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Aluminum/Plastic reservoir Master Cylinder correct replacement save 7lbs
My master cylinder went out and I have been doing hours of research into alternatives to the extremely outdated and overweight cast iron master cylinder. I ran across several threads, some people went with c5 masters, someone named Bee Jay with a really nice yellow vette installed an aluminum master cylinder with plastic reservoir on his that I was considering installing on mine. I have decided to go with a wilwood but wanted to share the info I found in case its of any use to someone else.
In the thread a master cylinder part number m2903 from napa was recommended, application 2000 c2500 3/4 ton. On napas website it lists that it has a 1.125 bore like the original c3 has, but that is not the complete picture. The 2000 c2500 master has a dual piston set up where the front part of the piston is 1.125 and the rear part of the piston is 40mm. Im not a brake engineer but I think this could cause some unpredictable changes in braking characteristics. You can just drive it and find out but I would rather error on the side of caution and see if theres a better master cylinder that matches the original specs. Also the reservoir will hit the hood, I purchased a m2903 to take measurements and it will definitely hit the hood. There are a couple other reservoir styles, the slanted reservoir and one that is similar to the m2903 but about a 1/2" shorter and should fit.
The C5 master cylinder seems like a lot of work for me, specifically the change from standard inverted flare to metric bubble flares. Im sure someone might have the part number to some perfect adapter but then you are still left with a master cylinder that has different specs than stock. I believe it is a 1" bore instead of the 1.125" on the c3. If there is a master with the right specs than why not just go with that
So i ended up at a napa across town looking at an outdated catalogue from 2007 that was luckily not thrown out. The catalogue was great, it had the specs of the bore and the outlet thread pitch so I could see if there was one with the perfect specs. I looked through all of the master cylinders, at least a few hundred of them, and a few pages from the end I found one that had the right bore, line sizes and the reservoir looked like the shorter one (I bought a master for a 1990ish? blazer that had the shorter reservoir that I measured and looks like it will clear the hood). So I found the trifecta, bore, outlet thread and reservoir. Only problem was the part number was outdated and napa no longer had it in their system. Luckily I found a random list on rockauto of dorman part numbers for master cylinders and it turns out they had a part with the same number as the outdated napa catalogue. Finally I was able to find the application and it was a 1996-2002 express 1500, 2500 and savana 1500, 2500. Part number is M390363 This has the 1.125 (1 1/8") bore and the 9/16 18 and 1/2 20 outlet threads.
So far the two master cylinders I bought from napa for testing were about $65-75. Not bad for a lifetime warranty and napa brand. Unfortunately the one for the express/savana are over $150 for a new master (I prefer new of reman) So for me that was out of the question since a wilwood is $175 on amazon with prime shipping.
The dorman master cylinder is about $65 on amazon which is not a bad deal. My only concern is that if I have an issue and need to make a warranty claim it will be much more of a PITA having to wait for and pay for shipping etc. not to mention you cant complain to dorman to their face if you have an issue so its easier for them to give you the run around.
Acdelco has an option on amazon for $100 part number 18M794. Again can only really find this online for that price so a warranty claim might be as fun as the dorman.
Oreilly and autozone have masters for about $110+tax which gets you a lifetime warranty and you can pick it up locally much quicker than ordering online and if you need to make a warranty claim you can possibly have a new one same day.
With all of these aluminum/plastic reservoirs you will need to get a new brake line for the rear line (the bigger one) since the newer masters have the ports swapped front to back. You can move the front line back easily but not the back one forward. You will need to but something like 24" of 1/4" hard line for the new line, I would just get 30" to be safe. Got this particular info from Bee Jays thread.
I was leaning toward the ACdelco or local store bought options, but since it was close enough to the price of a new wilwood from amazon prime ($175) I decided to go that route.
Just wanted to lay out all the option, you can choose what works for you depending on budget, time, an peace of mind.
Note how the m2903 for the 2002 c2500 has a larger bore/piston at the end that attaches to the brake booster. This is the dual piston set up I was mentioning which is not the same as what was in our cars. The C3 master cylinder is 1.125 the whole bore for front and rear. The Ac delco 18m794 has the correct 1.125 bore front and rear. Just to reiterate, the front and rear lines have to be swapped on these master cylinder upgrades. You will need a longer line for what was originally the rear line, which will now be the front line.
Also note the size of the reservoir and how the one for the 1996-2002 express/savan 1500/2500 is shorter than the one for the 2000 c2500 3/4 ton. This should give you the necessary clearance to the hood.
I got the SSBC aluminum master cyl. in my '69. Much lighter, but I didn't weigh it. Looks like stock, and all fittings fit correctly, no relocating necessary. This one...https://www.summitracing.com/parts/s...model/corvette
See in pic......
Last edited by C3 Stroker; 04-22-2019 at 03:29 PM.
I got the SSBC aluminum master cyl. in my '69. Much lighter, but I didn't weigh it. Looks like stock, and all fittings fit correctly, no relocating necessary. This one...https://www.summitracing.com/parts/s...model/corvette
See in pic......
Any idea why Summit recommends it only up to 1974 Corvettes?
The m2903 piston size differences you refer to make up what is called a quick take up master cylinder. The big piston at the back will push a higher volume of fluid past the 2 main piston lips seals to quickly remove any slack in the braking and put the pads against the rotors. Then, the smaller main piston seals take over and make the pressure to apply the brakes just like every other master cylinder. This is nothing to be scared of, it'll just give you a firm pedal as the brakes begin to work further from the floor.
Ok but why? Who cares about the weight, you're not carrying it around by hand. Why would you want to replace something that is metal with plastic? I lean on my master cylinder all the time to reach the dipstick, header bolts, etc, seems more fragile for no real gain.
Ok but why? Who cares about the weight, you're not carrying it around by hand. Why would you want to replace something that is metal with plastic? I lean on my master cylinder all the time to reach the dipstick, header bolts, etc, seems more fragile for no real gain.
Man... if you're into weight reduction, finding a part that shaves TWO pounds off is a happy day. Seven pounds? Done deal. No one questions the reliability ov new vehicles, and they're ALL aluminum and plastic. I mean, come on... the whole damn car is plastic...
no wonder I didn’t see it on Zips , they only offer the older C3 master cylinder in aluminum. I have an 81. Might just go wilwood and call it done, pricy, but has a good name cast in it, must be better, haha.
no wonder I didn’t see it on Zips , they only offer the older C3 master cylinder in aluminum. I have an 81. Might just go wilwood and call it done, pricy, but has a good name cast in it, must be better, haha.
Maybe on a shelf somewhere someone might have the discontinued 77-82 aluminum master cylinder..........here it is if you need the part number...https://www.summitracing.com/parts/ssb-0477
that c2500 is probably for dual rear wheeld and giant drum brakes. less pressure and more volume needed, i would think. it would probably still work but with a tendency for front brakes to lock first in really hard braking.
Ok but why? Who cares about the weight, you're not carrying it around by hand. Why would you want to replace something that is metal with plastic? I lean on my master cylinder all the time to reach the dipstick, header bolts, etc, seems more fragile for no real gain.
How many of us could lose 20 lbs or more? There is a big time weight savings.
Make the passenger seat quick disconnect and lose it when no occupant, remove carpeting and padding, eliminate electric window rollers, dump the spare tire and tub, composite spring, door panels, t-top inner panels, smaller battery, etc,etc, all kinds of low hanging fruit IMO. Lighter master cylinder would be pretty far down the list. To each his own however. or maybe you're already there.
How many of us could lose 20 lbs or more? There is a big time weight savings.
Make the passenger seat quick disconnect and lose it when no occupant, remove carpeting and padding, eliminate electric window rollers, dump the spare tire and tub, composite spring, door panels, t-top inner panels, smaller battery, etc,etc, all kinds of low hanging fruit IMO. Lighter master cylinder would be pretty far down the list. To each his own however. or maybe you're already there.
What if you've already done all the things on your list, and need to replace your brake MC? Having this info available to make an informed choice that is correct for your situation is always a good thing.
What if you've already done all the things on your list, and need to replace your brake MC? Having this info available to make an informed choice that is correct for your situation is always a good thing.
How many of us could lose 20 lbs or more? There is a big time weight savings.
I cant speak for the few experts here, but interestingly enough, pretty much every true gram-counter i've ever known was a small or thin guy... a couple like rail thin (diets ov cigarettes, **** beer, and grease i guess...). Myself, i'm 225lbs, but i aint anything approaching fat, and its literally my job to be this size. I'll take the extra out ov the car...
And thats 7 pounds off the front end ov a front-heavy car. If you have a big block, this is even more important.
04-22-2019, 01:10 PM
Aluminum/Plastic reservoir Master Cylinder correct replacement save 7lbs
