CRF rear shock spring

nilsen
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nilsen
Edited Date/Time 1/2/2019 5:18pm
can i use an crf250r 2016 shock spring on an crf450 2018 ?

They almost look the same apart from the spring for the 250 is aprox 3/4'' longer / higher than the 450. they are not the same stiffness, so is this the reason for the different length, or is it another type ?

the red one on the picture is for the 450

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kb228
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kb228 1/2/2019 1:17pm
1/2/2019 1:17pm
No they need to be the same length. That longer spring will be a LOT stiffer than you think. If you can even get it tightened down enough.
nilsen
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nilsen 1/2/2019 1:33pm
1/2/2019 1:33pm Edited Date/Time 1/2/2019 1:45pm
kb228 wrote:
No they need to be the same length. That longer spring will be a LOT stiffer than you think. If you can even get it tightened...
No they need to be the same length. That longer spring will be a LOT stiffer than you think. If you can even get it tightened down enough.
I found this post after i made this post... on that post some guy says that it dosnt matter. guess you dont agree with him Smile


https://www.vitalmx.com/forums/Tech-Help-Race-Shop,42/2016-KTM-shock-sp…
aees wrote:

Spring length does not affect ride height, geometric or any other suspension parameter. It is just a longer spring, adding some weight.

Stock spring is 247mm, but 255 and 260mm is also common from 3rd part and ok to use. You can still use the model where you drop the shock down and pull it out between swingarm and subframe on right side of bike with a 260mm spring but it just gets slightly more delicate.
Bruce372
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Bruce372 1/2/2019 2:37pm
1/2/2019 2:37pm
As long as the upper and lower collars fit correctly, and the coils dont bind during full compression, you should be ok.

It doesn't matter how long a spring is, that spring has a rate... only if you change the length of that spring (by shortening it) will the rate change.
kb228
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kb228 1/2/2019 5:17pm
1/2/2019 5:17pm Edited Date/Time 1/2/2019 5:18pm
i suggest you guys learn how springs work. To compress the longer spring to the length of the shorter one puts 3/4” of preload onto the spring before the rider even sets the sag. Its effectively going to make the compression stiffer. Crank your preload adjusters down on the bike you have. Youll see what im talking about.
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Wade221
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Wade221 1/2/2019 5:51pm
1/2/2019 5:51pm
kb228 wrote:
i suggest you guys learn how springs work. To compress the longer spring to the length of the shorter one puts 3/4” of preload onto the...
i suggest you guys learn how springs work. To compress the longer spring to the length of the shorter one puts 3/4” of preload onto the spring before the rider even sets the sag. Its effectively going to make the compression stiffer. Crank your preload adjusters down on the bike you have. Youll see what im talking about.
Exactly! Manufacture specified range from collar to eyelet with preload. I’m going to bet that blue spring is going be way outside of spec
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mx317
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mx317 1/2/2019 8:02pm
1/2/2019 8:02pm
It depends on how many threads you have. If you can back the preload collars far enough to put the spring at the right preload (approx 5-7mm) it would be ok. My friend had a 2017 CRF450 and his did not have enough threads to allow him to use a longer spring. Even backed all the way off to where there were no threads left, he had way too much preload on the spring. Get the right length spring.
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harescrambled
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harescrambled 1/6/2019 3:33pm
1/6/2019 3:33pm
mx317 wrote:
It depends on how many threads you have. If you can back the preload collars far enough to put the spring at the right preload (approx...
It depends on how many threads you have. If you can back the preload collars far enough to put the spring at the right preload (approx 5-7mm) it would be ok. My friend had a 2017 CRF450 and his did not have enough threads to allow him to use a longer spring. Even backed all the way off to where there were no threads left, he had way too much preload on the spring. Get the right length spring.
Either that or you have to have a shop cut a second groove for the shock spring retainer circlip...the new Showa shocks don't have a whole lot of threads, and they run a short spring. If you don't want to get the mod done you pretty much have to buy Showa springs

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