FZR Front Wheel question

[Flyover Country Joe]

Hein,
I'm going to weigh in on the discussion. I am not an engineer, I try not to play one on the Internet. I was a machinist for 14 years, started out with 2 years of vocational training before that. I have earned my FAA Airframe & Powerplant license, worked for a FAA repair facility for 7 years.. I know exactly what you mean by being afraid of flying if you don't trust thinwall bushings. I have made & installed literally thousands of bushings to repair worn bores on aircraft parts of all types. As you also know, every one of those repairs has to be proven to the satisfaction of the FAA to be an airworthy method of repairing those parts. I was involved with the approval process of several part repairs submitted to the FAA by the repair facility that I was employed by. Those repair procedures underwent an evaluation by an engineering review board to determine if the part will be airworthy after being repaired. I guess that is my rambling attempt to make the case that your idea of bushing the inner race of the front wheel bearing of a FZR 1000 wheel with the 17 mm ID is not so far fetched. You have not made the fork assembly of an FJ 1200 any weaker than before. It still has a 15 mm axle.  I have  never heard of anyone pulling the wheel bearings out of a front wheel and finding a damaged center spacer. I agree with your point that the bushing is no more likely to spin than the axle, if theaxle remains tight. Just my 2 cents, worth about that much.

[Mike Ramos]

Gentlemen,
When I did the front wheel conversion to the 3.5" rim, I simply had the bearing mating surface (within the rim)machined to accept the stock bearings.  It is relatively quick and inexpensive ($100.00) modification that allows the use of the stock fork sliders, axle and speedometer drive. It is a basic procedure that any competent machine shop can perform. I purchased the bearings at our local bearing supply house.
Hope that helps.
Mike Ramos.

[hein]

Morning Joe. Thanks for validating my point. I served in the Canadian air force back in the 60's and as you stated thinwall bushings were a commen solution to aircraft service problems.

Mike, you offered a good solution to the wheel issue. I've used this method myself in repairing a vintage wheel, and as you stated, its cheap and easy.

Problems are resolved through solution not fearmongering.   Hein.

[Pat Conlon]

Problems are resolved through solution not fearmongering.   Hein.

Well, that's rich.  I guess that was directed at me.
This is a first time (I recall) that my concerns have been labeled as a fear-mongering.

Oh well...So far I'm batting .500. At least I've gotten Hein to acknowledge that his 1mm thick bushings are in the load path.

That's a start.

However, getting Hein to admit that there is a potential for cracking failure of the 1mm thick bushings is where we part company.
If or when this happens, if ever, it will become intuitive to suggest that there are better solutions than cardboard thin axle bushings.

I simply had the bearing mating surface (within the rim)machined to accept the stock bearings.  It is relatively quick and inexpensive ($100.00) modification that allows the use of the stock fork sliders, axle and speedometer drive.

[edit] Mike, I don't understand your solution.
I thought we are talking about fitting a '89+ FZR rim which uses a 42mm OD bearing (42x17x13).
The stock bearing for the 15mm axle is 40mm OD. (40x15x13)
So..... How do you machine an existing 42mm hole in the rim to fit a 40mm bearing?

[Mike Ramos]

Hello Pat,
The rim I used was fitted with a bearing that had a smaller outside diameter bearing than the stock rim. It is a 3.5" X 17" from a Yamaha and looks very much like a stock rim. It has been over two years and I apologize that I do not recall the exact year of the bike that it came from. Over 75,000 miles later it is still doing well. I am not out to dissuade or convince anyone, I am just relating my own experience.
Mike.

[hein]

Pat, relax. My comment was not directed at you personally. I believe that Joe, who has a pretty good background on the topic, supports my contention that there is nothing wrong with thinwall bushings as they are commonly used in the aviation industry. For a bushing to crack it would have to have room to expand in terms of the OD. Since its pressed into a bearing race the inner race would have to change dimensionally first to allow room for expansion. If the idea of a split bushing scares you please consider that the bushings on most fork assemblies are in fact split bushings. If that doesn't scare you consider that they are made of a soft material and are not a press fit but are floating bushings. Yes they will wear out due to the fact they are constantly moving up and down in the fork stanchion but catastrophic failure

[hein]

Sorry but I hit a wrong button

Anyways failure under these conditions is rare. I'm quite sure that I will never be able to convince you that thinwall bushings are safe regardless of the fact that they are used in many industrial and aviation applications. Shimstock of a much thinner dimension is also used in many applications under a compression load. I can't think of any shimstock failure or splitting when I, and many others, use it in setup applications on machining jobs.

I appreciate your concern for safety but you have still not explained what would cause failure. Yes the bushing is in the load path but it is only subjected to a compression load. Its supported on the id. by the axle and by the bearing race on the od., nothing can move and there is no room to escape. Please enlighten me.

I'm not trying to be confrontational and I would prefer to keep this on a friendly level and I'm also willing to learn something from this.

Hein.

[Flynt]

I'm also willing to learn something from this.

Hein.

you guys need to chill IMHO...  seconds?   

Space truckin...

Frank

BTW - skiing in  Truckee today was excellent...

[Pat Conlon]

I appreciate your concern for safety but you have still not explained what would cause failure. Yes the bushing is in the load path but it is only subjected to a compression load. Its supported on the id. by the axle and by the bearing race on the od., nothing can move and there is no room to escape. Please enlighten me.

No worries Hein, it's all cool. This is a good discussion.

I know that there is an appropriate place for thin walled bushings. My instincts tell me that this application is not the place.
Why?
A couple of reasons off the top of my head;
First off remember, we are working with a very thin 1mm section of material under compressive and sometimes shock loads.
1) Is the 15mm axle perfectly round? No, so the transfer of forces from the bearing thru the bushing to the axle can become concentrated on the inside wall of the bushing. An uneven distribution of forces is not a good thing.
2) Is the surface of the 15mm axle perfectly smooth? No, so very small minute surface imperfections (air pockets) can cause load concentrations leading in time to micro-fractures in the thin walled bushing as the material becomes worked.
3) Does the 15mm axle deflect under load? Yes. How does this deflection affect the bushings? Unknown.
4) Do manufacturers know about this axle deflection? Yes. That is why newer motorcycles have larger diameter axles e.g. FJR=17mm
5) When you machine this thin walled bushing do you do any quality control inspections on the finished product? Not that you've reported. Do you Xray the bushing looking for microfractures? Ultrasound? Dye Penetrant? Any non destructive testing at all?
You FAA certified dudes should know a little about QC, do you really think FAA would certify this application without QC? How about TUV?

Which leads to my final thought:

Is it worth a chance? After all it's only the front wheel.... Are there other solutions out there? Yep.

Chillin out in Palm Desert....

[hein]

Hi Pat.
  Rather than debating each point ,which with my typing skills is painfull, consider this from a tottally different angle. First take a Torrington bearing cut in half, throw out the needle bearings and measure the wall thickness of the outer shell. Its much thinner than 1mm. A bearing of this type when pressed into a housing can sustain some pretty large loads and also act as a bearing surface for the moving rollers at the same time.The actual contact area of the rollers is much less than the surface area of the bearing shell. Typical service failure on these bearings is caused by the needle bearings wearing or the shaft which is supported by the bearing.

If you've misplaced your lathe or the neighbour has it use a hacksaw to cut the bearing.
I need to go home and open a bottle of wine.

Hein.

[FJmonkey]

Hi Pat.
  Rather than debating each point ,which with my typing skills is painfull, consider this from a tottally different angle. First take a Torrington bearing cut in half, throw out the needle bearings and measure the wall thickness of the outer shell. Its much thinner than 1mm. A bearing of this type when pressed into a housing can sustain some pretty large loads and also act as a bearing surface for the moving rollers at the same time.The actual contact area of the rollers is much less than the surface area of the bearing shell. Typical service failure on these bearings is caused by the needle bearings wearing or the shaft which is supported by the bearing.

If you've misplaced your lathe or the neighbour has it use a hacksaw to cut the bearing.
I need to go home and open a bottle of wine.

Hein.

Don't forget some nice cheese to go with that wine, see you at the 2012 WCFJR right Hein?

[fj11.5]

so did anybody try the fzr bushing method, or find bearings that could be used in the later fzr wheel to 88 /89 fj forks 

[jwh]

I have!, after getting the later wheel by mistake but in very good condition i tried getting a 40x15x13 bearing but no luck, so local bearing shop did me a 40x17x13 and gave me a 1mm bush/shim to fit inside, tight fit but works well front axle fits well and is everything seems tight enough, have only done about 500 miles on it but working well so far.

[JCainFJ]

Once, a long long time ago I was riding an XS750 that I bought new (It was once on the back cover of Cycle!) and one front wheel bearing went away. I was in south central Missouri just outside of Big Spring. The local auto parts store had the correct bearing, and I changed the bearing in the parking lot. If that bearing needed a bushing to make it work, I would have been out of luck. Will a bushing work? Yes it will. Do I want to be 400 miles from my lathe and need a bushing or 2 to be able to ride home?  No, not so much.

So: 1. I try to keep some things, like bearings, simple.   2. I no longer loan my motorcycles to roommates who will ride them through semi deep river crossings, and or wash them with a high pressure spray. He didn't tell me about either until after my parking lot repair.

There is a little more to this story, but I will save it for another day.

[fj11.5]

I have!, after getting the later wheel by mistake but in very good condition i tried getting a 40x15x13 bearing but no luck, so local bearing shop did me a 40x17x13 and gave me a 1mm bush/shim to fit inside, tight fit but works well front axle fits well and is everything seems tight enough, have only done about 500 miles on it but working well so far.

, no worries, thanks mate,  just seeing whats out there for when i ever get to do the fzr wheel swap, did the 84 to 89 forks ect years ago , seem the 3.5" is the way to go