Back brakes

[kapri]

Sorry , flipping axles over to work with reverse rotation is new to me ( not atrike guy) but i know my way round brakes . HAve you flipped the axle and if so have you moved the backplates around ?

To work the rear brakes you need a 5/8 m/c and a minimum of 4:1 ratio ( as Old Newbie said )though 6:1 would be better a sit will give even more line pressure and slightly more pedal travel ( and so easier more controlled braking ) . I'm not plucking figures out of the air on this or guessing, been on training courses etc

That set up will provide enough line pressure and volume to make them work IF the rest is set up correctly . The pushrod has to go into the m/c at a certian angle or you will lose line pressure due to vectoring .

If you haven't rotated the brakes backplates side to side and top to bottom then the brakes WILL be crap as leading shoes and edges will be all wrong.

A photo of your current pedal set up and rear of rear brakes wouldl help.

[BikerGran]

Got reliant drum brakes on my Kwak GT550 trike, they lock the rear wheel no problem!  I have a Girling ⁵/₈ master cylinder (landrover sorta thing).  You can just about see it at the bottom of this pic.

[Olds]

Agree with kapri, a pic of the linkage set up when using the "Triumph" Girling master would be helpful. At 5/8" it should be OK if you have suitable linkage ratios.
 Personally, I prefer a direct acting setup (pedal to master) but realise on conversions this isn't always easy to do.
One other point worth mentioning, If you are not using flexibles on the slaves, (Reliant didn't) then the brake pipes should not be clipped or fastened to the axle/frame, within about 16" of the slave cylinders, to allow flex and the cylinders to slide in the backplates.

[tbone]

O,N, Ratio aint got a clue but I just welded an extra inch on the lower side of me pedal cos someone sez it might help but trying to bleed the brakes I cannot get any pressure.

Welding an extra inch on the bottom will reduce the ratio, not increase it. You can read about ratio here........http://www.mankymonkeymotors.co.uk/forum/index.php?topic=8335.0

[tbone]

A quick google seems to show that the stock pan european rear master cyl is only 1/2" bore size.
This gives a surface area of 0.196 sq inches
300psi (working on 50psi pedal pressure @ 6:1 ratio) / 0.196 = 1530 psi = plenty of pressure but may impact volume of fluid working on the wheel cylinders.

[Olds]

A quick google seems to show that the stock pan european rear master cyl is only 1/2" bore size.
This gives a surface area of 0.196 sq inches
300psi (working on 50psi pedal pressure @ 6:1 ratio) / 0.196 = 1530 psi = plenty of pressure but may impact volume of fluid working on the wheel cylinders.

I think that it also has a short stroke. The 5/8" Girling in front of me, has a stroke of 1 1/2" (38mm).

[terry t]

Terry YES those are exactly what I fitted last summer,

When you changed them, did you make sure they moved up and down freely before fitting the brake shoes

[scannerzer]

on your linkage you can you an idler to change ratio or direction of pull etc to get your girling type m/c positioned where it will work

[shadowryder]

Argh so many numbers,I cant do numbers
right I done a sketch of my brake pedal set up its terrible but shows roughly how set up.
now its all in straight line with about 2ft bar between pedal and M/C{Red}
to use L/rover M/C I have to rig up a linkage and levers from front of bike virtually to back axle and there is 2 much play and leverage doing wrong things for it to work.
hope you can see my scribblings ok.

[scannerzer]

how heavy is the bar 2ft seems quite a lot when the bar is in compression.have you watched if it flexes when you press hard on it? move it to above the pivot and use an idler to change direction and height,may also work for the l/rover mc

[shadowryder]

Bar does not flex,but there is some movement where bar is bolted to M/C rod.

Sorry do not know what you mean by an idler.

[tbone]

Well from your picture, the original pedal looks quite long, thats good.
You need to change the master cylinder. Larger bore to increase fluid volume n longer stroke to push the fluid further.

[kapri]

Why is the m/c on the back axle ? If it connects direct to the pedal you can see what is heppening ,no pushrods or idlers required ?

[Olds]

Possible set ups if you have to fit the master to the rear.
1 is a definite no no ! but I have seen it tried.
2 is sort of ok if the rod is not too long.
3 is the safest.

[Olds]

A better solution is something like this. It would keep the MC clear of the exhausts & make checking easy. Perhaps on a bracket mounted on the foot peg/brake lever mounting.