Let's revisit the broken bolt in the chaincase

bolt tolerance

Just visited with a millwright and he says that the problem is 2 fold. The first problem is of course the 5mm gap and secondly the collar bolt hole being 1.2 mm larger than the bolt. I'm having a bushing turned that is 5mm thick with an exact 9.7 mm hole vs. the 10.8 mm hole in the collar. This should eliminate any freeplay that allows for shear loading on the bolt. In the event this ever does shear it should be under the the bolt head but I can't see it happening.
Man, I tell you guys that working on F-18's for 20 years has made me far too anal !! LOL
 

Mountaintech

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Just visited with a millwright and he says that the problem is 2 fold. The first problem is of course the 5mm gap and secondly the collar bolt hole being 1.2 mm larger than the bolt. I'm having a bushing turned that is 5mm thick with an exact 9.7 mm hole vs. the 10.8 mm hole in the collar. This should eliminate any freeplay that allows for shear loading on the bolt. In the event this ever does shear it should be under the the bolt head but I can't see it happening.
Man, I tell you guys that working on F-18's for 20 years has made me far too anal !! LOL
Sounds good. You must be using the newer bolt that's threaded the whole way. The original bolt mikes out at 10.3mm on the unthreaded portion ( which is about 21mm long), as opposed to the threaded portion at 9.69mm. Newer bolt is 2mm shorter as well. 40mm vs 42mm. How are those Hornets holding up? Airframe hours must be getting up there. I started working on those in '85 when they were new. Sure were a blast to fly. Miss those days.
 
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F-18s

The planes are ok but if you have been listening to the news it's pilots that we need. These young wet behind the ears kids are'nt up to par.
I've been retired since 04. I was a Rigger and worked on everything from CF-100s, Voodoo's, T-bags, F-5'S you name it. Where were you posted and when ROEST?
 
Feb 11, 2018
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I'm having an issue with my 08 nytro mtx. The drive shaft has shifted to the chaincase side. It has moved 1/4 to 3/8 of an inch which is enough to cause the speed sensor to not read properly. Any hints on what other damage I may find. I am ordering bearings and seals in the morning and will pull it apart after they arrive.
 

TecCrash

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I'm having an issue with my 08 nytro mtx. The drive shaft has shifted to the chaincase side. It has moved 1/4 to 3/8 of an inch which is enough to cause the speed sensor to not read properly. Any hints on what other damage I may find. I am ordering bearings and seals in the morning and will pull it apart after they arrive.
Realizing that this was an issue that was addressed back when these sleds were still new, lots of folks are dipping their toes into the Used 4 Strokes market. Does anyone have some long term feedback into how the spacers worked/solved the problems?

Thanks for your feedback!

TecCrash
 

Mountaintech

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The spacer did solve the problem. Yamaha ended up making the driveshaft slightly longer on the chain case side to solve the issue.
 
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