Rear disc conversion

[taysidedragon]

I know this is jumping the gun a bit Allan, but when you've finished the rear brake are you going to do an upgrade on the front brake?
I've toyed with the idea of machining a new front brake arm, doing away with the pivot so that the arm is fixed directly to the fork leg mountings, then using a suitable caliper with sliding pins. Maybe a floating disc as well, if available. Braking should be stronger and it would get rid of the pesky squeal! 🙂

[McCabe-Thiele (Ted)]

I know this is jumping the gun a bit Allan, but when you've finished the rear brake are you going to do an upgrade on the front brake?
I've toyed with the idea of machining a new front brake arm, doing away with the pivot so that the arm is fixed directly to the fork leg mountings, then using a suitable caliper with sliding pins. Maybe a floating disc as well, if available. Braking should be stronger and it would get rid of the pesky squeal! 🙂

Allan's bike has already got twin front discs.

[taysidedragon]

I know this is jumping the gun a bit Allan, but when you've finished the rear brake are you going to do an upgrade on the front brake?
I've toyed with the idea of machining a new front brake arm, doing away with the pivot so that the arm is fixed directly to the fork leg mountings, then using a suitable caliper with sliding pins. Maybe a floating disc as well, if available. Braking should be stronger and it would get rid of the pesky squeal! 🙂

Allan's bike has already got twin front discs.

Yeah, I  forgot that. I might try it myself,  but I'll probably need some help. 🙂

[allankelly1]

As Ted said twin upgrade done already with forks, calipers and discs from a cb400n as the calipers are the sliding type (plus a few other changes to fit the required speedo drive)




Big difference

Best wishes Al


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[taysidedragon]

As Ted said twin upgrade done already with forks, calipers and discs from a cb400n and some calipers that are the sliding type (plus a few other changes to fit the required speedo drive




Big difference

Best wishes Al

Looks great Allan. 👍


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[K2-K6]

I upgraded the rear brakes on my Cooper S back in the 1970,s no dual brake circuits on them at the time - the rear drums would lock up really easily after my rear wheel cylinder upgrade - ended up fitting an adjustable brake balancer to replace the existing fixed one mounted on the rear subframe. Worked a treat.

Cars like Triumph Dolomite Sprint had a proportioning valve on rear line that varied line pressure as the rear suspension rose under braking load to keep the balance toward optimum.  If the rear stayed down from payload it could use more rear brake without locking.

Something similar is on some current light vans to do the same for empty vs full cargo.

On a bike, I like the rear quite "dead" so you can don't have to concentrate on it in emergency. Also adjust the pedal so it's at further reaches of ankle position to help prevent ham fisted application from moi 

[allankelly1]

Hi all

A bit more playing with the project this morning

Did a quick design on the pc and printed out my possible layout for my master cylinder operating arm



It retains the original brake pedal mount / pivot unit  and is just a double arm to convert the rotary movement into a linear movement required for the master cylinder operation.

Also the master cylinder arm will have a series of holes in the master cylinder mounting arm side so you can adjust the ratio of pedal movement to master cylinder movement

Lastly as I am using the original brake  pedal pivot unit, I will also solve my brake light switch set up as it will be as original

Now off to design for now a simple back plate that boltsbto the Raask rear-set mount so I can dummy up the full assembly and once happily I can tidy up the design so it looks pleasing to the eye and then crack on with the final parts again in aluminium

Happy days

Catch up soon

Best wishes Al


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[allankelly1]

Quick update

Had a go at designing / testing out the master cylinder mount concept this evening

Not bad for a first try





Need to increase the cylinder movement but this should be a simple case of adjusting the hole position for both the original rearsets bell crank extension part where it mounts the the new lever and the master cylinder mounting position and rotate the master cylinder accordingly but in essence the idea looks ok and no modifications required to the original rearsets

Really made some progress this weekend

Best wishes and have a good week all Al

 


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[K2-K6]

Looks good in concept, obviously gives you real look at fine tuning before committing.

If you look at the changing alignment of the first link it's going toward a regressive ratio as it gets into travel. If you moved the top right pivot (first joint on white link) to halfway between current location and it's main pivot it will move the linkage to a more progressive ratio.

Aesthetically odd at rest as the geometry won't look parallel,  but as the brake pressure gets higher in use it will probably give it more feel as well as giving you more cylinder stroke with just one alteration.

[allankelly1]

Looks good in concept, obviously gives you real look at fine tuning before committing.

If you look at the changing alignment of the first link it's going toward a regressive ratio as it gets into travel. If you moved the top right pivot (first joint on white link) to halfway between current location and it's main pivot it will move the linkage to a more progressive ratio.

Aesthetically odd at rest as the geometry won't look parallel,  but as the brake pressure gets higher in use it will probably give it more feel as well as giving you more cylinder stroke with just one alteration.

Thanks for the input

Yes I think the long arm is a bit to long (copied the original arm) and if I shorten it it will both be more progressive with the knock on effect of increasing the cylinder movement in it current hole position

Like you said plenty of room to develop the correct positions/ ratios so the brake is progressive with lots of feel and.is not a on / off type brake with nothing in between


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[allankelly1]

Evening all

Had a play with the master cylinder set up an now not a million miles away

Ratio is much better and this is a video of the full master cylinder movement verses pedal which in theory will be less with fluid in the system



Also looks less like a mecanno part and more refined in shape and looks and now has added a remote fluid reservoir






Think the next stage is to get a custom hose made from Venhill so I can temporarily fill the system and just see what the final pedal movement is and hopefully the master cylinder suitable or is I need to source a different bore size and if it feels ok as just a bench test I will commit to aluminium parts that will be anodised black so the set up blends in with the Raask mounting plate

Catch up again soon and best wishes Al


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[Laverdaroo]

Awsome Al, my only notice is that master going to catch your heel knowing how feet move about on rear sets? theres still the HRC green pipe option and a lot less faff? Not that I'm biased with HRC or anything

Lovely work on the refinements, looks wicked and will be brilliant in anodised black

[allankelly1]

Hi Roo

At the  moment the master is well in board of the foot peg




But may make up a small cover plate again anodised in black that fixes to the outside of the MC to cover all and will stop your heel catching anything

Catch up soon

Best wishes Al


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[allankelly1]

Ps still may go the HRC route but also love the look of a small reservoir


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[Laverdaroo]

Ha ha, I know exactly what you  mean though