Agree with Terry and Ian. There's nothing wrong with standard brakes other than excessive wear and incorrect adjustment.
Feb 27, 2017 - 10:03AM
Re: Bowdenex Brake Cable Refitting
However, if you are committed, if there's enough spare length, you could get the extra inch you want on the inner cable by shortening the outer by a similar amount.
Austin in the shed
Mar 5, 2017 - 9:19AM
Re: Bowdenex Brake Cable Refitting
I have bowdenex brake cables on the front of a special and they are pretty useless,as others have said drag in the cables and weak outer cable brackets contribute.
Has anyone tried Twin leading shoeing or self servoing or similar to improve the brakes and are prepared to share their knowledge ?
I can't see how you can TLS an A7 brake as the king pin boss gets in the way,only self servo.Looking on a bike web site someone had altered a BSA gold Star SLS but from what he says it was probably prone to snatching when applying the brake.
I hoped for curiosity if the 7" brakes can be improved without grafting on hydraulics.
As Peter mentioned I manufactured a TLS conversion for my special but it uses few original parts. The reason for having four shoes was to make use of a motorcycle component that's available in the correct diameter.
The car is nearly finished but I've yet to try the brakes!
I am surprised at the lack of enthusiasm for the Bowdenex conversion. Over the years I have run three Sevens with Bowdenex brakes, and my rose-tinted spectacles suggest they were the ones with the best brakes.
Sorry, Alan, 'nothing' wrong with standard brakes? I'm not an engineer, but surely there are at least two fundamental things wrong with the standard brake design?
Firstly, with a pendant brake lever pulling backwards, any twisting of the king-pin inclination due to braking effort results in a negative servo effect, requiring an increase in pedal movement/pressure just to maintain existing braking. Secondly, pulling the brake lever with a cable running at 45° to the action of the lever is just plain bad design; it's bad enough when the steering is in the straight-ahead position, but on full lock the outer wheel requires the cable to pull at almost 90° to the desired movement (incidentally, has anyone ever tried cables operating round pulleys fixed to the back-plates, as used on Riley Nines, which would alleviate this problem?).
The Bowdenex conversion successfully addresses both of these problems. To condemn it because of stiff cables resulting from poor maintenance is hardly a fair criticism.
If anyone is thinking of discarding their Bowdenex system as a result of this thread, I am only too happy to receive their unwanted scrap!
I have kept quiet so far but I will come out as one who finds Bowdenex perfectly satisfactory when correctly fitted and maintained.
A really common experience with existing installations is to find that a former owner, faced with a grease nipple on the outer cable, has greased it. Fatal! Hanging up the cable and treating it with a hot air gun for a while helps no end with the cable drag induced by the grease. And as Michael says, it overcomes several small nastinesses.
I am the first to admit that a well set up standard system with soft linings and a suitable flexible brake cable can work very well.
Have you tried taking the drums off, pulling the brake levers on to 90deg to refit the clevis ends, (might also help to remove the bracket from the cross member and feed the outers in before refitting) then release the levers and refit drums. Just a thought.
Just a thought regarding Bowdenex type brakes, Many if not most modern hand brake cables have an inner liner of either nylon or ptfe type material in their construction to ease the friction. has anyone tried these as an alternative to the original steel cable within a steel sheath.
The Bowdenex that came with our Type "65" was more than a little sticky. Washing it in solvent and running oil into it improved the action somewhat, but a close inspection of the cable showed flat spots on the weave or braid of the cable, which was causing a lot of drag inside the outer housing.
We took the cables into our local Cableman who made up suitable replacements, Dad machined up some new fittings and the result was so good that we made another set for our single seater special which stopped really well at the Simola Hillclimb last year.
Currently close to completing a new supercharged single seater, we've had a third set made for it and I'll run them in at Simola this year.