Steering stem torque


6 replies to this topic
  • runester

Posted September 28, 2007 - 03:04 PM

#1

Hey all,
Finally got to greasing the stem bearings last night (07 yz450) and I torqued everything to spec, 24ft lbs and 105lbs and it just seems stiff to me...I was taught (way back) that the forks should be able to fall from side to side on their own once they are placed at about 20 degrees past center...
At spec (now) they stick at any point once I let go of them. They are not "stiff" and are easy to turn but do not fall on their own from any point.

Any school of thought on this...
Thanks,
Rune

  • grayracer513

Posted September 28, 2007 - 03:17 PM

#2

I'm not sure where the 24 ft/lb came from. The sequence is:

> Tighten the ring nut to 27 ft/lb and rotate the steering a few times.
> Loosen the ring nut and re-tighten to 5.1 ft/lb (61 in/lb)
> Tighten the crown nut to 105 ft/lb.

That second step, listed on 3-43, is what you may have missed.

  • runester

Posted September 28, 2007 - 11:43 PM

#3

SHIT...yep...I missed that one!!!I caught the instruction to loosen the ring nut one full turn after the intitial torque to 27 ( I wrote 24 but likely was 27...my memory sucks) but I sure did miss that other step...matter of fact I am out to the garage now to check the manual...were off to racetown tommorrow and I sure dont want to take it like this!
Thanks gray, I said before and I'll say it again...your the man!
Kind regards,
Rune

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  • runester

Posted September 28, 2007 - 11:49 PM

#4

Danm!!! Of course you are right, just looked in the book and what I did was quick glanced it and didnt look down to that last step...well that explains it...
All I can say is its a good thing I didnt take it out like that...no tellin what kinda damage ida' done to the bearings...
Good karma to you Gray!!!!

  • sirthumpalot

Posted October 01, 2007 - 05:03 AM

#5

I read in one of the Dirt Rider tech-tips articles that a pro team (I don't remember which one) runs the bearings a little tight for the steering damper type of effect. Headshake has always been an issue for me so I tried it myself and running the bearings a tad snug actually had a minor positive effect on headshake. Definitely not a cure, but it seems to keep the minor wiggles away a little.

  • grayracer513

Posted October 01, 2007 - 06:36 AM

#6

I read in one of the Dirt Rider tech-tips articles that a pro team (I don't remember which one) runs the bearings a little tight for the steering damper type of effect. Headshake has always been an issue for me so I tried it myself and running the bearings a tad snug actually had a minor positive effect on headshake. Definitely not a cure, but it seems to keep the minor wiggles away a little.

Tapered rollers can run a comparatively very high pre-load without issues, and in fact, require some pre-load to function well. For example, the rear axle pinion bearings in a rear wheel drive car, which spin at a constant 2-3000 rpm on the freeway, are typically loaded until it requires a torque of 20-30 inch pounds to rotate the pinion shaft. In the case of steering bearings, the pre-load helps them resist damage from hard impacts at the front wheel.

Something to remember when working with steering heads is this: You'll notice that when there is no torque on the ring nut, or any other nut, that you can jiggle it up and down on the shaft. This is the thread clearance. When you tighten the ring nut, that clearance is taken up by pushing the nut up on the stem. When you then tighten the crown nut down on it, you push the nut down the stem an amount equal to the thread clearance, which places a greater load on the bearings than what you saw when you ran the ring nut down to 5 pounds. Go by the rotating feel of the completely assembled top and bottom clamp assembly, not the lower clamp and ring nut alone.

  • BBrown626

Posted October 01, 2007 - 06:48 AM

#7

I overtorque the ring nut a little the help stabilize the front. My youngest son has been riding his brother's 250F the last couple weeks because his YZ85 had a crank bearing failure. Because he only weighs about 85lbs the 250 generates a lot of headshake. I tightened up the ring nut and the shake is nearly gone. I was told by a local shop owner that the pro riders over tighten it too, for the same reason.

Brent





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