Installing a Front Disc Brake on a Series ‘C’

highbury731

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The most powerful drum brake of all time is the duo-servo brake.

View attachment 21333
It was not a popular brake, but it is superior to double twin leading shoe brakes in performance. It is considered a single leading shoe brake by racing organizations. It is not very popular because it is wildly unstable, but if set up properly it will probably out-perform a big twin disc. This brake design was also used extensively in cars and hydraulically operated.

David
John Surtees had one of these Seeley front brakes on the front of a Vincent. I have been wanting to find out how the brake shoes and adjustment were designed on this hub. A quick internet search reveals that Molnar offer them, a snip at £1850 + VAT..... I have seen replica Ceriani 230mm 4ls brakes offered for a very similar sum. Are the Seeley brakes really comparable?

FWIW this arrangement of linked brake shoes can be found on bicycles for small children, usually Continental ones. They are very good for small hands without much strength.

Paul
 

bmetcalf

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air scoops struggle to capture much cooling air as the front wheel is splitting airflow and deflecting air

Here is an elaborate scoop arrangement on EBR 1190's:

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vibrac

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Almost the diameter of the stirrup rim brakes on my 1925 Douglas:rolleyes: now you really have to plan your stopping distances on that
I do have an upgraded the back brake though - the shoe that rubs in the belt rim it was once a mahogany chair leg:eek:
 

vibrac

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Now that it becomes clear that fitting a disc brake is not a substantial modification as far as the 40 year mot is concerned I can revisit this subject.
For a comet it would seem from the above that a single disc with a matching caliper and lever mounted on the LH side with a plate and Speedo drive on the RH side is the way to go (however if you have tried that and decided double is better even for a comet let me know)
if anyone has details of this mod pictures plans etc of a working installation it would save me and anyone else on this path some time to say the least.
i have a new steering stem girdraulic fork installation a lathe and a mill
 

BigEd

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Now that it becomes clear that fitting a disc brake is not a substantial modification as far as the 40 year mot is concerned I can revisit this subject.
For a comet it would seem from the above that a single disc with a matching caliper and lever mounted on the LH side with a plate and Speedo drive on the RH side is the way to go (however if you have tried that and decided double is better even for a comet let me know)
if anyone has details of this mod pictures plans etc of a working installation it would save me and anyone else on this path some time to say the least.
i have a new steering stem girdraulic fork installation a lathe and a mill
Dear Tim,
I have sent you an email with a link regarding a conversion.
 

timetraveller

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Would you chaps copy me in on this please. Someone who bought one of the new steering heads has left me a set of girdraulics, a front wheel with purpose made 320 mm discs and the hydraulics. He would like me to design, and get made, all the bracketry. It would ease the pain if we could come up with a design suitable for more than one person. Note that the discs were made specially to fit the Vin hub.
P4130261.JPG
 

Peter Holmes

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I missed getting one of the Dave Lambert kits, when I decided that I wanted a kit Dave had just sold his last one, no amount of pleading would cajole him to make just one more, I think Dave's kit was Honda 250N based. I have always thought that it would be great if there was a source we could just go to a purchase a tried and tested kit, I am sure 10 kits would sell immediately, maybe even 50, over to you Norman?
 

davidd

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Norman,

I think a universal design is a little difficult, but you look to have a very easy set-up to work with. I would do a variation of this:
Disc Caliper to Girdraulic.GIF

This is a flat plate. The lower hole is the axle hole. The plate thickness here is the thickness of the E80 nut and the stock brake plate thickness together.

The hole directly above the axle hole is the brake anchor. I put a SS bolt through hear and used it to bolt the plate in place. The curve in the outline of the plate, above and to the right of the anchor is to clear the lower spring box mount.

The remaining two holes are the caliper mounting holes. They were close to the blade on this design, but on yours, it is such a big disc that you have plenty of room to the left. I would keep the caliper close just to minimize the weight of the plate.

Finally, I milled the back of the plate to get the calipers to align properly with the disc. I think I used an overly thick plate that put the calipers in the right place and milled the remainder of the plate to the E80 nut and brake plate thickness. You may want to try out a flat piece of aluminum to make a fitting to calculate the caliper mounting offset relative to where the E80 nut and brake plate thickness are located. I used 4130 steel for the plate itself. I probably could have used 2024 aluminum, but I was being conservative.

It looks to me like the caliper in the photo is in a good place for the plate right now. The spring box is a little further forward when mounted on the eccentric, so I would move the caliper a little further forward.

Thus, the plate is in a fixed position and a fixed thickness where it replaces the brake plate and nut. The thickness of the rest of the plate will have to move slightly in or out depending on what the calipers want.

David
 

timetraveller

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Thanks David. This was not a project I was looking for. The owner left it with me to get someone else who has both machining and design facilities to sort it out. Unfortunately after two days that person asked me to take it away so either I do it or it gets abandoned. I like the fact that the owner got the disc manufacturers to make the disc specifically to fit a Vin which should allow a neater job but I am still trying to wind down the steering head job, it turned out to be 60 in the end, giving a five year total of about 140 out there, and I would like to get my own bike on the road. The old adage used to be "so many girls, so little time". This has now tuned in to "so many jobs, so little time". Could this be old age??o_O
 

vibrac

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Thank you all for the input on and off forum my thoughts are firming up round Half of a Kwaker disc I will feed back but it will be some time as mid season is a busy time
 
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