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Discussion Starter · #1 · (Edited)
So in replacing the wheel bearing in the rear wheel of my 1978 CB400A comstar I cam across the rubber dampers under a disintegrated black cover. The dampers are all made of rubber and go in between the lugs the sprockets bolts go into. They are shot, really brittle and falling apart. Anyone know where to get new ones? I found a source on eBay and the seller is in Germany. I've scoured the net trying to find them. Here's the pic. I entertained the idea of making my own using some 80A hardness urethane casting materials. Thoughts?

s-l200.jpg

Part number 41241-413-781

Cover part number 41265-413-780
 

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I have had luck with cutting short pieces of a 1.5" bicycle tube and sliding it over the large part to take up the slack.
 

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Discussion Starter · #5 · (Edited)
CMS has them in stock. $10.00 ea plus shipping.

Bill
I found them on there but for some reason I'm getting 10 pounds instead of $. I was actually thinking of making my own. I may experiment and document it all so that in case it works I will post a DIY for the group. Thank you everyone for the responses. I found them on eBay as well but they are $20 each plus shipping from Germany as that's the only vendor on there that I have found to have them in hand.
 

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Discussion Starter · #8 ·
Project dampers underway.

Materials:
Fake flower foam bricks.
Plasti-Dip to line the cavity.
Neoprene roofing sealant to use for the damper material and fill the cavity with.
 

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Discussion Starter · #10 · (Edited)
Here are the rest of the pictures so far. I figured out that 1 tube of roofing sealant fills 3 cavities. So off to get some more tomorrow after work. I'm all in for less than $20 so far. I may try and find a different Polyurethane sealant for the 4th one to see what the results are. I'm going to let them all cure till next week and then break the molds and get the forms out. Cheers.
 

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Interesting.

Would like to know how they turn out, how hard they are etc..

Since the mid eighties I too have been using inner tube squares for repairing/packing these dam things.

Be careful about the grease/lub used for the alloy tapers and drive pins as the wrong type will destroy the rubbers.

I also use o rings on the drive pins to keep lub in/crap out.

I have seen internet clips of people making there own poly bushes for engine mounts.

All we need now is a heat resistant hot oil tolerant hard wearing type rubber/material for the balance chain slipper A, cam chain blades and clutch basket damper remanufacture etc..

A heat tolerant easy formed plastic for stator bobbin re manufacture would also be good.

Material scientists out there please help !
 

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Discussion Starter · #12 ·
They are curing in the molds in the garage. It's been a bit chilly lately so the curing time will be longer. I'm expecting sometime next week or a little after to break the molds and see what they look like. Even with the second tube of material I'm still under $25 total and little time. I have used this method to make engine mounts before and that's where the idea came from other than the molds portion, that's a new avenue.
 

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Thanks and and a tip of the hat for a great idea.I was wondering how flex tape liquid would work for this. Ive never used the liquid but have used the tape even on the bed liner of my pick up.
Its tough stuff.


Bill
 

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If it's too chilly out in your garage, maybe you could improvise a warm curing oven with a cardboard box and droplight? I cure painted parts this way regularly at temps below freezing.
 

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Discussion Starter · #15 · (Edited)
So I have been letting these cure for quite some time now. About two weeks. Here are the results. The 3 that used the first rubber compound didn’t ever get hard. The 2nd compound that I used with the last one I did actually worked pretty well but didn’t get completely hard or solid. I cut it open and it was still squishy as displayed in the last photo. If I should ever do this again I would use the 2nd compound and do it in 1/4” layers so that it would harden completely. The other option is to buy some 80 or 90 durometer urethane and do the process after mixing the two parts and pouring that into the molds. There are kits online in the $35 range before shipping. The molds worked great to form the new parts. They just cut apart with a putty knife and I rubbed the rest of the material off.

Overall I’m going to say that I would do this again if I couldn’t source them online at all. Maybe someone else who would like to try just out of something to do may use this post and get some tips. It’s possible but with the additional steps for hardening. It works as a last ditch effort but I’m going to try adding some other rubber to tighten things up on the original ones and see what that does. I may buy new ones if that doesn’t pan out.
 

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You might try what I suggested in post #4.
 

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Discussion Starter · #18 ·
Very long overdue update. I ended up using the original pads and used the plastic-dip spray to make up the gaps and free play along with some rubber material to get them back to normal shape. They are solid and still give just enough to take the shock of the sprocket. I also got the bike back together to 90% with my youngest son who started the project with me 3 years ago.
 
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