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Old 01-22-2021, 05:37 AM   #61
gearhead
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Originally Posted by chuckster57 View Post
I don’t use air on bearings but I have a question:

If using air will spin the roller faster than designed, has there ever been a study that determines the max RPMs a roller can do? And what would the MPH of the vehicle be?

Just askin
That's one of my fascinations of race cars. What size bearings are normally found on NASCAR or F1 cars? 200+ MPH and heavy loaded under acceleration and braking. I'm familiar with turbines and centrifugal compressors running 14,000+ RPM on plain bearings but don't recall any equipment with ball bearings over 5,000 RPM. A Sundyne gearbox may be the exception. They had an output of 20,000 RPM+.
So what RPM is a NASCAR tire turning at 210MPH??
edit add: If our planned Spring trip happens we will be close to the Richard Childress NASCAR shop. If I can find a couple hours for a tour I'll try to find someone to ask that question of bearing size.
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Old 01-22-2021, 05:42 AM   #62
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Originally Posted by Lee View Post
Hi,

I've used the "palm of the hand" method for 30 years and for the heck of it I tried this:

https://www.amazon.com/Lisle-34550-H...omotive&sr=1-2

First I clean all old grease from the bearing then set it in and press (with hand pressure) new Red and Tacky into the bearing. Works like a champ.
I have one, works great.
I wipe my bearings off and re-grease generously, out with the old in with the new.
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Old 01-22-2021, 06:47 AM   #63
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Originally Posted by gearhead View Post
That's one of my fascinations of race cars. What size bearings are normally found on NASCAR or F1 cars? 200+ MPH and heavy loaded under acceleration and braking. I'm familiar with turbines and centrifugal compressors running 14,000+ RPM on plain bearings but don't recall any equipment with ball bearings over 5,000 RPM. A Sundyne gearbox may be the exception. They had an output of 20,000 RPM+.
So what RPM is a NASCAR tire turning at 210MPH??
edit add: If our planned Spring trip happens we will be close to the Richard Childress NASCAR shop. If I can find a couple hours for a tour I'll try to find someone to ask that question of bearing size.
It's easy math really. You would need to know the tire circumference which you can calculate if you have the diameter. The formula is C=P i*D or Circumference = 3.14 X the Diameter. then divide the inch equivalent of one mile by the inches of the circumference. That will give you the revolutions required for that tire to travel one mile. At 210 mph that's traveling at 1 mile in 3.5 seconds.

The bearing would be traveling at the the same rpm vas the tire but being a much small circumference the speed would be increased by the differential of the 2 circumference numbers. At least I think I got that correct. If I didn't someone can correct my math.
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Old 01-22-2021, 08:31 AM   #64
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Iím pretty sure the rpm of the bearing will be the exact same rpm as the tire/wheel assembly, regardless of the size of the tire.
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Old 01-22-2021, 11:41 AM   #65
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Iím pretty sure the rpm of the bearing will be the exact same rpm as the tire/wheel assembly, regardless of the size of the tire.
EXACTLY THE SAME !!!!!

Many people have no idea how fast wheel bearings spin. Most are surprised when the find out how "slow they really go"....

Here's how to figure the RPM:

The diameter x pi = circumference (typically results are in inches).
There are 5280' in a mile so that's 5280x12x= 63,360 inches in a mile.

Divide 63360 by the circumference and that will give you revolutions per mile.

At 60 MPH, it's a "direct comparison",

So, a 16" tire that has a 31" diameter would have a 97.4" circumference (31x3.1416=97.389)

63360/97.4=650 revolutions per mile = 650 RPM at 60MPH....

So, it's not the same as 100PSI blowing across a dry bearing causing it to spin at 1200RPM as the needle bearings "rattle around in the bearing cages"... I can't give you an exact figure, but if you've ever used a blow gun to spin dry bearings, they will "whir until they shreek" and I'd guess they are spinning somewhere significantly greater than 1000RPM as the sound changes from "shreek to shrill"... (I know, very unscientific descriptors for RPM)....

The point of all this: Wheel bearings on a trailer being towed at 60MPH only spin around 650-700 RPM and a dry bearing, spinning on your fingers by compressed air is probably spinning 3 times that fast with nothing to absorb the vibrations as the needle bearings rattle around in the bearing cages. That can't be "a good thing for reliability"......
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Old 01-22-2021, 11:51 AM   #66
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I work for a bearing manufacturer. We produce needle roller thrust bearings and actually a low quantity of ball bearings at this plant. OEM supplier for transmissions. We noise test our bearings around 240 rpm usually.
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Old 01-22-2021, 02:52 PM   #67
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On the Dexter 7,000 lb axle, the inner bearing will be 25580 with the race 25520. The outer bearing will be 14125A with the race 14276. You will use 10-36 seals for this axle. The bearing and race numbers are not Dexter numbers, but are industry standard numbers, so you can get any manufacturer's bearings with these numbers and they are the same. The seal number is the Dexter number K71-305-00, but the 10-36 will get you the correct number seal. If you go to page 80 of the manual, at this link, you will see the bearings, which they refer to as the cone, and the races are referred to as the cup. Page 78 has the seals, and the entire manual is an excellent thing to have, as it has everything you need to know about their axles, torques, and all maintenance. https://www.dexteraxle.com/docs/defa...sn=cfe1e328_42
Can you buy a bearing kit that gives you all these numbers, or is it better to buy individual parts?
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Old 01-22-2021, 05:37 PM   #68
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Uh, “ At 210 mph that's traveling at 1 mile in 3.5 seconds” if true, how does 60 mph produce 1 mile in 60 seconds? How about 210 mph gives about a mile in about 17 seconds?
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Old 01-22-2021, 05:57 PM   #69
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Uh, ď At 210 mph that's traveling at 1 mile in 3.5 secondsĒ if true, how does 60 mph produce 1 mile in 60 seconds? How about 210 mph gives about a mile in about 17 seconds?
Yep, Travelling 210 miles in one hour is travelling 3.5 miles in one minute. That's going 1 mile in about 17.4 seconds, not 1 mile in 3.5 seconds.

1 mile in 3.5 seconds would be 17.4 miles a minute which is about 1,028 MPH. The sound barrier (speed of sound) is about 12.79 miles per minute.
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Old 01-22-2021, 06:25 PM   #70
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Bearing in mind that I didnít think this tread would roll this way, Iím enjoying the fact that itís off to the races.

I think I used 3 ďreferencesĒ.
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Old 01-22-2021, 06:32 PM   #71
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Bearing in mind that I didnít think this tread would roll this way, Iím enjoying the fact that itís off to the races.

I think I used 3 ďreferencesĒ.
I like the 3 references but according to my math that should be 300 references! I give up, it's been a long day.
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Old 01-23-2021, 08:20 AM   #72
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Hey Chuckster I did a quick inspection and measured seal and got bearing numbers and found one wheel that grease had gotten past the seal and was on the pads and magnet so itís a good thing I checked. Keeping in mind this was on a one year old rv that came from the factory that way
Everything thing else looked fine and after reading your post I canít say Iíve had any problem with oem bearings as long as they are maintained
So Iím gonna get some good grease and the next weekend I have off do a thorough cleaning ,inspect and re pack
Btw I found another problem both front jacks are leaking oil!
I have 2019 Alpine and I have a front Jack leaking. I have spoke with Lippert, since itís out of warranty, I get to purchase a new one about $100. My buddy had a front Jack leak too.
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Old 01-23-2021, 09:27 AM   #73
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I have 2019 Alpine and I have a front Jack leaking. I have spoke with Lippert, since itís out of warranty, I get to purchase a new one about $100. My buddy had a front Jack leak too.
Some (not all) hydraulic jacks are rebuildable. All that's usually wrong is a "rolled" O-ring or a "damaged/pinched" O-ring. Any tractor dealership with a "not too busy service department" can rebuild most hydraulic jacks as can any pneudraulic hose dealer/fabricator. There's usually at least one available in most areas, tractor dealers in remote areas and pneudraulic fabricators in more populated areas.

Cost of a new jack: around $100
Cost to rebuild a jack" about a buck if you do it yourself, $30-50 if you have someone else do the work.
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Old 01-23-2021, 10:05 AM   #74
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You will not be buying a "New" Lippert hydraulic LG or mid/Rear leveler assy for $100...

The going rate in my small town to rebuild front LG hyd cylinder was $85... thats provided the internal bronze bushing and inner piston sleeve area is not scored too much
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Old 01-23-2021, 10:07 AM   #75
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Also if that leak is coming from topside there is a single banjo bolt that has an O ring that often leaks.. New o ring from most any auto parts store is less than a buck
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Old 01-23-2021, 01:48 PM   #76
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Thanks Chuckster
I’ll check that banjo bolt because both jacks have an oil film from top to bottom
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Old 01-23-2021, 04:29 PM   #77
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O ring under banjo bolt on front LG legs for Lippert level up
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Old 01-23-2021, 07:08 PM   #78
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The 90 degree hose fittings have O rings too.
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Old 01-24-2021, 09:25 AM   #79
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Thanks
I’ll check all those the next chance I get
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Old 01-24-2021, 03:37 PM   #80
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Can you buy a bearing kit that gives you all these numbers, or is it better to buy individual parts?
https://shop.redneck-trailer.com/p-4...l-bk3-200.aspx
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