![Reply](https://www.horizonsunlimited.com/hubb/images/buttons/reply.gif) |
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
5 Jun 2008
|
Registered Users
Veteran HUBBer
|
|
Join Date: May 2006
Location: Melbourne
Posts: 166
|
|
question about bearing speed ratings
g'day.
i just bought a spare final drive bearing for my r11gs. i was able to obtain the right size, but without the 'C3' rating for rpm.
as i understand it, high-speed rated bearings have a little more space between race and balls, i assume to allow for heating at speed. can anyone add to this?
the bearing i bought is NTN, should be good. though not C3, it is rated to 6300rpm, and my maths tells me that at 120km/h, my rear wheel is turning at about 1000rpm. according to the following maths:
c (circumference) = 2 x pi x r,
where r = .33m,
c = 2.1m
right, why should C3 speed rating be required at all when there is such a wide margin (6300 - 1000 = 5300) between real-world rotation speed and the rated tolerance?
i have not yet fitted the bearing. can anyone suggest why i would not? any input welcome and appreciated.
cheers,
andy.
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
5 Jun 2008
|
Registered Users
Veteran HUBBer
|
|
Join Date: Sep 2003
Location: Estonia
Posts: 787
|
|
Not a bearing specialist myself, but didn't BMW changed the ball numbers inside the main FD bearing? First it was something like a 17 balls and later 19 (not sure if the numbers are correct, but the difference was 1-2 balls) because of better tolerance capability.
My mind says it's all a compromise between a high speed and huge load. For huge load more balls seem to be a better option, since there's more support area in the bearing to take that load, while it'll be limited for speed (more drag=heat and wear!). Less balls mean better speed tolerance, but probably also less load tolerance (less "support" area in between the bearing race and balls).
R11xxGS main bevel box bearing is C3 rated in stock - 'C3' means there should be increased radial clearance between the inner race and outer race, usually used for bearings that are going to run fast and hot.
So I can't see how speed can be a "problem" (R11xxGSes are rated to 200km/h speeds), I rather see the load (big bike, 2 up, lot of luggage) and potholes/harsh road conditions as a threat to the bearing longetivity.
Anyways, make sure you shim it correctly on puting it on (=correct preload) - wrong shimming will cause it broke down after just few hundred miles to few thousand, since it'll start to wear out one side of the race coz it's preloaded (by shims) wrong. If you preload it precisely right, then I've seen them lasting for 150,000+miles! So it can be kind of "lottery" between the precision of the work versus the real-life road conditions and your riding style. Some last 10K miles, others last even stunning (for the bike that has been riding offroad too, not just smooth tarmac like Goldwings etc do) 200+K miles I've heard in UKGSer forum.
Always, being a bit paranoid person muyself not to be involved into the "lottery" game - I carry a spare main bearing, main seal and few different sizes of shims with me on my travels. They're so called "GSers spare chain kit" ![Smile](https://www.horizonsunlimited.com/hubb/images/smilies/smile.gif) - but they cost less than a good chain/sprocket kit, take much less room and weight less too. I bought mine from BMW since the same bearing from bearing shop was more expensive than from BMW.
Ride safe, Margus
Last edited by Margus; 5 Jun 2008 at 08:21.
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
5 Jun 2008
|
Contributing Member
Veteran HUBBer
|
|
Join Date: Jan 2006
Location: Sheffield
Posts: 994
|
|
Wheel bearings are bearings are bearings. Based on my (limited) experience the only bearings that need special construction are things like cam roller bearings, as these rotate at several times engine rpm.
Whenever I have to replace a bearing I just order the same bearing based on the number stamped on the side ( - Simply Bearings Ltd), which is generic across all jap bearing manufacturers. The only non-generic bearing I have used was a ceramic bearing from a skateboard (used the wheel as a chain roller, works GREAT)
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
24 Jun 2008
|
Registered Users
HUBB regular
|
|
Join Date: May 2007
Location: Riyadh
Posts: 27
|
|
What are C3 bearings?
What are C3 bearings?
C3 bearings are bearings that have an additional internal radial clearance to cope with high speed environments where excess heat is generated.
They are not suited to environments where critical alignment is required from the onset e.g. Where blades and cutters are set up to each other.
Applications like motorcycle wheels or bicycle wheels do not require C3 rated bearings.
Unless the bearing you are replacing specifically says C3 on it then you should not replace it with a C3 bearing, C3 Bearings are loose to the feel from new and often people complain at the quality of the bearing being poor and having more movement than the one they are replacing.
This is the characteristic of a C3 bearing.
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
24 Jun 2008
|
Registered Users
Veteran HUBBer
|
|
Join Date: Oct 2006
Location: Northumberland
Posts: 185
|
|
Quote:
Originally Posted by henryuk
only bearings that need special construction are things like cam roller bearings, as these rotate at several times engine rpm.
|
Cam's actually run at half the RPM speed of the engine.
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
25 Jun 2008
|
Registered Users
New on the HUBB
|
|
Join Date: Jun 2008
Location: BC, Canada
Posts: 7
|
|
Just to weigh in on this "C3" issue ...
it is correct that C3 indicates a "larger than standard" internal clearance but this suggests a tolerance "range". There is more than 50% overlap in the internal clearance "probability" between a standard and a C3 ball bearing.
Heat expansion of the shaft (especially on an electric motor) would tend to suggest a C3 bearing. At the speeds you're talking about, I wouldn't worry about C3 or not ... but C3 is quickly becoming the default here in North America.
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
25 Jun 2008
|
Registered Users
Veteran HUBBer
|
|
Join Date: Feb 2006
Posts: 1,598
|
|
This is interesting because Later Triumphs (post 1981) went from a C3 main bearing to a C2. But I do not know what the constructional difference is in actuality.. Are the C2 bearings capable of carry a heavier load ?
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
26 Jun 2008
|
Registered Users
New on the HUBB
|
|
Join Date: Jun 2008
Location: BC, Canada
Posts: 7
|
|
Ironically, C2 has an even "tighter" than "standard" (or C0) internal clearance.
Two steps tighter than C3.
Definitely won't provide a higher load capacity but will give better radial and axial running accuracy.
The entire bearing will tend to heat and cool at the same rate so a tight internal clearance running in an oil bath is a pretty stable application.
|
![Old](https://www.horizonsunlimited.com/hubb/images/statusicon/post_old.gif)
26 Jun 2008
|
Registered Users
Veteran HUBBer
|
|
Join Date: Feb 2006
Posts: 1,598
|
|
It is the crankshaft main bearing on the 750 twins. prior to that and on the 650's they ran C3's the 650's revved much higher.
|
Currently Active Users Viewing This Thread: 1 (0 Registered Users and/or Members and 1 guests)
|
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
Check the RAW segments; Grant, your HU host is on every month!
Episodes below to listen to while you, err, pretend to do something or other...
2020 Edition of Chris Scott's Adventure Motorcycling Handbook.
"Ultimate global guide for red-blooded bikers planning overseas exploration. Covers choice & preparation of best bike, shipping overseas, baggage design, riding techniques, travel health, visas, documentation, safety and useful addresses." Recommended. (Grant)
![Ripcord Rescue Travel Insurance.](/stuff/ripcord/ripcord-logo-250.jpg)
Ripcord Rescue Travel Insurance™ combines into a single integrated program the best evacuation and rescue with the premier travel insurance coverages designed for adventurers.
Led by special operations veterans, Stanford Medicine affiliated physicians, paramedics and other travel experts, Ripcord is perfect for adventure seekers, climbers, skiers, sports enthusiasts, hunters, international travelers, humanitarian efforts, expeditions and more.
Ripcord travel protection is now available for ALL nationalities, and travel is covered on motorcycles of all sizes!
What others say about HU...
"This site is the BIBLE for international bike travelers." Greg, Australia
"Thank you! The web site, The travels, The insight, The inspiration, Everything, just thanks." Colin, UK
"My friend and I are planning a trip from Singapore to England... We found (the HU) site invaluable as an aid to planning and have based a lot of our purchases (bikes, riding gear, etc.) on what we have learned from this site." Phil, Australia
"I for one always had an adventurous spirit, but you and Susan lit the fire for my trip and I'll be forever grateful for what you two do to inspire others to just do it." Brent, USA
"Your website is a mecca of valuable information and the (video) series is informative, entertaining, and inspiring!" Jennifer, Canada
"Your worldwide organisation and events are the Go To places to for all serious touring and aspiring touring bikers." Trevor, South Africa
"This is the answer to all my questions." Haydn, Australia
"Keep going the excellent work you are doing for Horizons Unlimited - I love it!" Thomas, Germany
Lots more comments here!
![Five books by Graham Field!](/stuff/grahamfield/graham-field-2021-280.jpg)
Diaries of a compulsive traveller
by Graham Field
Book, eBook, Audiobook
"A compelling, honest, inspiring and entertaining writing style with a built-in feel-good factor" Get them NOW from the authors' website and Amazon.com, Amazon.ca, Amazon.co.uk.
Back Road Map Books and Backroad GPS Maps for all of Canada - a must have!
New to Horizons Unlimited?
New to motorcycle travelling? New to the HU site? Confused? Too many options? It's really very simple - just 4 easy steps!
Horizons Unlimited was founded in 1997 by Grant and Susan Johnson following their journey around the world on a BMW R80G/S.
Read more about Grant & Susan's story
Membership - help keep us going!
Horizons Unlimited is not a big multi-national company, just two people who love motorcycle travel and have grown what started as a hobby in 1997 into a full time job (usually 8-10 hours per day and 7 days a week) and a labour of love. To keep it going and a roof over our heads, we run events all over the world with the help of volunteers; we sell inspirational and informative DVDs; we have a few selected advertisers; and we make a small amount from memberships.
You don't have to be a Member to come to an HU meeting, access the website, or ask questions on the HUBB. What you get for your membership contribution is our sincere gratitude, good karma and knowing that you're helping to keep the motorcycle travel dream alive. Contributing Members and Gold Members do get additional features on the HUBB. Here's a list of all the Member benefits on the HUBB.
|
|
|