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 Post subject: Possibe use of Yamaha TZ rear wheels.
PostPosted: Tue Nov 14, 2017 2:13 pm 
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Joined: Thu Oct 14, 2010 11:23 am
Posts: 1123
Where have all the cush drives gone? Notice how many wheels are for sale without them? I have also noticed that there are a lot of vintage Yamaha TZ rear wheels out there, but they did not originally use a cush drive; the sprocket was bolted directly to the wheel. Later (I am not an expert; 1990s?) it was moved to the wheel. These repro parts, from Vince at FONDSECA in the UK, can be put on those Campy, Marvic, and Tecno mags of the 1980s with the five-bolt pattern and 74mm raised bearing hub. Get a Yammy rear sprocket and fiddle around with these parts, and you are good to go. They are slightly thinner that the first version, so a small recess 74mm wide will have to be machined into the back to fit the bearing hub, and a thin spacer plate installed to make up the difference at the hub (or, machine down the hub a few mm). As usual, you will have to deal with sprocket offsets and centering the wheel. And you will need to make an axle bush/spacer for the center of the outer bearing to keep all in place. MikeV

11/15/17: Five photos at bottom added for Lou. First two are on older version of the cush plate, and then the new version in last three.

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Last edited by 618F1 on Wed Nov 15, 2017 3:50 pm, edited 3 times in total.

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 Post subject: Re: Possibe use of Yamaha TZ rear wheels.
PostPosted: Tue Nov 14, 2017 10:15 pm 
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OK Mike, the gold piece bolts to the hub with the bolts threw the rubber Cush and the sprocket bolts to the aluminum piece and then sits on the Cush rubbers??? Lou


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 Post subject: Re: Possibe use of Yamaha TZ rear wheels.
PostPosted: Tue Nov 14, 2017 11:00 pm 
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Joined: Thu Oct 14, 2010 11:23 am
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WHAT? You push the rubber cush bolts thru the sprocket, and tighten them (molded to allen head bolts) to the gold plate on the outside --- see the space in one of the photos --- that is where the sprocket will be. Then you just push the rubbers into the cush plate that is bolted to the wheel. Then you need an axle bush/spacer with a diameter wide enough to hold the bearing and gold plate in place. Probably need another bearing or spacer inside there somewhere --- details always come later. Is that clear as mud? MikeV

Maybe I will add some photos in a day or two.


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 Post subject: Re: Possibe use of Yamaha TZ rear wheels.
PostPosted: Wed Nov 15, 2017 3:38 am 
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Location: Scotland
There was some thing simalar on the Armstromg from the same era, this had two alloy top hat bushes one on either side of the rubber (the rubber was an easy press fit into the sprocket) the sprocket was then bolted through the top hats to the carrier which was attached to the wheel and had similar recesses to accept the top hat.

Sam

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 Post subject: Re: Possibe use of Yamaha TZ rear wheels.
PostPosted: Wed Nov 15, 2017 4:01 pm 
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And here is a later Tecno that has the cush holes cast into the hub. Same TZ setup using only the newer gold center and the new cushes will work. Or I could just put the old bolts back into the old donuts. I found this sprocket assembly on ebay just to see if it would work. MikeV

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This is how the original owner mounted a sprocket to the wheel --- he placed a sealed bearing on the outside! See the wear marks. Not so nifty.

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