On the '83, and '84 Camaros that came with 4 wheel disc brake-what size is the master cylinder bore?

I have heard that it is 15/16" but wanted to be sure before I ran out and got one.

Also, did GM go to metric fittings in '84? If so, did the '83 still have standard? I have heard that these M/C's both have the lines exiting on the correct (fender) side, that they are aluminum, and have plastic reservoirs that sit at an angle. Everything I need!

I want to go with this M/C because this is the second to last piece that I need in order to get my Big Brakes in place. The last piece being the caliper brackets which I will make myself.

Can anyone shed some light on this? If I go to the parts counter, I doubt they will know the bore size. Can I take an ID caliper and somehow measure it without taking it apart?


Thanks to all who make this site wonderful!

The aluminum master cyls will not fit your 69 booster, they have a third piston on the rear that is larger than the listed bore size. This is for the quick take up feature.

My book says the 82 and 83 master cyls had us threads but the ports are on the engine side.
Both 1" bore and 24mm bore are listed for the same year, don't know why there are two, the book doesnt explain.

84 up master cyls show the same two sizes, same engine side outlets, but are metric ports.

83-87 ElCamino, 83-95 S10 half ton pickup have drivers side us ports in 24mm bore, angled reservoir on Power brake versions.

84-87 Fiero, 85-95 chev truck "G" series have drivers side us ports 1" bore, angled reservoir on power brake versions.

You will need a later style booster to accept these master cyls due to the large rear piston.
David

Thanks David for the info.. Let me move forward.

If I understand you right, there is a "ring" on the back of the aluminum M/C's that is larger than the ring on the back of my current M/C that fits into the face of the booster. This ring is what would prevent me from using the newer style mc right now-UNLESS I turn the ring down to the same OD as my current MC. I can do that.

Moving on, of the vehicles you listed that have US standard threads, and the lines/ports exit on the fender side of the mc, none of them came with 4 wheel disc brake. I have 4 wheel disc brake right now with the standard single piston floating calipers in the front, and '79 Deville rear disc calipers in the rear (but will soon have the PBR twin calipers up front). Will any of these:

"83-87 ElCamino, 83-95 S10 half ton pickup have drivers side us ports in 24mm bore, angled reservoir on Power brake versions."

work in my configuration? And if so, when I go to the parts counter, which vehicle should I tell them, and which do I specify-manual or power application? My current booster/MC combo uses the shallow MC hole.

I have heard/read, on your site I believe, that the POWER application for the S10 is in fact a 1" bore and is NOT desirable in any of our applications. How do I specify the 15/16" / 24MM bore?

I don't mind machining the MC ring to work with my booster, and I don't mind buying and bending new brake lines should I have to. I guess what I am asking is, which is the easiest one to use at this point that will work with my Seville rear/ single piston (stock) fronts, and eventually the PBR front/Seville rear combo?

I believe Torker said he turned his 24mm Master cyl down to fit his hydroboost. I don't know for sure if it can be turned down enough to fit a stock first gen booster. I can take a couple of measurements off mine and see.

Someone stated the power brake S-10's had 1" bores, but my Wagner parts book is showing 24mm with photo of angled reservoir for an S-10 half ton pickup.
The Wagner part number is 107050 which is the actual part in the photo I have. It is the El-Camino version.
107747 is the S-10 version.

All the other numbers are listed under the same illistration photo but you never know if something is different...
By the way, all Wagner replacement master cyls are IRON, not aluminum like the origonals. If you get a Delco rebuilt or other they most likely will be aluminum.

I'll check the 24mm S-10 manual brake master rear OD and compare it to a booster and stock iron Master cyl I have here and post back the info.

I think the PBR caliper bores are a lot smaller than the single piston calipers so they require a 15/16 bore master cyl. Baer supplied a 15/16" bore master for my wife's 73RS 13" Track brake system.
David

David,
Thanks for the fast response! I figured out from reading posts on this, and the sister Chevelle site, that the 15/16" bore was the way to go when using the PBR calipers.

So if I go to the parts store and ask for an '83 El Camino M/C, I should end up with an aluminum M/C, with fender side ports/line exits that are US standard thread, with a 24MM (15/16") bore, that has the angled plastic reservoir? I assume there was no MANUAL application for this vehicle so no point in specifying MANUAL or POWER. Then, I can turn down the rear ring OD and I should be in business????????

That is the million dollar question! Well, that and if the rear ring can be turned down far enough to work with my existing booster.. I am waiting to hear back from you my friend. I guess I could always go to the parts store and ask to see an original MC for my car, and an '83 El Camino MC and then measure them with my calipers to see if it will work..

Thanks for the updates so far! Keep the info coming.

I did some quick measurements:
stock cast iron mc OD: 1.475"
24mm S-10 MANUAL master cyl OD: 1.766"
24mm S-10 ID: 1.435"
I measured a firstgen booster and it looks like you need to turn down the master cyl to 1.635" maybe a little more than that.

You would have .200 thou total, .100 of metal remaining on each side of the bore, that is enough but you need to be careful of the snap ring groove on the rear. I didn't measure it, but it's maybe .025" to .050" deep?
I think it will work. I'd order the ElCamino master cyl and check it out. The ports are 1/2"X20 and 9/16"X18.
You can verify it is a 24mm bore by the rear piston od of 1.435" I'm pretty sure the 1" is larger and I have a 1 1/8" version that has a huge rear piston...

Hope this helps, let me know how it turns out.
David

Go69,

Take you M/C to a local friendly Parts Place along with a small tape measure and politely tell the Parts Person what you are doing and ask if they will let you look at what they have in stock.

I bet they will be glad to if you catch them in the middle of a slow time!!

That's how I measured rotor diameter's and their thicknesses and hat's as well as M/C piston bores and line fittings and finally caliper jaw pad widths and hose clockings...

pdq67

PS., a very nice knowledgeable, (a nice looking, NOT P/C now), young Lady P/P helped me out the first time I did this...

Here's the deal:

The disk/disk mc for the 80's camaros uses a 1" bore. The disk/drum mc for the 80's camaros uses a 15/16" (24mm) bore. The 1LE camaro (1989) utilized the 15/16" disk/drum mc because of the smaller volumed pbr calipers. I agree with David - 1984 camaro mc's and up use metric fittings.

When going to the parts store do as David suggests and make sure to measure the rear piston diameter. Since this is a quick take up mc the rear piston will be larger. On a 15/16" mc the rear piston will measure approx. 1.250". If you want a 15/16" aluminum mc with US style fender side ports, a shallow push rod hole, and you have a Pep Boys or other auto parts store that carries the Pro-Stop Brand, order Pro-Stop part number 20-1905. This part however does not come with a plastic reservoir. For that go to your local junk yard and pull one out of a camaro or other GM car that has the slanted reservoir. Here in the Los Angeles area junk yards these are a dime a dozen so they probably are as well were you live. While at the auto parts store go to the "help" isle and buy a new lid for the reservoir - it also comes with a new rubber gasket.

If you plan on putting this mc in an early model booster you will have to machine about 1/8" off the rear o.d. of the mc to get it to fit. You can check out the pictures of this on my website.

Or if you don't mind engine side mounts I have a new aluminum Cardone brand camaro 15/16" mc complete with the correct plastic reservoir with new gaskets and the necessary metric fittings sitting on my bench. All you will have to do is run new line using the included metric fittings. It is all new and will sell it all for $10 plus shipping. If interested email me.

By the way if you are going to switch to front pbrs and leave the Seville calipers in the back, your brake pedal may have a longer travel to make up for the volume required to fill the rear calipers – remember GM used a 1” bore mc with a larger rear piston for those calipers. You'll just have to try it – maybe it will work. Good Luck.

John

Torker,
Thanks for the info. My book has no info on if the master cyl is power brake or four wheel disc, it's not a big help! It's also listed by master cyl part number not application. It's actually a "buyers guide" not a real catalog. I also have an illustration book to view photos of the parts.

Most Delco rebuilt and Wagner new master cyls come with the reservoirs. The Wagner are new but are cast iron, not aluminum. I have a Delco rebuilt that is aluminum, but it is the S-10 manual (I guess) version with level reservoir.
David

Torker,
Thanks for the offer on the M/C. I think I will settle on using the '83 El Camino M/C as it will require the least amount of re-work. The only thing I will need to do for it to be a bolt in is to turn down the OD of the ring on the back.

According to the information provided above, the El Cam. M/C should have standard fittings that exit on the fender side, and have the 24 MM bore with plastic reservoir.

In regards to the Seville rear calipers-my plan is to eventually go to the 93-97 F-body rear calipers. Those calipers have a smaller piston in them than my current calipers and should correct any pedal travel issues. I am going to try it with the current calipers first and see what type of pedal travel I get.

I will keep you guys posted on my progress.

Torker,
Does the fourth gen rear caliper have enough bore size to lock a rear wheel?
I have heard it's so small it may not give full rear braking.
David

David,

Yes, I can lock up the rear brakes without a problem. In fact, I have to run an adjustable prop. valve to balance them with the front. They work very well when matched with the correct 15/16" quick take-up mc, assuming of course one were to have enough engine vacuum or a hydroboost. I have been very happy with the way that the rear brakes perform.

The rear pbr calipers used on the 93-97 z28 camaro, the 1989 1LE camaro, the C4 corvette, and in the Baer rear track kits are all identical. The corvette just used a different bracket and e-brake mount than the camaro, Baer uses the stock camaro caliper and ebrake but then just makes their own bracket.


John

Torker,
Thanks for the info. graemlins/thumbsup.gif