Front brake slowing you down too much?

[reborn]

Might sound daft but are you finding it harder to push your bike around? Does it feel a bit slow when you are riding it?
Well this may be of interest to some of the younger or newer Diversion owners.

If you are finding it harder to move your bike, it may not be because you are getting weaker but your brakes are starting to bind.
It’s easy to check the back brake if you have a centre stand.
To check the front brake with the bike on the centre stand you will need to find a way to lift the wheel of the ground. With my bike it’s possible to lift long enough with one hand under the handlebar fairing to try spinning the wheel with the other hand. Other wise get your other half to sit on the back seat.
If the wheel doesn’t spin freely, it’s likely your brakes need some attention.

Now I’ve been aware that my Diversion (which I use all year round and never gets a wash) needed doing for a week or two so today I finally got around to sorting them.
Most people will tell you that the pistons get stuck because of dirt but as you’ll see that’s not always true.
I slackened the floating pins and unbolted the callipers. I removed the floating pin and the pad holder then swung free and was removed.
Checking the pistons for movement by gently pumping the brake level showed the pistons were moving freely.



The dirt on the pistons is actually stuck to the red grease (just about visible on the lower piston) that I applied last time I serviced the brakes. I cleaned the pistons up and applied a new coating of red grease and pushed the pistons back in. The pistons should move with just finger pressure.

I then turned to the pad holder and found the problem. Held like this (in the picture) the pads should fall out.



It took a small hammer to get the pads out and unfortunately I dropped them about a foot or so onto the driveway. New pads needed now.



Luckily I had a set of pads I bought some time ago.
The reason the pads get stuck in these particular brakes is that there is a shim on each end of the pad holder.



These shims (easily removed by gently levering with a screwdriver) get salt underneath during the winter and the resulting corrosion lifts the shims, stopping the pads from moving properly.



All this corrosion needs scraping off. I’ve just started on the right edge in the next picture.



Once it is all cleaned off, I apply grease and replace the clip. Reassemble the brakes now (not so easy as the pads will keep dropping out of the holder as you try to put it all together.) Don’t forget to grease the floating pin and shaft and put a little copper grease on the back of the pad that the pistons press on. Pump up the slack in the system and you’ve got better brakes (once the new pads bed in) and a bike that’s easier to move and probably accelerates a bit better and may even go a bit faster at the top end..

Note to myself: Don’t put it off so long next time.

[ugly]

very informative and I like the pictures.. I bet the camera/phone got dirty!
I've always used copper grease on brakes, but thus far havent ever greased a calliper piston, what grease do you use for it?

[General Gman]

Use red rubber grease on caliper pistons, but only a light smear.
Good write-up - those brakes really were nasty.
I rebuilt the tokico 4 pots on Jools' bike this week - the brakes worked ok-ish, but far too much lever travel.
I stripped the calipers, removed pistons / seals etc and cleaned the fluid seal grooves out with a small blunt screwdriver and a dremel whizzy tool with a brass brush wheel to avouid enlarging the seal seat.
Got it bled up last night, and now the lever feel is excellent and the brakes work like they should
Will be doing my 6 pot tokicos next week (although they are good anyway, but might as well do it while I have new brake fluid)
do it

[badger]

Hi first time poster here

I'm fairly new to the Divvy scene (3 weeks in and still grinning, despite the cold weather, so it’s all good so far).

As the weather was chilly but clear and sunny this morning I decided to have a quick zip out on the bike, much to my chagrin I could barley move the bike, the front left calliper had completely locked solid.

I ended up stripping the calliper completely and even had to pop the pistons. To get them out however, I had to use mole grips and have marked the top of both pistons. The mole grip teeth marks are higher than the point where the dust seals should be (both were missing).

Ordered new seal kits all round front and back from wemoto at a cost of 48 quid the lot.

I was just wondering if you guys had a tip to get seized pistons out of the body, they wouldn’t move at all when the brake lever was squeezed this morning hence the desperate mole grip method.

[bobh]

I'm surprised you managed to get them out with mole grips if you couldn't move them with hydraulic pressure. I hear there is some kind of expanding collet tool that fits inside the pistons to pull them out, but I've never actually seen one. No use on calipers with opposing pistons (such as Divvy rear ones) either.

I have to say I've always managed (just) to pump them out, one at a time, with the lever. Hold the caliper with the pistons facing upwards, clamp one and push the other out hydraulically, clean it up so it goes back in fairly easily (and remove the dust seal if it's still there) and repeat for the other one. If you're lucky you won't trap too much air so shouldn't have to bleed the caliper in between. You then have two pistons that should come out fairly easily when you take the caliper off and work on it on the bench.

[bobh]

Oh, and I forgot to say, one or two people on here have said that seals from Wemoto have been unsatisfactory because they were under- or over-sized, so just be wary of this. I've always used genuine Yamaha parts.

[badger]

Thanks for the heads up on the seals, front ones were listed as genuine Yam, rear seals werent stated.

Never thought to try clamping one of the pistons as the other is pumped. I'll try that when the new seals turn up.

[redtorro1999]

Nov 28, 2010 23:41:50 GMT badger said:

Thanks for the heads up on the seals, front ones were listed as genuine Yam, rear seals werent stated.

Never thought to try clamping one of the pistons as the other is pumped. I'll try that when the new seals turn up.

hi!! badger welcome mate

[Stooby]

Hi first time poster here.

As well as the shim issue, I'd recommend pulling the pistons and checking the seal seats. Yamaha brakes are very good at getting corrosion behind the seals - it pushes the seal out by a tiny amount - but in lots of places which is enough for the seal to grab the piston. The measure shouldn't be if they move out under hydraulic pressure - rather, you should be able to push them back in fairly easily. If they don't then the pads will continually bind. The old XJ900's were really bad for this, the Divvies seem to be a lot better.

It's worth pulling the whole calliper to pieces and really cleaning everything. I'd also recommend checking your discs if you've had a lot of binding. The ones in that pic look a tad worn.

[joriff]

This is a great thread, i havent ridden my div in a year now, its been sat outside and the front caliper has seized, or corroded. i bought a new one for 25 quid off ebay, but i'll use this guide too!

[muckerboy2205]

have done this this morning, and now moves a lot easier, glad I read this now .

[gacf]

I just bought my divvie last week and noticed the front brakes were dragging. By chance I came across this forum and this excellent guide while looking up common issues with the bike. My front brakes weren't as bad as those photos, but the grime build up was still enough to make a noticeable difference. I'm a bit surprised as the pads seem almost new, the previous owner obviously didn't apply too much attention to detail when getting them replaced. There's still a slight drag, it might be the pistons not retracting smoothly... I didn't grease them up as I didn't have appropriate lube, but I'll strip the caliper down fully soon and do a proper job of it.

Excellent thread reborn, as a newbie to bikes I really appreciate the effort you have taken with the photos.