Fitting E32 Master Cylinder

Parts

E32 735i Servo, Master Cylinder and Reservoir

Tools

• 3/8 socket set
• 11mm brake pipe spanner or combination if you don’t have one
• Screwdrivers
• Electric drill and bits up to 12mm
• Carbide burrs
• Grinder and discs
• Tap and die set (M10x1.5)
• Cutting oil (wd40)
• Rags for keeping stuff clean
• Some washers

Procedure

With the E34 calipers on the front, and potentially bigger brakes on the rear as well, the standard E30 master cylinder isn't big enough to move enough fluid. To get around this, most people use the E32 750i MC but I also wanted more assistance to match. The 750i MC is also becoming increasingly expensive due to its rareity, so I'm opting to use a more mundane E32 735i MC and servo instead. This master cylinder is still 25mm, so should improve the feeling to near stock level

However, a few mods will be needed to make this fit.

The E32 I got mine from had a spacer on the back of the servo. There are two options here:

1. Use the spacer. This requires the least mods but the brake fluid reservior will be right underneath the inlet boot on the M20 engine, and might not fit.
2. Ditch the spacer, but make a few mods instead. This involves:

Grinding down and shortening the push rod to put the clevis at its original level Open up 2 holes in the bulkhead Bend the brake lines slightly

I choose number 2 for an original look to the engine bay

Start by opening up the mounting holes E34Brakes005

Grind down the pushrod E34Brakes006

Start making the thread using your die E34Brakes007

Cut about an inch and half cut off (37mm), and thread it as far as you dare E34Brakes008

Remember if you're doing this yourself then leave the die wound on before you cut the excess off. That way, you can then unwind it and clean the threads so that the clevis can go on with no trouble

test fit E34Brakes009

I was made up that the standard E32 vacuum line was in the perfect place to line up to the E30 system

The clevis is the trickiest part I lost the E30 clevis so I used the E32 one but it was way too long. This required trimming and slight mods so please keep your E30 one unless you want some trial and error fitment issues that involves installing and removing the servo/clevis multiple times E34Brakes010

All done apart from take it all apart to paint the servo and bench bleed the MC E34Brakes011