GS550 front caliper OEM parts won't fit!

[yossarian]

Hi all,
I am rebuilding my front calipers of my 79 GS550en at the moment, luckily the pistons were fine so that saved me some dough but I am replacing the boots and seals as they are a bit past it. I went ahead and bought the OEM piston seals (#59307-45020) and piston boots (#59308-45020) and went to install them, however they are too big! The seal has an outside diameter that is 3mm bigger than the one I removed, meaning it wont fit into the cylinder wall no matter how hard I try. The diameter of the part of the boot that also fits into the cylinder wall is also 3mm bigger than the one that I took out and also wont fit. As far as I can tell the part of the boot that fits into the piston seems to be the right size. I hope this all makes sense to someone out there and was wondering if anyone that has rebuilt front calipers from the same or similar bike has had the same problem. I took some pictures of the caliper, boots and seals and will upload them when i get a chance. In the meantime here is a link to the fiche of the caliper http://www.internationalmotoparts.com/oemparts/a/suz/50d3f5a2f8700230d8b4c70c/calipers

If I have been a complete idiot and bought the wrong parts can someone please let me know, but I am pretty sure I haven't as the caliper in the fiche is identical to mine! the only thing is that the piston seal that I ordered has a slightly different part # than what I actually received (59307-45021 as opposed to 59307-45020) but it seems from searching on the internet that it is the same part just and updated part number. If it to any value of anyway that happens to make it this far through my complaining, the identifiers on the actual boots themselves are completely different though I don't know if this is relevant.

I probably wouldn't be too surprised by all this if I had bought a generic rebuild kit but I did the right thing and went OEM. You guys with your accumulated knowledge are amazing and I thank you for any assistance that you can give me, as I am a bit confused as to how to proceed.

yours,
yoss

 

[cowboyup3371]

I looked at Alpha Sports' parts fiche and those are the right part numbers so I wonder if maybe the size difference is not due to shrinking from age or, more likely, maybe you have calipers from a different bike. Would you post a picture of the caliper and parts?

 

[yossarian]

hi Cowboyup, thanks for replying. here are some pictures of the caliper in question

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[cowboyup3371]

Which seal are you having issues with? You'll have one that sits down inside a groove within the piston chamber (59307-45020) and then the boot that sits at the top of the piston and is pulled over the top of the caliper.

 

[yossarian]

Both of them. The seal diameter is 3mm too big and won't fit in to the groove in the chamber. It just gathers up too much once it is about three quarters in. The boot is the same. It seems to fit on the piston but won't fit in its groove in the chamber as its diameter is also about 3 mm too big