John Schmidt
Member
Posts: 15240
a/k/a Stuffy. '99 I/S Valk Roadsmith Trike
De Pere, WI (Green Bay)
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« on: October 21, 2013, 05:42:19 PM » |
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Have set of Valk front calipers and can only get one piston of the four to move using air pressure. I want to rebuild the calipers to use on my GL1200 project but darned if I can get them to move. Don't want to ruin them if possible but might be forced to drill a hole in the bottom of the three that are stuck and run a self tapping type fastener in there. I've done that in the past by running it through a piece of metal and it works like a steering wheel puller. Any suggestions? I have them soaking in some penetrating fluid for now, I'll see how that works out.  |
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Pepmyster
Member
Posts: 698
Go Bonzo, Go!!!!
Mascouche, Quebec, Canada
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« Reply #1 on: October 21, 2013, 05:59:53 PM » |
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They should have popped out with the air pressure, if they were not seized, they should have moved.......
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Now this is getting interesting........
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Rio Wil
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« Reply #2 on: October 21, 2013, 07:14:42 PM » |
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John, can you hook these up to the 1200 master cylinder....bleed and use hydraulics to push them out....use a suitable thickness of material between the brake pads to act as a buffer.
If you remove the one thats not stuck, , does it look all rusted and corroded inside the caliper.
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John Schmidt
Member
Posts: 15240
a/k/a Stuffy. '99 I/S Valk Roadsmith Trike
De Pere, WI (Green Bay)
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« Reply #3 on: October 21, 2013, 08:08:04 PM » |
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John, can you hook these up to the 1200 master cylinder....bleed and use hydraulics to push them out....use a suitable thickness of material between the brake pads to act as a buffer.
If you remove the one thats not stuck, , does it look all rusted and corroded inside the caliper.
I'm using a spare set of Valk m/c and nothing is mounted so would be difficult to use hydraulics to release them. And...I don't want to remove the one that does move, not just yet. If I do, that allows air to escape through that side and I'd have no way to plug it. At present, I have the moveable one held in place with a small "C" clamp with the hope that more pressure will be applied to the other side. I'll give it a couple more days soaking and if they don't come out, I'll have to take them to my friend's shop. He's a long time gear head, about 65 and has more tricks up his sleeve than I do. |
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gordonv
Member
Posts: 5763
VRCC # 31419
Richmond BC
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« Reply #4 on: October 21, 2013, 08:27:49 PM » |
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I would do the hydraulic method, hook it up to your system, and using oil pressure to remove/move the pistons. It shouldn't take much, and a lot simpler than taking them to a shop.
You've also already mounted the C-clamp to hold the moving one in place.
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1999 Black with custom paint IS   |
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Gryphon Rider
Member
Posts: 5227
2000 Tourer
Calgary, Alberta
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« Reply #5 on: October 22, 2013, 07:09:25 AM » |
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Note: I have NO experience with seized brake pistons.
If they are seized in a position that is not fully retracted, could you use a C-clamp to push them in a little farther, thus freeing them, or at least exposing more contaminated cylinder surface to your penetrating fluid?
Also, what about applying heat to the caliper?
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bentwrench
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« Reply #6 on: October 22, 2013, 07:27:45 AM » |
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I've had some luck using battery terminal spreaders,just to get them to turn in the bore.If they turn they should come out.The other posts about pumping them out with a m/cyl. is right ,if air won't move em.just find some thin wood shims to keep them both in there till they're almost all the way out then you should be able to rockem out from there.
BW
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John Schmidt
Member
Posts: 15240
a/k/a Stuffy. '99 I/S Valk Roadsmith Trike
De Pere, WI (Green Bay)
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« Reply #7 on: October 22, 2013, 07:40:02 AM » |
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Since nothing is mounted yet it would be difficult to set up a hydraulic system. This is a restoration project with some major mods on a GL1200 Standard and very much in the early stages of the build. . At this point I don't have the frame up on wheels, no handlebars mounted so no master cylinders or brake lines. As one little guy down the street once said; "guess I'ze gonna 'spearment."  |
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quexpress
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« Reply #8 on: October 22, 2013, 08:30:02 AM » |
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Hi John, In the past, I have manged to release stuck caliper pistons with a grease gun. On one set, I believe that I had removed the brake line hose, and screwed in (just a bit) the tip of the grease gun (while leaving the bleeder screw tight). I have also heard of screwing in a metric zerk in the brake hose hole ... and then connecting the grease gun on that zerk ... but have not tried that method yet. Hope this helps!  |
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I still have a full deck.
I just shuffle slower ...
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John Schmidt
Member
Posts: 15240
a/k/a Stuffy. '99 I/S Valk Roadsmith Trike
De Pere, WI (Green Bay)
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« Reply #9 on: October 22, 2013, 12:40:11 PM » |
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Hi John, In the past, I have manged to release stuck caliper pistons with a grease gun. On one set, I believe that I had removed the brake line hose, and screwed in (just a bit) the tip of the grease gun (while leaving the bleeder screw tight). I have also heard of screwing in a metric zerk in the brake hose hole ... and then connecting the grease gun on that zerk ... but have not tried that method yet. Hope this helps! Normand, thanks for the ideas, I'll try anything to save a buck on new pistons. I think it's called "cheap."  |
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quexpress
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« Reply #10 on: October 22, 2013, 01:27:07 PM » |
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Normand, thanks for the ideas, I'll try anything to save a buck on new pistons. I think it's called "cheap." We're on the same page!  |
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I still have a full deck.
I just shuffle slower ...
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John Schmidt
Member
Posts: 15240
a/k/a Stuffy. '99 I/S Valk Roadsmith Trike
De Pere, WI (Green Bay)
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« Reply #11 on: October 22, 2013, 05:14:39 PM » |
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Well, I got three of the four out. Soaking in penetrating fluid(bearcat pee) seemed to help. That fourth one is a bugger so I quit for the night after filling the chamber behind it with "BP" and set it so the stuff will run down alongside the piston. One popped out with air and shot halfway across the garage. I've done it before and it still startled me. Thankfully it was aimed away from the bike.
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R J
Member
Posts: 13380
DS-0009 ...... # 173
Des Moines, IA
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« Reply #12 on: October 22, 2013, 05:22:35 PM » |
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John, at the shop we have had good luck soaking them in diesel fuel.
If they are super duty stuck, the grease zert method usually works when all else fails.
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44 Harley ServiCar   |
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John Schmidt
Member
Posts: 15240
a/k/a Stuffy. '99 I/S Valk Roadsmith Trike
De Pere, WI (Green Bay)
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« Reply #13 on: October 22, 2013, 07:54:20 PM » |
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John, at the shop we have had good luck soaking them in diesel fuel.
If they are super duty stuck, the grease zert method usually works when all else fails.
I hit four auto parts stores this afternoon and couldn't find a zerk with the right thread. As I recall, the thread on the bleeder is 1.25...the only one that came close was an 8mm but wrong thread. Might check a NAPA shop tomorrow. Guess I'm too cheap, I can replace all the pistons for slightly less than $100 and another $25 for the seals. Maybe it's the challenge...or idiocy. |
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R J
Member
Posts: 13380
DS-0009 ...... # 173
Des Moines, IA
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« Reply #14 on: October 22, 2013, 09:05:11 PM » |
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John, I all for the challenge. I'm cheap also at times.
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44 Harley ServiCar |
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John Schmidt
Member
Posts: 15240
a/k/a Stuffy. '99 I/S Valk Roadsmith Trike
De Pere, WI (Green Bay)
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« Reply #15 on: October 23, 2013, 12:46:33 PM » |
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Got them all out but really buggered up that last one. Figured if I had to replace one might as well go new on all four. Was $90.66 for the pistons and $18.24 for the seals. Also had to order one of the small boots for another $3.49, w/shipping I'll have rebuilt calipers for $127.92. Sure not looking forward to getting the pistons pressed in through the new seals, has always been a PITA in the past. Any suggestions? I usually give everything a good brake fluid bath but still tests my patience....and sanity!!!  |
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Brian
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« Reply #16 on: October 23, 2013, 04:08:48 PM » |
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Got them all out but really buggered up that last one. Figured if I had to replace one might as well go new on all four. Was $90.66 for the pistons and $18.24 for the seals. Also had to order one of the small boots for another $3.49, w/shipping I'll have rebuilt calipers for $127.92. Sure not looking forward to getting the pistons pressed in through the new seals, has always been a PITA in the past. Any suggestions? I usually give everything a good brake fluid bath but still tests my patience....and sanity!!! I have never done this John, but was thinking you could use a piece plate steel and c-clamp? The Honda manual states using silicone grease on the seals and the dust boots and brake fluid on the piston. It says nothing about pressing them in. Maybe Daniel can give us a tip here? |
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Tropic traveler
Member
Posts: 3117
Livin' the Valk, er, F6B life in Central Florida.
Silver Springs, Florida
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« Reply #17 on: October 23, 2013, 05:15:22 PM » |
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John, Ive never had a problem resetting the pistons back in the caliper bore. Just make sure everything is lubed up with brake fluid or brake assembly lube & that the pistons & bores are smooth. Never used new pistons but always sanded the used pistons with 400-600 grit wet or dry sandpaper {wet} before reassembly.  |
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saddlesore
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« Reply #18 on: October 23, 2013, 08:02:16 PM » |
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Got them all out but really buggered up that last one. Figured if I had to replace one might as well go new on all four. Was $90.66 for the pistons and $18.24 for the seals. Also had to order one of the small boots for another $3.49, w/shipping I'll have rebuilt calipers for $127.92. Sure not looking forward to getting the pistons pressed in through the new seals, has always been a PITA in the past. Any suggestions? I usually give everything a good brake fluid bath but still tests my patience....and sanity!!! I have never done this John, but was thinking you could use a piece plate steel and c-clamp? The Honda manual states using silicone grease on the seals and the dust boots and brake fluid on the piston. It says nothing about pressing them in. Maybe Daniel can give us a tip here? Good idea, but instead of using a steel plate I just slide both brake pads over and use the c-clamp. |
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DARE TO BE DIFFERENT
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