Fitting E34 Brakes

If you've dramatically increased your engine's power, either by an engine swap or Forced Induction, then you're going to need some bigger Brakes.

This guide walks you through fitting E34 front calipers. We also recommend following the sister article about fitting an E32 servo and master cylinder. The standard E30 master cylinder is not big enough for the E34 calipers.

This is not a bolt-on process. Some fabrication and custom parts are required to fit everything together.

Parts

• E34 540i Front calipers, Carriers, bolts, clips
• Audi TT MK1 312x25mm vented front discs x2
• E34 540i Brake pads (your choice, I chose brembo OE)
• Caliper adapters
• M12x40 Nylock nut and bolts x8 (ebay)

Tools

• 13mm brake pipe spanner
• 17mm spanner
• Allen key set
• Hammer
• Jack and jack stands (or post-lift if you're a flash git)
• Grinder with discs
• Drill and steel drill bits (up to 12mm)

Preparation

Loosen the front wheel nuts on each side, then jack the car up using the appropriate Jacking Points and secure it on jack stands. Remove the wheels and place them under the car for safety.

Next crack off the brake hoses going into the front calipers. Undo the caliper carrier bolts (17mm), remove the entire caliper assembly from the disc, and rotate it multiple times to get the brake hose out.

Take the appropriate sized Allen key and undo the brake disc retaining bolt. With that off, the brake disc should wiggle off the hub. A few clouts with a hammer from behind can help.

You should now have a bare naked hub to attach your new brakes to.

Brake Discs

First on is the new brake discs. We're using 312mm discs from an Audi TT Mk1, and these will need some modification to fit. The centre bore needs opeing up 1mm and two holes need drilling in between the two current bolt holes

You can either give the discs to a machine shop to mod for you, or do it yourself using a drill and a Dremel.

To do this yourself, bolt the Audi 312mm disc to the BMW 260mm disc with the E30 wheel nuts so that the cone centers the discs. Use a carbide burr to open up the centre to match the BMW disc, then drill the required wheel bolt holes through the BMW disc and into the Audi disc. Start with a small drill bit before moving up to a 12mm bit.

Before you attach the disc, bolt the front bracket to the hub with two of the M12x40mm nuts and bolts

Attach the disc and bolt to the hub using the wheel nuts to stop it moving about while we fit the calipers.

Calipers

Scored the front brackets first all the way from Germany. These are the 300mm.de adapters.

If you're more creative, you can opt to make your own based on the following dimensions:

These were designed to be used with the E34 caliper and an audi 312mm disc. As you can see, these calipers are particluarly beefy.

The brake carrier needs some slight grinding to line up the holes in the bracket and carrier, because it hits the hub. This will be trial and error on your part but I found it to be about 3-4mm (grind you carrier at your own risk)

Once the carrier is bolted in nice and tight you can install the pads with copper grease on the contact parts.

Wind the caliper onto the brake hose, then attach the caliper to the carrier with the two slide bolts (7mm allen)

Tighten the brake hose in caliper with your 13mm spanner

REPEAT THE OTHER SIDE and admire your new front brakes