Bushing Question

Dietofnothing

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Nov 7, 2020
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Correct me if I’m wrong please. When replacing bushings , you ream through the inside of the plate & push the bushing through the plate from inside to outside. If the new bushing has an oil sink, it goes on outside.

Correct?

Thanks.
 

wow

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Sometimes it is impossible to ream and push from the back side due to a lever mount or some object in the way of the bushing machine. In that case, I ream and push in the bushing from the front making sure the rear side of the bushing is flush with the plate. If you are bushing by hand, this does not apply. Since reamers cut a straight hole rather than tapered, it really doesn’t matter as long as the rear of the bushing is flush with the plate. If you use a file or broach that is tapered, however, it probably would be better to broach/file and push from the rear side so the bushing won’t pop out. And, yes, the oil sink always goes on the outside.
Will
 

Dietofnothing

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Thank you - so you pretty much do everything from “inside” of plates (side gears are on) generally. Also, I’m wondering if on “outside” of plates, if new bushing stands proud of the plate (bushing is thicker than plate) if you need to file it flush?

It seems to preserve the end shake, you want the bushing flush with the plate on the inside. I’ve seen pics of various movements where it looks like someone filed the bushing flat on the outside (I’m assuming because it was too tall) and it makes the movement look horrible because there were scratches all over the plate. Not sure if it’s their technique or just the cost of filing the bushing. Is there any reason the bushing needs to be flush on outside of plate? Or, if it’s a little tall can you just leave it? Trying to learn the right way, thanks in advance.
 

wow

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A bulls foot file is great for grinding proud bushings without scratching the plate. Once ground down, an oil sink can be formed on the outside of the plate using a chamfering tool, dental burr, or other tools. Do a search on bulls foot file and there are threads concerning oil sinks on this message board.
 

shutterbug

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What you want to prevent is tunneling. That happens when the bushing extends beyond the pivot. Otherwise it's just cosmetic. I've seen many proud bushings that caused no issues.
 

bikerclockguy

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What you want to prevent is tunneling. That happens when the bushing extends beyond the pivot. Otherwise it's just cosmetic. I've seen many proud bushings that caused no issues.
I’ve never ground/filed a bushing completely flush with the outside of the plate, for the reasons mentioned in the original post; didn’t want to scratch the plate and also couldn’t see how a bushing that was just slightly proud could cause any problems. Your reply piqued my curiosity though, Shut. What are the issues with “tunneling”?
 

shutterbug

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The wearing eats away under the surface of the bushing, and puts pressure on it from the top and sides. It can go unnoticed, since it looks fine from the surface.
 
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Dietofnothing

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So, I think I get it. If the pivot exceeds the bushing (pomes out) - you’re good. If not - shorten the bushing.
 

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