| Author |
Message |
    
Aaomy
| | Posted on Friday, March 02, 2007 - 10:09 am: | 
|
hey sleez. here is a billet choice.. hope this helps...
http://cgi.ebay.com/ebaymotors/Billet-front-Isolat er-engine-mount-fits-Buell-M2-NEW_W0QQcmdZViewItem QQcategoryZ35572QQihZ010QQitemZ200039262747QQrdZ1Q QsspagenameZWD1V
aaron |
Sleez
| | Posted on Friday, March 02, 2007 - 10:29 am: |
|
thanks aaron,
i believe those are the ones that al was going to carry, but wasn't happy with the design, said the bolt bosses were thinner or something causing the bolts not to engage the same. something along those lines. plus i don't like that the two arms aren't tied together, even though now i've discovered at least one bracket that was triangulated has had broken bolts. a bit overwhelming as what to do. |
Djkaplan
| | Posted on Friday, March 02, 2007 - 10:41 am: |
|
Has anyone ever heard of a failure with any billet mount? |
Sleez
| | Posted on Friday, March 02, 2007 - 01:18 pm: |
|
i haven't heard of any billet brackets associated with a bolt failure yet. |
Aaomy
| | Posted on Friday, March 02, 2007 - 03:13 pm: |
|
just a couple thoughts..
how many cast motor mounts have broke??
i dont think the cast is the problem..
i have really only heard of bolts and heads breaking..
most heads i think were early ones that some one claimed weren't taped deep enough or long enough bolts werent used..???
the lightening and thunderstorm heads use 1/2"??? bolts and the firestorm heads use 7/16"??? bolts.. yet how many people have had bolt or head failures with the firestorm heads on a tuber???
lightening and thunderstorm heads i think are torqued to 110 ft lbs???
fire storm are torqued to like 45-55 ft lbs..
just a couple little thought to get you guys thinking..
maybe it dosen't have anything to do with the cast part or billet.. maybe more with the mating surface area and applied leverage..
think the head bosses are a lot bigger on the fire storm heads.. giving the bracket less leverage on the bolts. thunderstorm and lightening move the pivot point of the mating surfaces closer creating more leverage..
but thats just a little more of me thinking again??????
ps this is at work with nothing to look at.. just going from memory.. |
Sleez
| | Posted on Friday, March 02, 2007 - 03:44 pm: |
|
i assume you mean XB series when you mention firestorm?
i don't believe it has anything to do with the fact that the original parts were cast versus billet, only that most of the billet brackets tie the two arms together, i believe that is significant. it may not be the answer since there have been at least one case of the 96 style bracket having a broken bolt incident.
the only time i have heard of a bracket actually breaking, is following at least one bolt failure and usually both bolts and or head damage. i have yet to hear of a bracket breaking without at least one bolt being broken. this leads me to believe that the bracket is not the weak link. however with the numbers of broken bolts on non triangulated brackets, even with the new bolts and torque procedures followed still breaking, i am lead to the conclusion that the bracket is allowing forces to be applied differently to the bolts.
the XB style bracket is wider and triangulated, i have not heard of any failures of that configuration.
my latest information on the tempering of the F911 bolts makes me wonder if they aren't being heat cycle fatigued due to the head temps being greater than the bolts tempering range??? it is my understanding that a bolt heated above its tempering will degrade significantly. |
Sleez
| | Posted on Friday, March 02, 2007 - 03:50 pm: |
|
taken from a document online, and NO, i don't treat everything i read online as gospel. curious none the less.
High strength bolts are typically tempered in the range of between 800-degrees F and 1,200-degrees F. Normally, bolts that have been exposed to fires will not experience changes in their properties; however, if the bolts are exposed to fire temperatures in the range of the tempering value for more than one or two hours, they will experience relaxation of their pre-tensioning. There is a very narrow range of temperatures between a high strength bolt’s tempering temperature and phase transformation temperature. Therefore, if a high strength bolt has been exposed to a fire above the tempering temperature, it likely that they will have a reduced capacity and should be replaced. Conversely, those connections for Category A components that have remained straight would not have been exposed to temperatures above the tempering value and could remain in place. |
Sleez
| | Posted on Friday, March 02, 2007 - 03:54 pm: |
|
more info;
Question 2: Can welding be performed on high strength anchor bolts and fasteners?
Answer: The short answer is that in most cases, welding is not allowed on high strength bolts.
In the fastener industry, the term “high strength” typically refers to any medium carbon or alloy material which undergoes a heat treating process to develop the strength properties necessary to meet the requirements of a given specification. These ASTM specifications include A449, A325, A193 grade B7, F1554 grade 105, A354 grades BC and BD, and A490 among others. When heat is reapplied to a bolt that has been heat treated, it is probable that the physical properties (strength) of the bolt may be altered. When heat is applied in an uncontrolled environment, it is impossible to determine what effect this application of heat has had on the fastener. Therefore, welding to high strength bolts is not recommended.
Two references occur to back up this statement. On page 4-4 of the Ninth Edition of the AISC Manual (American Institute of Steel Construction), the following statement occurs:
“Anchor bolt material that is quenched and tempered (heat treated) should not be welded or heated.”
The other reference prohibiting the heating of high strength bolts (which would occur during welding) can be found in the ASTM F1554 specification. Section 6.4.3 of the ASTM F1554 specification states:
“Hot bending performed on heat-treated bar stock shall not have the temperature come within 100°F (56°C) of the tempering (stress relieve) temperature of the heat-treat process at any location during hot bending and shall be allowed to air cool after bending.”
Although this statement refers to hot bending, it implies that any process (including welding) that applies heat approaching or exceeding the tempering temperature to a high strength bolt may potentially alter the mechanical properties of the fastener and should therefore be avoided.
The issue of reheating high strength bolts when welding can be avoided by performing the welding operation prior to the fastener undergoing the heat treating process. In other words a plate, nut, or other component can be welded to a bolt prior to the fastener being heat treated. However, this must be performed by a fastener manufacturer and eliminates the ability for high strength bolts to be welded in the field or by another company once the bolts have been tested and certified to meet a particular ASTM specification. |
Rocketman
| | Posted on Friday, March 02, 2007 - 04:22 pm: |
|
With regard to the heat theory.
800F to 1200F (426C to 642C) I think that's pretty hot for those head mount bolts. I'd be surprised if they get up to anywhere near those temp's.
Rocket |
Sleez
| | Posted on Friday, March 02, 2007 - 04:28 pm: |
|
hey rocketman,
so far my research indicates the bolts currently used are tempered at 716F.
i was hoping someone could do some measuring with either a thermocouple or infrared heat gun to read some real world temps near the bolts.
i don't have much of a guess as to what temps they might be seeing.
i spoke with a bolt engineer who said if the temps are getting near the tempering range of the bolt, it may make it actually stronger, or weaker, therefore either more brittle or more elastic. i am considering pulling the remaining bolt and having its properties analysed. |
Oldog
| | Posted on Friday, March 02, 2007 - 04:58 pm: |
|
Sleez
Aluminum Melts at over 1000f
the heads on an Fi bike see temps in the 300 400 f range normaly on the rear head in the chimney
I say this as the read head of MY X1 reaches 400+ f at idle if left standing still for an extended time. the hottest areas would be the top center of the combustion area and to a lesser degree the exhaust port area, the header is subjected to temps approaching 600f going by the color of the stainless,
the "gold" hue is produced at lower temps in the 400f range,
the bolts are not in the direct exhaust path, i would not be shocked at 300+ temps on the bolts though. |
Oldog
| | Posted on Friday, March 02, 2007 - 05:02 pm: |
|
steel melts at + 2000f and becomes plastic at about 1800f IIRC tool steels are heated into the 1200+ range for heat treatment depending on steel type and properties desired.
there was a long descussion on this a while back (long while back )
Rocket did you have the face of the cast boss remachined for a flat mating surface relative to the mount? |
Djkaplan
| | Posted on Friday, March 02, 2007 - 05:23 pm: |
|
"i dont think the cast is the problem.."
Here's my current hypothesis:
Cast alloys generally aren't as ductile as wrought or forged alloys. The front mount is only attached to the cylinder by two bolts at the bottom. The Uni-planer mounting allows the engine a certain amount of movement in one plane. I think the fore and aft movement of the engine is leveraging the bolts through the mount. Because cast material is less ductile, it may be allowing more stress to reach the bolts, whereas a billet mount may have enough plastic deflection to absorb the stress.
I pulled this theory from my ass just now, btw. |
Sleez
| | Posted on Friday, March 02, 2007 - 05:31 pm: |
|
hi jim, thanks for the input.
what are these temp measurements taken with?
i am not concerned that anything is melting. my concern is that multiple heat cycles on a bolt that is treated at 716F is causing it to degrade in some way, whether that is becoming more brittle or not...who knows yet.
i just spoke with the bolt manufacturer and i am going to send them my remaining unbroken bolt for analysis. i wish i could get the broken bolt stub out without damaging it, but i am not sacrificing the head to do that!!! and of course the bolt head is long gone. so the unbroken bolt on the other hole will have to do, although i will take some pictures of the broken bolt stub as best i can with some macro settings. |
Sleez
| | Posted on Friday, March 02, 2007 - 05:33 pm: |
|
dj,
interesting thought, i will have to research that theory, thanks. |
99cyclone
| | Posted on Saturday, March 03, 2007 - 12:29 am: |
|
Djkaplan - I'm not sure I completely agree with your theory.
For a given part geometry, the relative ductility really won't have anything to do with vibratinal "G" loads being transferred between the bolts and motor mount bracket. The vibrational system cares most about mass and stiffness (Young's modulus). For most aluminum alloys, the stiffness will be about the same regardless of whether the part is cast or wrought aluminum(~69-70 GPa).
It is well known that high strength bolts are very susceptible to stress corrosion cracking. I've run across this before, where water is able to wick under the bolt head. Stress cracking initiates at the fillet under the bolt head. The result is basically the heads popping off the bolts. High strength bolts with a high preload are most susceptible to SCC.
Additionally, it is critical that an electroplated high strength bolt be baked after plating to prevent hydrogen embrittlement. A hydrogen embrittlement failure would be pretty much the same as stress corrosion cracking. |
Rocketman
| | Posted on Sunday, March 04, 2007 - 07:32 am: |
|
Rocket did you have the face of the cast boss remachined for a flat mating surface relative to the mount?
No, just had it welded back in place, but I wasn't of the opinion it was out of line enough if at all to make a hapeth worth of difference. I doubt a cats •••• hair of malalignement is going to be a problem. I suppose I'm trying to say it looked damn near perfect anyway.
I didn't believe back then, nor now, that the problem lies with the brackets anyway. The way I see it, once the bracket is bolted up in place it's an integral part of the cylinder head/engine assembly that is fastened to the frame with a fairly substantial rubber mounting. If that rubber mounting isn't protecting the whole assembly then that is where the modification is needed.
Rocket |
Djkaplan
| | Posted on Monday, March 05, 2007 - 09:28 am: |
|
"Djkaplan - I'm not sure I completely agree with your theory."
Considering the source... neither do I. |
|
