83 rear caliper question

[Hummel]

i have to rebuilt my rear caliper 250r 83. i found a little washer, curved. my clymer does not say where it belongs. looks like it goes into the hole where the rod of the piston for the parking brake goes. am i wright? little rubber o-ring and the wascher? i am not sure from what part of the caliper it came from...:wondering

[Aulbaugh]

Here is a parts diagram of the 83-84 front brake caliper. Is #21 the washer in question?

parts diagram (http://www.partzilla.com/parts/search/Honda/ATV/1983/ATC250R+A/FRONT+BRAKE+CALIPER+83-84/parts.html)

picture of washer (http://www.partzilla.com/parts/detail/honda/HP-45218-166-006.html)

[Hummel]

no it is not that one. it is from the rear caliper. i can not find it anywhere... the little o_ring for the pin of the piston goes all the down in the caliper, is it just the rubber o-ring or is it held by something like the little washer. it is almost as big as the little rubber oil seal for the pin wich is for the parking brake. i have a blockoff plate but there is no seal on it. do i just put the o-ring in the caliper and make a seal for the plate just to be safe?

edit: i´ll post a picture of this thing.

[Hummel]

246869

That´s how it looks.

[AMK]

http://www.babbittsonline.com/oemparts/a/hon/50bff044f87002341cac2792/rear-brake-caliper

Is it #25 here?

Never mind, after second look it isn't.

[Hummel]

thanks for the help but i tried everything to find it. watched many vids of rebuilding calipers, clymer, parts diagraph... looks like it does not belong into the caliper. but i am sure it was withe the rear caliper cause i took it apart seperatly.

[wonderboy]

It is just what you mentioned in your post. I rebuilt my 350x rear caliper and it has the same small cupped washer. It holds the o-ring in the caliper hole to seal the rod coming out of the back of the piston. So the o-ring goes in first, then the cupped washer. I found one of my small 1/4" drive sockets that fit perfectly into the cup and use that to lightly tap the washer into place. Don't hammer it hard or else you'll just flatten the o-ring.

[hipturn]

I've done some heavy thinking with wonderboy. I had this washer on my rear brake caliper piston parking brake shaft.

Unfortunately I destroyed it while unfreezing the caliper during a rebuild.

After the rebuild, i'm leaking fluid out of the rear brake caliper. When engaging the brake, fluid is forced out of the caliper through the piston parking brake shaft assembly. I.e. where the washer would be. So, I think the part is a necessary one. I think the part retains the o-ring. The washer is necessary to keep the rear caliper from leaking fluid at each brake depression.

Also, here's confirmation that the part doesn't appear on any honda BOM or schematic I could find. Wonderboy and I have both cross referenced the piston. The part is "Honda 43109-961-006 PISTON." The piston appears on a bunch of ATVs, even modern ones. So we both thought that by cross referencing the part, we'd eventually find the mysterious washer in another rear caliper assembly. Alas, no dice. Again, the part does not appear on any honda BOM that we could find.

Finally exhaustive google searches on "cup washer", "retaining washer", "o-ring washer" and the like turn up close hits, but nothing exact.

So, if any one has an extra one of these washers, please PM me.

Else, if you know the dimensions. Let me know that. ID, OD, anything else.

Else, any advice?

Any help is much appreciated.

Here's a drawing of how I found the washer riding on the brake shaft. If I remember correctly.
258361

Also, here's a dude making a similar part on youtube. Again, close, but not the same.


https://www.youtube.com/watch?v=u7WULLs2nV8

[hipturn]

closing this out.

Bottom line: the metal retaining washer is not needed.

I finished rebuilding the rear caliper with a kit. Once we tightened everything down, including installing the parking brake, we are leak free.

And the brakes work.

So, apparently the part is optional.

--hipturn

[wonderboy]

The more hipturn and I discussed this, we figured that any pressure applied to the brakes will only tend to force the o-ring further into it's small bore. Especially in his case, where there is no parking brake, there shouldn't be any appreciable motion of the piston in the other direction that isn't happening due to building up brake pressure. Even if the parking brake were hooked up, the amount of travel of the piston to clamp the rotor is so small, and I think the o-ring is deeper in the bore than there is travel of the piston that would tend to pull the o-ring out...