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2nd problem?


Harri
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Hi again guys.


Everything seems to work as it should on my XF650 ... at a standstill. On the move all is okay so far with just a run of a mile or two. BUT, the rear brake is useless :shock: I said at a standstill because the back brake does bring the bike to a standstill from a roll. But on the road ... it was only when I used the back brake on its own without the front brake that I discovered it wasn't doing anything to slow the bike down ! The front disc looks quite shiny and is obviously working fine. The rear disc on the other hand looks a bit rusty and doesn't look as if it is being used by the pads.


New disc, pads and fluid? Or is there something I can do or look at to see what is going on? And then take it from there.


Barcud

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Hi Stu, so just go for a caliper rebuild. Basically take it apart, clean cylinders and renew seals. I will renew the disc I think as it is looks quite grubby. So is my shopping list, new seals, brake fluid and disc?


The brake lever seems to work so that should be okay.


Is there any benefit from renewing brake hoses or replacing with braided?


Cheers.

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pull the caliper off and operate the lever first to see if the pistons are moving freely


if they are then if probably doesnt been a rebuild


also if its on sliders make sure these are nice and free


you wont see much difference with braided hoses to be fair

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I've ordered caliper seals for when I take the rear caliper off. I should be able to check out and clean the caliper pistons then. I might need pads if they check out no good. Is it best to renew disc as well if it doesn't look too good?

If all fails at this end I will get a master cylinder kit.

Does this sound like a logical plan?


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Hi again. Well I removed the caliper and the piston didn't take too much pressure from the brake pedal to come out. So that seems to move freely enough. I gave it a rub clean and replaced it with the new cylinder seals. There seemed to still be a bit of meat on the pads though I couldn't see any marks to indicate excessive wear. How would you clean the disc, wire wool maybe?


I was gonna give the brake a try out but the battery appears to be flat! Though as before the brake does bring the bike to a halt when the bike is pushed from a standstill.


Barcud

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Did the caliper float ok on the pins? The ones on my Honda are seized solid, so even though the piston moves freely the caliper can't float and clamp both sides of the disk...... :wink:

Are you sure it's rust on the disk and not pad material that's stuck to it? I cleaned mine up with a fine Garryflex block.......did the job ok..... 8-)

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sounds like the pins need a damn good lubing


although from looking at pics on the net you should have removed the sliding pins when you took the caliper off so they cant be seized now!

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Hi, I didn't remove any pins!


On a diagram I can see a shim. Looks like it is between a pad and the piston. I don't remember seeing a shim of any sort?


Wotcha think?

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thats just an anti squeal shim nothing to worry about


the pins are the bolts that hold the caliper on they should be long and a threaded end bit like these


http://www.filtsai.com/accord/brake_rotors/caliper_pins_3.jpg

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I removed 2 bolts that hold the caliper on to the bracket. The only other pin goes through the top with what looks like a straight screwdriver head.


I greased these bolts when I replaced them. One goes through a rubber sleeve.


If the pads are worn I would expect a squeal when the brake is applied.

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Yeah.....sounds like you greased them ok, so they should be ok. The other pin is the pad guide pin, which should be smooth so the pads can move freely. The flat blade screw is normally just a small blanking plug......when it's removed you see the allen head on the end of the pin so it can be unscrewed using a hex key..... :wink:

Bear in mind that the quality of brake pads varies a bit.......so the stopping power of some are not as good as others.... :wink:

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Thanks again chaps. The guy that sold me the bike must have had the same problem :roll: And to honest if for some stupid reason I was going full pelt and tried to stop in a hurry the front brake would probably have put me over the top in an effort to come to a halt :x mmmmmmmm. Not good.

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Okay, had a spin around the block and the rear brake is the same, useless!


So, Brake fluid replaced, piston cleaned, new seals fitted, bolts greased. The next cheapest thing is the pads. These though may not be here until after Xmas now because of the time of year :( The next cheapest thing to change if pads make no difference is new cylinder kit. The final thing would be the disc.


How about the adjustable linkage from the brake pedal to the cylinder? Could this make a difference?


Barcud

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The adjustable linkage will only make a difference of you're running out of travel on the brake pedal.....if you've not got a lot of free play on the pedal I'd tend to leave it as it is...... :wink:

Given the age of the bike, a master cylinder rebuild may not be out of the question.

Mind you, I'm not sure what you're expecting from the rear brake........mine will not lock the rear wheel at speed, but most of the braking is done by the front brakes anyway..... :wink: The rear is only really effective for holding the bike on a hill or slow speed manouvring.

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Cheers Bob. When I apply the rear brake there isn't any noticeable difference no matter what speed I'm doing. I can apply the rear brake at a standstill and I'm still able to push the bike forward! When I took the GSX for a spin the rear brake definitely made a difference bringing me to a standstill.


Brake cylinder kit sounds a good move if new pads don't change anything.


Barcud

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