31
Coffee Shop / Re: George's 50
« on: May 15, 2012, 09:38:52 am »
Happy Birthday George! Here's to many, many mower!
Show Posts
This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.
32
Newcomers / Meet the Moderators
« on: May 15, 2012, 09:36:36 am »
Welcome to the forum! This thread is here so the heymow moderators can introduce themselves to you. The site would never have become what it has without the help of the moderators, many of whom have been here since day one.
My name is Tom Cole and I started this forum in 2005 to help promote lawn mower racing and the businesses associated with it by helping those involved connect and learn from one another. I'm the computer guy behind the technical operation of the website.
My name is Tom Cole and I started this forum in 2005 to help promote lawn mower racing and the businesses associated with it by helping those involved connect and learn from one another. I'm the computer guy behind the technical operation of the website.
33
Coffee Shop / Re: Re: ****Free Speech on Heymow****
« on: May 10, 2012, 09:08:29 am »
EC gets advertising here BECAUSE of George's help on this site. Not just his ongoing input, but his original help in getting the site going almost 7 years ago (wow!).
So it appears that many of you need to understand that I attribute a good part the success of this site to George and the moderators. It would not be what it is without them and and far as I am concerned, I hope they are able to reap some rewards for their efforts.
As far as any member of this forum calling any moderator and cussing him goes, that is going to be met with a full and permanent ban from this website, and you can just assume that I am the one who flicked the switch. I don't think it is funny to even joke about it and life is just too short to put up with any more negative garbage than what we all already have to handle.
So it appears that many of you need to understand that I attribute a good part the success of this site to George and the moderators. It would not be what it is without them and and far as I am concerned, I hope they are able to reap some rewards for their efforts.
As far as any member of this forum calling any moderator and cussing him goes, that is going to be met with a full and permanent ban from this website, and you can just assume that I am the one who flicked the switch. I don't think it is funny to even joke about it and life is just too short to put up with any more negative garbage than what we all already have to handle.
34
Coffee Shop / Re: Get free ground shipping at ARC's webstore
« on: December 22, 2011, 11:51:23 am »
There is a banner at the top of the page on the website that says "Enter promo code FREESHIP during checkout"
But don't worry, If anyone places an order that qualifies for the free shipping, we are giving it to you anyway.
But don't worry, If anyone places an order that qualifies for the free shipping, we are giving it to you anyway.
35
Coffee Shop / Get free ground shipping at ARC's webstore
« on: December 21, 2011, 06:56:14 am »
It's a good time to shop at www.arcracing.com
Now through January 2nd, you can get free ground shipping to the 48 lower United States on any web store order over $100
Your order may be shipped either UPS ground or USPS Priority Mail.
Now through January 2nd, you can get free ground shipping to the 48 lower United States on any web store order over $100
Your order may be shipped either UPS ground or USPS Priority Mail.
36
Coffee Shop / Sale at ARCracing.com ...This Weekend Only
« on: November 25, 2011, 06:56:41 am »
We are having an online Thanksgiving sale at ARC. Everything on our web store has been marked down 10% and if you enter the promo code SHIP during checkout, you can save 20% off of UPS ground shipping too!
This sale is for web store orders only and it will end Monday 11/28 at midnight.
This sale is for web store orders only and it will end Monday 11/28 at midnight.
37
Briggs OHV & Vanguard / Re: scored crank shaft
« on: July 07, 2011, 03:04:14 pm »
Oil clearance is the difference between the crank journal outside diameter and the inside diameter of the rod journal bore.
Example: If a new crank measures .9985" using an outside micrometer and your rod bore measures 1.002" using a dial bore gauge, then your oil clearance is 1.002 -.9985 = .0035" or three and a half thousandths of an inch, which happens to be real good.
If you polish your crank down to a journal diameter that is .008" smaller than a new crank, then it will now be .9905" and your oil clearance is now 1.002 - .9905 = .0115" or eleven and a half thousandths of an inch and you are now begging for a broken rod, or a broken crank.
Your oil cushion is determined by oil pressure, oil viscosity, and oil film strength. If you don't have an oil pump, you don't have any oil pressure so you must have enough clearance between the rod and the crank to allow oil to get in from the splash caused by the rotating parts in your crankcase. The greater the oil viscosity (thickness), the greater this clearance must be BUT, the clearance can't be so great that the crank journal has room to get a running start at crashing into the rod bearing. Oil's film strength can resist this crash to a point, but again, if clearance is too great and the crank journal has room to get a running start at the rod bearing, it will squeeze or pinch the oil out. When the two pieces crash together the hard crank journal deforms the soft babbit (or aluminum) which further opens up oil clearance for subsequent crashes to do greater and greater damage until finally, the rod or crank breaks. Sometimes, if the oil film fails due to the intensity of the crash, the crank journal and the rod bearing (or aluminum) make enough contact to melt the babbit or aluminum. This is called galling and it is what causes the scoring and metal transfer you will find on the crank. Galling also occurs when the oil clearance is too tight (or oil is too thick) to allow enough oil to splash between the crank journal and rod bearing to keep things properly lubricated and cool.
Here's a few tips:
*Run thinner oil in cooler weather and thicker oil in hotter weather.
*Run thinner oil when an engine is fresh and go thicker and thicker as rebuild time approaches.
*Oil clearance should be about .0035" with a 10w30 full synthetic oil.
*Tighter clearances (.0025" to .003") will need thinner oil, maybe 5w20.
*Wider clearances (.0045" to .005") will need a thicker oil, maybe 10w40.
*If you run more than .005" oil clearance (and I have), be prepared to change bearings more often and be ready for a failure if you don't.
*If you run more than .006" oil clearance (and again, I have) don't blame the parts WHEN it breaks. You are taking a risk and Big Boy pants are required.
*The more RPM and power your engine makes, the better your grasp of all this must be so you can plan a proper maintenance schedule for your engine.
If you don't understand what I am talking about above, you will really be much better off letting someone who does understand build your engine. I'm not saying you CAN'T run the excessive clearances, I'm simply saying that you need to understand how some things relate to one another before doing so in order to avoid catastrophic failures...which ALWAYS occur at the wrong time.
Example: If a new crank measures .9985" using an outside micrometer and your rod bore measures 1.002" using a dial bore gauge, then your oil clearance is 1.002 -.9985 = .0035" or three and a half thousandths of an inch, which happens to be real good.
If you polish your crank down to a journal diameter that is .008" smaller than a new crank, then it will now be .9905" and your oil clearance is now 1.002 - .9905 = .0115" or eleven and a half thousandths of an inch and you are now begging for a broken rod, or a broken crank.
Your oil cushion is determined by oil pressure, oil viscosity, and oil film strength. If you don't have an oil pump, you don't have any oil pressure so you must have enough clearance between the rod and the crank to allow oil to get in from the splash caused by the rotating parts in your crankcase. The greater the oil viscosity (thickness), the greater this clearance must be BUT, the clearance can't be so great that the crank journal has room to get a running start at crashing into the rod bearing. Oil's film strength can resist this crash to a point, but again, if clearance is too great and the crank journal has room to get a running start at the rod bearing, it will squeeze or pinch the oil out. When the two pieces crash together the hard crank journal deforms the soft babbit (or aluminum) which further opens up oil clearance for subsequent crashes to do greater and greater damage until finally, the rod or crank breaks. Sometimes, if the oil film fails due to the intensity of the crash, the crank journal and the rod bearing (or aluminum) make enough contact to melt the babbit or aluminum. This is called galling and it is what causes the scoring and metal transfer you will find on the crank. Galling also occurs when the oil clearance is too tight (or oil is too thick) to allow enough oil to splash between the crank journal and rod bearing to keep things properly lubricated and cool.
Here's a few tips:
*Run thinner oil in cooler weather and thicker oil in hotter weather.
*Run thinner oil when an engine is fresh and go thicker and thicker as rebuild time approaches.
*Oil clearance should be about .0035" with a 10w30 full synthetic oil.
*Tighter clearances (.0025" to .003") will need thinner oil, maybe 5w20.
*Wider clearances (.0045" to .005") will need a thicker oil, maybe 10w40.
*If you run more than .005" oil clearance (and I have), be prepared to change bearings more often and be ready for a failure if you don't.
*If you run more than .006" oil clearance (and again, I have) don't blame the parts WHEN it breaks. You are taking a risk and Big Boy pants are required.
*The more RPM and power your engine makes, the better your grasp of all this must be so you can plan a proper maintenance schedule for your engine.
If you don't understand what I am talking about above, you will really be much better off letting someone who does understand build your engine. I'm not saying you CAN'T run the excessive clearances, I'm simply saying that you need to understand how some things relate to one another before doing so in order to avoid catastrophic failures...which ALWAYS occur at the wrong time.
38
Briggs OHV & Vanguard / Re: Broken ARC billet crank
« on: June 23, 2011, 10:52:19 am »
By the way, about 90% of all single cylinder crank failures in engines like these are on the flywheel side of the rod journal. The reason is because it is the weakest part of the crank and in the zone where the most flex occurs. Just saying so we don't go down a path thinking that common fracture points are a revealation. What it does indicate is that there was not a flaw in the material at the point of fracture since it would be very unlikely that two cranks would have a material flaw in exactly the same place. Especially when chemical analysis indicates consistency in the material composition.
39
Briggs OHV & Vanguard / Re: Broken ARC billet crank
« on: June 23, 2011, 10:42:44 am »
The SAE Chemical Composition specs of SAE 4340 "Chromoly" Steel (hardened)
are as follows:
Carbon 0.38 - 0.43
Chromium 0.7 - 0.9
Iron Balance
Manganese 0.6 - 0.8
Molybdenum 0.2 - 0.3
Nickel 1.65 - 2
Phosphorus 0.035 max
Silicon 0.15 - 0.3
Sulphur 0.04 max
The way I read the spectrometer test results posted above, ALL chemicals are present and within spec.
So, the 6562-C crank is made of the material we advertise. The test above not only proves that, but it also shows that the material is consistently within spec, as multiple tests seem to have been done.
Is there stronger material? Sure! BUT...
We make cranks from a material that is CONSIDERABLY tougher than hardened chromoly...It is also CONSIDERABLY more expensive than hardened chromoly. The blank itself would be more than $200 and a length of that material would cost us about $4000. Figure that along with the increased machine time and tooling cost and that crank would cost the racer somewhere around $600. A $600 crank won't sell when it is cheaper to just start with a better engine!
Why this one failed is a mystery to me because I have not seen enough pieces of the puzzle to come anywhere close to being able to speculate.
are as follows:
Carbon 0.38 - 0.43
Chromium 0.7 - 0.9
Iron Balance
Manganese 0.6 - 0.8
Molybdenum 0.2 - 0.3
Nickel 1.65 - 2
Phosphorus 0.035 max
Silicon 0.15 - 0.3
Sulphur 0.04 max
The way I read the spectrometer test results posted above, ALL chemicals are present and within spec.
So, the 6562-C crank is made of the material we advertise. The test above not only proves that, but it also shows that the material is consistently within spec, as multiple tests seem to have been done.
Is there stronger material? Sure! BUT...
We make cranks from a material that is CONSIDERABLY tougher than hardened chromoly...It is also CONSIDERABLY more expensive than hardened chromoly. The blank itself would be more than $200 and a length of that material would cost us about $4000. Figure that along with the increased machine time and tooling cost and that crank would cost the racer somewhere around $600. A $600 crank won't sell when it is cheaper to just start with a better engine!
Why this one failed is a mystery to me because I have not seen enough pieces of the puzzle to come anywhere close to being able to speculate.
40
Briggs OHV & Vanguard / Re: Broken ARC billet crank
« on: June 15, 2011, 08:47:53 am »
Joel,
I asked Hunter about this when the crank came in and he told me you were supposed to contact him with further information (like inside diameter measurements) about the bearing and/or bushing on the PTO side. He has not heard back from either you or your brother.
The reason he wanted this information is because there are marks on the PTO main journal that are suspect. (see attached picture http://db.tt/KKP7z6t ) These marks make the PTO main Journal look AND FEEL like a rotary file and would eat into any bushing in a matter of seconds. This would create excessive clearance at the PTO main journal and that could very easily be the cause.
Excessive Ignition timing normally breaks rods first or screws up pistons like George said. However, if The main journal clearance was too much, then it could also contributed to the failure.
We have hundreds of these cranks in the field and this is the only failure that I have seen.
It is NOT a bad batch of material because we test every bar before we begin cutting...could you imagine the cost if we discovered a flaw AFTER processing an entire bar? These cranks each take several hours of machine time, and we don't like to waste machine time.
If you are looking to find a solution, we are willing to help you discover what happened, but you must supply us with the information we request. We do not volunteer information about what we suspect until we are satisfied with the information supplied to us. This is due to the fact that the information supplied often changes as we present ideas because the goal is too often to obtain a free replacement part and not so much to discover the problem.
Now Joel, please explain why, when you were questioned in this thread about whether or not you had heard from ARC you did not mention that you were supposed to get back with us with inside diameter measurements of the bushing? Not only did you fail to mention that, but you helped people get the impression that we were ignoring this. That is an unfair representation and it tells me a lot about how I should proceed.
To the armchair quarterbacks. I think I have earned a little more respect than to just immediately be vilified. Maybe next time get a little more information before slinging me up on the cross.
Moderators, you don't need to moderate this thread. I'll handle it.
I asked Hunter about this when the crank came in and he told me you were supposed to contact him with further information (like inside diameter measurements) about the bearing and/or bushing on the PTO side. He has not heard back from either you or your brother.
The reason he wanted this information is because there are marks on the PTO main journal that are suspect. (see attached picture http://db.tt/KKP7z6t ) These marks make the PTO main Journal look AND FEEL like a rotary file and would eat into any bushing in a matter of seconds. This would create excessive clearance at the PTO main journal and that could very easily be the cause.
Excessive Ignition timing normally breaks rods first or screws up pistons like George said. However, if The main journal clearance was too much, then it could also contributed to the failure.
We have hundreds of these cranks in the field and this is the only failure that I have seen.
It is NOT a bad batch of material because we test every bar before we begin cutting...could you imagine the cost if we discovered a flaw AFTER processing an entire bar? These cranks each take several hours of machine time, and we don't like to waste machine time.
If you are looking to find a solution, we are willing to help you discover what happened, but you must supply us with the information we request. We do not volunteer information about what we suspect until we are satisfied with the information supplied to us. This is due to the fact that the information supplied often changes as we present ideas because the goal is too often to obtain a free replacement part and not so much to discover the problem.
Now Joel, please explain why, when you were questioned in this thread about whether or not you had heard from ARC you did not mention that you were supposed to get back with us with inside diameter measurements of the bushing? Not only did you fail to mention that, but you helped people get the impression that we were ignoring this. That is an unfair representation and it tells me a lot about how I should proceed.
To the armchair quarterbacks. I think I have earned a little more respect than to just immediately be vilified. Maybe next time get a little more information before slinging me up on the cross.
Moderators, you don't need to moderate this thread. I'll handle it.
41
Coffee Shop / Re: A new milestone crossed by heymow.com!
« on: June 02, 2011, 01:17:33 pm »
Topped out at 1,111,702 page views in May. That beat the old record by more than 112,000!
42
Coffee Shop / A new milestone crossed by heymow.com!
« on: May 31, 2011, 12:10:40 pm »
For the first time, there have been more than a million page views in one month here at heymow.com!
44
Coffee Shop / Re: Unable to post pics...
« on: May 17, 2011, 07:26:04 pm »
I doubled the database size about a year ago and it is full again. I'm going to have to figure out something.
Tom
Tom
45
Coffee Shop / Re: rod bolts = snap
« on: April 23, 2011, 04:28:57 pm »I might be a little wee-tarded, but I've been turnin wrenches for bout 40 years now and I have never seen a ft/lb torque wrench that works, much less be accurate, below 20 ft/lbs. To be accurate with those kind of torques (170 in/lbs) you need an in/lb torque wrench.
BINGO
An interesting test....Take an inch/lb torque wrence and see how far beyond 170 you can go with an old rod and old bolts (as in, something you are going to throw away) Even if the bolt/washer isnt lubed, you will be suprised. If I recall correctly, last time we did it with a 1/4 bolt, we got 2 full turns on the bolt head beyond 170 inch lbs before the bolt broke. The torque wrench topped out at like 240 or something, and we went beyond that. What we were checking was the thread strength of the aluminum threads in the beam of the rod. We couldn't pull out the threads without breaking the bolt and the bolt went way beyond its specified torque value.
Remember, torque specs are different depending on the lubricant used on the bolt/washer. 170 in/lbs lubed with oil has never failed me.