ZX 1.4i new brakes overheating on offside front

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jeremy
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Post by jeremy »

Which all suggests that the off side caliper isn't sliding quite as freely as it should.

There is no actual retraction mechanism for the piston - just a removal of force and general run-out etc. The original Dunlop disc braking system as fitted to Mk 11 and E Type Jaguars and a few others did have a strange pin arrangement that was supposed to retract the pistons but no-one else copied it and the system died with the Dunlop system in the late 60's.
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AndersDK
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Post by AndersDK »

When the wheels are removed - nothing is holding the discs true. The small countersink bolts are there ONLY to keep the disc located until the wheel & wheelbolts are fitted.

Therefore you can not turn the disc by hand and check for any true gaps or runouts. You will need a special spacer disc and the wheelbolts to check the discs.

If you try torque the small countersink bolts - you will NEVER get them out again when the disc has worn down. Meaning they MUST be screwed in - then loosened 1/8-1/4 turn.

Which wheel do you think have the largest load - even under breaking - when you are in the driver's seat ?
Where/how do the brakes energy disappear ?
Anders (DK) - '90 BX16Image
DHJ
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Post by DHJ »

AndersDK wrote:Which wheel do you think have the largest load - even under breaking - when you are in the driver's seat ?
Probably the driver's; what would you estimate the percentage braking load each side to be in this scenario?

Of the journeys where I have checked the wheel temperatures, about half had just the driver, the remainder had a passenger too. The temperature differences were similar in each case.
AndersDK wrote:Where/how do the brakes energy disappear ?
Heat, obviously.
jeremy
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Post by jeremy »

The best test is to drive it somewhere without using the brakes and stop again without using them and then see how hot the front one has got.

Under gentle braking the back ones should join in and do about 50% of the work. Heavy applications will bring the pressure relief system into operation to prevent rear wheel locking. All is affected by load - but I'm not sure if the ZX rears are load sensitive or just limit the force on a heavy application. (Some have a load compensator with a spring connecting to the suspension I think)

Its more common than you think for the rears to do very little - especially as the adjusters may stick. You may be able to feel the rear shoes move against their springs when you apply the brakes - and a useful retardation is produced by the front discs while this is happening. (ie while you are taking up the 'slack.')
jeremy
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