Master cylinder for Blazer brake upgrade with C5 fronts and (stock drum rears) 12/18-upgrade to rear disc

64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
824
904
93
Upstate NY
#1
Completed the front upgrade over this past winter and have been running it with the stock master cylinder and proportioning valve. The car will actually stop now from high speeds, in a straight line at least, but the pedal is deep as expected with the larger volume calipers on the fronts. I do not want to nor intend to change the rears to discs due to we run a 275/60R15 drag radial when the car goes to the dragstrip. So I'm looking for a replacement master cylinder that will bolt onto the stock booster that will work and feel correct in terms of pedal travel.

I'm probably going to be installing a line lock at the same time I upgrade the master cylinder despite my sour opinion of line locks - lol :) To elaborate, I hate seeing burnouts with line locks as a VW Bug will do a burnout if using a line lock. But being able to control the line lock and launch control function with the same switch should help my 60' times (at least I think :/ )

What have you guys found for a aster cylinder that works like I would like it to with what I have?

As always, thanks in advance :)
 
UNGN

UNGN

Comic Book Super Hero
Sep 6, 2016
2,595
1,971
113
Southlake, TX
#2
I'm not a brake expert, but the B-Body wagons (like an '89 Electra) had 12" front disks. and I think the 12" single piston (3" diameter) actually has more volume than the dual piston C5/LS1 calipers (1.75" diameter).

Electra Master cylinders are like $25 on Rockauto, so It might be worth a shot.
 
8

81cutlass

Royal Smart Person
Feb 16, 2009
1,455
1,799
113
Western MN
#3
Yep, Caprice B body works great. I have that on my blazer rear disk LS1 front setup. Firm pedal, low travel.

RAYBESTOS MC39328 is $28 on rock auto.

Bolts right on and looks stock. People claim you have to swap the lines front to rear but I hooked it up the same as the stock one that came off and it was fine.

Other options I have seen is a 98-02 s10 right hand drive.

Same goes for 96 impala SS, they had a big master cylinder but issue with the lines being bubble flare so you have to reflare.
 
Last edited:
TURNA

TURNA

Geezer
Jul 24, 2009
6,326
8,011
113
Socialist NY
#4
ACDelco 18M974 direct bolt in

kjhg-jpg.92958
 
vanrah

vanrah

G-Body Guru
Apr 16, 2013
717
736
93
Near Afton, Wisconsin
#5
Greetings NailHead & all; When I switched to the WilWood GM III calipers & went threw the entire system I wanted to replace the master cylinder. Well the 9C1 master is not the same as other G cars. Even though the calipers are! So after a few returns & mine not available from GM we discovered that I have an Eldorado, Rivera- Tornado master cylinder from 1980. No new ones available from GM so I went to Bumper to Bumper & got a rebuilt. Well it was ugly & mine looked new yet. So I dissembled both & to my amazement mine was in like new condition after 24 years (2003). So lesson #79 use 5 dot silicone fluid. I had put 5 dot in back in 1980 when I took off the Full metallic (9C1) brakes & had changed once around 1991? The only less than perfect parts were the rear wheel cylinders. The rubbers were soft & playable, the bore was perfect in my old cylinder. I put it back on the car with fresh 5 dot. And the new rebuilt unit is in the box as spare parts. The only down side of 5 dot that I've encountered is the pedal is maybe (?) not as hard as the new 3-4 dot synthetic? But I can lock down all four. If your have trouble finding the cylinder that Mr Turna is recommending, & I'll bet that it is the exact same one (?) I sell ya my Bumper to Bumper spare. Good luck, Ole' Bob.
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
824
904
93
Upstate NY
#6
Yep, Caprice B body works great. I have that on my blazer rear disk LS1 front setup. Firm pedal, low travel.

RAYBESTOS MC39328 is $28 on rock auto.

Bolts right on and looks stock. People claim you have to swap the lines front to rear but I hooked it up the same as the stock one that came off and it was fine.

Other options I have seen is a 98-02 s10 right hand drive. Problem there is its metric bubble flare so you need to reflare lines or use adaptor fittings, and it's not that much bigger.
Same goes for 96 impala SS, they had a big master cylinder but again issue with the lines being bubble flare.
I don't have rear discs.


ACDelco 18M974 direct bolt in

View attachment 92958
Have you used this Turna? I've seen this M/C referenced before here, but couldn't find anyone with 1st hand experience. If it will work, then I'm fine with changing to bubble flares.
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
824
904
93
Upstate NY
#7
Did some more reading on this. It appears this M/C uses double flare. Either way it seems it should bolt on and work. Are the port locations the same orientation?
 
TURNA

TURNA

Geezer
Jul 24, 2009
6,326
8,011
113
Socialist NY
#8
TURNA

TURNA

Geezer
Jul 24, 2009
6,326
8,011
113
Socialist NY
#9
img_0637-jpg.92976


Pic
 
UNGN

UNGN

Comic Book Super Hero
Sep 6, 2016
2,595
1,971
113
Southlake, TX
#10
I don't have rear discs.
B-body wagons didn't have rear disks either. S10 Blazers do. Turna's was originally for rear disc and "right hand Drive" Blazers (post office?). Its main advantage is the screw on cap.
 

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