Brake system on 1987 460 280GE

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Sat, 14/05/2011 - 08:32
JimmyGwagon
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The brakes being a bit spongy, I decided to bleed the system...

First I mistook the small reservoir just in front of the battery and labelled “Brake and Clutch fluid only” for the Brake reservoir, anybody know what it is?

The two front brakes were straight forward, and I pumped plenty of fluid through to clear out the old fluid...

next the rear wheels, and unbelievably a nipple sheared...no fluid showed, so I tried pumping the peddle and still no fluid from the sheared nipple, maybe the cylinder is seized...

Then I tried bleeding the Automatic brake pressure regulator, but again no fluid when pumped...

How does the Automatic system work? Under what condition does it kick in...

THX

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Sat, 14/05/2011 - 17:13
#1
fixwin38
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Re: Brake system on 1987 460 280GE

Hi
Reservoir in front of the battery is for the difflocks... a bleed nipple is fitted to each difflock ram attached to the front and rear axle.....brake bleed points are front callipers --rear cylinders    what are you calling the "automatic brake pressure regulator" and where is it located??? brake master cylinder is bolted to the front of the brake servo.. in the engine bay if you broke a nipple the brakes may no longer be safe and you may have to replace the cylinder...if when you bled the system the fluid was cloudy or black this is a sign of corrosion in callipers/cylinders/plumbing and will result in premature leaks or pistons sticking causing the brakes to bind..... .over the counter exchange callipers and cylinders avaialble from International Brake in Bolton  the difflock and clutch fluid may be contaminated too..use DOT 4 + or Dot Five hydraulic fluid in all systems....

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Sat, 14/05/2011 - 17:35
#2
Pistonhead
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Re: Brake system on 1987 460 280GE

You can have spongy brakes as a result of excessive play in the rear shoe adjustment, although having automatic adjustment, these do not necessarily work, it can be necessary to manually adjust the shoes.

For the rear cylinder, it is better that you replace the cylinder adjust the shoes and re-try bleeding.  Before you do adjust the shoes, slacken the handbrake cable, make your shoe adjustment, bleed your system then adjust back the handbrake.

There can be other reasons for spongy brakes, it depends on the how the brake behaves, for example, spongy brakes after turning the steering at a lock or full lock intimates the wheel bearing has excessive play, at a turn the play in the bearing acts against the pads pushing in the caliper pistons in, upon straightening the wheel and at a first brake application, if one experiences a soft pedal, almost to the floor, and the second application of the pedal immediately hards the brakes, is one example. 

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