Reverse Pull a Brake or Not!

[alex_hughes]

Also interested in what Storkfoot asked, what milling operation is required to correct circlips escaping? And how do we decide that milling is required please? Ta

[nsaints]

I hope this isn’t going off topic

Any forum conversation is good by me

The CamLam disc brake cable arrived as I was just leaving for a weeks holiday
I did get a chance to measure it and it’s 2.5mm

Next is it made of the correct type of Bowden cable per Dickie’s point
I wouldn’t know what to look for, but, I’ll compare with my GP’s brake cable when I’m back.

[Rich Oswald]

I may be way off with this suggestion but could you utilise one of the 3 position UNI clutch levers that AF use for their clutch conversion?

[dickie]

I hope this isn’t going off topic, Nsaints was referring to a standard disc brake and obviously substituting brake lever for clutch lever is referring to standard drum brakes, which of course can also be reverse pulled.

For reference, a standard Italian lever, a Spanish lever, and a standard clutch lever.

That the clutch lever bends the wrong way is worrying me! And I’m not sure how you’d cable it up, because it’s narrower at the end. I guess there’s a way





Mr B sells shorter clutch levers, same length as Spanish, but also bending the wrong way.

The Spanish lever is going to get a trial on my S1 tomorrow. Didn’t even know I had it!

I'd forgotten about the cable being too thick for the clutch lever as well. I just ran a slitting disc through the slot to widen it.

As you say, it bends the wrong way too, but I just bent it in the vice and it was fine.

The best reverse pull drum I've had (and I've tried all the variants I can think of) was this:
LI cam, standard cable reverse pulled, and Spanish brake lever.

The worst ever was with a GP cam. This made it so harsh that it was almost unusable.

[dickie]

I think it's also worth remembering what storkfoot(?) said in another thread, that his reverse pull drum suffered badly from heat fade in the mountains of somewhere or other. I tend to just knock about locally, but if I'd done the c2c last weekend as intended, I wonder how well I'd have coped coming down from hardknott?

[Storkfoot]

I think it's also worth remembering what storkfoot(?) said in another thread, that his reverse pull drum suffered badly from heat fade in the mountains of somewhere or other. I tend to just knock about locally, but if I'd done the c2c last weekend as intended, I wonder how well I'd have coped coming down from hardknott?

Yes. Happened to me twice whilst abroad in the heat. Disc pads are significantly less prone to heat fade than brake shoes in my experience.

[Fast n Furious]

It could be that the actuator rentention circlip is weaker on the SX and is flexing outward more under braking, giving you a spongy, full travel brake feel.
A simple visual inspection of the clip whilst pulling in the lever will confirm if this is a contributor. If the lever moves but the actuator doesn't, then the springing is in the cable
I would advise against using stainless circlips here as these do stretch. Just use regular carbon spring steel ones.
Make sure that the circlip groove is completely free of paint, so the circlip can sit in the groove as far down as possible. (I use a little wire brush attachment on my Dremmel)
The circlip groove does suffer over time on Disk brakes that have seen their fair share of service. The constant eccentric force applied to the groove wall by the circlip, causes the outer wall of the circlip groove to bevel. The more it bevels, the more the clip will "spring" laterally under braking.
There is a solution to redressing this issue but it involves a milling machine.
A modern quality front brake cable these days is 2.5mm and well worth fitting. The bigger the cable the less is the stretch.

Over the years I've heard many myths as to reverse pull or not. The only reason I can see to favour reverse pull is because the cable is slightly shorter and has less bends in it therefore making it more efficient.

What’s the remedy with the milling machine please, F&F?

I’ve had a circlip pop off under braking. The circlip, I later discovered, was substantially thinner than the spare one I replaced it with but I can’t be sure that was the only reason it came off. The disc hub is an original Italian with virtually no paint left in the groove.

It's been alot of years since I did one of these and if memory recalls correctly, it's a faf of a job.
The hub casting was chocked and clamped down level onto the mill bed.
An adjustable boring tool with an adjustable tool tip was set up and centred on the circlip area.
The mill I last used for this belonged to a friend of mine and it was fitted with an inverter drive on the motor so the tool could be turned at a very very slow speed. If I had to do it again, I would consider clamping the hub down on the bed of a pillar drill and just turn the chuck by hand because it only needs a slight scrape to restore the circlip wall.
The circlip should be 42mm (under tension) x 1.75mm thick. Unfortunately, there isn't enough metal around the circlip groove to consider an alternative size of circlip. It's a very poor design and little can be done to improve it.