Soggy rear brake Series 3

[Les McLean]

I know this has been probably been done to death on the 'old' forum, but I'm struggling to sort out a spongey as anything rear brake.

I had a GP200 engine fitted into my S3 Li125, everything running fine except the back brake.

I've tried the usual 'fixes'

- Made sure the cable is tight to the footbrake
-replaced the inner/outer cable to correct length as detailed in Spanners
-replaced the inner cable with a quick adjust threaded cable
-tried different brake shoes (li/gp)
-lightly sanded the hub

I noticed that both drum brakes are making contact with the hub, with no obvious 'clean' patches.

If I adjust too much, the wheels lock on, If I back off the adjustment a turn or two , the brake is spongey as anything?

Any pointers to where I should look next?

Thanks

[Paul Slack]

is the rear wheel running true?
Is there any play or too much play?
How does the cone look?

[Les McLean]

Rear wheel running true, no play on cable (I think this is what you mean), and the cone looks fine (it's new)

[grandpa]

Hi,
Have you any play in rear wheel bearing i.e can you rock the rear wheel
Had this on my Gp and it was brake shoe friction material coming adrift from the metal shoe. sent shoes back and fitted Makino.
Grandpa

[Mark ULC]

When you say spongey what do you mean? Does it lock at all or drift on when the pedal is full to the floor? If it is an Indian gp then the two spigots holding the shoes are rarely true causing the brake shoes not to engage correctly on all areas of the drum. This was my problem and fitted the Jockeyboxenstop thingy magigy and after a bit of setting up it worked great.

[Les McLean]

When you say spongey what do you mean? Does it lock at all or drift on when the pedal is full to the floor? If it is an Indian gp then the two spigots holding the shoes are rarely true causing the brake shoes not to engage correctly on all areas of the drum. This was my problem and fitted the Jockeyboxenstop thingy magigy and after a bit of setting up it worked great.

It drifts on when pedal is full to the floor, I saw a mention of the Jockeyboxenstop thingy during googling of the problem, but couldn't find any UK suppliers?

Hi,
Have you any play in rear wheel bearing i.e can you rock the rear wheel
Had this on my Gp and it was brake shoe friction material coming adrift from the metal shoe. sent shoes back and fitted Makino.
Grandpa

No, just tested , and definitely no play in the rear bearing.

[Mark ULC]

Les, my symptom was that when the pedal was down it would lock but if you pushed the scoot forward with the pedal down, the wheel would rotate being free then lock then free. I had the hub machined true but still the same as the brake does only bit on part of the hub. The jocky thing is one spigot with an adjustable cam to change the orientation of the shoes to allow more contact. I ordered direct from Jocky's.

[itisgonnarunproperly]

Have a look at the shoes themselves, I think that one has a leading edge ie: front of the lining comes down further than the other, that is the leading edge and needs to be on the top so more of the shoe lining is in contact with drum when brake applied when wheel is turning anti-clockwise, if I remember rightly, nothing to loose by checking

[Les McLean]

Have a look at the shoes themselves, I think that one has a leading edge i.e.: front of the lining comes down further than the other, that is the leading edge and needs to be on the top so more of the shoe lining is in contact with drum when brake applied when wheel is turning anti-clockwise, if I remember rightly, nothing to loose by checking

Thanks for that, I checked, and the shoes were installed correctly (more through good luck than good fortune )

Les, my symptom was that when the pedal was down it would lock but if you pushed the scoot forward with the pedal down, the wheel would rotate being free then lock then free. I had the hub machined true but still the same as the brake does only bit on part of the hub. The jocky thing is one spigot with an adjustable cam to change the orientation of the shoes to allow more contact. I ordered direct from Jocky's.

Another thanks, I think I may be getting somewhere, I realised after reading all the constructive replies, there wasn't a quick fix to the problem. So I persevered with the issue , gently adjusting, moving the actuator spline a couple of notches. Still a bit soft, but a lot more responsive than previously. I've got around a month till it's MOT, if I haven't sorted it over the next week or so (and it stops bloody raining), then I'll order a set directly from Jocky's.