Idle thoughts about the GS rear brake

[cheb]

I like the idea of the rear disc conversion but don't think it's worth doing. Has anyone ever tried converting the drum from cable operation to hydraulics? Are there hydraulicly operated brake shoes that small available?

I doubt it's worth doing for the same reasons as the disc conversion, solving a problem that doesn't really exist. But it would look cool to those who like that sort of thing.

 

[B Murr]

I wouldn't bother . seems like an awful lot of effort with some bad side effects such as offset wheel. There must be brake shoes out there with optimal grip and that should be enough for a back brake. I'm always wary of the back brake fearing locking up on wet curves so I'd imagine disk more hazardous for me, but then we are all different and some can ride closer to the edge than me and might like that extra bite.

 

[steve in nz]

Hydraulic brake just been done. Go to advrider.com. Second last page. Prusters bike stinks. Page 26 re rear hydraulic brake. Search inmate Phreaky Phil. He has thread in conversion on his R100gs. Phil has another thread I want one like theirs. Just starting another conversion I think. Cheers Steve

 

[ianboydsnr]

I was thinking of having my shoes relined, with something that is less hard than original,
My drums are like new though
http://villiersservices.co.uk/index.php?main_page=product_info&products_id=146

Phil on advrider is currently doing a disc conversion to a mono,

http://advrider.com/index.php?threads/i-hate-drum-brakes.1195259/

 

[Kenny]

Have to be honest, paralever back brakes are the worst I have ever encountered on a motorcycle !
Guess I'll have to get the sandpaper onto them

 

[Redboots]

Guess I'll have to get the sandpaper onto them

That's the way. Sort of.
I put blue chalk on the shoes, spun the wheel with the brake just dragging.
Removed and filed off the high spot(s). Repeated Ad nauseam until there are no high spots.
It works. I can lock it at 60kph on tarmac... if I want to,

 

[Beemerboff]

On my BSA B44 with the 8" x 1 1/2" single sided brake the conversion is simple - the shoes and cylinders from some Mini's fit straight in!
The Mead & Tomkinson B50 which won the Barcelona 24 hour race had the conversion---.
With the Mini parts there are T shaped double ended cylinders each end of the shoes which ensures that all of the linings are in contact with the drum, which is essential if a drum brake is to reach its full potential, and is difficult to achieve with a cam one end and a fixed pivot the other.
But if some way can be found to to make the pivot end , or the whole backplate, float you can get pretty close.

The schoolboy tip was to elongate the semi circular groove at the pivot end to make it a longer channnel which allows the shoes to move outwards, but the downside was that this allows the brakes to become in effect self servo and markedly more progressive, and it becomes hard the use full power without locking the wheel.
The design of the GS brake lever would score about 1 out of 10 for effective design - it needs to be about 50% longer and the angle of the crank increased from around 20 degrees to 90 so that it gets a straight pull on the cable and this alone will give all the power most people need.

 

[abrasion]

There was a post on here many Years ago about improving the paralever brake. It was all to do with the angle of the cable in relation to the brake lever. The answer was a cut anbanbd shut on the brake lever so the cable operated at 90 degrees to the lever.

 

[Rob Farmer]

Cookie posted this years ago. I think it was a Kiwi who owned the bike.

Getting a disc and hyraulic setup is pretty straightforward its the wheel that's the issue.

 

[markjackson]

My Monolever and Twin shock rear brakes are great and perfectly good respectively (for rear brakes); I just wish the front brakes were half as capable (relative to application).

Both rear drums seem much more powerful than my Paralever rear drum did, so that suggests that the Paralever drum has plenty of potential to perform better? Could it be the cable losing some goodness or just basic leverage-ratio changes needed?

Incidentally, both my twin-shock and mono lever hubs have drums worn near or to the wear limit. Who (UK ideally) is proven, trustworthy and cost-effective to re-sleeve them?

 

[Beemerboff]

https://www.google.com.au/patents/US6112802 - the Alfin process is quite complex so I doubt if any additional liner in an a alfin style drum will perform satisfactorily.
FWIW most cast in liners have a flange at the open end , which can give a misleading impression as to their thickness - there may not be nearly as much metal at the bottom of the groove between the fins!

The problem with the GS brake pedal is easily understood if you compare it with the long alloy pedal found on my 1977 R75/7 and bikes of a similar vintage - there must be a picture of both somewhere on the internet!

There was a thread on ADV where someone asked a similar question about the GS brake, and in an almost unprecedented action, actually listened to the replies and modified the pedal as the other posters suggested .
Hard to believe , I know, but it did actually happen, and the advice was correct and the brake worked much better too.

 

[r100gser]

you can get this off Ebay for less than £20 - and a few brackets and a bit of pipe - it can't make it any worse

 

[markjackson]

https://www.google.com.au/patents/US6112802 - the Alfin process is quite complex so I doubt if any additional liner in an a alfin style drum will perform satisfactorily.

Ta fella... so really I need to keep my rear wheels 'For Sunday best' and look harder for some good hubs with relatively little drum wear to rebuild into wheels (or good whole wheels).

Maybe I'll find some hooked over a unicorn's horn, next to a nice G/S binnacle with all the innards.

 

[solidstate100]

Maybe I'll find some hooked over a unicorn's horn, next to a nice G/S binnacle with all the innards.

The binnicle itself is now remanufactured and available easily (not cheaply tho). The G/S speedo on the other hand.............good luck with that........!

(You can use an r80 one no trouble, its what I have in mine)

 

[markjackson]

The binnicle itself is now remanufactured and available easily (not cheaply tho). The G/S speedo on the other hand.............good luck with that........!

(You can use an r80 one no trouble, its what I have in mine)

Is that the ST one? In which case I have three that could fit: the ST speedo, the KPH Kalahari one and the £15 G/S replica that came from India.

I was looking at the Binnacles at 'Works, 'Bins and Seibenrock, and Seibenrock's top cover & PCB, but it's the bit that sits above the PCB that seems the prob.

Did the ST headlamp fit too?

 

[solidstate100]

Is that the ST one? In which case I have three that could fit: the ST speedo, the KPH Kalahari one and the £15 G/S replica that came from India.

I was looking at the Binnacles at 'Works, 'Bins and Seibenrock, and Seibenrock's top cover & PCB, but it's the bit that sits above the PCB that seems the prob.

Did the ST headlamp fit too?

Not the ST speedo as (from memory) it has idiot lights etc in it - just a standard vanilla r80 one. I havnt done a ST conversion btw (mine was already a G/S) so dont know about the headlight but once the unit is out of the shell I suspect it may be the same as the G/S. And yes the warning light lens holder is still not available (and actually never was available as a spare, even from BMW from new). Mine has been repaired quite a few times now with superglue, the roads here do shake it to bits.....

 

[Packer]

Instead of trying to maintain 1980's specifications why not embrace the 21st century to build a bike that looks the way you want it to but performs the way you dream it could?

Having said that, a good geomtetrically sound mechanical (especially rod) operated mechanical brake has to be at least as efficient as a hydraulic set up.

 

[markjackson]

Not the ST speedo as (from memory) it has idiot lights etc in it - just a standard vanilla r80 one.

This is the creature.

It looks like the Basic one (which is sitting in a G/S style binnacle) from the top, but it's a bit deeper so I'm not sure if the base will foul the ledge inside a G/S binnacle?