Shimano RS505 free-stroke adjustment - how???

gweeds

Has anyone done this - mine have more travel before they bite than I'd like and I can't see how they adjust......

dj58

Adjustment is covered on page 65 of the Shimano Dealer Manual DM-BR0008-08 ENG.pdf
Check the tick box then select the download button.
http://si.shimano.com/#/en/search/Compo ... lic%20Disc)

gweeds

You star - sorted. Thanks very much

comsense

Gweeds wrote:

Has anyone done this - mine have more travel before they bite than I'd like and I can't see how they adjust......

Did you set piston travel with the Red Spacer?

I spent ages trying to get decent travel before I found that out. I must have bled the brakes 10 times. Once I realised you need to put the the Red Spacer in between the pistons and work the levers a few times to set travel ( obviously with the wheels out...) I got a firm lever immediately. I then tried a plastic credit card and this improved lever travel further. I now have the one fingered braking I was dreaming of

gweeds

comsense wrote:

Gweeds wrote:

Has anyone done this - mine have more travel before they bite than I'd like and I can't see how they adjust......

Did you set piston travel with the Red Spacer?

I spent ages trying to get decent travel before I found that out. I must have bled the brakes 10 times. Once I realised you need to put the the Red Spacer in between the pistons and work the levers a few times to set travel ( obviously with the wheels out...) I got a firm lever immediately. I then tried a plastic credit card and this improved lever travel further. I now have the one fingered braking I was dreaming of

No - but these are already on the bike so I don't have them....

comsense

Gweeds wrote:

No - but these are already on the bike so I don't have them....

Try 2 old credit cards or loyalty cards instead - any clean plastic aprx 1mm thick, that is total 1mm, will do. Just put them between pads and work your brake lever until the pads close up to the cards. Then put your wheel in and see how your travel is. If you like you can then try a single card - this was optimal for me. I think a card is .5mm thick. Anyway, with mine the end result was fantastic and night and day compared to before I tried this.

gweeds

Will give that a go tomorrow. Thanks very much!

comsense

Any Luck?

mugensi

comsense wrote:

Gweeds wrote:

Has anyone done this - mine have more travel before they bite than I'd like and I can't see how they adjust......

Did you set piston travel with the Red Spacer?

I spent ages trying to get decent travel before I found that out. I must have bled the brakes 10 times. Once I realised you need to put the the Red Spacer in between the pistons and work the levers a few times to set travel ( obviously with the wheels out...) I got a firm lever immediately. I then tried a plastic credit card and this improved lever travel further. I now have the one fingered braking I was dreaming of

I'm typical of those who never read instructions and then wonder why things don't work the way they do. I have the red spacer but hadn't a clue what it was for and was too eager to get the bike on the road to look up what it was for, anyway, I nearly have to pull the lever full way in towards the handle bars before I get the brakes to bite fully so you have answered what the spacer is for however I'm curious as to how you used a credit card...if a card is only 0.5mm thick and the disc is much thicker, then surely spacing the pads 1mm wont leave enough room to fit the disc back into the caliper again?

comsense

MugenSi wrote:

I'm curious as to how you used a credit card...if a card is only 0.5mm thick and the disc is much thicker, then surely spacing the pads 1mm wont leave enough room to fit the disc back into the caliper again?

I thought the same as you, that it would be too thin and the disc wouldn't fit back in.
I've no idea why but it just works. As I said I tried first with the red spacer and that was a big improvement. Then two plastic cards and that was better , so next I tried a single card and that was excellent. Its worth noting that the calipers do "back off" or "settle" after the first ride but I am left with great brakes.

EDIT: you've nothing to lose by trying - its not like you are left with the pads stuck in - they can be easily backed off.

chrisw12

Be careful, I lost £40 but gained a bit of knowledge after trying this trick! Granted I'm sound with most bike mechanics but new to discs.

Anyway I tried two credit cards instead of the disc. I pumped the brakes and to my horror fluid came out of the pistons. I think the pistons had popped. I tried to get them back in whilst on the bike and I'm not sure if I damaged them in the process.

I tried a bleed, no joy. I took the calliper off the bike and tried different things and no joy. I eventually replaced the calliper and re filled the system.

Either this trick caused some damage or the calipers were damaged anyway, I'm not really sure but I won't be trying this again and will avoid at all costs popping the calipers

£40+ poorer but I know how to bleed and how discs work now basically so hey ho.

My brake levers are set close to the lever as possible and there's still too much free stroke for my liking but I think that's just the way they are. At the end of the day they're still light years ahead of rim brakes.

mugensi

@chrisw12 I'd say you had some other problem which only raised its head at that time, if you had two cards acting as a spacer then the pistons couldn't have come out past their seals so the seal was already damaged and you trying to space the pads tipped them over the edge and one leaked.

chrisw12

Yep I agree. One of two things happened, the piston already had problems or this trick can cause problems. The first being a lot more likely, but since I can't rule out totally option two, I won't be trying it again unless desperate.

The Rookie

If one piston sticks so that the meeting point is significantly off to one side then one piston can indeed pop out.