanges and as you can see in the pics it makes contact with the firewall before the booster flanges do. This doesn't look right. Is something wrong?

Thx.
 

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Discussion Starter #8
Anybody have any advice? Thx
 

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If you dont like it can you use your old one?
Otherwise the plastic one should give I would think.
I cracked an old plastic one but it was a bit brittle being so old.
 

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Discussion Starter #10
The old one wouldn't hold a vacuum when I tested it.
 

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Discussion Starter #12
I don't think it does. I just know the plastic piece is contacting the firewall before the mounting flanges are. I will have to compress the plastic piece by tightening the 4 bolts. I don't know that the plastic piece is designed to be compressed.

I don't want to ruin the new booster if something is wrong. As you can see in my earlier pics the original booster's plastic piece was in line with the mounting flanges.

Thx for any help.
 
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