BRAKE BOOSTER CHOICE HELP/REVIEW

[ELCAM]

To measure the piston you would need to remove the C clip and remove the piston from the housing.

The El Camino piston is 24mm or 15/16". 83 up have the quick take up valve, 78-82 do not.

 

[spidereyes455]

I did the blazer brake upgrade on my 81 grand prix (front and rear) a bunch of years ago. What you ultimately use is up to you but a can tell you what I used for my swap.
Blazer discs front and rear
Proportioning valve from an 84 el Dorado, since they had 4 wheel disc and are similar in size and weight to a g body.
And a master cylinder for a 1981 trans am with 4 wheel disc brakes since it is aluminum andl ooks very similar to a stock g body master. The brakes work great like that and the only mild complaint I could make is the the power assist is slightly lacking with the original power booster , probably because of the large master bore and 4 wheel disc. The only thing I would bother to change if I was still driving the car would be to upgrade to the b body (caprice) power booster to regain some of the power assist feeling in the pedal.

 

[toyinhawaii]

To measure the piston you would need to remove the C clip and remove the piston from the housing.
View attachment 240362
The El Camino piston is 24mm or 15/16". 83 up have the quick take up valve, 78-82 do not.

Thank you for making it clearer, is the bore size(say for the elkys 15/16") taken on the Primary piston (#6) or the secondary( #10). Sorry if this is a stupid question.

 

[toyinhawaii]

I did the blazer brake upgrade on my 81 grand prix (front and rear) a bunch of years ago. What you ultimately use is up to you but a can tell you what I used for my swap.
Blazer discs front and rear
Proportioning valve from an 84 el Dorado, since they had 4 wheel disc and are similar in size and weight to a g body.
And a master cylinder for a 1981 trans am with 4 wheel disc brakes since it is aluminum andl ooks very similar to a stock g body master. The brakes work great like that and the only mild complaint I could make is the the power assist is slightly lacking with the original power booster , probably because of the large master bore and 4 wheel disc. The only thing I would bother to change if I was still driving the car would be to upgrade to the b body (caprice) power booster to regain some of the power assist feeling in the pedal.

i did some searching on Rockauto and Amazon, i do want the best option and quality so it does look like the Caprice one is it.
Saw a few Cardones, 5471040 (reman).5C471040 (new) and a Quality Built B1062... seems like the new Cardone 5C471040 is the same as the Q.B. one. Amazon @ $132 (free shipping vs RA shipping $48(total $167)

As far as the Master Cylinder as i said earlier i have the Blazer disc front/elky drum rear but have the Blazer rear disc ready to go on at a later time

ACDELCO 18M172 (FITS THE 81 TRANS AND 90 CAPRICE) DISC/DRUM / 1.125 BORE
QUALITY BUILT NM1870 (FOR BOTH) DISC/DRUM / 1.575 BORE
QUALITY BUILT NM1873 (81 TRANS ONLY) DISC/DISC / 1.575 BORE

So the new Cardone 5C471040 booster and the M.C. QUALITY BUILT NM1873 (81 TRANS ONLY) DISC/DISC / 1.575 BORE would be the best match? Since i still have the drums on the rear still(for now) is the NM1873 still ok to use? Thanks so much for all the help and knowledge

 

[Sweet_Johnny]

i did some searching on Rockauto and Amazon, i do want the best option and quality so it does look like the Caprice one is it.
Saw a few Cardones, 5471040 (reman).5C471040 (new) and a Quality Built B1062... seems like the new Cardone 5C471040 is the same as the Q.B. one. Amazon @ $132 (free shipping vs RA shipping $48(total $167)

As far as the Master Cylinder as i said earlier i have the Blazer disc front/elky drum rear but have the Blazer rear disc ready to go on at a later time

ACDELCO 18M172 (FITS THE 81 TRANS AND 90 CAPRICE) DISC/DRUM / 1.125 BORE
QUALITY BUILT NM1870 (FOR BOTH) DISC/DRUM / 1.575 BORE
QUALITY BUILT NM1873 (81 TRANS ONLY) DISC/DISC / 1.575 BORE

So the new Cardone 5C471040 booster and the M.C. QUALITY BUILT NM1873 (81 TRANS ONLY) DISC/DISC / 1.575 BORE would be the best match? Since i still have the drums on the rear still(for now) is the NM1873 still ok to use? Thanks so much for all the help and knowledge

As I said I'm still learning, so please take everything I type with a grain of salt, but a dual bore master sounded like a bad idea based on what I read. As I understood it the dual bore was for the Low Drag calipers to first come out of seclusion, with the bigger bore being the one that matters. I also noticed what I hope is a typo in an earlier comment stating you were interested in pre '82 boosters- while they were paired with the non Low Drag calipers the pin for the master cylinder is the incorrect size, though some seem to have had no problems. I'm unsure if a larger booster will make an '81 4 disc master cylinder work perfectly, as I think the issue would stem from the bore being 2 sizes for absolutely no reason at all. I believe at least one link provided stated that the Caprice booster wasn't really an upgrade from the Blazer unit but would work well, and multiple agreed that the dual 9" G booster was sufficient.

I really don't know anything for certain but would really like to learn as much as possible on the subject. It appears to be one that gets very complicated very quickly if you allow it to, with varying opinions from people who are decidedly smarter than I am.

 

[ELCAM]

One thing at a time.

The stock G body brake booster is 8.75 to 9" in diameter the 5C471040 is 10.4" in diameter. Will the bigger booster interfere with the valve cover or something else?

 

[spidereyes455]

I wouldn't use the disc disc master until you put rear disc on the car. For disc drum I'd probably just use a larger disc drum unit like the caprice one. Though many people have reported good results with the stock g master when upgrading to blazer front discs. Your mileage may vary.

 

[toyinhawaii]

As I said I'm still learning, so please take everything I type with a grain of salt, but a dual bore master sounded like a bad idea based on what I read. As I understood it the dual bore was for the Low Drag calipers to first come out of seclusion, with the bigger bore being the one that matters. I also noticed what I hope is a typo in an earlier comment stating you were interested in pre '82 boosters- while they were paired with the non Low Drag calipers the pin for the master cylinder is the incorrect size, though some seem to have had no problems. I'm unsure if a larger booster will make an '81 4 disc master cylinder work perfectly, as I think the issue would stem from the bore being 2 sizes for absolutely no reason at all. I believe at least one link provided stated that the Caprice booster wasn't really an upgrade from the Blazer unit but would work well, and multiple agreed that the dual 9" G booster was sufficient.

I really don't know anything for certain but would really like to learn as much as possible on the subject. It appears to be one that gets very complicated very quickly if you allow it to, with varying opinions from people who are decidedly smarter than I am.

No worries, blogs like these help a lot of people out with their projects, Mods, upgrades ,etc and are part of the fun/experience. We all take and absorb all the info in to get everyone's experience before hopefully pulling the trigger on stuff. i came over here from Elcaminocentral as from time to time some of us do and i wouldnt be surprised if some Gbody members go over there. Even though i am mechanically inclined and rebuilt the elky along with my 73' Corona, i couldnt have done a lot without help from blog members of different sites. Heck, my real job is in subs... no, not the kind u eat 😆

 

[toyinhawaii]

One thing at a time.

The stock G body brake booster is 8.75 to 9" in diameter the 5C471040 is 10.4" in diameter. Will the bigger booster interfere with the valve cover or something else?

Back on Elcaminocentral i found a thread that involved the install of the Caprices' booster...seemed to work fine! just following up with conformation over there though

 

[toyinhawaii]

I wouldn't use the disc disc master until you put rear disc on the car. For disc drum I'd probably just use a larger disc drum unit like the caprice one. Though many people have reported good results with the stock g master when upgrading to blazer front discs. Your mileage may vary.

yea, that does make sense, use a M.C. built to what you have because of the application of the brakes used.... disc/disc, disc/ drum. i'm also sure that my summit proportioning valve that i got for the elky is correct... which would be disc/drum