Brake Piston Insertion
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- Dr. Frankenstein
- Silver Member
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Brake Piston Insertion
As paranoid as I am about putting together new brakes, I want to make sure I don't mar or otherwise mess up the new, very expensive new brake pistons I just got for the front and rear brakes on my '78 GL1000. I'm working on the rear brakes and have a bit of a size difference in the pistons - 42.84mm for the old ones, and 43.00mm for the new ones...that's like, what...one sixteenth of a millimeter difference..?
The reason I ask is, the old ones will slide right in by hand as per the manual instructions; the New ones (from Brakecrafters for the '78 GL1000) seem to hang up or 'stick', and I don't know if it's because they're new, or if they are just a fraction of a millimeter bigger...and I don't want to press them in for fear of buggering up the brakes and the piston.
My question is, am I just being paranoid and the seals and pistons are stiff because they're new, or are they indeed too big?? I'm thinking about putting them in the vise and pressing them in, but I've read that if they don't 'go in', somethings wrong, and I do NOT want to mess this up.
The reason I ask is, the old ones will slide right in by hand as per the manual instructions; the New ones (from Brakecrafters for the '78 GL1000) seem to hang up or 'stick', and I don't know if it's because they're new, or if they are just a fraction of a millimeter bigger...and I don't want to press them in for fear of buggering up the brakes and the piston.
My question is, am I just being paranoid and the seals and pistons are stiff because they're new, or are they indeed too big?? I'm thinking about putting them in the vise and pressing them in, but I've read that if they don't 'go in', somethings wrong, and I do NOT want to mess this up.
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Re: Brake Piston Insertion
I would first remove the seal from the groove and then you will be able to slide the old one in and out easily. Then compare it to the new one. After you polish the cylinder, the new one should easily slide in and out just like the old one.
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- Cast Iron Member
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Re: Brake Piston Insertion
When I pulled the seals out of mine the grooves were really caked with crud. Took a while to get them cleaned out good.
1981 Goldwing GL1100
Microsquirt efi
Microsquirt efi
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Re: Brake Piston Insertion
A good way to clean the groove is with a Dremel using a fine wire wheel.
- pidjones
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Re: Brake Piston Insertion
With the seal out and the bore clean, the piston should drop right in (lubricated with brake fluid first). If it doesn't, send it back.
"Love 'em all.... let God sort 'em out!"
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Ex 2006 GL1800 - the Black Pearl SOLD! to make room for:
2021 Can-Am Spyder RT Limited Dark Chalk Metallic
1975 Red GL1000 project - ex Pistol Pete project
1972 Triumph T150V Trident rescue - finished and FOR SALE!
1976 Yamaha RD400c
1978 GL1000 with '75 engine - the Hunley
Ex 1978 GL1000
Ex 1979 GL1000
Ex '79 CB750F rat bike
Ex '86 SEi
Ex '77 GL1000
Ex '76 RD400
Ex '72 Penton 125 set up for flat track
Ex '73 RD250
Ex '68 TR6C - chopped
- flyin900
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Re: Brake Piston Insertion
The most overlooked part of a caliper rebuild and the most important for an easier assembly. If there is any residue of dried old brake fluid still in that seal groove it will extend the seal slightly and stop the piston from sliding into the cavity easily.
That said, if your putting those parts in dry with no brake fluid or seal grease, it will also hang up and not go together easily.
Brakecrafters has a good reputation from my recollection. Just like painting; its all in the prep work and cleaning of the parts.
If everything is cleaned properly and lubed, you should be able to push the piston into the caliper by hand, if not I would contact the supplier for further info.
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1978 CB550K - Very original bike with only 7499 Km. from new - light cleanup and refresh done.
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1966 CL77 - Honda 305cc - Dual purpose - "Gentleman's Scrambler" was a period moniker.
1967 CL175K0 - Low production number with #802 engine serial- winter 2019/2020 full restoration.
1972 CB350F - Baby Four with low mileage - Cosmetic refresh to the next level 2021/2022.
1978 CB550K - Very original bike with only 7499 Km. from new - light cleanup and refresh done.
1983 CB1100F - Canadian model - DOHC Supersport in pristine low kilometre condition from new.
1984 GL1200 - Standard model in showroom condition - two owner bike from new.
1984 CX650E - Restored summer 2017 - a rare Eurosport model - excellent one owner bike.
- NotSoLilCrippseys
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Re: Brake Piston Insertion
I'd contact Brakecrafters. Not promising anything, as I have no relationship to them beyond being a customer, but I had a similar-sounding experience with a GL1100 front piston last winter and Brakecrafters took care of me.
My son rebuilt 3 dual-piston calipers (front/rear) with Brakecrafters kits, and one of the pistons in one kit went in hard but wouldn't slide back out. He followed their tutorials, and everything was clean enough to eat from. I swore that piston had to be bigger than spec.
I emailed them about the issue, claiming that one of the pistons had to be too large. They had me mail the offending caliper out to them. They pulled the stuck piston, replaced seals with new, and shipped it back for a basic shipping charge. Report was something about us botching the seal install, not using enough grease, or the like. No shaming. No hassle. Turnaround was about 5 days round trip.
Best of luck!
My son rebuilt 3 dual-piston calipers (front/rear) with Brakecrafters kits, and one of the pistons in one kit went in hard but wouldn't slide back out. He followed their tutorials, and everything was clean enough to eat from. I swore that piston had to be bigger than spec.
I emailed them about the issue, claiming that one of the pistons had to be too large. They had me mail the offending caliper out to them. They pulled the stuck piston, replaced seals with new, and shipped it back for a basic shipping charge. Report was something about us botching the seal install, not using enough grease, or the like. No shaming. No hassle. Turnaround was about 5 days round trip.
Best of luck!
Avatar is a summer '21 photo of the Blue Phoenix, our 1983 GL1100I rescue gone naked.
In the Stable and Ridable
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1987 VFR700 - son's latest, in blue/silver
1983 - GL1100I - naked Blue Phoenix (son's, really)
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Active Project(s)
1979 GL1000 - Confirmed one owner, with original paperwork. Vetter fairing and bags, off the road in dry, heated storage for 35 years.
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In the Stable and Ridable
1992 ST1100 - my longer haul tourer
1992 XJ600S - son's streetfighter
1987 VFR700 - son's latest, in blue/silver
1983 - GL1100I - naked Blue Phoenix (son's, really)
1982 GL1100I - naked bagger Cabernet
1979 GL1000 - Ginger Lynn, but not that Ginger Lynn (Wing and a Prayer)
1978 CB550K - son's cafe (carb issues still vex)
Active Project(s)
1979 GL1000 - Confirmed one owner, with original paperwork. Vetter fairing and bags, off the road in dry, heated storage for 35 years.
Sold
Not lookin' back to avoid regrets
- Sidecar Bob
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Re: Brake Piston Insertion
Make sure you use a brass wire wheel not a steel one (check with a magnet - there are brass plated steel ones). Steel is harder than aluminum....cfairweather wrote: ↑Thu Oct 14, 2021 7:47 pm A good way to clean the groove is with a Dremel using a fine wire wheel.
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The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
- Dr. Frankenstein
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Re: Brake Piston Insertion
Actually I did get back in touch with Brakecrafters, they said the machinist they use made a batch of the wrong size. They sent me out the correct ones, I sent them back the wrong ones, and all is good. They're a great bunch!
(And Yes, I did use a brass dremel to clean the groove).
(And Yes, I did use a brass dremel to clean the groove).
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