AMP D1 disc brake calipers. rebuildable?

ylwgto

Retro Guru
Hi. I have an AMP B4 with the D1 disc brakes on it. I'm selling it, b/c the calipers do not work, but would consider keeping it if I could get the brakes working.

Anyone have any info on how these are rebuilt? I've see the PDF of the AMP manual, but it is not entirely helpful and I have no idea where to access parts (or if they are even available). It can't be much more complicated than o-rings and oil, can it? All the hardware is there, but I am missing the brake pad pin and cotter pin from one caliper.

thanks.
 

2manyoranges

Senior Retro Guru
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Re:

Depends on what the issue is/are.

Usually there is a problem of the seals (yes O rings) going plastic and sticky, and often expanding and hardening. Remedy: soak, strip and replace seals.

Sometimes a problem of corrosion in the caliper barrel. If a 'lip' of corrosion has formed, this jams the piston. Removing it can create pitting and leakage. But sometimes, after dismantling, just rubbing and rubbing with a coarse cloth can fix it. If the inside of the bore is too badly damaged you need to do a whole load of measurements - sometimes you can get the bore reamed, and fit a bigger seal. And if the pads are really worn there can be quite an issue - you fit new pads, and that pushes the pistons way back in the bores, and all seems fine. Then they wear, and then the seals pass the ring of corrosion and the little devils then lose pressure. which can be scary scary. Although it is unlikely to happen to front and rear simultaneously. Reaming the bores changes the volume of the pot which can be an issue on the tiny bike systems, but changing the piston sweep in the master cylinder can fix this, depending on the lever fitted. I think Amp are alloy piston in alloy cylinder - frequently scored (bad) and often had water sitting in them (pitting and lips). You will have to bite the bullet and dismantle to see what's happening.

Of course, might not be the calliper. Could be the master cylinder (as well or instead of) - again, leaking master cylinder piston seal, or water incursion into the lever.

pins and springs usually proprietary and if you take them to a brake specialist they will go 'ah right, yes we have one of those....'.
 

ylwgto

Retro Guru
Re:

Thanks. Cosmetically, the bike and the calipers themselves are very clean. I'd be very surprised if corrosion was an issue. It was definitely not an off road bike. But, good to know the only way to diagnose is to dismantle.

So if I do, what o-rings do I need and is there any re assembly instruction help/wisdom out there? Don't want to take them apart until I've the parts I need to fix while they are off.

Alternatively, are there options for these AMP frames/forks to convert to modern IS mount calipers?

Thanks!!
 

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2manyoranges

Senior Retro Guru
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I don't think you need to be a machinist...you just need to give the drawing to one....will not be much to make up. Colin Furze would be up for it.

And I think you need this:

/var/folders/_t/hlxw9hmj6vdg4fbnk7b2vdn00000gn/T/com.apple.Preview/com.apple.Preview.PasteboardItems/d1-manual (dragged).pdf
 

ylwgto

Retro Guru
Re: Re:

2manyoranges":209hqdhr said:
I don't think you need to be a machinist...you just need to give the drawing to one....will not be much to make up. Colin Furze would be up for it.

And I think you need this:

/var/folders/_t/hlxw9hmj6vdg4fbnk7b2vdn00000gn/T/com.apple.Preview/com.apple.Preview.PasteboardItems/d1-manual (dragged).pdf


Just saw the middle pic showing the guy made it from a cassette cog. brilliant. I need a rear too!

at any rate, i'm in NYC with no garage space or metal working tools. I'm really after someone else who's already done the troubleshooting and has either the brackets made and for sale OR a design I could buy and get to a machinist to fab up.

Thanks for the help
 

2manyoranges

Senior Retro Guru
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There definitely are machine shops on the East Side or def in Brooklyn who could do this for not-very-much.....the dimensions for the bracket are same front and rear and the drawing already sent has the exact dimensions....
 

ylwgto

Retro Guru
I don’t see a drawing in the links...did I miss it? Only see the link to the manual and the link to that guys conversion in ‘09
 
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