Dang, I gotta decide AND put my name on the list!?

CERAMIC BEARING

1. RMADERMAN
2. tighed1
3.
4.
5.
6.
7.


STAINLESS BEARING

1.
2.
3.
4.
5.
6.

 

CERAMIC BEARING

1. RMADERMAN
2. tighed1
3. distantpulse
4.
5.
6.
7.


STAINLESS BEARING

1. Bulldogger
2.
3.
4.
5.
6.

 

distantpulseCERAMIC BEARING

1. RMADERMAN
2. tighed1
3. distantpulse
4.
5.
6.
7.


STAINLESS BEARING

1. Bulldogger
2.Waldig - Woody
3.
4.
5.
6.

 

...................

 

Quote:
Originally Posted by waldig
distantpulseCERAMIC BEARING

1. RMADERMAN
2. tighed1
3. distantpulse
4. moparrbust
5. AMA FIRE
6.
7.


STAINLESS BEARING

1. Bulldogger
2.Waldig - Woody
3.
4.
5.
6.

...................

 

I can only provide a warranty on the SS bearing. Just FYI

 

CERAMIC BEARING

1. RMADERMAN
2. tighed1
3. distantpulse
4. moparrbust
5. AMA FIRE
6.
7.


STAINLESS BEARING

1. Bulldogger
2.Waldig - Woody
3. Bluemdsrt6
4.
5.
6.

 

[quote=BlUEMDsrt6]CERAMIC BEARING

1. RMADERMAN
2. tighed1
3. distantpulse
4. moparrbust
5. AMA FIRE
6.
7.


STAINLESS BEARING

1. Bulldogger
2.Waldig - Woody
3. Bluemdsrt6
4.MDSRT6
5.
6.
7.
8.
9.

 

[quote=MD SRT6]..................

 

CERAMIC BEARING1. RMADERMAN2. tighed13. distantpulse4. moparrbust5. AMA FIRE6. REDRIOT7.STAINLESS BEARING1. Bulldogger2.Waldig - Woody3. Bluemdsrt64.MDSRT65.Cruzinquick6.7.8.9.

 

CERAMIC BEARING1. RMADERMAN2. tighed13. distantpulse4. moparrbust5. AMA FIRE 6. REDRIOT7.STAINLESS BEARING1. Bulldogger2.Waldig - Woody3. Bluemdsrt64.MDSRT65.Cruzinquick6.7.8.9.

 

Can one of the more proficient engineering minds on here outline the pro's and con's of ceramic vs. SS for the bearing material? (also known as "what does the additional $$$ spent going ceramic get you, other than no warranty which definitely should be in the "con" column)

Thanks!

 

http://www.bearingkinetics.com/ceramic-bearings.htm

Last line is interesting - last time I looked for a ceramic bearing it was $200+ for our pulley. - but that was purchasing a single bearing.
Jerry will need to confirm if these are a "ceramic coated" bearing

Also at this price I am guessing that only the ball bearings are ceramic - not the race/case. Correct?


Jerry is this the ceramic bearing quoted from your supplier? If so $50 is a deal.
http://www.ortechceramics.com/store/...ID=215&orderID=

 

15,000 is the max RPM at a given radial load, with a much higher radial load the RPM max has to be lowered drastically. This means that 15,000 RPM is probably not the max. RPM in this case, because of the radial load. Tensioners are capable of exerting varying radial loads onto the idler pulley depending on its position as it swings through its arc.

Increasing pulley sizes elsewhere on the belt requires the idler pulley diameter be decreased proportionally. If the smaller idler pulley center is back in the same relative position as it was 'stock' then it is rotating at a higher RPM with the same radial load, this will decrease its life compared to the 'stock' version. To increase the bearings life the tensioner load has to be decreased. Obviously this cannot be allowed too much or the belt will slip on the pulleys. As the belt stretches in use the belt tensioner exerts a little less pressure on the belt.

Ball bearings do not take radial loads well, thats why roller bearings are used in high radial load situations, like wheels. Solid bearings are the best bet in even higher loadings situations, like engine bearings.

Bearings fail for a variety of reasons, no lubrication, over loading, and too high speeds that cause the oil or grease to fail. Circulating oil is the best lubricant when it is applied at the bearing contact points, this is harder as the speed increases. For this bearing, oil lubrication pushes the max RPM up to the 18,000 - 19,000 range, but again only at a certain radial load.

These are my humble comments, I am sure that others out there on this forum have a deeper knowledge on this subject. The weakest link fails first, so next time make it stronger, do not repeat the mistake.

PS Ceramic bearings are over kill in my mind. Speed did not ruin this bearing, the radial load or a lubrication failure did. You can get a roller bearing with the same sizes as the 6303, the dynamic load of the roller bearing is 50% greater albeit with a lower slightly lower max RPM (14,000)

 

Quote:
Originally Posted by BlUEMDsrt6
CERAMIC BEARING

1. RMADERMAN
2. tighed1
3. distantpulse
4. moparrbust
5. AMA FIRE
6. SRT6-Man
7.


STAINLESS BEARING

1. Bulldogger
2.Waldig - Woody
3. Bluemdsrt6
4.MDSRT6
5.Cruzinquick
6.
7.
8.
9.

 

Well I'm the other guy with a recent failure just like the original poster. Looks like I was lucky since my failure was limited to the belt and the water pump and of course the idler pulley.

I have the ASP kit. From what I gathered it is the same as the Let. If so put me down for the Ceramic... thanks!

 

Am I missing something here?

Ceramic ball bearings are used in high speed applications when the shaft has balanced radial forces on it, like turbines. This application does not have balanced radial forces acting on it. In my research I found that replacing a normal bearing with a ceramic bearing when the steel bearing failed because of a radial load will lead to an even earlier failure of the ceramic bearing.
The reason is that the steel ball collapses slightly under load and returns to its original shape when the load is removed. Ceramic does not and starts to crack. Steel ***** have a softer inside than the outside, ceramics do not.

Stainless bearings are not much better, as when they start to fail they rapidly seize up, cold welding itself to the bearing face. They can only take moderate loads because of this fact.

I would suggest looking at this problem again rather than replacing the existing design with a worse one. But what do I know, I just designed stuff for 50 years.

The pulley is pulled sideways by the belt and the load is taken in turn by a few of the ***** ( basically two maybe three) not all of them.

Balance shafts share the load on all the ***** all the time. BIG diff.

The bearings are cheap, the tow home is not.

 

LOL - so true.

Question for you, however - you mentioned a roller bearing solution might max at 14K rpm; in an application that occasionally runs 18K+, logic would seem to suggest this unwise. Or is that not necessarily correct?

In addition, reading up on these concepts recently seems to frequently link to skateboarding and/or rollerblading sites - while admittedly a bit apples and oranges to this application, they share the same trait of "only a few bearings are carrying the load at any given time" don't they? They seem to spec ball bearings, for what that's worth...

 

I mention the roller bearing as an example of greater load carrying capabilty, not as a solution. If two of the bearings that are currently used were set up side by side they would nominally split the load between them and therefore be able to take higher revs. This is a possible solution.

The skateboarding bearings do not rotate so fast, but they carry a heavier load in comparison to the idler as these skateboard bearings are small. They take a lot of shock as well, seemingly they last as used. Less friction seems to be the selling point.

I think that the high revs plus the sideload contribute to the failure of the idler bearings. Bearings have a certain life span and that can be roughly calculated. To do this certain factors, load, speed, temperature, lubrication etc are put into a formula and it results in a figure at which n% or so will last a certain amount of time. The reliability required in the application determines what 'n' is and the time. The remainder will have failed by that time. Normal life is X hours at a certain RPM with a constant radial load. The RPM is not the max RPM of the bearing. So life is shortened by higher RPM and loads.

The 6,000 RPM is being touted in this thread as if it was constant, it is not. How many times and for how long does the engine achieve this limit? answer ..... not many and not too long. This bearing can take the max RPM it is given but probably only for a short length of time with the load it sees.
It would be easy to say that in this application the higher revs have resulted in failure sooner than it would have failed if it had the stock pulley on it. This may have been a bearing that would have failed anyway, who knows. If a pattern shows up then a conclusion can be drawn.

The engine itself would fail if it was held at 6,000 RPM for too long. Try the car on the Salt Flats and it would not be too long before something went wrong if it was not prepared with stronger parts all over. At maximum power everything gets stressed, keep that stress up and parts start to fail.

 

Thanks for your good points in the discussion!!

Is this solution in your opinion better than the ASP-Idler ? Is there an additional risk to open the old idler and put the new bearing in?

The part is ss6303-2rs sealed with oil. 20,000 RPM max.

Stainless races and retainer with rubber seals.

$21.50 is my cost at 50-100 units. I'm going to need 100.


Thanks for your thoughts!

Best Regards.