Preloading shocks

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Sep 25, 2017 | 12:47 PM

adamk

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Preloading shocks

My new mechanic told me that my bike has a lowered front end and that if I preload the shocks by adding a bit of PVC I'd have an improved ride, esp. over bumps.

It would be nice to know what size PVC and washer I need before I begin the project.

Does anyone happen to know off hand?

Sep 25, 2017 | 01:56 PM

Scuba10jdl

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If it's the 39mm forks like most sportys, 3/4" schedule 40 PVC with 7/16" USS washers (the OD for this is 1 1/4").

Sep 25, 2017 | 02:01 PM

grbrown

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Scuba doesn't leave much room to add anything, except to point out that your spacers need to be square-ended, so don't rely on a hacksaw! Best to use a pipe-cutter or lathe, to get neat true ends.

Sep 25, 2017 | 02:29 PM

adamk

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GrBrown, how square do they need to be?

Is a hacksaw in a jig good enough, or do I need more precision than that?

Last edited by adamk; Sep 25, 2017 at 02:31 PM.

Sep 25, 2017 | 02:46 PM

grbrown

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From: Bedford UK

Quote:

Originally Posted by adamk

GrBrown, how square do they need to be?

Is a hacksaw in a jig good enough, or do I need more precision than that?

If you look at a suspension spring for the shocks or forks, they have machined ends to both springs. This is so that when compressed the spring stays true as it moves. The ends of the spacer should also be square, otherwise the spring will not stay reasonably straight, such as when hitting a bump. A pipe cutter is probably the simplest and cheapest tool and should be available from a local hardware store or plumbing store.

A hacksaw isn't going to cut it - if you get my drift! I suspect it isn't possible to get a flat true surface on each end and also get two spacers the same length. It will be interesting to see what tips others can offer.

Last edited by grbrown; Sep 25, 2017 at 02:48 PM.

Sep 25, 2017 | 06:51 PM

Grey_Beard

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Another option would be to use a chop / miter saw. Just make sure the blade is set to 90deg and hold the PVC squarely against the back fence. Perhaps your have a buddy that could cut it for you. As grbrown stated a hack saw just isn't going to cut it square enough for what it needs to be.