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2gofast

YZ426 Saving Weight, Help!

13 posts in this topic

I was told that I could put a 2006 Yz125 swing arm on my 2001 yz426 and save approx 4lbs. Is this true and is it a worth doing?:worthy:

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I doubt it will fit but you could try the parts fiche and see if the swingarm bearings are the same. That would be a start. Buy one off of Ebay if you are curious and let us know.

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I was told that I could put a 2006 Yz125 swing arm on my 2001 yz426 and save approx 4lbs. Is this true and is it a worth doing?:worthy:

Don't know about the 06 but they changed to the lighter swingarm in 02 I think. They will bolt on but you will need the new longer shock that they use also as the bike will sit to low without it. There is also a difference in the axle blocks that adjust the chain. I have a swingarm if you are interested.

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There were some changes in the dimensions of the swing arm made between the '01 and '02 model years, the pivot diameter, I think, and as I remember, those two will not interchange.

In any case, Yamaha did not make the 426 swing arm as heavy as they did just to weigh your bike down, and the 125 swing arm is only that light because it reliably can be. This is not something I would do, even for 4 pounds.

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I agree with Grayracer, by changing swing arms you could have a bit of a safety issue.

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Believe it or not, the 400/426450, the 250 pinger and 250F and 125 use the same swing are within the model year (check the fiche on the Yamaha website). As far as the year interchange, I don't know about from 01 to 06, but I do know that an 02 swing arm will fit on the 01 426...with a few additional parts. You need to use the inner bearing races from an 02, the pivot bolt from an 02, and the relay arm to swing arm bolt from an 02, then it's a direct bolt on. I did it on my 426 when I dorked up the swing arm, and all I could find for cheap was an 02 arm. The 02 arm was about a pound and a half lighter than the 01 arm, and is supposed to be stiffer as well. Even though the majority of the weight is unsprung, I really couldn't feel any difference in handling, though (but I'm not a real fast guy, either). As far as needing a different shock, the pivot points are all in the same locations (I verified this on a coordinate measuring machine at work) between the two years, and you use the same linkage, so the shock stays the same. The ride engineering axle blocks that were on my 426 worked just as well on the 02 arm as they did on the 01 arm.

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I did it on my 426 ....
Then the swing arm pivot diameter is not different? If it is, how did you get it to fit the frame?
Even though the majority of the weight is unsprung, I really couldn't feel any difference in handling,
The majority of the weight is sprung, actually. With any pivoting suspension component, the unsprung weight is that which is borne at the axle end, while the sprung weight is what is borne at the pivot. So, if you held the swing arm in your hands by its ends, in one hand you would feel the weight of half of both trailing arms and the weight of the pivot and cross bracing, shock mount, etc., and in the other only the weight of half the arms and the axle lugs.

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No, the pivot bolt diameter is not different...as I think back on it, maybe I didn't get the pivot bolt from the '02...

The seals are the same, and the needle bearing OD is the same, but the diameter of the needles inthe pivot bearings is larger, so the inner race is thinner, and probably a different material or heat treat to handle the higher stresses that come from having the same loads with thinner walls.

The relay arm bolt is the same diameter, but the 01 arm has a round hole that allows access with a socket to hold the hex head of the bolt. The 02 arm has a D shaped hole and a mating anti-rotation flat on the head keeps the bolt from spinning when you torque it.

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Thanks. The details of the differences were never very clearly laid out that I've seen. Good to know.

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save weight by getting a newer bike

i'm sure a few extra pounds is worth teh green sticker

4 pounds is not worth the trouble even if it works

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Thanks. The details of the differences were never very clearly laid out that I've seen. Good to know.

The new style arm will work with a few changes, I had mine installed until I got to the shock. The old style shock is shorter and will make the bike set about 1 1/2 to 2 inches lower. The pivot bolt's are different size's but all you do is use the collars and bolt for your bike, the swingarm bearings are the same. The rear axle and wheel will bolt up but my 2000 model axle blocks were to big to fit the new arm, not sure about 01 blocks. The rear caliper sits at a little different angle but will work. I do not think the weight saving's would be noticeable but the position of the linkage is designed to help the action of the suspension. There again you have to use the longer shock to make it work.

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