Master cylinder for Blazer brake upgrade with C5 fronts and stock drum rears

8

81cutlass

Royal Smart Person
Feb 16, 2009
1,186
1,022
113
Western MN
#22
From doing some more reading, and looking at pictures on Rock Auto, it appears that later models might have an option for a larger bore booster to accept the mater cylinder I bought. We have the double diaphragm booster that appears to be the stock '80 Cutlass 'HD' unit. But it does not interchange, according to Rock Auto with much of anything newer than an '81.

81cutlass, what year is your car that you put the larger m/c onto?

Does anyone else have a booster laying around that could be measured?

Lastly, we were thinking of swapping to the single diaphragm booster for appearance only. Is the stopping power, required foot/leg pressure varied from the double diaphragm?
I put it on an 86 grand Prix v8 car. I got the mc from a salave yard off a 89 Caprice I thought. I looked back at car-part.com and they don't note any difference in big vs. Small mc on b bodies. Rock-auto does seem to have 2 different fitment sizes. Maybe I got a small b body one? Regardless it still helped
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
728
425
63
Upstate NY
#23
I've had both & never noticed a difference.
That's what I'm looking for - thank you.

Also, I drove the car yesterday in an attempt to tune the traction control with the local dyno operator running the laptop, implying there's about 5000 miles less rear tire today than yesterday. And the stock master works fabulously other than the pedal is a little deep. It really has me rethinking the entire swap because the car stops so well. I'm going to check out a newer booster locally and see of it will accept the larger master.
 
TURNA

TURNA

Comic Book Super Hero
Jul 24, 2009
4,475
2,589
113
Socialist NY
#25
Disk/drum
 
1

1KWIKSIX

Apprentice
Jun 26, 2017
57
71
18
#26
That's what I'm looking for - thank you.

Also, I drove the car yesterday in an attempt to tune the traction control with the local dyno operator running the laptop, implying there's about 5000 miles less rear tire today than yesterday. And the stock master works fabulously other than the pedal is a little deep. It really has me rethinking the entire swap because the car stops so well. I'm going to check out a newer booster locally and see of it will accept the larger master.

Suggest installing 2# residual pressure valve(s) in front brake line(s) & 10# in rear line = much more immediate braking response (less pedal travel to engage the brakes)

residual-pressure-valves-jpg.95556
 
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1

1KWIKSIX

Apprentice
Jun 26, 2017
57
71
18
#27
I"ve got a gently used B Body dual diaphragm brake booster , just taken off car. This is a larger diameter than the G body unit and should offer better braking. $50 + shipping
 

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