Front brake pistons - how free of stiff is normal?

[iceman]

Hi, I wonder if someone can advise how free a movement in and out with the caliper block removed from the bike should the piston movement be?
I've tried searching google and youtube and it seems they are normally quite tight even when in good condition and coated in brake fluid (recommended when re-fitting and cleaned up).
Should they be fairly easy to press back home (all three taking into account CBS) or take a lot of effort?

[cnikonpete]

Pistons must be a very good fit in the bore for obvious reasons,make sure any seal is correctly fitted ,remove top of brake reservoir,place rag around to catch any spillage etc. If the calliper is off the bike just make sure you insert evenly,they will appear to be tight until more of the piston is in the bore. Hope this helps.

[cnikonpete]

I should have read your post more carefully,apologies, I have found that if you lubricate the seals in the calliper and the piston with brake fluid,get the piston square on and then push with a slight twisting motion,they should go in with a moderate amount of pressure. I assume you have cleaned the Pistons so there is nothing to grab on the seals.

[iceman]

I should have read your post more carefully,apologies, I have found that if you lubricate the seals in the calliper and the piston with brake fluid,get the piston square on and then push with a slight twisting motion,they should go in with a moderate amount of pressure. I assume you have cleaned the Pistons so there is nothing to grab on the seals.

Thanks!
Many months ago, must be 6 months+ when I changed the pads, I cleaned the caliper and pistons to an extent, but did not coat any surface with brake fluid, just pushed the pistons home - may be why they are stiff now. They were also a bit pitted, so thinking I need to clean them and lubricate things as best as possible, and look into purchasing new seals/pistons.
Also looks like I need a suitable plastic tube to place on the bleed nipple rather than just open and let drip into a container.
Strange the service manual seems to suggest brake fluid for the pistons but normal oil for the seals!

[cnikonpete]

I assumed you were servicing the calliper as it was off the bike,so I thought you were fitting new seals,don't know if a calliper kit is available for our bikes,but if it is and you have the calliper partially dismantled, I would consider going down that route.

[iceman]

I assumed you were servicing the calliper as it was off the bike,so I thought you were fitting new seals,don't know if a calliper kit is available for our bikes,but if it is and you have the calliper partially dismantled, I would consider going down that route.

Seems there are lots of kits on Ebay, i.e. https://tinyurl.com/y8wadtzt

[cnikonpete]

M and P are pretty good,can you clean your pistons up? I've used autosol chrome cleaner before,just make sure its all off.

[iceman]

I ordered some bits for the front caliper and also a whole new caliper assembly, which I can keep as a spare if needed as it has everything except the pads and two main bolts (so includes new pistons with seals pre-assembled). It seems there's a lot of work draining both the front and CBS systems to remove and work on the caliper or even to check and clean the front master piston that actuates the master cylinder fluid.

So, anyone know of videos for the PCX showing this kind of work, especially for removal and fitting of the caliper and draining both main and CBS systems? Has anyone taken the master piston apart and found issues?

I'm not sure where my problem lies, as the front brakes work, just the lever is very stiff to use. It's free and normal when I start to press it then kind of gets tight, then if I press a bit more goes further, so not sure where the system is sticking. I assume the pistons but it may be more than that.
Thanks for any help.

It seems removing the caliper or servicing where the brake lever controls the

[cnikonpete]

If I had a new caliper,I would fit it to eliminate at least one part of your puzzle,and keep the old one as a spare.

If you go this route,I would have the new caliper to hand,so that the least possible brake fluid is lost.

I would then bleed front brake only at first,as it is by far the easiest to do, I would only bleed rear portion of CBS if the lever showed any sign of sponginess. Just checking the CBS reservoir looks like you need to be a contortionist,let alone topping it up.

The only time I can remember symptoms such as yours,it turned out to be a sliver of a failed seal at the master cylinder end that was partially blocking brake line,and it would act like a little valve where you don't want one.

[iceman]

yep, another 'valve check' fiasco getting to the CBS reservoir - damn Honda. I thought removing the pipes would mean air-bubbles and topping up, hence the need to get to the CBS resorvoir.

Prices for the caliper assembly here ranged from £240-370! (but I did find one outlet selling for £90) but Partzilla had it for $47 (reduced from $60) so I ordered that, a new centre stand as mine is getting rusty, new CS rod and spring, all for £73 delivered + any customs charges. Partzilla were still cheapest for new pistons alone, but still best part of $20-30 each, wheres the whole assembly including pistons was $47.

A new pcx caliper kit with things such as six different sized piston seals and other bits for replacement on the caliper arrived today and that cost £18 (no pistons obviously for that price).

Am I right in thinking 6mm inner diameter tubing is needed to go over the bleed nipples, or is it smaller on the pcx?

[you you]

The only time I can remember symptoms such as yours,it turned out to be a sliver of a failed seal at the master cylinder end that was partially blocking brake line,and it would act like a little valve where you don't want one.

Yes and the master cylinder pushrod going over centre. But that’s unlikely on the front.

[cnikonpete]

I think you only have to remove three panels

6mm sounds about right

[iceman]

I think you only have to remove three panels, 6mm sounds about right

- the manual suggests it's much easier on the '13 model which has a maintenance lid, but got more involved on later models such as my '14 LED - rear meter panel which in turn needs the front meter panel & meter visor & grill to come off, body cover & grab rail, right inner outer cover, center cover & luggage box and other bits.
All that was needed was a removable hatch to be added to the front panelling by the key area to allow access to it - come on Honda, get it right in future models.

[iceman]

I think you only have to remove three panels, 6mm sounds about right

- the manual suggests it's much easier on the '13 model which has a maintenance lid, but got more involved on later models such as my '14 LED - rear meter panel which in turn needs the front meter panel & meter visor & grill to come off, body cover & grab rail, right inner outer cover, center cover & luggage box and other bits.
All that was needed was a removable hatch to be added to the front panelling by the key area to allow access to it - come on Honda, get it right in future models.

The above is the order given in the service manual, referring page to page to page, but the body panel chart shows the left and right inner covers by the ignition should come off on their own - hmm, wonder if that is true.

[cnikonpete]

I have a pdf manual which was gratefully received from Mel, I only looked at was logical,shouldn't have been so naive, let us know how you get on.

[superandyp]

My pcx is a 2016 model and has done 12,000 miles. I changed my pads in the winter having to push the pistons with a lot of force. By Easter one pad was down to the metal after 2000 miles. I decided to strip and clean the caliper. I thought the piston pots and seals would need replacing but what I thought was corrosion was just a build up of road dirt and pad material baked on by heat from heavy braking. I used brake cleaner and a nylon cleaning pad to remove the baked on dirt. I then smeared some fork seal grease I had in the piston bore. They then went in no problem. My advice would be to strip the caliper and clean all the parts. I have put an additional 3000 miles on the bike following the caliper rebuild and they pads have lots of life left.

[iceman]

My pcx is a 2016 model and has done 12,000 miles. I changed my pads in the winter having to push the pistons with a lot of force. By Easter one pad was down to the metal after 2000 miles. I decided to strip and clean the caliper. I thought the piston pots and seals would need replacing but what I thought was corrosion was just a build up of road dirt and pad material baked on by heat from heavy braking. I used brake cleaner and a nylon cleaning pad to remove the baked on dirt. I then smeared some fork seal grease I had in the piston bore. They then went in no problem. My advice would be to strip the caliper and clean all the parts. I have put an additional 3000 miles on the bike following the caliper rebuild and they pads have lots of life left.

Thanks! Waiting for a long stint of days off to tackle this issue as working nights at present.
So, what did you have to remove panel wise to do this, as the service manual for later models suggests quite a lot has to come off to get to the CBS reservoir. Also, the manual and some videos show the two smaller upper inside front panels (the one around the ignition 2nd off after the lhs one is prised off - nothing else need come off to get these off, just brute force - do you know if this is true?)

[iceman]

As I have several days off I decided to get on with investigating the cause of the very stiff and hard to press front brake lever (the lhs rear brake lever was fine).

It took ages to get the left inner outer cover off and in doing so I had cracked the lower bottom plastic edge and broken all but one of the yellow 'clips'! I have the service manual and watched several videos that all indicated the lhs inner cover pulls off upwards and takes some effort, but even so the lhs front inner proved to be a real nightmare to come off, and I even bent the ends of two small trim removers. Now it's off I see the direction of the clips indicate the lhs pulls off upwards and to the right (not just upwards) and the rhs up and to the left, but the yellow 'press' parts of the broken clips are so hard no wonder they proved difficult to pull or squeeze out of their holders. I'll have to use some large headed self-tap screws to hold it back on.

The above allowed very tight access to the CBS reservoir as without taking lots more panelling off the bolt/nut could not be got at to free it, but I used a syringe and tube to suck the reservoir dry and then bled from the bottom, and bled the master reservoir normally. Phew!

I had purchased a caliper rebuild kit (seals, washers but no pistons), a complete caliper assembly in case it was needed and included new pistons,

Having got the caliper off, it was obvious why I had issues - the pistons were very rusty and the rest of the assembly was in need of a lot of re-work, so I went with the new caliper assembly - much easier and now fitted to the bike. Tomorrow I will fill both brake systems with brake fluid as I've had enough for today - I may reverse bleed the CBS and perhaps the front one to as I believe it helps to lessen the possbility of air bubbles (?)

[iceman]

Well, I re-filled both front and CBS reservoirs but less than happy with both.
For the CBS, with only the two inner panels off I used a syringe to add fluid to the CBS reservoir and bled the system as recommened but using rear brake lever and opening / closing the CBS nipple rather than the inner ratchet mechanism - rear brake lever does not feel that great.
For the front system, I bled using the same approved method but top reservoir and open / close of the bleed nipple. I did this twice as still not happy with the front brake performance - when the lever is pulled it passes brake switch and gets firm about half way, but stopping power seems worse than before. Could there still be an air blockage? When should the front lever start getting firm when pressed?
btw - looking up under the front fender, the steering brace that attached to the shocks is very rusty epsecially where the large bolt to colum is - guess it's easier to replace the whole assemble when needed (or get a new bike)

[iceman]

So, I reverse bled the front system and it's improved now. Not much fluid in and no visible air bubbles appearing in the top reservoir during replacement, but this method has made the front brake firmer, sooner. I was going to do the same with the CBS system, but even with most fastenings broken off the inner lhs panel, and the lower part of it cracked in two, it still did not want to come off easily, so I gave up for now (strewth, those yellow clip fasteners are really tight!)
Turns out I was no where near to rear shoe replacement going by the wear marker with lever pulled, so I just tightened the adjuster and mechanically at least, if not CBS piston wise, it's better.
Pre MOT next year, I ordered a new stainless steel front disc and rear shoes just in case.