Do Airheads have brakes?

[fatbaldbob]

I have recently become the owner of a 1978 R80/7, it been built as a cafe racer and fitted with rear sets, my question to the collective is: should I expect the bike to have brakes?

It has twin discs on the front, cable operated to the master cylinder under the tank then braided hose to the calipers, standard setup I think these are just about adequate but by no means good. The rear is my main problem, it has no rear break at all, I thought at first perhaps the pads were knackered or contaminated etc, so pulled the wheel off and they are pretty much as new, not glazed and the hub seems fine too, all the linkages work as they should, basically the whole system works as intended but no matter how hard you push the pedal at best it might slow you down a tiny bit, but it's bearly noticeable in fact it would struggle to hold the weight of the bike and rider on a hill, it cannot stop the bike at any speed. I thought perhaps it may be the rear sets which probably give less leverage ov the standard pedal. Also the actuation arm from the hub is straight up as opposed to straight down, to suit the configuration of the rear sets, in theory I don't see that this would have an adverse effect.

So am I expecting too much from a 36 year old bike, are the brakes naturally crap, is it the rear sets? Any ideas on a potential problem or method of improvement gratefully received. As said before it works as it should but just has no braking power.

 

[MikeO]

Airhead brakes tend to work chiefly in an advisory capacity and are a great way to encourage forward observation and planning.

I have a MC on the handlebar of my 83 RT and the front brakes are OK - the rear isn't as bad as yours, but isn't anything like as good as a modern rear brake. I'd have a look to see if the rear hub is cracked, while you're investigating - I seem to remember it's not an uncommon fault...

 

[Paul S]

I remember buying a brand new R100GS in the late eighties - the back brake never had any effect in slowing down the bike

 

[(RIP) Proff]

Do Airheads have Brakes ?



You're having a Giraffe ain't ya ??

best Airhead brake is the throttle and drop a couple of gears

 

[Edward]

I can't make out from your post if you have a rear disc or drum. If it's a drum and the 'pads' look new then they will need time to bed in. I have airheads of both types and the rear brakes are absolutely fine, controllable,progressive and either will lock the wheel should I want to. I think there is clearly something amiss with yours.

 

[fatbaldbob]

It's a drum brake on the rear.

 

[(RIP) Proff]

post a pic of the back brake set up,,
I've an idea, but need a pic

 

[tuftywhite]

Do Airheads have Brakes ?


best Airhead brake is the throttle and drop a couple of gears

Another aid to stopping is to sit up straight.

 

[Flipfly]

It's all part of the charm

Anticipate your escape route and use it if necessary

 

[fayeslane]

The term 'bearing heater' springs to mind They do an adequate job of this.

Spend some time with some chalk and a file and reshape the shoes until you have 100 per cent contact between the shoes and the drum. This can make a noticeable difference.

 

[ianboydsnr]

My r80 Rt has excellent brakes, and it's a single disc front!

 

[DrFarkoff]

Mine Does but there are more bits to added to frame yet!¬ #

 

[Captain Black]

I prefer to think of my airhead brakes as a sort of comfort blanket, your know the one with perforations in it and the nice feeling silk trim around the edge.
Very comforting but in any event still pretty fecking useless.

 

[fatbaldbob]

post a pic of the back brake set up,,
I've an idea, but need a pic

I'll try and sort a pic tomorrow, but so far it would appear I'm being over optimistic!

 

[Beemerboff]

I don't think the cam works backwards - someone sells a cam which does, probably HPN , so you are going to have to wait 14 months to get an answer to the phone then a bit of a delay with the order.

The long twin shock brake pedal works much better than the shorter mono and para ones, so the rearsets will cost you something.

IMHO the best way to bed in brakes is to use them - bonded brake shoes are usually ground to the correct radius after bonding, but sometimes they end up too thick and the cam doesnt get any leverage on them - only answer is to have them skimmed by someone who knows what he is doing, on the backplate, to fit your drum, and setting up the backplate on the machine tool can be a slow job , DAHIK , but the results are worth it

Contrary to popular fable a handlebar M/C doesnt improve things much at the front, unless you can find a 11 mm master cylinder, or your existing set up is stuffed.

Just get used to squeezing it hard.

 

[Garry H]

Do Airheads have brakes?


NO

 

[fatbaldbob]

Photos

As requested heres some photos of the set up:

 

[ken brooks]

as beemerboff pointed out, you would need a special cam in the hub, because it the brake arm is 'up' instead of 'down' youre trying to turn the shaft in the wrong direction!

 

[fatbaldbob]

as beemerboff pointed out, you would need a special cam in the hub, because it the brake arm is 'up' instead of 'down' youre trying to turn the shaft in the wrong direction!

I initially thought that too, but looking at the cam ( from inside the hub) it appears to be the same profile on both sides, so I can't see that it makes a difference down or up

 

[Myke Rocks]

Sorry to prick some bubbles, but:

As the late Denis Thatcher once said:
It is better to keep your mouth shut and be thought a fool than open it and confirm their thoughts.
On to your brakes. (Not breaks)
As has already been stated, the twin disk with cable to master cylinder under tank front brke is purely advisory. A new cable may help, but unless you put a master cylinder on the handlebars, that is as good as it is going to get.

Rear Brake. You have two problems here: Geometry and geometry.
Geometry (1)
Not as bad as it could be, but nevertheless there.
For the best possible brake operation, the front and rear fulcrums should have the two arms at 90 degrees to the operating rod when the brake is applied.
Looking at the pictures, it is likely that the arm on the brake drum will match this profile, but the front one will be well past the 90 degree point. Given the error in geometry(2) this will probably do no harm at present, because it reduces the effective length of the front arm a little.
geometry(2).
The person who built this rearset had his or her head firmly up their own arse, with no knowledge or understanding of mechanical advantage or braking.
The front arm is approximately the same length as the rear arm. As a result, the mechanical advantage is zero.
Most mechanical rear brakes have a mechanical advantage of better than 2 to 1 and maybe 4 to 1.
How do you achieve such a mechanical advantage?
Shorten the front brake arm.
Currently, the front arm is circa 100mm long at a guess and the brake rod is attached to the tip of it. Drill a series of holes down the rear edge of it whereby the brake rod may be moved down to say 50mm from fulcrum, or 25mm from fulcrum, and try these. You will soon see the effect of the change when you try it.
Myke