CK30 came in

Wattsfurniture · Jul 14, 2005

Perhaps I can be some help rather than just asking questions.

I happen to own an engineering/ R&D firm that designs robotic machine tools. I am an aeronautical engineer.

The quoted torque seems unusually high even for a grade 8 stud and nut. Normally we like to torque to about 75% of yield
on such a bolt. A properly torqued bolt or stud carries no external load unless forces exceed that.

The most accurate torqueing sequence is usually to tighten to a relatively small torque figure to seat the threads then do a specific angular displacement. This is commonly seen on things like head studs.

The grade 8 split lockwashers I see on my ck30 wheels would have little consequence.

Might be a translation problem here. If I can get the thread details I can do a sanity check.

TractorLegend · Jul 14, 2005

The most accurate torqueing sequence is usually to tighten to a relatively small torque figure to seat the threads then do a specific angular displacement. This is commonly seen on things like head studs.

I thought we were talking lug studs?
TTY head BOLTS are are a special circumstance where the fastners are non reusable and stretched after proper use in order to clamp two dissimilar materials together such as aluminum heads to cast iron blocks?

I think I'll check out now and let the hypothetical experience of engineers take over.
I was offering my experience on my tractor which was asked for btw
It wasn't intended to be a credential exhibition.
Maybe the whole manual is a misprint.

>>>If I can get the thread details I can do a sanity check<<<

Donnyj · Jul 14, 2005

I checked my owners manual about wheel torque. Front wheels are 196.1 - 225.5 N-m, 144.7 -166.3 lbf-ft. The rear wheels are 196 -226 N-m 145 - 165lbf-ft. Sounds like there is a error in the manual for the Ck30. 240 to 260 sounds really high. Its a good thing you caught your lug nuts before any damage happened. Good job for taking the time to look it over. I probably should check mine more often. /forums/images/graemlins/smile.gif

grdngrrl · Jul 15, 2005

Good lord, there seems to be quite a disparity in officially published torque specs for the CK 25/30 wheel nuts. My Kioti workshop manual states 50.6 ft.lbs. front and 209.7 ft.lbs. rear.
Though we tend to see fasteners as garden variety items of simple design, there is a whole science that revolves around these nifty little devices. For us folks that have a somewhat complete collection of workshop hand tools, but are not heavily invested in the big stuff for heavy equipment I t sort of makes sense to me to use a good 3/4 in drive breaker bar and a cheater about 3 ft long to check our rear wheel lug nuts. I have some pretty old 1/2 and 3/4 drive impact wrenches that I use to disassemble with but NOT tighten since I don't know what force they are REALLY exerting on a fastener. I guess, in theory anyway, if I were to put my entire 140 pounds of body weight on the end of an 18 inch long breaker bar I would be exerting aproximately 209 ft.lbs on the lug nut. Hmmm, hows that fer shade tree mechanickin?

Wattsfurniture · Jul 15, 2005

Tractorlegend, I didn't mean to put on airs or anything. You have been very helpful. Thanks.

With all the reports of loose lug nuts and such on new tractors the torque values are an issue, particularly when the specified
values are out of the range of common mechanic's tools.

Ok, I checked the engineering formulas. I was expecting the studs to be metric, but they seem to be SAE 5/8-18. Correct me if i'm wrong.

I have no way of knowing the SAE grade since they are not marked. I would imagine they are grade 8 or higher.

I calculate for grade 8 75% of proof and 0.2 coefficient of friction (typical for dry phosphated fasteners) the proper torque value is 240 lb ft.

For 85% of proof it is 284 lb ft.

So either they recommend going up to about 85% or the studs are higher than grade 8.

Therefore even though the number seems high to me it IS in the ballpark.

At that proof percentage one would want an accurate wrench and some care to not lube up the treads. Things like anti-seize would likely result in yielding the stud.

Some of this stuff is not so clear in the manual. I saw Kiotijohn's nice appendix and I wish they would contract him to do a complete re-write and pay him well to do so.

gmsssi · Jul 15, 2005

Quite frankly, I think you'll have trouble getting it to 210 with that set up at 140 lbs. I bounced on my 1/2 " drive torque wrench set @ 160 and I'm over 300 lbs...........LOL

/forums/images/graemlins/tongue.gif

VictorW · Jul 15, 2005

Thanks for the number from the workshop manual. 209.7 ft/lbs sounds more correct for the torque. It matches the converted Nm from my owners manual. The printed 290.7 ft/lbs must have been a misprint in the manual.
The calculations from Les would put the torque a bit higher but he was going for grade 8 fasteners.
Be careful standing on that breaker bar. It hurts if you slip off. /forums/images/graemlins/grin.gif

Wattsfurniture · Jul 15, 2005

Yes if 209.7 lb ft in the owners manual matches the converted
nm figure in the service manual then that must be it.

Clearly the 284.4 nm/290 lb ft is no where near the ratio of 1.356 nm/lb ft. Something is wrong for sure.

I'll go with the 209.7. My figures were for grade 8 and this might be grade 5...who knows. Even with grade 8 that wrong
number is enough to permanently deform (not break) the fastener. 75% proof torques usually end up with 90% stress in the outer fibers anyway due to the added contribution of
torsional stress. Having a little grease on the washer could raise it 20% more.

This is kind of important...perhaps you guys should open a
thread with this information so people will see it?

Might save some folks from damaging the wheel studs.

Wattsfurniture · Jul 15, 2005

Oh quick side note....

converted sevice manual torque=209.7 lb ft
owner's manual torque =290.7 lb ft

The 9 and 0 were accidently switched!!
Kiotijohn, you know the Kioti folks. They ought
to be informed.