Stuck caliper pistons - retracted

Torontonian said:

Gee , I guess you didn't know you need stainless. The original steel will only continue to corrode and muck things up. So that would be backtracking. This thread also let me know the seals have been changed from original rebuild kit style. Go figure.

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Stainless steel is great stuff... fabricated about 20 tons worth of 304L years ago. However, it's not the end-all.. the propensity to corrode the adjoining aluminum will increase. It is increasingly popular in MANY areas because it's cheaper to make a SS part than to make a carbon steel part and plate/polish/grind to finish. Just my .02

dennisgb said:

One thing that can happen if the surface is turned down or there is some scratching in the finish is the pistons may cock a little and bind up in the bores...from what you described in your earlier posts this sounds like it might have happened. The only caveate would be using petro lube rather than brake fluid when you assembled. I usually wipe some brake fluid on the bores and the pistons and seals before assembling. You should have been able to just push the pistons back with your fingers on the bench...this is what tells me the pistons "cocked" in the bores...easy to do...and they will lock up when it happens. You can get away with some clearance on the fit, but need to use care when assembling. Once the brake fluid is bled and is behind the pistons binding is no longer a problem.

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I do think they were cocked. Had a helluva time getting them to move one way or the other. So my new plan of attack is to see if I can free them up. But, I already ordered a new pair of pistons so I should have a solution either way in a few days. The weather has been extremely cooperative this month and I would like nothing more than to be able to roll this scooter out of my shed before November!

Thanks for your help,
Peter

hobot said:

Likely have to wait till next owner cussing at the mess. Vendors got to eat now and then too.

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What next owner?! I am taking this machine with me!

contours said:

I would like nothing more than to be able to roll this scooter out of my shed before November!

Thanks for your help,
Peter

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Won't the snow be five feet deep by then?

In the old days, maybe. I used to worry about ice storms when November 1st drew near. Not so much now with Global Warming.

contours said:

In the old days, maybe. I used to worry about ice storms when November 1st drew near. Not so much now with Global Warming.

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I knew there was an upside, more motorcycle riding weather. Win/win.

Hopefully the Image is visible. They look pretty beat, don't they?




It took brake cleaner, brake fluid, heat, a piston puller, a glass of Rum and a whole lotta muscle to remove those suckers this time. Somethin' ain't right. Think I will wait for the new Stainless Steel versions to arrive before goin' any further.

They look as good as what I've got in Trixie in the actual seal working area, which shifts as pads wear. Have ya tried the fit w/o the seals? should slip in an out fairly easy But Only If perfectly aligned as I'm sure the Rum made ya so aware of. Mine would squeal in with hard multi finger straining pressure, once surface polished on buffer wheel and brake fluid lubed. If ya want to experiment for us - much appreciated to figure out what is happening but sheeze I'm lazy and would just wait for the SS and get back to riding. There is definitely a test of will power when I run into Norton normal, ugh.

your pistons look pretty much like mine did when I pulled them out

I did not bother trying to lightly sand and polish to remove all the little pits, etc

like you I just ordered a new set, put em in, and all was well

hobot said:

They look as good as what I've got in Trixie in the actual seal working area, which shifts as pads wear. Have ya tried the fit w/o the seals? should slip in an out fairly easy But Only If perfectly aligned as I'm sure the Rum made ya so aware of. Mine would squeal in with hard multi finger straining pressure, once surface polished on buffer wheel and brake fluid lubed. If ya want to experiment for us - much appreciated to figure out what is happening but sheeze I'm lazy and would just wait for the SS and get back to riding. There is definitely a test of will power when I run into Norton normal, ugh.

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I can certainly identify with the "I'm lazy" part. I am beginning to think the ceramic based grease I used was way too stiff for this application. But then there 's the pits in the pistons to consider. Since I need to wait once again (if it ain't parts it's tools) I may try to fit the outer piston once more with just brake fluid to see if it gets stuck again.

This whole thing wouldn't be so bad if I could have continued to ride my '03 Daytona. But it, too, has a sticking caliper (the rear) and I decided not to ride it until I can address the issue. Only I need to work out in the gravel driveway for that repair - not ideal. I was hoping to resolve the issue with he Norton a lot sooner so I could swap places. As it is I can't imagine rolling the Norton down the ramp without a front brake.

1up3down said:

your pistons look pretty much like mine did when I pulled them out

I did not bother trying to lightly sand and polish to remove all the little pits, etc

like you I just ordered a new set, put em in, and all was well

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You're smarter than me. I didn't give in until weeks had gone by.

This whole thing wouldn't be so bad if I could have continued to ride my '03 Daytona. But it, too, has a sticking caliper (the rear) and I decided not to ride it until I can address the issue. Only I need to work out in the gravel driveway for that repair - not ideal. I was hoping to resolve the issue with he Norton a lot sooner so I could swap places. As it is I can't imagine rolling the Norton down the ramp without a front brake.

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On man sorry to know you got some rough working conditions and more than one thing wrong at once to hurry up and wait on some more. I've retired my Combat till kicker/tranny gone though and cases opened to seal up again, in mean time 2 months about daily attention got my SV650 ready to ride presentable, then lifted a bit off stand which spring pulled up w/o me knowing so it fell with its bikini fairing on a car battery a few days ago, hurt my neck straining to lift it. At least the fairing got knocked back more perfect alinged than I was able to from last knock over parked. Don't try to roll down the Norton w/o front brake or couple of strong helpers. Damhik.

hobot said:

On man sorry to know you got some rough working conditions and more than one thing wrong at once to hurry up and wait on some more. I've retired my Combat till kicker/tranny gone though and cases opened to seal up again, in mean time 2 months about daily attention got my SV650 ready to ride presentable, then lifted a bit off stand which spring pulled up w/o me knowing so it fell with its bikini fairing on a car battery a few days ago, hurt my neck straining to lift it. At least the fairing got knocked back more perfect alinged than I was able to from last knock over parked. Don't try to roll down the Norton w/o front brake or couple of strong helpers. Damhik.

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Tough all over. Well, in addition to bein' lazy I like to work on level ground. Every now and then I think about paving the top of my driveway so I could have a nice landing when I roll these beasts off the ramp. But then reality sets in and I see a hundred other things up higher on the list. I'm damn lucky my wife bought me a shed to put these bikes in!

Spit after you say Gravel in my presence. Only good for Scorpions to cross. I put down old carpet or plywood if I can plan ahead of the need to. Rather strange your fairly decent pistons being such buggers but reminds me its past time I drain fluid to flush out moisture or will be sweating and swearing like you, again. Good on your wife and hope you deserve it and her. After a while we collect a good lot of used stuff that's a question what to do with. Never thought I'd have a use for used spokes but I've needed one and yesterday so did my buddy so maybe grease them pucks up and keep for who knows what.

Amen, Brother.

contours said:

Hopefully the Image is visible. They look pretty beat, don't they?




It took brake cleaner, brake fluid, heat, a piston puller, a glass of Rum and a whole lotta muscle to remove those suckers this time. Somethin' ain't right. Think I will wait for the new Stainless Steel versions to arrive before goin' any further.

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Those are very serviceable, they are not the reason you were stuck. Please give us an equally good image of the bores. As previously said, they should whistle right in and out with NO SEALS installed. Test and report back. If not, your bores are fouled with corrosion still, easily polished out. Also, the grooves the seals sit in MUST be cleaned of corrosion that will push the seals too tight, again binding. The giant red flag here is the (ceramic???? :?: :!: :shock: ) grease you have mentioned. Petrol based lubricating grease will swell those rubbers fast, binding the piston.

concours

look carefully those pistons are shot ( big chips in the chrome just perfect for bedding in new seals )

I would bin them and make sure there is no scoring in the bore and then fit fit stainless replacements with new seals

in the UK you can buy brake grease red in colour specifically for lubricating brake seals try your local motor factors
as it is often supplied with car brake seal kits

Quite surprised to receive the new pistons today. Went to work on the caliper right away when I got home from work. I lubricated the bore, the pistons and the seals with brake fluid. Things fit in nicely, though I did notice that one, not both, of my new seals had that taper we'd been talking about. Now I had to pause and read several posts about the correct orientation. I confess I'm still not sure it's in there right., but I made a point to use it in the outer bore (where the cap fits) so I could get that piston out if it seemed to stick. After some pressure with my fingers and a little push with the handle end of a screw driver it did seat properly.

I went on to install everything and used a tiny bit of sealant on the threads of the lower pipe since that was where I got some leaking last time around. Then on to bleeding the air out. It took quite a while and I'm still not finished, but at last I have a front brake! At this point it just requires some pumping. It is nice and solid when the pressure is up. I hope to get back to bleeding again on Monday. With any luck I can feel confident about rolling it out and down the ramp to start 'er up. It's been several weeks since I rode it into the shed.

Thanks so much for everyone's advice. This forum is such a help!

concours said:

As previously said, they should whistle right in and out with NO SEALS installed. Test and report back. If not, your bores are fouled with corrosion still, easily polished out. Also, the grooves the seals sit in MUST be cleaned of corrosion that will push the seals too tight, again binding. The giant red flag here is the (ceramic???? :?: :!: :shock: ) grease you have mentioned. Petrol based lubricating grease will swell those rubbers fast, binding the piston.

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Now that everything is installed I can't provide that image. I'm pretty sure the bores were clean. The pits on the old pistons along with the wrong choice of grease was most likely the problem. But ceramic is not petroleum, so I don't believe the seals were compromised. They were new and after cleaning them I used them again without any problem. The only reason I went shopping for grease (and bought the wrong stuff) was because of what I read on the OldBritts website about not using brake fluid if the calipers were not going to be re-installed right away, which was very possible with my schedule. I think the stuff I bought was meant for protecting the external components. I doubt I'll use it for anything now.

Brake fluid is rather hydrophilic so rust enhancement is the concern if set up - as always [silicon fluid ain't hydophillic but still allows condensation over time to settle on steel]. Dang still ain't drained Trixie's in a coon's age. Will go open to drain now while last rusted event still on my mind.