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Rear disc conversion
K2-K6:
--- Quote from: Macabethiele (Ted) on October 31, 2021, 10:07:01 AM ---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.
--- End quote ---
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 :D
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:
--- Quote from: K2-K6 on October 31, 2021, 08:22:16 PM ---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.
--- End quote ---
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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