Friday, October 17, 2014

Rear Brakes - Somewhat Confused Shoes!

Ever since owning the car, the rear brakes have always had a bit of a low level grinding noise when used. As it wasn't that bad and knowing no better, I assumed it was normal. Recently however the noise has become worse, so bad in fact that even a numpty like myself cannot fail to realise something was not right.

So taking the drums off to investigate I found a build up of brake dust sat on top of the adjuster housing. Having rebuilt the brakes recently, I knew something was afoot with these shoes! And thanks to the help from friends on facebook, I was able to work out what it was...


Withing minutes of posting the picture on facebook the problem was diagnosed by a number of people. Some idiot had put one of the brake shoes on upside down. You can guess who that idiot was of course! But in my defense, I just put them back on the way they were taken off.

For my own sanity I had a look back over my photos and found this picture taken back in November 2013 when I started to overhaul the rear subframe. It clearly shows the brake shoes in the same position.



So Whats Wrong?
Having now done a little research into drum brakes and also following the comments on facebook, I realise now that the brake shoes are made with a leading edge and a trailing edge. Get them the wrong way round (like me) and you end up with problems (like me). 

So that begs the question, how do you tell which edge is which? Looking at the brake shoes again, it is obvious now that the friction material is bonded closer to one edge than the other.

The edge with the largest gap is the leading edge



and the smaller gap is the trailing edge

This might be blatantly obvious to the seasoned mechanic, so much so that chapter 9 section 5 of the Haynes manual makes no reference to it at all. It simply says to ensure the shoes are fitted correctly, but fails to detail how. In section 1 - 'General Information', it does make a vague reference to leading and trailing brake shoes, but again, it's not exactly brimming with details.


So How To Fix It
Although the existing shoes did have plenty of meat left on them, they were looking a bit chewed up so I decided to replace them, and at £9 from Huddersfield Mini spares they hardly broke the bank. I even went mad and splashed out a further £5 on a new set of springs



Thankfully fitting the shoes the correct way was made easier with the kind help of Rico Nijhof and Andy McPhail as they both posted a link to a picture showing the correct fitting for the passenger side. 

From this picture I was able to work out that the direction of rotation dictated where the leading edge was to be positioned. If you were to take a single point on the wheel, as it rotates, the leading edge should be the first part of the brake shoe it meets.

Applying this logic, I was able to work out both sides with ease.




Result!
Once the brake shoes were correctly fitted (making sure that the springs were on the inside) I slackened off the adjuster to enable the drum to be reattached. With the drum secured in place with its screw, I was now able to give the brakes their final re-adjustment and fit the road wheels to complete the job.

And wow! what a difference it has made. The brake peddle is firmer, the car brakes smoother and better and also the handbrake is easier to use. I am staggered by the result, and also by the fact that they were so wrong for so long.


Conclusions
If you have read my blog before you will know that I have no prior knowledge of fixing cars and one of the reasons for owning the Mini is to fix that problem. And this is a classic case of fixing a hole in my knowledge. For some, this will be just obvious stuff that you are supposed to know, but for others such as myself, it's not. 

Finding problems such as this and being able to learn new skills and gain new knowledge is what it's all about.


<Next Post> - 'Soggy Drivers Footwell'
<This Post> - 'Rear Brakes - Somewhat Confused Shoes!'
<Previous Post> - 'A Shot of Lead in the Head!'


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2 comments:

  1. Good work but (there is always a but..) the Rover Manual AKM 6353 says: Position the shoes as illustrated. The illustration is similar to your Passenger Side pic. So both sides the same.
    Bye! John (Holland).

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    Replies
    1. Hi John, thanks for the comments. I wil have to get my hands on the Rover Manual you mentioned, it sounds better than the Haynes.

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