Hello, I have two questions regarding brakes (of course) on my RP 1933.
1) On full lock, the end of the cable on the wheel on the outside of the turn bends by 15 degrees or so (see photo) This appears to me to be most odd, but perhaps it is by design. I would have thought the cable bend would contribute to brakes binding on full lock?
2) the front brake levers (short), angle forward towards front of car by 15-20 degrees or so, definitely NOT in line with King Pin....presumably the major cause of my problem with binding on full lock.
When I removed the brake lever, (Nut on cotter was to front of car) the flat on the brake cams (actuators) seems to me to be at a very steep angle (see photo). When the cable is disconnected, and brake pad ends lie flat against the cam faces (ie brakes 10% off) the brake lever adopts an angle of 40 degrees of so (estimate) to the front of car.
I would have thought with the cable disconnected that the ball on the lever would have naturally been almost in line with the king pin? but obviously I don't fully understand the design of the brakes sufficiently.
I am a relative novice with A7's so any information or advise will be gratefully received, no matter how basic or obvious (to the experienced)
The brake cams are handed, so they may have been put on the wrong sides.
The cotters are angled, and can be put in from the front or the rear - this changes the final position of the ball on the lever end in relation to the kingpin.
Modifications to the brake shoe pivots or the shoes might have been done, though unlikely.
The brake levers might be worn or bent.
So you have a bit of trial and error inspection to do.
The design rarely works perfectly, but yours does look to be set up incorrectly.
My first action would be to check the cams, swap them over to see what difference that makes.
Unless one side is ok, in which case you have (say) two left handed cams.
What does the set up at the rear axle look like?
If different each side, the cams are probably mixed up.
I’ve just read Simon’s response which I think is spot on.
I’ve had your first problem in the past and found that the connection at the end of the cable does not move freely on the ball of the lever. Different suppliers have different designs for the end cap and I’ve found the cables with a round ended cap seem to fit better. I think you need to do a closer inspection of this area and check that the cable end cap is not binding on the straight part of the lever.
Although the angle of the lever looks quite steep it does need to take up a little slack before the drums start to bite and this may put the lever closer to vertical under the king pin.
Unfortunately a good look at the brakes, including removing the cams does entail completely stripping the hub.
The levers should always be working towards the vertical position to ensure maximum leverage, never away from it. If the lever is vertical to start with, in line with the king pin, the brakes will be less effective the further they are pulled on. The amount that the lever is inclined is dependant on the cam and the shoes.
The brake cables and cams look like modern replacements, sometimes these are too stiff/not properly fitted/require fettling. That's why the cable is bending, which you have correctly identified as a problem. The cable should be a good fit on the ball of the lever at all angles and the components may need to be fettled to achieve this.
Hi Novice
The pre girling brakes are especially basic. Ideally the ball should be vaguely under the kp when operated but with no adj the position varies thru lining life. The direction of the cotter gives some adjustment. Without incurring drag and premature front op when turning, it is not realistic to aim for very short pedal travel as a modern
At a guess I would say that by far the most likely cause is the end caps not swivelling fully on the ball of the lever. If they are modern replacements I would get hold of a couple of originals and try them before doing anything more involved.
If the levers are pointing forward, that is correct, although the degree of angle may not be. If you swapped the cams over they would be pointing rearwards, definitely incorrect. If you had two cams of the same hand one lever would be pointing forward and the other rearwards, very obvious and most definitely not correct!
The ball of the lever should be facing the backplate, not away from it. I would check these points out, good used original end caps may be available from the cherished suppliers if you are stuck for them.
What Parazine said.
I played with mine when I put on new linings and I set up so that the levers were about 10-15 degrees away from vertical. Then about 5 degrees is taken up in the slack when pressing on pedal and some of the rest is taken up under pressure of brakes applied, so they never quite get to vertical where leverage is progressively reduced. I was very pleased with results from both new pads and set up as braking was markedly improved.
I had previously replaced the cable with a replacement from David C which fitted well but yes also agree that it should move smoothly and not catch.
Andy B
The A7CA archive contains technical drawings originating from Longbridge, including one of a later (semi Girling) front end. One can measure the angle of the brake lever which is circa 12 degrees of "lead"- I just used a protractor on the screen. Looking at your photos I think it is probable that your brake cams are machined correctly but I have come across after market brake cams in the past that are machined with a much greater"lead", indeed I have two such in my possession.
It is also my experience that small differences at the operating end of the system have a large influence, so it may be worth reversing the cotters.
I had forgotten that - quite a bit of filing was required on mine to guarantee the free movement of the cap on the ball.
And, if we are talking about replacement parts, they may fit straight away - but they may not.
For example: when I replaced a brake cam like yours I had to adjust the outer diameter of the bit that meets the backplate, the backplate is recessed and the cam wouldn't go in.
Also, it was tight on the brake shoe, which had to be adjusted.
The lever had to be eased before it went on the cam spindle, and before that happened I had to open up the hole for the cotter.
And after that, the end cap of the cable.
Not a lot of work, really, but if you haven't worked much on these cars before, you might think you are doing things wrongly.
