KymcoForum.com
General => Technical | How To => Topic started by: monkeybongos on May 16, 2023, 02:07:30 PM
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What's the trick to replacing brake pads (rear in this case) without all the brake fluid dripping out?
I removed the two screws holding the caliper together, could that be the problem?
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look this over. https://www.youtube.com/watch?v=QiqT44lFtww
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I removed the two screws holding the caliper together, could that be the problem
@MB, no IMHO this is not the prob. Even if you remove all bolts on this calipers there will no brake fluid leakin' out.
I'm inclined to think one of your piston seals is either pushed out or demaged. Please check them and replace if neccessary.
Also check your brake line and bleeder valve for leaks.
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When I remove the calipers on my bike I make absolutely certain to put something between the pads to ensure the pistons don't push out far enough to leak out the fluid. When replacing pads I make certain to never touch the brake levers or parking brake. Both must be off. Usually the only bolt that really needs to be removed on many calipers is the pad pin or pins. But my Burgman needed the caliper to be removed from the disk to change the pads. Again, being very careful not to pull the brake levers or parking brake and even push the pistons back into the calipers if needed to insert the pads.
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Yeah, MB, you have some bigger problem with your caliper. On slide calipers the only way to leak fluid is to crack open the bleeder or the banjo bolt..or have leaks around the pistons. As Ruffus suggested, likely piston seals.
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Appreciate the replies, everyone.
Think Ruffus and Hawk are correct about the seals, as there is still leaking of brake fluid w the caliper reassembled and back in place.
At 27,000 miles, guess it shouldn't be a surprise the seals need replacing, but why there was no leaking before replacing the pads?
Not sure which rebuild kit from All Balls will fit--sent them an email asking. May have to get a whole new caliper if they don't know
which rebuild kit would work.
Really like the Cali Classic, only downside is Lance is not widely recognized, so many part mfgrs don't list Lance scooters on their parts list.
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@MB, it's leaking anyway.
Take these pistons out and measure.
There are slightly differrent shapes available but this doesn't matter. Diameter is important.
Why is it leaking now:
- by pushing the piston and the gasket forward you loosened most probably some crusts in your caliper cylinders, destroyed the gaskets, which now caused it leaking.
Means: close observation and cleaning of this cylinders is recommended. If there are corrosion rings which cannot be removed by hand and @SCOTCHBRITE or similar, you will face leaking again.
Solution: honing plus new pistons and gaskets. Actually very easy, because this calipers are made from pretty soft alu, but needs some experience.
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Leaking brake fluid is a serious concern. You could lose the braking when you need it most.
Art
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@MB, pls see pic/link, this guys should have your Lance stuff... give them a ring, or...
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.scooterdynasty.com/caliclassic200i4tac-2.aspx&ved=2ahUKEwj1rviB8fz-AhXMi_0HHQwyBPUQFnoECBIQAQ&usg=AOvVaw3KClc9VC9ZXe4dhOx86_Yb
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Ruffus, doctor of diagnosis. Surprised you know about Scooter Dynasty. They are my go to for Lance parts,
but don't carry replacement pistons as far as I know. Not sure where to go for that (auto parts store?).
New caliper will take care of pistons and gaskets/seals--as well as brake pads, which I already bought--so most likely
will go that route. Will take current caliper apart tomorrow to examine seals and pistons, see whether they can be rehabbed.
You make a good point, Art. Front brake works fine, plus w my riding style and the engine braking this scoot has, I'm not
too concerned. But the leaking needs to be addressed for sure.
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@MB, if you are handy, then:
Rubber gloves and eye protection needed!
-take your caliper off hose and apart
-take detailed pics
-wash all parts with rubbing alcohol
-take a magnifier and check all parts for possible demages
-maybe your piston gaskets are still without holes
-IF YES (without gushes) put them short (10 min) in fuel they will swell a little bit
- out again and rinse with lots of alcohol, put aside
Caliper and cylinders:
-as I said, try to remove corrosion rings within cylinders with such a kitchen sponge and alcohol
-if you cannot feel any demage anymore, rinse and aside
-pistons are usually crome plated, if you see or feel lots of blisters or pittings, forget them
-if only some small blisters or pits, this piston might be able to be saved
-kitchensponge, alcohol again
Dryblow them.
If all your parts are refurbished and in halfway shape, reassamble with brake fluid or better with brake paste.
This is an emergency or oldtimer way to safe what is not longer available anymore.
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I replaced the rear caliper on my Grandvista 250 and it cost $100 from Kymco via Leeson's, which seems a bargain to me compared to trying to repair it. I tried once to rebuild a caliper and it leaked anyway. I hope you have better luck than I did.
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Is this enough pitting to cause leakage?
And is this a consequence of not changing the brake fluid for 4 years?
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MB, IMHO no,
this pistons can be used again. Polish them a shiny as possible, check your gaskets for leaks (better new one), take brakefluid to assamble and you will be good to go.
New (thicker) brake pads make the gaskets sit at a different spot on your pistons and should hold tight.
And YES, water in your brakefluid causes this corrosion and pitting.
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After brake fluid leaked while installing the new pads,
I filled the master cylinder w a bottle opened months ago to see if the caliper continued leaking.
I figured why use new fluid until I knew the leak stopped. I know, it's not expensive, but I never thought it
would cause problems when used only to test for a leak.
I took the caliper off to check the pistons, and find the coating on the new brake pads is peeling off.
Would this be caused by old brake fluid? In just a day? Can these pads still be used if I scrub off all the black coating?
If there is a way to screw up, I'll find it. Should change my name to Mechanic from Hell.
Pics show the front and back of the pads. Single pad on top is the old on, two beneath it are the new ones.
Old pad = no peeling after 28,000 miles. New pads = peeling after a few hours in 6 month old brake fluid.
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Is that just paint peeling off the metal backing plates from contact with brake fluid? Brake fluid will peel any paint after extended exposure.
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Is that just paint peeling off the metal backing plates from contact with brake fluid? Brake fluid will peel any paint after extended exposure.
Could be paint, could be some king of plastic coating. Hard to tell. But the coating is unblemished on the 5 yr old pads. And the fluid wasn’t even changed for 4 yrs (b/c I didn’t know better). Besides, wouldn’t EBC coat them w something that isn’t affected by brake fluid?
Emailed EBC about this, but they are closed till Tuesday. Hoping someone here could shed some light in the meantime.
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Could be paint, could be some king of plastic coating. Hard to tell. But the coating is unblemished on the 5 yr old pads. And the fluid wasn’t even changed for 4 yrs (b/c I didn’t know better). Besides, wouldn’t EBC coat them w something that isn’t affected by brake fluid?
Emailed EBC about this, but they are closed till Tuesday. Hoping someone here could shed some light in the meantime.
Definitely paint peeling. And brake fluid will peel paint. No, the likely don't use paint that is resistant to brake fluid since, if all is working as it should, there should be no brake fluid getting on there to worry about.
I just received the new rear pads for my AK to have on hand (old pads are still in great shape and have a lot of miles left) and they are painted. Often brake pads are not painted so this issue is not experienced.
I have no answer about why the old pads were not affected like this. But then, you did originally say there was no leaking until you pulled out the old pads so likely didn't have any fluid on them.
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if all is working as it should, there should be no brake fluid getting on there to worry about.
That makes sense, Bob
there was no leaking until you pulled out the old pads so likely didn't have any fluid on them.
Correct
Think if I get all the peeling paint off, the pads will be ok to use?
What is the purpose of the paint, anyway?
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yes, those pads will be fine to use if you scrape the peeling paint off of them. They may be a little more susceptible to corrosion without the paint coating protecting them but it will have zero effect on their ability to stop your scoot!
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Do not know exactely how and what you did to this brake pads.
For security reason take new ones.
EDIT:
DOT 4 consists primarely of two components, glycerine and alcohol. This first part soaked into pads sinter material and is hard to get rid of, therefore my recommandation to renew.
To check leaking or not leave the caliper off shim, put a piece of wood or plastic between pads and pump.
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As Iahawk mentions, just remove the peeling paint and they should be good to use for a little while. They will rust faster without that paint protection but the pad material is likely unaffected. New pads would be best, but these should be good for a while.
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Do not know exactely how and what you did to this brake pads.
Think rjs987 explains what happened
For security reason take new ones.
EDIT:
DOT 4 consists primarely of two components, glycerine and alcohol. This first part soaked into pads sinter material and is hard to get rid of, therefore my recommandation to renew.
How will that affect function of the pads? Since it is the rear brake and I brake little anyway (mostly coast w engine braking, rarely go about 40 mph), I'm not overly concerned if they're a little less than 100%
Here are the naked pads, stripped of paint. Also a pic of the tools used, in case anyone ever has a similar issue.
Took out the seals and wiped them down, and cleaned inside the caliper where the pistons go w a small brass brush drill attachment.
It's a real brass brush, not brass coated steel.
I'll check for leak w the ruffus method, then a test ride if they pass the leak test.
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Pads might be contaminated by brake fluid which could affect friction on your disc.
Recomm: put your pads on a few layers of kitchen paper, shove them (metal side up) into an oven and "bake" brakefluid out of them for a while.(180°C for 20 min)
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Thanks to everyone that chimed in.
After examining/cleaning the seals, scrubbing/buffing the pistons, cleaning the inside of the caliper, and getting all the peeling paint off the new
brake pads, the caliper still leaked. Slower than before, but a leak is a leak. So got a new caliper and all is fine.
Would have saved time and aggravation going that route from the beginning, but at least now I completely understand how brakes work and
can take apart/put together calipers in my sleep. Also got lots of practice bleeding the brakes, as well as my french, if you know what I mean.
Big thumbs up to oemcycles.com on Ebay. Asked them about the peeling paint on the pads (purchased from them), they quickly responded w an offer
to refund or replace. After rjs987 explained how it likely happened, I realized it was user error, not any defect of the pads. I told oemcycles that, and
since it was my fault I wouldn't return them.
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glad it all worked out in the end and I'm glad you learned a new skill along the way! That's how these things usually happen..you dig into it and then are completely capable / knowledgeable about that particular part. Next thing you know you'll be working on the calipers on your car!