Hydroboost conversion

[Gussie]

Hello; I am converting my 86 k20 to hydroboost using parts from a 85 k30. My question is if I can still use my k20 stock master cylinder? If not is there a suggested part number which will work with my stock line size and fitting thread? Thank you all

 

[SquareRoot]

I did the same thing. Keep the 86 master will work fine. More importantly is to keep the OEM master cylinder matched to its original brake size.

 

[Gussie]

Thanks SquareRoot. Did u notice a better pedal when braking after conversion?

 

[SquareRoot]

Yes, it is noticeably better than the vacuum I had before.

 

[Bennyt]

Just a reminder...you may have to drill out the brake pedal arm to get the correct stroke for hydroboost.

 

[SquareRoot]

Mine was exactly the same. I have several pedal assembly versions from the 85-87 model years. The only difference between them is 2 versus 4 studs in the mounting bracket to the firewall. And that's only between manual vs automatic transmission. I can't say if that's the case for the earlier years.

 

[Bennyt]

Mine was exactly the same. I have several pedal assembly versions from the 85-87 model years. The only difference between them is 2 versus 4 studs in the mounting bracket to the firewall. And that's only between manual vs automatic transmission. I can't say if that's the case for the earlier years.

You may be correct that it's just the early ones. We had to drill the correct hole on my son's '77. I've done 2-3 conversions and I had to drill every one but none of those were models that ever came with hydroboost as an option/ configuration.

 

[Gussie]

I bought the brake pedal assembly that went with the hydroboost so I hope it all goes in like it was meant to be.

 

[Gussie]

Ran into a snag with install...my original brake pedal brake light bracket doesn't transfer to the hydroboost pedal. I've searched around and no luck yet. Any sources besides folks parting out? The pic is what I'm needing. Everything else went in perfect

 

[Ricko1966]

You may be correct that it's just the early ones. We had to drill the correct hole on my son's '77. I've done 2-3 conversions and I had to drill every one but none of those were models that ever came with hydroboost as an option/ configuration.

We're they power brake vehicles to begin with. Manual brake and power brake usually have a different pushrod pivot location to gain mechanical leverage

 

[Gussie]

Hello, original was power brakes. I have the matching brake pedal assembly and pushrod that came on the hydroboost until. Just didn't get the brake switch bumper bracket. That piece seems to be elusive for purchase