More Ruby Brake questions

[Denis Sweeney]

Having recently returned from the very successful A7 Centenary Eurotour to France, Germany and Belgium covering 1500+ "trouble free" miles over many long, steep climbs and equally long and steep, white knuckle descents, with up to 200 miles being covered in a day. 

I had noticed during the trip that some days Ruby flew along and yet others she seemed sluggish and lacking what little power she had.

I have since returning been checking Ruby over, greasing oiling and adjusting as required and found that the front brakes have been sticking on and not releasing.

Having completely stripped the front end I found that the brake lever cams to be stuck in the "Oilite" bush, upon removal I found the bush and cam to be coated in a hard black substance and the bush looked to have been burnt, see top pic attached.

I realise I am showing my naivety here by confessing that I did not know one should soak the "Oilite" bushes prior to their use, in hot oil at very specific temperatures or cold oil for 24 hours or ....... depending upon where you searched, but having looked up the manufacturers recommendations, it did not appear to be required as all "Oilite" bushes are supplied vacuum injected with a minimum of 20% volume of oil??

I have also found that the brakes themselves have only been operating on half the width of the linings, see second pic attached.  I have mentioned this on a previous occasion on this forum and that the tabs that held the shoes square needed to be a close fit to prevent the shoes being pulled out of line by the springs.  Obviously I failed again to adjust them correctly as the shoes have obviously not been sitting square.

Any advice (....or abuse) as to how I correct these issues would be gladly received, I am sure I am not the first to make these errors but hopefully if someone can assist it will help someone else from doing the same in future.

Cheers Denis S

[Peter Naulls]

Denis,

I'm glad you had a successful Eurotour, I'm sure it will have given you a great deal of confidence in the Ruby despite the brake issues.

I can't see your photos for some reason, but in terms of setting the shoes square with the drums, I know some people have a drum with a segment removed in order to see where each shoe is touching - or perhaps get a feeler gauge in to measure for gaps. 

This was my alternative technique: Firstly  I made sure the drums were round, getting a couple of them skimmed by a few thou to correct ovality. I used Saftek bonded linings which were slightly too thick and also had slight variation in thickness; these were also skimmed (on the shoes) to make them absolutely round and the same diameter as the drums. Before fitting the drums I put a line across the inside of the drum with a permanent marker pen. Then fitted the drum and turned with a light brake application, next removed the drum to see where the marker had been scraped away and on which shoe it had been deposited. You can then adjust the tabs to square up the offending shoe(s) and repeat the process. Eventually you'll have a situation where the marker line disappears across its whole width and both shoes are blackened with ink.

I did find that the linings needed to be relieved on the outer edge, just on the very corner as they were inclined to press against the face of the drum and force everything out of line.

I hope that helps. I'll let someone else answer your oilite bush question!

[Ivor Hawkins]

I remember as a callow youth greasing the brake pivot shafts when assembling the brakes on my Ruby and after cooking the brakes after several fast decent of Harrow Hill found them very stiff and looking just like that...I think it may be baked on low temperature grease.

A clean up with a wire brush a good soaking of the oilite bushes and that was that problem sorted.

[Denis Sweeney]

Peter for some reason the I could not attach them in the normal manner and so added them as a word document, which should open when clicking the attachment
But thanks for the comments

[John Cornforth]

Hi Denis

The 1938 handbook, which covers semi-girling braked cars like yours, says "The front wheel brake cam spindle is lubricated from the swivel pin". I believe this to be untrue, and a carry over from the older design where there was a passage to allow grease flow.

The Austin Magazine for November 1936 says "The actual braking mechanism of each axle requires no lubrication, being packed with grease when first assembled which should last indefinitely" Such confidence !

Personally, although I assembled my brake cam shafts with a smear of high temperature grease, I also give the occasional squirt of engine oil to the felt washer which sits in the recess of the brake cam operating lever. This ensures that things are free enough to allow the external pull off spring (on the lever) to do its job and return the lever such that there is no effort on the shoes with the brakes off and the cables slightly slack. This enables the upper adjuster alone to establish the necessary small clearance between shoe and drum with the brakes off.

With semi-girling brakes there is more leverage than the previous designs, partly by virtue of the smaller brake cam heads. The downside is that brake wear has a bigger effect on brake pedal height, so convenient adjusters were used on each wheel to enable wear to be compensated for. Unlike the earlier arrangment, the cables should not need adjustment for a very long time once properly set up.

Bearing in mind the tremendous forces involved, I doubt if your "dry" bush would much impair braking effort unless it were really tight. However, if the brakes drag and heat up, it could easily further dry out the grease and exacerbate the problem.

The shoes are pretty firmly held sideways to the backplate by curved spring tabs riveted to the backplate, which should establish "square on" alignment It would be worth checking that these are still in good shape, and haven't been bent by some long-ago owner trying to remove the shoes.

[frequentflyer]

No substitute for good quality high temp grease. The cheap stuff avoid.

[Denis Sweeney]

Only ever used Castrol LM grease which is the high melting point grease.
But, if my memory serves me right, I believe the “oilite” own data says no grease only oil, but like I say that is from memory.