I have a new in the box master cylinder for an 81 malibu that fits the dual diaphram brake booster. Will the MC fit an 83 malibu? part numbers are different but look the same. would like to use it instead of buying another one. money is kinda tight at the moment.
MASTER CYLINDER INTERCHANGABILITY
- Thread starter 81msw79
- Start date
- Status
If the part numbers are different, it may not work. I know this from experience as I went to replace the original m/c on my 80 Cutlass with one from a Monte Carlo SS and it would not fit. It’s a possibility that the size of the bore in your ‘81 Malibu’s booster might be smaller than the ‘83 one (what happened to me).
For me, rather than exchange the MC m/c for the proper one, I just used it as an opportunity to replace the original booster with a MC one as well. It worked out fine, no issues whatsoever.
Hope this helps, good luck.
The bore size is larger in the 83 master
https://www.autozone.com/brakes-and...ew-master-cylinder-brake-system-/49328_0_2558
https://www.autozone.com/brakes-and...ster-cylinder-brake-system-/49343_0_2558_2060
https://www.autozone.com/brakes-and...ew-master-cylinder-brake-system-/49328_0_2558
https://www.autozone.com/brakes-and...ster-cylinder-brake-system-/49343_0_2558_2060
i wish i could just exchange it. i bought it about 1 1/2 years ago. i could not find it in my stock of stuff when i did my 81 malibu brakes and just ended up order another to get the job done . fast foward 8 months later and found it digging for something else. guess i will shelve it and mark it well for whenever i get to my 78.
since i need to swap out both booster and mc what would be a decent budget freindly upgrade for booster and mc for the 83? will eventually go blazer brakes once finances settle.
1978-1981 "g-body" vacuum boosted power brakes came with a 24mm strait bore master cylinder. These where used on cars with normal calipers.
1982-1988 g-body vacuum boosted power brakes came with a step bore master cylinder. A step bore master cylinder has two bore sizes. It has smaller 24mm pressure bore to produce increased line pressures and caliper clamping forces. A step bore master also has a larger 1.125" bore. Some step bore master cylinder have even larger step bores, but all g-bodies will have a smaller 24mm pressure bore.
In 1982, GM went to a LOW drag caliper in g-bodies to help with gas mileage. The caliper is the same style casting as the earlier 1978-1981 calipers, but the piston seal was beveled so the piston would retract the pads away from the rotor to reduce drag. Because the pads retracted further away from the rotor, more fluid volume is needed to get the pad back up against the rotor during braking. This is why the step bore master cylinder was developed to supply the volume of fluid needed from the larger 1.125"+ bore to push the pads back up against the rotor during braking. At about 100 ftlb of internal pressure in the master cylinder, the master cylinder would transition to the smaller 24mm bore to increase line pressure and clamping force at the caliper and stop the car.
Usually a 1978-1981 strait bore master cylinder can be used on a 1983-1988 booster because the strait bore master cylinder is physically smaller diameter where the piston goes into the master cylinder than a step bore master cylinder. A step bore master cylinder will not physically fit in a 1978-1981 vacuum booster.
If you want to use the 1981 master cylinder on the 1983 booster, you should be able to. You can test fit the 1981 master by unbolting the stock 1983 master cylinder from the booster and NOT unbolting the brake lines from the 1983 booster.
BUT...
If you have the stock, 1983, from the factory, original calipers on the front of the 1983, then they will have to be charged out with NON low drag, normal calipers which can be bought at the local auto parts store.
All remanufactured calipers that you can buy at the auto parts are rebuilt to NON low drag, or normal, standards so they can be used with both LOW and normal, NON low drag calipers. All part numbers are the same for any vehicle using the "metric" caliper from 1978-2004. 1978-1988 G-body, 1982-1992 F-body, and 1982-2004 S10
1982-1988 g-body vacuum boosted power brakes came with a step bore master cylinder. A step bore master cylinder has two bore sizes. It has smaller 24mm pressure bore to produce increased line pressures and caliper clamping forces. A step bore master also has a larger 1.125" bore. Some step bore master cylinder have even larger step bores, but all g-bodies will have a smaller 24mm pressure bore.
In 1982, GM went to a LOW drag caliper in g-bodies to help with gas mileage. The caliper is the same style casting as the earlier 1978-1981 calipers, but the piston seal was beveled so the piston would retract the pads away from the rotor to reduce drag. Because the pads retracted further away from the rotor, more fluid volume is needed to get the pad back up against the rotor during braking. This is why the step bore master cylinder was developed to supply the volume of fluid needed from the larger 1.125"+ bore to push the pads back up against the rotor during braking. At about 100 ftlb of internal pressure in the master cylinder, the master cylinder would transition to the smaller 24mm bore to increase line pressure and clamping force at the caliper and stop the car.
Usually a 1978-1981 strait bore master cylinder can be used on a 1983-1988 booster because the strait bore master cylinder is physically smaller diameter where the piston goes into the master cylinder than a step bore master cylinder. A step bore master cylinder will not physically fit in a 1978-1981 vacuum booster.
If you want to use the 1981 master cylinder on the 1983 booster, you should be able to. You can test fit the 1981 master by unbolting the stock 1983 master cylinder from the booster and NOT unbolting the brake lines from the 1983 booster.
BUT...
If you have the stock, 1983, from the factory, original calipers on the front of the 1983, then they will have to be charged out with NON low drag, normal calipers which can be bought at the local auto parts store.
All remanufactured calipers that you can buy at the auto parts are rebuilt to NON low drag, or normal, standards so they can be used with both LOW and normal, NON low drag calipers. All part numbers are the same for any vehicle using the "metric" caliper from 1978-2004. 1978-1988 G-body, 1982-1992 F-body, and 1982-2004 S10
Thank you very much for the well detailed info of why they are so different. i actual have reman calipers on the car from napa i installed about 1 year ago. So now i will just source a new booster and swap out that at the same time as when i do the MC
- Status
Similar threads
