| Author | Message | ||
     Clyde_the_ape |
Was putting some grade 8 bolts in my front iso mount, so I could move the bike around the shop, the bolts went in ok, but then just kept turning & never got tight. Ran a chaser & pulled out what looks like an old helicoil. Is it safe to put a new helicoil in the head?? | ||
| Preybird1 |
I have used them before on the exhaust stud but never on the head. I am sure you could try it. try these guys out for repairs. http://www.timesert.com/ | ||
| Clyde_the_ape |
Ouch those things are crazy expensive. $80.00 for one size kit & that was before shipping | ||
| Preybird1 |
if it ends up at a HD dealer they wont fix that. they will replace it. try cycle rama inc. http://www.cycle-rama.com/ Oldog and other badwebbers swear by these guys. They will fill the hole and drill it and re-tap it. | ||
| Oldog |
Get it welded up and re machined you may fail that head other wise... YMMV | ||
| Psykick_machanik |
i agree with Oldog. the helicoil threads arnt long enough to match the mount bolt fully, putting to much force in a smaller area. the aluminum threads in the head would fail before to long. iv had my head welded up, drilled and tapped with no problems at all. didnt cost much either. | ||
| Reepicheep |
Can't you just put two heli-coils in the one hole? That's what I did to repair one of my side bag mounts when it was stripped out of the subframe by a careless Toyota driver. When I have seen a heli-coil fail, it didn't roll or anything, it just ripped out the aluminum like a bolt would have done. That makes me think they are just as strong as the bolt would be... provided you have enough thread engagement surface. But I would never be confused with a mechanical engineer...  | ||
| Oldog |
the aluminum is thin to start with and you are going to make it thinner with a helicoil and you do need all of the threads present to develop maximum strength, this is one time a patch is not really a good idea. bear in mind the bolts are trying to apply a clamp load to the mount | ||
| Gmaan03 |
Being a machinist, I have heli-coiled many alum parts. You should be able to get the correct length, and not use two(BAD)! Agree welding would be the best fix. A heli-coil will produce a stronger thread, but like Oldog said, side load might shear the alum casting if it is too thin. Oh by the way usually 2x the diameter of the bolt is all you need for maximum strength(tensile) as the bolt is seated onto the face some of the clamping force will be AXIAL, this is where it might fail. | ||
| Reepicheep |
Got it, thanks Jim and Gmaan03. Agreed, if the sides of the hole are too thin to support the new bigger hole, then it's broken. I use that "2x bolt diameter to be stronger than the bolt" rule all the time, perhaps not universal, but a very useful rule of thumb. Gmaan03, why are two heli-coils in one hole bad? Or is it just overkill, because one heli-coil is already 2x the diameter, so you already have a hole stronger than the bolt with just one? | ||
| Fast1075 |
Pull the head and sent it to Pammy and Wes at Cycle Rama...it will come back in better shape than new...Pull both heads and have the valve job touched up and some of their double trick valve guide seals while they are in there... | ||
| Oldog |
Fast1075 + 2 consider a side of porting with those heads | ||
| Gmaan03 |
using two will work but you might as well get the correct lenght. Besides if you install one and one on top of the other to create the desired lenght, some times you create a burr from not removing the tang properly. The Burr will gall up the screw you are trying to install. I know I did it once on a machining fixture. | ||
| Reepicheep |
Thanks Gmaan, that's useful information. Thanks for sharing your experience! The great thing about sending heads to Wes and Pammy is that it doesn't really matter what the problem was, it's a great solution regardless. | ||
| Mtjm2 |
I would have to agree with Fast1075 . Why risk it , do it rite . |
