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Replacing rear discs (Bendix) in board

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Replacing rear discs(rotors) Giugiaro  Lotus S3/ Turbo 1985 onwards
My Esprit S3 only just passed the rear brake balance test in the MOT. One disc was pitted. The tester suggested I get it skimmed/use the car more. (I am doing 1500 miles per year).  I investigated the option of skimming the disc on the car but the in-board brakes made this impossible. So I steeled myself and decide to have a go. I found a local garage with an engineering facility and was quoted £36 to skim the disc.  The Lotus workshop manual was not much help.
Tools needed
17, 18, 19 mm sockets (1/2”) and ring spanners including a long 19mm one (approx. 400mm)
8mm allen socket
Torque wrench up to 60ft lbs
Heavy hammer
½” breaker bar
Plus gas or similar
Brake cleaner
Lubricant for Bendix wedges
Copper grease

Parts.  New discs and most brake parts are available from specialists such as SJ Sportscars.
General advice on brake wear.  Good advice on brake wear, pitting, rusting etc:
http://www.theaa.com/motoring_advice/general-advice/brakes-discs-drums-pads.html
 If possible decide if the discs can be skimmed or need replacing before you start. The minimum thickness is 11mm. Distorted or badly pitted ones need replacing. 
Removal
1.  Jack the car up and put two axle stands underneath the chassis where they will not obstruct the work. Soak screws/ bolts below in Plus Gas or similar and leave for a few hours. Do not get any fluid on the pads.
2.  Remove the 6 allen screws holding the drive shaft to the disc. These would have been torqued to 60ft lbs and could have been on the car a long while.  Use an 8mm allen socket and a very long breaker bar. Pull the hand brake as tight as you can to stop the drive shaft turning. A sharp tap on the bar with a large hammer may help. To access each screw you will need to rotate the wheel and re-apply the hand brake.  These allen screws will be rusty and so hammer the socket in to ensure there is no slippage.
3. Suspend the disconnected drive shaft using wire tied to the suspension.
4. Now loosen the three bolts holding the disc to the gearbox output shaft one or two turns applying the hand brake hard to stop the disc turning. Do not undo the nuts completely.
5. Time for some tea or coffee!
6. Remove the brake calliper. Do this by removing the wedges and lifting the calliper out of its mountings. Suspend the calliper so there is no strain on the flexible brake pipe.
7. Take out the brake pads. Note how the anti-rattle springs are located and check these are not broken.
8. Remove the calliper mounting. There are two 19mm bolts. The bottom one is easy to access but the top one can only be accessed with a very long ring spanner. The bolt on my car was so tight I had to buy a 19mm, long ring spanner to shift it and then it needed a sharp tap. Draper do a spanner costing £17 on the Internet, 19mm ring at one end 19mm ratchet at the other and 400mm long.
9.  Remove the disc by undoing the three bolts you have already loosened. A spacer to the output shaft should drop out with it. 
Assembly
1.  Clean up the new disc with brake cleaner. My re-skimmed one was covered in thick grease which took some time to clean.
2.  Clean all surfaces to ensure disc runs true.  
3. Attach disc to output shaft using the three bolts.  A little bit of copper grease will help future dismantling. Keep bolts loose at this stage.
4. Bolt on calliper mounting with the two 19mm bolts, again with some copper grease. Torque to 48ft lbs. The top one will be guess work!
5. Tighten the three bolts on the disc gradually. Final tightening comes later.
6. Place pads and anti-rattle springs in place.
7. If you are replacing the pads, first screw back the brake cylinder using a ¼” ratchet - removing the cap on the master cylinder will help. Then insert caliper assembly into mounting and insert wedges with a smear of brake lubricant. Place the top wedge first then use a long screw driver to lever the calliper against the springs and insert the second wedge in one corner the gently tap home. Do not forget to fit the securing clips in the wedges.
8. Gradually torque tighten the disc to 60ft lbs, applying the hand brake very hard to help you.
9. This is not strictly necessary but at this stage I used a dial gauge to check the run out – it should be a maximum of 0.008”. Mine was 0.004”   - better than before skimming. 
10. Time for a break.
11. Reconnect the drive shaft, applying a small amount of copper grease and torque tighten gradually to 60ft lbs. This is tedious as you will need to apply and release the hand brake to each allen screw in turn. Make sure the socket is tapped firmly into each screw to stop it slipping.
12. Ensure hand brake and foot brake work while car is jacked up. Ensure there are no brake fluid leaks and brakes are not binding. Then road test.
Note. This worked for me but the usual disclaimers about responsibility, health and safety!
 

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Very good write up.

Did you change pads? What part number, x-reference?

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One thing, most engineering firms will end up cutting both surfaces separately, that;s not ideal. If skimmed correctly you have two cutting points, one on each face of the disc, at the same time. That ensure the two surfaces are parallel which is more important than them being flat or smooth.

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A quick way of loosening/tightening the 6 allen bolts, without stressing the handbrake, is to jack up the rear of the car so tyres are just off the ground.  If you put a 'brick' against the leading edge of the tyre it locks the axle with 100% certainty as you load up the allen key. Obviously frees off the instant the load is released.  - Clearly ensure your front wheels are securely chocked!

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Are the rear discs of Lancia Gamma?

What year?

Where to get them at a reasonable price?

Edited by MrDangerUS

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I had mine skimmed. I know SJ Sportscars of the UK have them on their price list but I do not know if they are in stock.

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I was told the rear discs are no longer available, if they are does anyone have a cross ref for them.

 

John.

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They are 274mm dia,162mm hat,12mm thick, total thickness w/hat 31-32mm, 3 mounting holes.

Calipers may be Matra

http://www.matraclub.org.uk/pdf/Brakes.pdf

Here's some additional [unverified !] cross-ref info from some other website:

Brake Discs, Esprit Rear

1983-84 R5 Renault Le Car front brakes used as Esprit rear brakes

Edited by MrDangerUS

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