Rear disc conversion

[allankelly1]

Hi

Yes it was my intention to hang the caliper below the swing arm and use the original torque arm fixed point on the swing arm to add the torque arm

Also had a dig about in the garage and have found the original hanger that came with the caliper

(Just will need a torque arm mounting point adding if I decide to use this)

 


And also have a possibly a remote brake master cylinder



So now that I have a disc on the way I have possibly all the main “bought in”components for this conversion

Once disc is here I will do the final disc carrier design that I will share here for critic and then crack on with its manufacture

Best wishes Al


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[Laverdaroo]

Both of those will lick up a treat, that hanger needs minimal 'nannying' and come up a treat. Are you going to keep the reservoir or go for the HRC 'green tube' m/c 'get out of jail free card' option?
Think theyre about £9 or similar with the kit included on some sites. Might give you a number of different options for mounting, just depends how much modification you need to do to get the desired effect I guess. yo ucan hide it behind the frame rail though if it needs hiding???

[allankelly1]

Both of those will lick up a treat, that hanger needs minimal 'nannying' and come up a treat. Are you going to keep the reservoir or go for the HRC 'green tube' m/c 'get out of jail free card' option?
Think theyre about £9 or similar with the kit included on some sites. Might give you a number of different options for mounting, just depends how much modification you need to do to get the desired effect I guess. yo ucan hide it behind the frame rail though if it needs hiding???

Thats a good option if needed

Thanks for the info

Best wishes Al


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[Laverdaroo]

https://www.ebay.co.uk/itm/Genuine-HRC-Honda-Racing-Corporation-Complete-Rear-Brake-Reservoir-4-Parts-Kit-/114336241932?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338268676&toolid=10044&customid=CjwKCAjwh5qLBhALEiwAioodsz5QQqvqf2gv2nbJ4PAEZ3A0CAFWCPgktpJ5elL3NHQqwP2WOi2uyhoCnqcQAvD_BwE

[Arfa]

Wow Alan, that's quite something for a spot of tinkering, well done.

[McCabe-Thiele (Ted)]

Looks like an upside down mickey mouse mask

You are just being unkind as its a Yamaha Oddjob.

As you have said earlier this is an impressive rear brake engineering project by Allan - it will be interesting to see how it progresses.

[allankelly1]

Hi Ted

I’m not worried as RD owners have thick skins

Back to the main subject yes a interesting project with lots of challenges but looks to be totally practical to do, and a nice one off touch to the bike.

(Plus I don’t have to take the rear wheel apart and try and repair the cracked drum brake cast iron insert)

Offered up the caliper  tonight and found I needed to move the disc out by another 7mm to allow enough space between the caliper inner piston and the disc carrier as I need 28mm between the disc carrier face and the disk to allow the caliper to fit in the gap due to it being a twin piston unit rather than the original plan to use a single piston floating unit




Not a problem and that why I did a 3d print to see if there are any issues before I make the final carrier in aluminium and there is still plenty of room between the disc and swing arm even with the disc moved out by this extra 7mm



The only thing is my plan to use the original caliper hanger is a no go and will need to make up a hanger that has a dog leg to place the caliper in the correct position on the disc that I will most likely design and then print and then offer up to check my design

Still waiting for the correct disc to arrive but once that’s in I can modify the original design and print another dummy disc carrier that include this extra disc  off set  and will include two bearings locations in it (and a spacer tube) like the rear wheel itself as suggested by K2-K6

Lastly so you all know kick starter now sold

Catch up soon

Best wishes Al


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[Laverdaroo]

Loving this!!!

Lppks mint, well done mate.

[allankelly1]

Hi all

Ok like to ask all what they think to my idea

Now sorted out out how to control lateral “float” using an out rigger bearing that is spaced with a sleeve just like a wheel bearing assembly and I will share the final design once I have my pc repaired

Now looking on how to lock the disc carrier in place to stop rotational movement relative to the main wheel hub and have come up with this idea

I have four 30mm diameter”dogs” that will located in the four internal pockets of the wheel hub and under braking they will sit against the four cast bosses for the external rear sprocket bonded rubber bushes thus preventing any rotational movement







But to ensure there is no “slop” in the system (as there will be clearance in the other direction) my thoughts were to create a set up piece so the dogs are correct positioned like this



Then once I am happy I was going to make up some 90 shore polyurethane casting rubber ( like you use for custom engine mounts) and then fill each hub pocket up to the top of the ribs ( just below the original brake drum lining) so the dogs are held firmly in place and you have an inbuilt cush drive

And then to finish the assembly the disc carrier simply bolt onto the fixed dogs as shown with my second generation3d printed disc carrier




There will be no actual flex of the rubber under heavy braking as the dogs are already positioned hard up again the four internal bosses in the right direction direction but this design both solves the disc carrier to wheel hub  drive connection and solves the possibility of mechanical backlash

Also access to the original wheel bearing is not an issue as you simply remove the disc and then the disc carrier

What are people thoughts please?

Best wishes Al


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[SteveD CB500K0]

I've changed the name of this tread to "Rear disc conversion" (was "Rear drum conversion") as someone search for the topic would more likely choose those words.

Steve

[allankelly1]

I'm wondering that if you have access to a 3D printer why not just do an entire hub, saves any chance of something coming adrift under braking.

Wish I could but I  can only print plastic parts

To be honest it all bolts  together like a normal disc brake assembly and just assembly everything with a bit of blue  loctite


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[allankelly1]

Ok

Quick update for those following

Correct  disc arrive today and bolted it to the revised disc carrier ok

All the off sets with the wheel in place look spot on and plenty of clearance for the caliper now I can place it over the disc itself





Next job is to turn the disc down to 230mm from the current size so it is a match  for a Cagiva Mito rear disc (and the pad width then will match the discs face width and then I can start the design of the caliper hanger itself)




Once that is sorted will update the thread and then I will commit to finishing the rear wheel with aluminium production parts with the additional seals and bearing etc

Catch up again soon

Best wishes Al


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[allankelly1]

Hi Oddjob

Yes I would be totally happy to model up a complete hub in SolidWorks but the crunch is the cost for a billet hub

To the cost to have a hub made from a single billet would be I estimate to be at least £800 -£1000  or maybe more based on the one off parts I get made by my local suppliers for work projects

I did look around for an alternative 36 hole rear hub that carries a disc as standard but then you still need to sort out correcting the chain alignment ensure correct bearings for a 17mm axle bolt correct spoke length  etc etc. and again prices start around £200 plus

Due to my access to mill lathe etc and my time is free total for this project for the bought in parts is minimal and I estimate when all done will be no more than £150 all in and the the additional carrier means no major modification to the current wheel

Catch up again soon

Best wishes Al


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[smoothoperator]

Following with great interest, I haven't worked out what your going to attach the caliper to yet. 

[allankelly1]

Going to make up / design a caliper “hanger” that fits the rear wheel spindle and then hold the caliper out at the correct distance a bit like this example where the wheel spindle past thru the big hole furthest away fro the caliper



Here is the same type of set up on my hybrid I am building that is currently under a dust sheet as the little CB400F has stolen my







Then a torque arm will run from the hanger to the original torque arm mounting point on the swing arm


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