# 66 GTO Brake booster/master cylinder



## El Monte Slim (Sep 8, 2014)

I have a friend (not on this forum) that has a nice very original driver. He wants to upgrade to a dual master cylinder and keep things looking as original as possible.

Here are the questions.

1. Will a stock 1967 dual master cylinder fit on and work with a stock 1966 power brake booster?

2. If not, and you use a 1967 dual master cylinder and power booster, will that work and fit?

Thanks for your replies.


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## El Monte Slim (Sep 8, 2014)

*The sounds of silence...*

No one has done this???


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## PontiacJim (Dec 29, 2012)

I would hit *Pinion head* with a PM. He would probably know if the power boosters were the same. The parts catalogs seem to show a different part number for the '66 vs '67 power booster, so my guess is that putting a '67 MC on the '66 power booster may not work. It seems the '64-'66 are the same and '67 and up are the same.

So I would think that the other option would be installing the '67 power booster/MC combo if there were no problems with the brake pedal geometry. It may be that your friend would also need to swap out his '66 brake pedal for a '67 brake pedal to match the dual MC combo if there are any differences.


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## cij911 (Oct 25, 2017)

I am actually looking at similar options and am leaning towards a hydra boost (vs vacuum) setup.


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## 64GTOConvertible (Aug 28, 2016)

I didn't answer because I don't know.

That said, my guess is it will work either way.


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## PontiacJim (Dec 29, 2012)

Found a diagram of both the '66 and '67 power booster and they are indeed different. The same book states that the '66 vs '67 brake pedal is also different.

So, my best guess would be that in order to do the swap, short of purchasing an aftermarket set-up, is that you would need to treat the swap as a 1967 dual master cylinder/power booster set-up, complete with the correct lines/distribution block and brake pedal.

Again, never did this, no expert on this, and the information is what I found in going through my Pontiac resources. :thumbsup:


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