Fitting a light-weight aluminium brake master cylinder
Posted: 03 May 2002 18:55There are two (or more?) versions of the aluminium master cylinder. With manual brakes you want a smaller bore so you can generate enough pressure with your foot. So go for one with a bore of one inch or less. Also it is important that you DO NOT use one from a front wheel drive car.
These things were fitted on all Mopars from the late 1970s/early 1980s onwards so you could find a used one if you wanted although I don't think they are that expensive to buy new. However they mount with two studs instead of four so you need to make an adapter or buy the Mopar performance adapter.
The adapter is just a thick aluminium plate (about 9mm) with two studs for the new master cylinder and four holes to fit over the existing studs. Easy to make.
Now look at how a power assist brake is mounted.
Can you see how the brake pedal does not directly connect to the pushrod? Instead there is what is known as a bell crank arrangement. This has to go because it reduces the amount of pressure you can apply with your foot.
To get the new master cylinder to line up with the joint on the brake pedal you have to mount the master cylinder lower on the firewall. Lucky for us Chrysler allowed for this on its manual braked cars so the mounting position is already there. You just need to make a plate to cover the gap created in the firewall when you have moved it.
The other thing you might need is a longer pushrod from the brake pedal to the master cylinder piston. MP make an adjustable one but I found that to get the brake pedal to the right height I needed to shorten it and cut the adjusting thread along it's whole length to give enough adjustment.
These things were fitted on all Mopars from the late 1970s/early 1980s onwards so you could find a used one if you wanted although I don't think they are that expensive to buy new. However they mount with two studs instead of four so you need to make an adapter or buy the Mopar performance adapter.
The adapter is just a thick aluminium plate (about 9mm) with two studs for the new master cylinder and four holes to fit over the existing studs. Easy to make.
Now look at how a power assist brake is mounted.
Can you see how the brake pedal does not directly connect to the pushrod? Instead there is what is known as a bell crank arrangement. This has to go because it reduces the amount of pressure you can apply with your foot.
To get the new master cylinder to line up with the joint on the brake pedal you have to mount the master cylinder lower on the firewall. Lucky for us Chrysler allowed for this on its manual braked cars so the mounting position is already there. You just need to make a plate to cover the gap created in the firewall when you have moved it.
The other thing you might need is a longer pushrod from the brake pedal to the master cylinder piston. MP make an adjustable one but I found that to get the brake pedal to the right height I needed to shorten it and cut the adjusting thread along it's whole length to give enough adjustment.