OT-Ceramic bearings any better?

Racebrewer · Dec 3, 2007

Hi,

I'm involved in building and modifying Kart racing engines. So far, I've avoided ceramic bearings in engine and chassis applications because of the cost.

I now have a customer that is willing to foot the bill if there is anything to be gained in terms of performance (durability would be nice, too).

In the engine there are ball bearings available with ceramic balls and races and teflon retainers. For the chassis there are "hybrid" bearings available with bearing steel or stainless steel races and retainers with ceramic balls.

I've gotten mixed reviews from racers but nobody in racing likes to admit to a mistake or give away a 'secret'. Also, my gut is that because the ceramic balls are so hard any dirt that gets into a hybrid/ceramic bearing will chew up the steel races.

So, turning to the most helpful folks I've met, do you guys have any suggestions or input?

Actual experience appreciated. Any input appreciated.
Thanks,
John

Rstewart · Dec 3, 2007

I don't know too much about Ceramics, but some blowers incorperate them. They can withstand extremely high RPM's and high heat!

JRIowa · Dec 3, 2007

Ceramic bearings or hydrids are good for high RPM, but will not take an impact.

scojen · Dec 3, 2007

Ceramic bearings are good for use in 2 stroke engines you will see an RPM gain however the key is cleaniness and more important ball size. In the 2 stroke engines I work with the difference in a couple of tenths on the diameter of a bearing will make all the difference in the world as much as a 1000 rpm. In some cases you will have to play with that factor inorder to see a gain in RPM. For instance a ceramic bearing from Boca with a C3 specification is too tight. But after changing to balls with a tenth less in diameter this gave a 1500 rpm gain. Another factor is to make sure there is no side load on the bearing.

Scott

Carl Darnell · Dec 3, 2007

They are used in model airplane engines that turn 20,000 rpm +/-. I suppose in a go cart engine they would be good if the proper class bearing is chosen with the proper oil.

cdn farmer · Dec 3, 2007

I know several guys that run ceramic bearings in the transmissions and wheels on their dragbikes,, they swear that it helps gain a few tenths off of their time and they seem to get a bit more horsepower on the dyno,,as for durability they survive over 600hp in a 1300cc 4cyl engine without to much trouble,,

Racebrewer · Dec 4, 2007

Grin and bear(ing) it

Thanks Guys,

I'm looking at C-4's in the motor and probably C-3's in the chassis. From BOCA.

It seems like a lot of the places selling ceramics don't have any real knowledge regarding their products. BOCA seems the best I've found so far. One place didn't even speak English (at least not any English I could understand).

Scott, what type of motors/uses are you involved in?

All in all it seems like there will be a small but measurable improvement (time/speed) from using these hybrid bearings, but they may be somewhat fragile.

Any other input will be appreciated.
Thanks,
John

RDL · Dec 4, 2007

Rstewart said:
I don't know too much about Ceramics, but some blowers incorperate them. They can withstand extremely high RPM's and high heat!

They will take higher RPM than steel balls but the steel races have a high heat problem. Of course that does depend what you consider high heat. At 250 Celsius using high temperature grease they last about 50 hours. It was possible to increase that to 200 hrs with an experimental mixture. To get a reasonable MTBF you have to use engineered steel that does not soften at the temperature it will be used.

Raymond

scojen · Dec 4, 2007

RaceBrewer,
Model airplane engines that turn in excess of 28,000 rpm, Ceramics have been used in our sport/hobby for about 5 years give or take. As I mentioned earlier ball size and side load are the two greatest factors. When I get my avatar back on it will give you an ideal of the motors we run. Another factor to consider is the bearing cage, metal cages are not good a polymide plastic cage is the perferred choice. C3 bearings in the motor are really all you need C4 will be too tight and subject to the balls degrading quickly. Another item is you can play with the percentage of oil you run in your fuel. Normally with steel bearings and based on the size of the engine I run up to 22% oil in a glow motor this can be reduced a bit down to 15% in some situations. With our diesel motors we run as little as 10%. Believe me when i say the ball size is the key.

Scott

precisionmetal · Dec 4, 2007

Racebrewer,

Save your money.

Get the bearing interference correct and make sure everything is lined up straight... that counts far more.

Spend the rest on extra tires and practice/testing at the track.

MCritchley · Dec 4, 2007

There are some folks in the midwest using ceramic bearings on there axles in their shifter carts. These are 100+ MPH carts. The gentleman that i spoke with said he averaged 4 percent lower lap times when using ceramic berarings. He stated that nascar has switched to ceramic bearings on the driveshaft & the rear end. The rolling resistance with ceramics is much less than steel on steel.

dsergison · Dec 4, 2007

i dont know a dang thing about ceramic bearings

but i do know that in racing of any sort that the claims of other racers, and the marketing of expensive crap directed toward racers is the very least credible and least scientific source of information ever.

tomwalz · Dec 4, 2007

Ceramics can be much more wear resistant
They can be much slicker (higher lubricity)
They can be lighter in weight.
They conduct heat very poorly so they don’t grow with heat.
They can be tough enough to use as saw tips in saw mills.
The results you get depend on what you mean by ceramic. There are well over a thousand grades of ceramics currently being used.

C-3 and C-4 are most commonly grades of cemented tungsten carbide. If he is recommending tungsten carbide I think I would ignore it and go with a ceramic.

I think I would try the Saint Gobain web site
http://www.cerbec.com/main/home.asp

Norton also makes bearings.
Norton's Silicon Nitride NC-132

I would go for a solid material, not a cemented material.
You ought to be able to get a value for lubricity or coefficient of friction on the material to tell you how slick it is.
There should be a Rockwell hardness, usually Rockwell A.
Toughness will probably be expressed as Transverse Rupture Strength. Higher the better.

You can search Google or Yahoo for “ceramic balls” and build your own.

Tom

P.s. If you want to argue, I am happy to agree with you.

bikebuilder · Dec 4, 2007

They're taking the cycling world by storm..... perhaps the ultimate arena for efficiency gains. I have yet to dive into the topic, but I think their main claim to fame is roundness far beyond that of metal. Sounds like there are other pluses as well.

bb

Dave P. · Dec 4, 2007

MCritchley said:
There are some folks in the midwest using ceramic bearings on there axles in their shifter carts. These are 100+ MPH carts. The gentleman that i spoke with said he averaged 4 percent lower lap times when using ceramic berarings. He stated that nascar has switched to ceramic bearings on the driveshaft & the rear end. The rolling resistance with ceramics is much less than steel on steel.

Not sure who you spoke to but lap times dropping 4 percent????
2.4 seconds on a 60 second lap, maybe he put in a new engine
and 4 fresh tires at the same time......

Motomoron · Dec 4, 2007

I've raced motorcycles, bicycles, RC cars, karts, cars and skateboards. None very well, but nonetheless, I've showed up and been ready for green flag. Ceramic bearings have been frequently used in most of those disciplines. BTW, I'm a product development engineer by trade, and truly dislike bullsh1t claims regarding performance. Ceramics are probably a fine idea when you're able to consistantly run at the front of your class or within a couple percent of track record times, and you're willing to occasionally build a new motor when one lets go due to getting walloped in the sprocket and inputting too much shock or some such. They're not snake oil, but on the basis of bang=$$, they're well up on the diminishing returns scale.

dsergison · Dec 4, 2007

"They're taking the cycling world by storm..... perhaps the ultimate arena for..."

bologney marketing
--my point exactly

I can see high speed engines, but for axles, or much less for bicycle parts it's probably so far up the diminishing returns scale as to be totally unquatifiable in anyhting but the most well controlled experiments.

Racebrewer · Dec 5, 2007

Lost my bearings.......

Thanks to all of you for the input.

We are going to give them a try using hybrids (ceramic balls and steel races).

Here is a little more info. The guy I am working with generally comes home with a trophy. Perhaps not a great trophy, but a trophy none the less. I (we) would like to move him a bit more forward. He is fairly new to karting but has other racing under his belt. I'm not sure if the experiences interchange, karting being very much on the edge at every second.

My impression is that the ceramic bearings will help, as long as they are properly maintained (cleaned).

Yes, it would be better to spend more time practicing, more new tires, etc, but when you are out there every practice session, and spend many, many nights in the shop looking for tiny improvements already, one looks to other areas.

I'll let you know what happens. Besides the ceramics, I have other bearings that have been treated with tungsten disulphide (slipperyest substance known to mankind) to see if those help.

Life is interesting. One has to keep stimulating the brain<LOL>

John

qualitymachinetools · Dec 5, 2007

You may want to talk to this guy Jack, here is his web site: http://www.performancebearing.com/
He is a customer of mine, and really seems to know his stuff about them. From my understanding, he actually makes the bearings right there.
May be worth a try anyway!

bikebuilder · Dec 5, 2007

dsergison said:
"They're taking the cycling world by storm..... perhaps the ultimate arena for..."

bologney marketing
--my point exactly

I can see high speed engines, but for axles, or much less for bicycle parts it's probably so far up the diminishing returns scale as to be totally unquatifiable in anyhting but the most well controlled experiments.

Could be... Gawd knows I'm a marketing curmudgeon. These top pro racers hit 60 mph pretty regularly on decents... which are often right before a finish.. and the finishes are often photo finishes. What rpm are bearings doing in a bike hub going 60 mph? I wouldn't be *too* quick to dismiss any possible gains. And then there's the time trials......

bb

OT-Ceramic bearings any better?

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