Steer with the rear


11 replies to this topic
  • yam 3

Posted October 29, 2012 - 06:51 AM

#1

I have a 2010 yz450. I would like to set up the chassis to steer with the rear a litle easier.
Right now I have the DrD engine kit on it. I have also tried the link arm. I have 100 mm sag.
Dunlop 756 on front M51 rear. The bike hooks up almost too good where I would rather it slide a bit more.

Any ideas?

  • skoobeesnak

Posted October 29, 2012 - 08:11 AM

#2

I would try a different tire. I used to be a die hard 756 fan but have since switched to a Pirelli MT-16 which works better for me when it is leaned over but has a bit more spin when straight up and down. It will spin but I found it more predictable than the Dunlops and easier for me to control. A side benefit it is that it holds up much better and I get 3-4 times the life I would get from a 756 and about 2-3 times the life I was getting from a MX-51 before they started getting unpredictable. This is on my '09 YZ450F but my son has been running the same tire on his '10 YZ450F and likes it as well.

  • ka24s14am

Posted October 29, 2012 - 09:29 AM

#3

Not sure what your gearing is but my 2012 came with 13 front 48 rear. It hooked up too much too. I changed the rear sprocket to a 49 and it breaks loose easier now. It acclerrates harder too :)

  • bigj450

Posted October 29, 2012 - 01:04 PM

#4

i just changed to a 13 - 50t combo at the same time as putting in a drd kit, found it to loosen up quite alot, running mx 51 font and rear

  • yam 3

Posted October 30, 2012 - 07:22 AM

#5

Thanks for the replies.
I am running a 13/49 combo.
Forks are about 5mm up in clamps.

  • migs647

Posted October 30, 2012 - 01:36 PM

#6

The front is undersprung compared to the rear. Rear is a .57 I believe? Front is .48? Someone correct the numbers if they are wrong. Either way, that's a huge unbalance. They did that because the engine was more rearward facing and needed to offset the normal weak suspension that comes on all 450s. I'd suggest getting the suspension done and having the front sprung a bit heavier.

If you're not into spending that much, I'd take what the others suggested and bump up the rear a tooth. Not only will you get more bark, but you'll be shortening the wheel base which will make it easier to oversteer in the corners.

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  • dfinn

Posted October 30, 2012 - 01:52 PM

#7

You think 1 tooth really makes a noticeable difference in shortening the rear?

  • grayracer513

Posted October 30, 2012 - 02:15 PM

#8

The spring rate numbers are .48 kg/mm front and 5.7 kg/mm rear. Some do think that the bike is imbalanced with respect to front/rear springing, but the disparity in the numbers you see is not the root of it.

The front springs work as a pair, and they carry the weight directly, so the real front spring rate is the sum of the two fronts, or .96 kg/mm. The rear works by itself at a mechanical disadvantage of about 3.3:1 or better, so dividing the rate by that, it comes out 1.7 kg/mm at the axle (very, very roughly, because the linkage rate changes as the suspension works). Then you have to take into account weight distribution and how you want the bike to behave.

Compared to an '06 or '07, you'd say that the difference in the front and rear rates are greater than they were, but a lot of that is due to a different linkage rate curve on the newer bike.

  • migs647

Posted October 31, 2012 - 12:23 PM

#9

You think 1 tooth really makes a noticeable difference in shortening the rear?


Cyclenews seemed to think so. According to them, going a tooth or two bigger changed the wheel base enough to make the bike handle better during higher rpm situations. Personally, I just run whatever sprocket works best for the track and forget about the rest.

  • migs647

Posted October 31, 2012 - 12:25 PM

#10

Compared to an '06 or '07, you'd say that the difference in the front and rear rates are greater than they were, but a lot of that is due to a different linkage rate curve on the newer bike.


This is what I based my hypothesis on. I believe the 06/07 came with 5.4 rear but still came with .48 front?

  • grayracer513

Posted October 31, 2012 - 01:31 PM

#11

The linkage makes any direct comparisons between the two invalid.

  • migs647

Posted October 31, 2012 - 02:48 PM

#12

Gotcha.

Either way, I'm 190lbs, Jason McCormick is putting stiffer springs in the front, leaving the rear to change the geometry.

With that being said, what aftermarket linkage is there for this bike? Perhaps would could help as well for oversteering.

Edited by migs647, October 31, 2012 - 02:49 PM.






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