Changed brake pads tight on rotor?

[soundbeltfarm]

changed the pads on the dr tonight as they were shagged and put new ones in and they are pretty tight on the rotor i can turn the wheel by hand but it is pretty hard so something not right.
ive changed them before and they were sweet the last time i did it.
could it be the pistons are full of shit and they aren't retracting fully?
any help appreciated.

SBF

[Grahameeboy]

changed the pads on the dr tonight as they were shagged and put new ones in and they are pretty tight on the rotor i can turn the wheel by hand but it is pretty hard so something not right.
ive changed them before and they were sweet the last time i did it.
could it be the pistons are full of shit and they aren't retracting fully?
any help appreciated.

SBF

I have had same on previous bikes...just removed the backing plates but would suggest checking the pistons first as this looks like likely problem if okay last time.

[Danger]

Some pads are thicker than others if you went aftermarket. I've had some pads that were so thick I could not even get them in to use them. Remove the heat backing pad is there is one and refit it later once they have worn a little.
Also I would suggest you take things easy until you are sure they are free enough. I have seen them when the pads are too tight the brakes heat up, the fluid expands and the brakes progressively come on tighter and they get even hotter and next thing the brakes are locked on just as you try to go around a corner.

[paturoa]

Also check the pins that the calipers slide on. They can get crap in them and not retract far enough for new pads.

Not sure about your model of DR (you may have to un-bolt the whole caliper from the forks, but unlikely) Drop the wheel off and then pull the caliper off the holder thingie, clean and re-grease the pins. Prolly should also have rubber grommets to stop shit getting back in there too - check those.

[F5 Dave]

as above, but
Every so often crap builds up behind the piston as it is the lowest place to fall.

Pump the piston out & check it is clean & clean behind. Scrupulously clean it first & don't use anything silly on the seals. Easy job though. Obviously remove the pads till all back together so don't get contaminated with cleaning or whatever.

[mc4aregreat]

this maybe a little bit out of date, but i have just read about this same problem in an off road magazine, and they suggest to file the leading edge of the pads to a chamfer so the disc will centralize easier.

[soundbeltfarm]

fixed the problem.
was the little pins as was suggested.
was a mission to get apart one was o.k but the other was pretty tight.
took it for a spin out the back of whanga today and brakes went good.

[Rupe]

anyone got any more advise on this?

Put some new pads (goldfren standard) on to my brakes (nissin) to replace the old pads(nissin) as they were getting thin. My new pads now rub on the rotor a fair bit, even after a little run to see if they'd sort them selves out.

There doesn't appear to be any heat backing pad to remove, and I have cleaned the pins and pistons and followed the advise in this thread but still no joy.

I also bled the brakes as the lever feels a bit mushy, but it has since I've had the bike even though I've bled it serveral times now. But don't think this is related as there is no change on the lever from old to new pads.

Just wondering if anyone has had any experience with this before that could help.

Thanks

[F5 Dave]

ok so far a start std brakes on the GG are great. Having tried other pads the Nissins are pretty good. Interesting to hear how the Goldfrens work out, never used any (or seen any).

If the brake drags for a start try the lever adjusters (there are 2) so there is def freeplay, you can adjust back from there. esp the one on the MC as opposed to the lever will give you more grasp so will help with mushyness. However I've never felt mine was mushy. I brake 1 or 2 fingered.

Did you remove the pistons? Sometimes gunk forms behind them & prevents the pistons fully retracting. Also check the disc doesn't deflect too much when applying possibly the disc may have warped or the mounting taken a blow bending it.

[Rupe]

ok so far a start std brakes on the GG are great. Having tried other pads the Nissins are pretty good. Interesting to hear how the Goldfrens work out, never used any (or seen any).

If the brake drags for a start try the lever adjusters (there are 2) so there is def freeplay, you can adjust back from there. esp the one on the MC as opposed to the lever will give you more grasp so will help with mushyness. However I've never felt mine was mushy. I brake 1 or 2 fingered.

Did you remove the pistons? Sometimes gunk forms behind them & prevents the pistons fully retracting. Also check the disc doesn't deflect too much when applying possibly the disc may have warped or the mounting taken a blow bending it.

No I didn't remove the pistons, as I wasn't 100% sure how to. I just extended them fully and cleaned round them and lubed them. Maybe I should remove them anyone got any tips, will I lose the brake fluid?

I also took the bike for a good ride at the weekend, and the binding didn't get any better. Although the brakes felt firmer, but still mushy. The brakes were stronger, but I removed the pads when I got home and they were only really rubbing/braking with the back edge of the pads, which can't be right.

Any help would be great.

[Danger]

The sponginess can be a result of air in the line due to the fluid boiling due to the pads rubbing/binding all the time. Be sure the pins on the calipers are not rusted or take them apart and clean and lube them so the calipers move freely (ok see you have done this). Don't remove the pistons at this point.
Often bleeding will not remove air in the line.
Once you are sure the pins are clean and lubed and the caliper moves freely in and out, rotate the resorvair at the lever so that it is level, remove the resorvair cap and suck out what fluid you can with a syringe, but don't expose the plastic port with the holes to air. Replace the fluid about half way up the resorvair with Dot 5.1 fluid, then lean the bike to the left as far as you can without exposing the plastic port to air and pull the hose down so that the resorvair is at the highest point. Tap the fluid line with a screwdriver handle, pull and release the lever and watch for any bubbles that pop out of the line and through the port. I bet you find quite a few coming to the surface. Soon the lever will start feeling firm again.
Top of the fluid with more fresh 5.1 fluid just to the 3/4 point, install cap, clean any spilt fluid with a squirt of water and a rag and go riding.

Alternatively once the caliper moves freely you can back bleed the brakes under pressure from the caliper to the resorvair. Air gets trapped in the line at the high point so you need to create a straighter line to the resorvair. Some banjo bolds benefit from an extra hole drilled in them as when installed the hole in the banjo bolt is at the bottom and air gets trapped in the banjo bolt rather than released into the resorvair.

[cheese]

Hmm I might give that a try too.

[F5 Dave]

I agree about the checking the pins first (which may be the extent of the problem), but it sounds like the rear pistons are either slightly seizing or restricted from moving right back.

Pumping out the pistons is pretty easy with the pads removed the pistons are pumped (make sure fluid level doesn't drop to suck air). Then pump pistons out evenly restricting the over eager ones with spacers so they all come evenly out & get wiggly by hand. This takes some care but in this instance it is the rear ones in particular you want out. Do this over a bowl, the oil will run out when the pistons come out.

Then being scrupulously clean paper towel out the calliper & check for crud that sometimes settles in the lowest position. On such a new bike this is not as common. Also on older bikes, although maybe pos is there is a build up of gunk behind the dust & main seals, like hard dandruff. Check the M/C rubber has no rips.

The seals can be removed carefully & inspected. Then the whole lot is put back together with brake fluid as a lube & pushed home. The system will need to be bleed from scratch, but it is a good idea to replace the brake fluid every yearish so no drama.

[FROSTY:Me]

I agree totally with dave.
The only thing I'd like to add is that sometimes aftermarket pads clearances are a bit out.Ive made it a habit to clean out all pin holes and bearing surfaces with 800 grit wet and dry paper.
I can't comment in this case but Ive had issues where there is soposed to be a shim plate fitted and its missing meaning the pads aren't sitting propperly against the disk.
The other point has already been covered off. Sometimes aftermarket pads are just too thick.

[Reckless]

just a little clarification here. There are two sets of pins.
The pins that hold the pads in place and the pins that locate each half of the caliper. The pins that both halves of the calipers slide on as you put on and release the brakes are most important. They usually have little rubber expandable boots on them. They are the most common reason for jamming brakes. They must slide freely! So both halves of your calipers can move towards and away from the disk freely.

Actually once you have the brakes apart this much it is most common for me to do the pads, check and grease all the pins, pop the pistons (if necessary), replace and reblead the fluid. Only takes about an hour.
Do it all then there is no unanswered questions.