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Technical Rear brakes

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Sep 2, 2007
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Hi there,

A few problems with the rear brakes on my 1993 Mk2 Uno (999cc FIRE engine), would appreciate a second opinion if anyone can help :).

About two years ago, I had two new drums and shoes fitted on each side along with a couple of wheel cylinders (all on the rear of the car).

Recently, I was nearly involved in a high speed accident when one of the rear wheels locked up and the car spun round in a circle several times before I caught it as it straightened out, thankfully I lived to tell the tale as no other vehicles were close by
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.

On examination, one of the wheel cylinders was found to be leaking, contaminating the shoes on that side but also the brakes weren't balanced properly across the rear. The cylinder was replaced (other side deemed to be okay), shoes cleaned up, refitted and adjusted.

Problems I'm getting are excessive rear noise when pressing the brake pedal, this takes the form of a grinding sound - it's a lot louder than the noise you might get in winter as a result of a surface build up of rust on the drum linings/shoes but does start to go after some braking, only to reappear a short time after car is parked (45 mins).

Also, in an emergency stop in a safe place at 20mph, the back end of the car either pulls towards the centre of the road, or skids a lot in a straight line but starts with the rear tyres. Tyres have plenty of tread on the rear (6mm), fronts about 3mm on each side.

I did think it might be an issue with the brake power regulator (separate spring is relatively new) or brake master cylinder - this probably the original from twenty five years ago! Front brakes (discs and pads) have been checked.

Overall, the brakes feel twitchy and less assured than normal so taking things steady when driving, just in case.

Any ideas welcomed :)

Cheers,
Andy
 
Last edited:
Renew the brake power regulator or bias valve if the rest of the system is working properly and freely. Then take the car to Fiat for them to adjust / reset the valve to factory setting. Make sure you tell them to test the car on the road.

A job like this shouldn't take them more than an hours work. Because you have asked the question, I am hesitant to say, fit and adjust it yourself using the haynes manual. You definitely need to know what you are doing with brakes.

Hope that helps.
 
I`ve had similar issue with the brakes, one wheel locks up when hard braking, other did not brake at all. What i have do to fix this is changed the master cylinder, wheel cylinders and flushed the brake fluid. Now it stops like a charm, except there is a little bit of grinding noise when braking.

Or it can be the brake power regulator as ourfather777 suggested.

Cheers (y)
 
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