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Brake Upgrade: Volvo Calipers/320i Rotors & drums/E12 Ma


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I thought I would post about my brake set up to possibly help anybody thinking about doing the upgrade(s).

My 1600 is a 1968, it came with the 5 line master cylinder and 320i rear drums.

The brake system was in poor conditon when I got the car (disc below minimum, stuck left caliper, and zero brake pad life).

I installed the front calipers from a Volvo along with the 320i hubs and 1977 320i vented rotors. When I had everything installed I noticed the pads were sitting outside the diameter of the rotor.

So I removed the caliper and milled the bolt holes into a slots. The caliper/pads now encompass the disc completely.

The car stopped much better, but the pedal nearly went to the floor.

So I opted to upgrade the master cylinder, I decided to go with a 1978 E12 530i master cylinder, 23.8mm bore I believe.

When installing the master cylinder, I realized the E12 MC did not have the provisions to accept the residual pressure valve.

The reason being, the E12 was equipped with rear disc brakes.

The residual pressure valve keeps about 10 psi in the rear brakes to keep the drums preloaded (so when you hit the brakes, you dont have to pump them to get the shoes to contact the drum friction liner).

So I ran to my local junk yard, there was a 320i there, but it had the 3 line master cylinder. I was poking around different cars when I found an MK1 VW Rabbit. I noticed the rabbit had two large valves/cylinders on the master cylinder (one per line for the rear brakes).

So I pulled them off.

I did some googling and the reserach showed they were residual pressure/proportioning valves. So I installed the valve between the master and rear brakes.

I bleed the system. I was a little nervous as I wasn't sure this would work.

But so far the car stops very well. I didn't get a chance to watch someone hit the brakes hard to see if the car nose dives (rear brakes not working), but since the VW Rabbits are front heavy I think it will work/feel like it is working.

The master cylinder gave the pedal an excellent stiff feeling (like my E86 M Coupe). I still need to adjust and lube the rear drums, but I suspect everything will work out well and braking will improve even more.

I will post an update this week.

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Nice post!

so when you hit the brakes, you dont have to pump them to get the shoes to contact the drum friction liner

Actually, in a 2002, the adjusters do this. The valve keeps the hydraulics

prelaoded against the shoes, but the springs in the shoes can overcome

the valve.

That's why adjusting the rear drums is such a direct way to get a higher pedal.


"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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You seem to have put a lot of thought into that setup and tried a lot, but that:

So I removed the caliper and milled the bolt holes into a slots.

made me shudder a bit.

Why not try larger brake discs from another car instead? Maybe turning down the diameter of the brake disc to make larger ones fit instead?

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The Volvo/320 conversion is very common (there is a write up on the FAQ). As for the milling, the diameter remained 12mm, I milled into the portion of the caliper that has plenty of meat, I can assure it is more than safe.

What matters is the bolt preload, I ran the calculations to ensure there wouldn't be any joint slip.


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