R25/3 Seat Bearing Silent Block

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kingcowie
Posts: 60
Joined: Wed Oct 28, 2020 1:29 pm
Location: Wollongong

R25/3 Seat Bearing Silent Block

Post by kingcowie »

Hello Guys,
It was late yesterday and i thought i would just knock off a job quickly and install my new silent block for the seat bearing. See attached images.
Anyway you should never rush a job
After making up a puller i was able to remove the old block, but the problem came when trying to install the new one, in short i ended up getting it seized 2/3 the way through and i could not move it for love nor money.

So i left it grumbling and thinking about over night i am going to pull it out and try again.

Anyway my new process is to make up a puller that will remove the old one and install the new one.

But it got me thinking about the type of fit and i assumed that it is a press fit which is hard to do on a bike frame. So i did some calculation and think that i need to heat up the bush to about 180 degrees celcius and then install the new silent block. At this temperature a bush of diameter of 25 mm will expand about 0.0508 which is 2 thou. 2 thou is usually the interference fit for a press fit.

Would appreciate comments if i have missed anything, or there is an easier way.
Attachments
Seat Bearing Silent Block.jpg
IMG_2459.jpg
Frame.jpg
Shane
Wollongong, Australia
Tooo many projects —— oh well
53 R25/3 Project
57 R26 Project
62 R50/2 Restored
64 R50/2 Project
67 R69S Original
71 R75/5 Original
77 R100RS Project

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VintageJim
Posts: 30
Joined: Thu Oct 07, 2021 2:07 pm
Location: Arizona

Re: R25/3 Seat Bearing Silent Block

Post by VintageJim »

If this was my project before going the heating route I would lightly sand the outside of the bushing to make it a little smaller and then use some red Loctite to make sure it doesn't work loose.
Jim

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jwonder
Posts: 547
Joined: Wed Nov 23, 2016 7:50 pm
Location: Long Island, New York
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Re: R25/3 Seat Bearing Silent Block

Post by jwonder »

I had a problem like this for my R 69 S and I think it was not made perfectly.

I chucked it up on the lathe and took a few thousands off and was able to drive it in just fine.
James Wonder
Long Island, New York

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VintageJim
Posts: 30
Joined: Thu Oct 07, 2021 2:07 pm
Location: Arizona

Re: R25/3 Seat Bearing Silent Block

Post by VintageJim »

If you have access to a lathe that would be the more elegant way to do it for sure. If you don't, for a part like this seat bushing, I wouldn't worry about using the emery cloth method to get it good enough to press into the hole.

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kingcowie
Posts: 60
Joined: Wed Oct 28, 2020 1:29 pm
Location: Wollongong

Re: R25/3 Seat Bearing Silent Block

Post by kingcowie »

thanks guys great idea..

i will put it on lathe and take a few thou off.
Shane
Wollongong, Australia
Tooo many projects —— oh well
53 R25/3 Project
57 R26 Project
62 R50/2 Restored
64 R50/2 Project
67 R69S Original
71 R75/5 Original
77 R100RS Project

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