Re: to change a Honda Accord 1988 model timing belt
- From: jim beam <nospam@xxxxxxxxxxx>
- Date: Mon, 31 Oct 2005 20:42:43 -0800
TeGGeR® wrote:
jim beam <nospam@xxxxxxxxxxx> wrote in
news:Ap6dnV6_ytVekfjeRVn-rQ@xxxxxxxxxxxxx:
regarding citations for the honda pulley bolt, i don't have anything immediately to hand. you have to go back to basic engineering principles. if you can accept that there is some angular lash in the pulley, you can figure out the inertial predominance of that lash as the crank rotates.
It's still wrong. That bolt does NOT turn.
it can and it does. for a simple citiation, check out:
http://www.sheldonbrown.com/gloss_p.html
and read the section labeled "pedal" and note the reference to precession.
Honda is very particular about the treatment of this critical fastener. They specify that oil be applied to the /threads/, but not to the /bolt face or washer/. Not only that, but they also specify that if a new fastener is used, it should be pre-stretched to a higher-than-final-torque before being loosened and final-torqued to the lower number.
If the bolt could tighten and stretch itself some unknown amount, do you really think Honda would risk such an unknown variable in such a critical area? What if the bolt tightened too much? Disaster!
it doesn't continue to tighten indefinitely - it reaches equilibrium.
And if that final higher torque /were/ predictable, don't you think Honda would specify that final torque to begin with, and simply tell you to set it to that in order to eliminate that variable?
why? it ony needs to be initially set to hold it in place. anything subsequent to that would come out in testing.
Also, if you look at bolt torque charts, there is NO bolt of that size, not even an aircraft-grade M10.9, that is intended to be torqued to anywhere close to the 300 ft lbs that Elle guesses at.
The highest rating I can find in my charts is for a 12mm 11T with 1.25mm pitch. It's rating is...130 ft lbs, exactly what Honda specifies for the crank bolt, which I'm pretty sure is that size!
with respect, i've bounced on a day-old pulley wheel bolt. i weigh 200 lbs. at 18" from center, assuming i can exert a momentary "weight" of 300 lbs, that's 450 ft.lbs. and that shifted it. static weight alone [300 ft.lbs] didn't.
In areas where Honda suspects torque change may occur, it specifies staking, lockwashers, bent tabs, and nylon inserts. But not at the crank bolt.
i know. i said other cars.
Incidentally, our Toyota Tercel's engine runs so as to LOOSEN the crank bolt. The bolt is tightened to 114 ft lbs. There is no lockwasher.
try some fords or vw.
And as far as relative movement due to inertia? Consider this: The bolt is less than one pound. The combined reciprocating and rotating mass of the engine is about 50 lbs. It is physically /impossible/, even considering firing pulses, for a 50lb mass to accelerate faster than a one-pound mass given the same impulses to both.
it's the pulley, not the bolt. i invite you to either operate the engine without a woodruff key or calculate the inertia of a 10 lb pulley wheel.
Even considering the frictional resistance of the PS pump, A/C compressor, and alternator, there is no way all that exceeds the inertial mass of the engine. It is physically /impossible/ for the crank to force the bolt to tighten.
again, that's assuming no lash in the pulley. but there is. otherwise there would be no need for the woodruff key.
It is true that there are certain circumstances where a fastener can be forced to tighten or loosen even when tightened properly, such as knock-off wheels. In that case, the weight of the entire car is pulling and pushing the fastener around. That, combined with splines that are a less-than perfect fit, and wheel flex, means the wheel's knockoff nut is subject to unique stresses that a crankshaft bolt is not.
but that's an example that proves my point. i don't understand how you can accept this fact that bolts move in service in one situation, but not another. you accept elastic distortion, right? if there's distortion of one component more than another, there's relative movement. it may not be large enough to see with the naked eye, but it does occur.
The relevant paragraph on Elle's page is totally wrong and needs to be removed.
.
- Follow-Ups:
- Re: to change a Honda Accord 1988 model timing belt
- From: TeGGeR®
- Re: to change a Honda Accord 1988 model timing belt
- Prev by Date: Re: 2006 Civic mileage too low?
- Next by Date: Re: to change a Honda Accord 1988 model timing belt
- Previous by thread: Re: to change a Honda Accord 1988 model timing belt
- Next by thread: Re: to change a Honda Accord 1988 model timing belt
- Index(es):
Relevant Pages
|
