Rear tokico piston seized?

Yet more issues and problems with the Sv...
This time after putting the wheel back together..

I have gone to put the wheel back In the correct position and found that the rear brake has been pressed in so the left hand piston on the rear brake has been pushed in.. And it has seized or has got stuck, have had a look on a few other forums and a couple have said to put some between the shoes.. Hence a spanner with a tight fit

Would it be worth getting a whole new calliper or just some shoes or a new piston...

Provided the in the picture the seal behind the piston has snapped? Would that be why the piston has seized up and stopped?
In the process we have moved the piston back into his original place.. We have move it back around half and inch?

Would like some more Information or help from people who have had the same problem.

Liam

Originally Posted by liam111

Yet more issues and problems with the Sv...
This time after putting the wheel back together..

I have gone to put the wheel back In the correct position and found that the rear brake has been pressed in so the left hand piston on the rear brake has been pushed in.. And it has seized or has got stuck, have had a look on a few other forums and a couple have said to put some between the shoes.. Hence a spanner with a tight fit

Would it be worth getting a whole new calliper or just some shoes or a new piston...

Provided the in the picture the seal behind the piston has snapped? Would that be why the piston has seized up and stopped?
In the process we have moved the piston back into his original place.. We have move it back around half and inch?

Would like some more Information or help from people who have had the same problem.

Liam

.

New pistons are between £20-25 each.

Get both pistons out and inspect would be the best way. I got a bar and clamped them to the caliper and pumped the brake which worked the seized piston out.

There is also a hole in one side of the caliper which you can use to work out one of the pistons (if you're lucky enough for it to be that side that is seized).

Usually a good clean up of the seals area, pistons and a new seal will sort it.

[650]

Doubt a new piston is needed, new seals and a bloody good clean should sort it. I did both my front ones with a mate, the left brake was absolutely toast, the sliding bit was seized solid and one piston was half out...took me (absolute mechanical noob) about 4 hours to rebuild both calipers with new inner and outer seals and a fluid renewal...bike stopped on a penny (kinda) after that!

Looks like it needs new pistons to me. And pads

[650]

Oh sorry yeah, didn't look at the picture...scrolled down too fast to see it. Apologies

[andrewsmith]

Strip and rebuild it.
Its a okay caliper but a right big to keep right

Originally Posted by andrewsmith

Strip and rebuild it.
Its a okay caliper but a right big to keep right

Know it sounds bad.. where do i start aha?

[Fallout]

Here's a decent tut I used to learn from.

http://www.perthstreetbikes.com/foru...es-pics-64664/

Then you'll need to find one about renewing brake fluid/bleeding once you've put it all back together, if you've not done that before. Take your time, be thorough, but an easy job with some patience.

The key things not to forget are:
- Make sure the pistons are out as far as possible before you disassemble the calliper/remove from the hydraulics, otherwise they can be hard to get out. You don't want to damage them by gripping them with grips.
- Crack all the bolts before you take the calliper off the bike, otherwise they can be next to impossible to undo without clamping the calliper in a vice

The rest of it is just taking it apart, giving it a good deep clean and putting it back together with some red rubber grease.

[Sid Squid]

Pump the pistons out first, as Fallabout rightly says, and by all means give the caliper half bolts a try when the caliper is on the bike, but be gentle - they will almost certainly be stuck. The heads are a pathetic 6mm recess*, in a fairly soft material and will round out in a heartbeat. If they come out no bother - go buy a lottery ticket you lucky lucky *******.

But, if they don't just fall out with the first caress of your tool, (fnaar!), back the caliper up on something properly chunky and using a good big drift, (important that), give the heads a properly good, perfectly straight and square spank with a bigger-the-better hammer. This will do two things, firstly it will shock the undoubtedly corroded threads, secondly it will compress the material of the caliper under the bolt heads - which means the bolt will no longer be tight as the two pieces it holds together are effectively thinner. Full of win on all fronts right? Hmmmm... Threads may still be stuck, if so give it another thrapping and see what happens, but use a drift or the bolt head will so distorted it won't matter if it's not stuck - you'll never get a tool in there to undo it. Even if you're careful you might need to tap the tool in anyway - the bolt's pretty soft.

Some things to know:

The inner piston may not pump out no matter how hard you hold the outer one - not unusual. There are two small angled drillings in the caliper body that carry fluid from the banjo side bore to the inner bore - at the bottom - where all the sludge and should-have-been-changed-yonks-ago fluid lies. Where it goes hard and crystalline - and you need those bolts out or you'll never be using it as a caliper again. There's a rubber seal in there too, commonly corrosion of the caliper body has made it bitter and twisted and uncooperative - clean the recesses where it fits veery carefully indeed - they must be flat to seal properly.
If you can't get the bolts out but both pistons move, it's a sod, but you can rebuild the caliper while it's in one bit, you must make double sure that the seal grooves are perfectly clean - did I mention it's a git to do like that? 'Cos it is. Don't gouge lumps out of the body, but make sure the grooves are completely clean and square.
Pad pins; often stuck. Drill a hole dead centre of the blind end of the hole ~1mm ish smaller than the pin diameter - they'll drift out dead easy.

Lastly, where the pads fit, are the areas where they touch the caliper completely flat and square, or are they grooved? If they are at all grooved ignore everything I scribbled and use the caliper as a doorstop - it's a complete waste of time repairing it.


*Why? I ask myself. When originally seen, (early 80s), same caliper bolts had nice manly 14mm hex heads - plenty to lean on and always came out no bother.