| Author | Message | ||
     Nortnlvr |
My M2 front engine mount just broke, Any advise? Heard there is an aftermarket replacement better than OEM? Should I replace the rear ones too? | ||
| Dpg |
Sorry to hear of your problem. Did just the mount break or is the front isolator gone and/or head bolts broken off too? I just replaced my front mount with the Nallin Racing Head Service billet mount. You can get them from NRHS direct or from Al at American Sport Bike. About $250 shipped. ABS will have the replacement bolt kit too. Read the multiple earlier threads on the front isolator if you find that had gone out too. Oh, 60lbs torque on those head to mount bolts per the B-018 service notice. Safe ride, Gary in Oaktown | ||
| Kdkerr2 |
Also S&S makes a t6 billet aluminum replacement front motor mount. It's much stronger then the stock cast units. | ||
| Firstbuell |
Q - is billet stronger than something forged? thx | ||
| Jramsey |
>> is billet stronger than something forged? Short answer is no. | ||
| Richsm2 |
it is the same strength if,the same alloy,has the proper grain direction ,is heat treated to the same "T" (highest)yield for that alloy,after machining. the spec from the factory is cast. | ||
| Richsm2 |
rewrite: the head is "cast", cast being the weakest of the three.,yet the steel bolts are breaking. | ||
| Jramsey |
Proper grain direction is fact of the forging process. Most all heat treating is done before machining. | ||
| Jramsey |
200+ pounds of engine hung by two 7/16 bolts in single shear + the riders weight pulling the shock, I'm surprised more failures haven't happened. | ||
| Dave_02_1200 |
Does that make a case for enlarging the bolts to 1/2"? Seems logical unless there is a reason not to do that. | ||
| Richsm2 |
the shear capacity of a 7/16 grade 8 bolt is 13680lbs lbs /sq in ,greater for a ms(milspec) at 19840. | ||
| Cbig |
But what we have here is (13680 lbs/in2)*[(7/16 bolt diameter)/2]^2 *pi =2056 lbs on that bolt. Since I don't have a way of calculating the instantaneous vibe forces, I can't, but I would have to assume repeated slamming down after wheelies and such put a lot of abuse on it.. | ||
| Richsm2 |
I intended to edit this as the 13680 & 19840 are not psi/sq in,but loads in lbs. (see /www.rockcrawler.com/techreports/fasteners/index.as p) these figures are already calculated for area. a grade 8 bolt is a 150,000lbs/sq in bolt, ms 220000. I need to get the reference book at harbor freight,all kinds of this stuff in a handbook,toolbox size . | ||
| Richsm2 |
question,does the xb have a rear head mount,if so why not install on the tuber? |
