| Author | Message | ||
     Lady_asb |
DON'T use the service manual for torquing those bolts!! You need to use the B-018 Service Bulletin, which says to clean the threads prior to installing (important so that the torque spec is truly indicating bolt preload and not just overcoming thread friction), put 20W-50 oil under the heads and washers (I bet 10W-40 works as good), red loctite the threads (and keep the oil away from the loctite and vice versa), torque the bolts to 60 Ft-lbs, loosen them one full turn, and re-torque to 60 ft-lb. My S3 broke a few of these. I got them out just like you did. Once I put the NRHS head mount on, no more breakage. Al | ||
| Djkaplan |
I have never heard of the bolts shearing with the NRHS billet mount. It's good insurance and a beauty to boot. | ||
| Rocketman |
Well you NRHS mount fans might just have something there. Seems the stock X1 type mount on my S1W has had contact with the rocker covers.  Rocket | ||
| Rocketman |
You can see in the above pic the two points of contact. One area is dark, the other the shiny bit. You can perhaps see better in this shot.  The shiny part is the high point to the right side, and low mark is the darker area on the left. Rocket | ||
| Rocketman |
I can only assume this contact must have put unnecessary stress on the bolt. It's a clue for sure. Not conclusive but I'd say it's imperative to get these front mounts on absolutely perfectly aligned and torqued correctly (thanks Al). In this shot this is the backside of the mount (hole)which the snapped stud went through. I don't know if this chafing effect is pre or post bolt snapping. Maybe a bit of both.  I think a billet mount is upon me. Rocket | ||
| Rocketman |
For now though, I took the grinder and a round file to the stock mount, and gave it a proper dressing.  I need to ride before I start spending more hard cash on this ole dog Buell of mine, lol. Rocket | ||
| Court |
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| Pammy |
S&S makes an excellent motor mount. Have for some years now. To fit many configurations as well. I modified my stock unit. Works fine. | ||
| Blake |
Assuming that failures are due to or prevented by any particular configuration of mounting bracket might not be valid. Not sure how many billet mount Buells are out there, not very many compared to those with stock mounts. Statistically it's very difficult to conclude anything with such disparity between the sample populations. Personally I think the stock XB mount is about optimum in the form/function/art categories. The billet mounts are excessive overkill and thus not artful from an engineering perspective, in my opinion. They are shiny and pretty though. Anyone have a pic of an XB mounting bracket? (Message edited by Blake on August 22, 2006) | ||
| Jackbequick |
Sean, So how did you wind finally getting enough heat into the broken bolt? Jack | ||
| Blake |
I take that back, the S&S mount available through Cycle Rama isn't near as massive/overkill as the one shown above. My bad. | ||
| Tattoodnscrewd |
Couldn't find the S&S motor mount on the Cycle Rama website .. anyone have a picture ? I have an X1 mount I was going to powder coat and use to replace the M2 mount (no need to have the extra arm on the mount with the race air cleaner) | ||
| Rocketman |
I too find the above mount a little more than needed for my Buell. I'd prefer something a little less ostentatious! Jack, once I had the 3/16th hole drilled I heated the stud itself using a #3 tip in the oxy acetylene torch. Let it cool down, then knocked in the easy out and started twisting. Rocket | ||
| Djkaplan |
"I'd prefer something a little less ostentatious!" I'm sure your nickel plated frame would out-bling the beefy NRHS mount and it would barely be noticed. | ||
| Pammy |
Guys, my motor is substantially more...beefy, shall we say, than a standard Buell motor. My motor is a bit taller(heads) as well and I still use the stock mount(modified. The S&S bracket would be even better, IMHO. If I weren't so darned stupid, I would post a pic or two. They are probably pictured on the S&S site. I will check for ya's. | ||
| Ceejay |
 | ||
| Ceejay |
image quality aint great but hey i'm learning... | ||
| Pammy |
Thanks Corey...you're my hero | ||
| Rocketman |
Dj, no actually, there's nothing bling about my nickel frame. I make no bones about it - my S1W isn't the shiniest brightest bike on the block. Yes it's clean and looked after but it certainly has a few flaws here and there. Only minor stuff mind you, but never the less I'd certainly not call my bike mint, which is what that NHRS mounting looks like it needs to go on, a mint bike. Anyway, it also looks way too heavy like I said before. Rocket | ||
| Ceejay |
that makes three, well soon to be four, he, he, he... | ||
| Blake |
A state-of-the-art aerospace engineered version of the mount would do away with most or all of the material between the two cylinder head bolt locations. Why is that? Anyone? | ||
| Blake |
What else would a state-of-the-art mounting configuration include that is not included in any of the existing OEM or aftermarket mount designs? Hint: Relying on friction alone, especially in a vibration saturated environment is rarely a good idea. | ||
| Djkaplan |
"Why is that?" You got the bait mister. It's because the cylinder and the mount aren't going to expand at the same rate. "What else would a state-of-the-art mounting configuration include that is not included in any of the existing OEM or aftermarket mount designs?" Another surface to bolt to. It wouldn't necessarily have to be 90 degrees from the front fasteners, but it'd have to be on a different plane. But the Company would have to cast different heads to keep the Sportster clean. I think the bean counters shouted louder in that meeting. | ||
| Djkaplan |
...pure speculation, of course. | ||
| Pammy |
Corey, I guess a congratulations is in order? There are some really smart fellers on this here board. | ||
| Blake |
The main answer that this stress analyst was looking for was that there is no load there, which is why the OEM bracket doesn't include any connecting material between its two bolt bosses. Your point about the cylinder head expanding due to higher temperatures is a good and valid one too. In effect by putting material between the two bosses there, one is introducing stresses into the part that would not otherwise exist. The bracket would be forced to resist the differential themal expansion of the cylinder head compared to the significantly cooler bracket material. Without the connecting material the bracket can easily flex the small amount in order to accomodate the thermal expansion of the cylinder head. I agree that a third out-of-plane connetion point would eliminate bending at existing bolted connetion points. That would be an optimum solution for sure. However, that appears to be a difficult configuration to realize. If the mating or "faying" surfaces of the bolted connections are properly designed, they can be made to carry bending. You are correct that a single bolt joint in a bending scenario is usually not a desirable configuration, but it can be made to work just fine. That is the case for the OEM design, where large contact bosses are provided to allow heel and toe reactions that can carry significant bending thanks to the huge compression (preload) forces imparted to those faying surfaces by the bolt(s), thus it is not necessary to have a third connection point to eliminate said bending loads from the individual bolted joints. But what would seem to be ideal would be to have more than just friction at the faying surfaces to transfer shear loads through the joint(s). Aluminum to aluminum faying surfaces may not provide a lot of friction. Under extreme loading and coupled with extremes of tolerance and assembly variables, the bolted joints through their smooth and flat faying surfaces may allow slight relative movement between bracket and cylinder head faying surfaces. It seems like some kind of direct mechanical engagement between the mating bosses would be helpful, even a matching knurled-type finish would be helpful. More conventionally, counterbores in the cylinder head could be made to positively engage with close tolerance mating annular protrusions on the bracket. Anything to provide a solid direct mechanical engagement for the transfer of shear loads without the need to rely entirely upon friction to prevent relative movement between bracket and cylinder head, even under the most severe vibration and high stress loading scenarios combined with extremes of tolerance and assembly variables. I dunno. I've done no actual analysis, don't know the design loading, and am just blathering. But it seems like it might be worth looking into.  Other than those resulting from crashes/impacts, I don't recall seeing any reports of front engine support bracket or bolt failures on XB models, so it seems that the great engineers at Buell have solved the problem. That front engine mounting bracket for the XBs is truly a thing of beauty. It would be right at home on a fighter jet or stealth bomber. True engineering as art. | ||
| Blake |
Sean, Before reassembly, it might not be a bad idea to rough up the faying surfaces on the bracket and cylinder head with some course sandpaper or equivalent. Might help achieve a better friction coefficient. | ||
| Pammy |
Something is terribly, terribly wrong here...I could picture Blakes explaination in my head. I may have a tumor...  | ||
| Blake |
 I agree, you'd best see a doctor forthwith! | ||
| Davegess |
You could cast the head and bracket and then "break" the two apart along pre-engineered stress lines. Then bolt them together to achieve and amazing amount of mating surface. BMW does this with the big end on the twins. |
