Rear brakes. Rear pad replacement

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1 Rear brakes The rear brakes are a very unusual design, first seen on the Alfetta I think. The brake calipers are inboard with dual opposed pistons, but there is a lot of extra complexity from the handbrake mechanism. How it works: The handbrake cable operates a cam inside each caliper to push the inner pad against the disc. To get a decent handbrake on a disc, you need a lot of leverage. Which means very little movement. So the calipers contain screw adjusters that hold the pads no more than 0.1mm from the disc. This also has the effect of "locking" the outer pads in place, which gives the inner pads something to push against. What this means in practice is that the calipers are complex, and have a lot of O-ring seals, all of which can leak. Adjustment is critical, and 0.1mm doesn't give much allowance for rusty, grooved or warped discs. Finally, operation of the calipers is not at all obvious, and it is very easy to damage them if you don't understand how they work. Note that 75's seem to be prone to soggy brakes. This happens if any part of the system is below par. In your quest for great brakes, don't ignore condition of the back setup - it is as important as the front. Over time I have repaired or replaced almost every component. Every little bit helps... Rear pad replacement Changing the pads is fairly straightforward. However, they aren't cheap - especially the type with wear indicators. If the discs are at all worn, it is well worth replacing them at the same time. 1. Disconnect the wear indicator wires (if fitted). 2. Remove the R-clips, pad pins and anti-rattle spring. 3. Slacken off the handrake cable adjuster and caliper adjusters. 4. Fit new pads. You might need to slacken the adjusters a bit more to get the pads in. Note that the pads are directional. If you look at the back of the pads, you'll see that there is a recess to one side. The recess should be towards the rear of the car. Thanks to Tim Hayes for confirming this - the Lockheed pads I used don't say which way is correct. 5. Replace the anti-rattle spring, pad pins and R-clips.

2 6. Adjust the calipers. 7. Adjust the handbrake cable. 8. Reconnect the wear indicator wires (if fitted). Rear disc replacement As I've aready said, caliper adjustment is very critical. It is almost impossible to get it right if the discs aren't smooth. The minimum specified disc thickness is 9mm. Mine weren't badly worn, but replacing them brought an immediate improvement in brake feel, with a firmer pedal and better handbrake as well. 1. Remove the six allen bolts which attach the driveshaft to the disc. 2. Slacken off the handrake cable adjuster and caliper adjusters. 3. Withdraw the disc, and replace it. 4. Oil and re-fit the six allen bolts. Make sure they are torqued correctly. 5. Fit new pads. 6. Adjust the calipers. 7. Adjust the handbrake cable. Rear caliper inspection/replacement If all is not well with a caliper, then the best thing is to remove it from the car and inspect it on the bench. To do this, disconnect the handbrake cable and remove the brake disc. Then you can release the brake pipe and undo the two nuts holding the caliper to the gearbox. With the caliper on the bench, check for any obvious signs of fluid leaks. The main piston seals are replaceable, but any leak from the adjusters or handbrake lever is more serious. Next, check the adjustment mechanism actually works. The inner piston is operated by a 7mm hex spanner. The outer adjuster needs a 5mm allen key, after removing the plastic cap and releasing the 17mm locknut. The Alfa manual says that you should use a "spreader" to apply force to the pistons while drawing them into the caliper. So long as the pistons aren't siezed, it should be OK without this. It should be possible to wind the pistons in & out using the adjusters. If they don't seem to work at all, then it's possible that the mechanism has parted company with the piston. The automatic adjuster is held in place inside the piston with a snap ring, and it is possible for it to pop out. Try removing the piston from the caliper: if it comes out, but the adjuster stays in the caliper, then you've found the problem. If the mechanism is intact, the pistons should unscrew from the adjuster bolt. The above (fuzzy) picture of a dismantled caliper should explain this a bit more. The auto adjuster should snap-fit into the piston. Then, the adjuster bolt screws into the piston. Now, the whole assembly can be put back in the caliper. Next, try moving the handbrake lever. The inner piston should move out a few millimetres. If it all checks out OK, the caliper can be refitted. If not, the bad news is that a new caliper is very expensive. I had to replace the right-hand caliper after it siezed on, and refused to adjust properly. I think the inner adjuster gear had got munged by a previous owner :-( Paul Irvine's Tech Pages.

3 Rear caliper adjustment This is a nice easy job, so long as the brakes are in good condition. 1. Slacken off the handbrake cable adjuster. 2. Remove the plastic cap from the outer adjuster, and slacken the 17mm locknut. 3. Slacken off the inner & outer adjusters. The direction isn't obvious at first. Here's how to slacken them: 4. Place a 0.1mm feeler gauge between each pad and the disc. It's better to do both pads at once. 5. Carefully tighten the adjusters until the pads just begin to nip. 6. Tighten the outer locknut, and remove the feeler guages.

4 7. Finally, adjust the handbrake cable. Once set, the adjustment is automatic. So you shouldn't need to do this again until the next pad change. Rear flexi pipe replacement The flexi is simple to replace. It is also relatively cheap. The fixing nut is likely to be very corroded, so it's a good idea to get one of these as well (they are an odd size). By all means use a steel-braided replacement if you wish - these can give a firmer pedal. Rear brake pipe replacement There's only one pipe to the rear. It is prone to corrosion where it makes a sharp turn at the front of the gearbox, so check it carefully. It is easy to replace, but be especially careful to route it clear of the propshaft and gear linkage. Bleeding tips Sometimes the rear brakes can be tricky to bleed. Suggestions to make it easier: Raise the rear of the car on ramps. This makes sure any air bubbles rise up towards the bleed nipples, as well as making access easier. Open a bleed nipple fully, then *gently* pump the brake pedal until most of the air is expelled. If you pump hard, you will operate the balance valve, which shuts off the fluid to the rear. Note you'll only be able to press the pedal half way before the valve operates anyway. Once most of the air is out, bleed each of the four nipples starting with the outside ones first. Either get an assistant to operate the pedal, or use a one-way bleed valve to make sure you get all the air out of the system. If you get a lot of air in the system, it's possible for it to airlock near the balance valve, making it impossible to get a decent pedal. Try bleeding the pipes from the master cylinder to the balance valve. Handbrake cable replacement Bit of a swine, this one. The cable will rust and stretch with time. If the adjuster is right at the end of its travel, and the handbrake still comes too far up, then unfortunately it's replacement time... The rear end is easily detached, but access to the front is almost impossible. The "correct" method requires removal of the exhaust, gear linkage and very possibly the propshaft :-( Horrible bodge method: If you remove the console and handbrake inside the car, you can detach the handbrake rod there. BUT, the rod is too big to go through the hole in the floorpan. Solution: A hammer and chisel will enlarge that hole just nicely, so you can push the rod though. Now the front end of the cable will hang down, and you can release it. I did warn you... The cable takes an awkward route over the top of the gearbox. I found the old cable very difficult to remove, but the new one went in OK. The clearance is minimal, so expect skinned knuckles. Once you've got the new cable back on, adjust it as follows: Handbrake cable adjustment First, make sure the calipers are correctly adjusted. Then, simply release the locknut, and move the adjuster to eliminate all free play - i.e. tighten the adjuster until the handbrake levers just start to move. A neat way to avoid over-tightening the cable is to put 0.1mm feeler gauges between the inner pads and the discs. When you have finished the adjustment, check that the feeler gauges aren't tight. Finally, tighten the locknut.

5 Road test After doing any of the above, always check and top up the master cylinder, then road-test the car. It should stop smoothly and predictably, and it should be possible to lock both front wheels under extreme braking. It's important that the brakes don't bind, although it'll be obvious if they're really overheating! Jack up the rear axle, and make sure both rear wheels turn freely. If not, re-adjust the calipers and/or handbrake. Torque settings Nm Driveshaft bolts 54 Caliper mounting nuts 54 Parts VVL015 (Brembo) Rear brake disc each LP484 (Lockheed) Rear brake pad (with wires) set BM521 (pattern) Rear caliper (R) Rear brake flexi pipe Rear brake flexi nut Genuine part is over 200!