Bearings and drag reduction

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
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godlameroso
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Re: Bearings and drag reduction

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Greg Locock wrote:
Sat Aug 05, 2017 1:58 am
Be careful, are you sure you are talking about hub units?

These things

http://www.skf.com/binary/30-147232/457284.pdf

As you can see, tightening the axle nut merely compresses the female spline, it does nothing much to the bearing preload.
In this case the bearing is pressed into the knuckle, and the hub is then pressed into the bearing. As is the case with all Hondas.

Image
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Greg Locock
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Re: Bearings and drag reduction

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That's not what I'd call a hub unit. See the previous post.

ChrisDanger
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Re: Bearings and drag reduction

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godlameroso wrote:
Sat Aug 05, 2017 2:27 am
Spec is 180ft lbs and was later updated to 220ft I do at least 300, and put a light coat of oil on the face of the nut to get proper tension as torque does not always equal tension, especially if there's any rust on the hub.
The tightening torque for lubricated nuts is always specified to be lower than dry nuts (see info below). If they don't specify either and just give one value it's safe to assume it's dry. Adding lubrication is a good practice, especially when the friction between the nut and the washer/housing is affected by something like rust, as it will minimise the difference in friction and therefore bolt preload.

I'm not questioning your method (if it works it works, and that's great) but you are tightening the hell out of those bolts.

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The phenomenon described in the graph leads to tables like that below.

Image

Image

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godlameroso
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Re: Bearings and drag reduction

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Porsche uses 400ft lbs on all their axle nuts, and center locking wheels on most super cars. They need a big 3/4 inch drive tq wrench.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee

riff_raff
riff_raff
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Re: Bearings and drag reduction

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Greg Locock wrote:
Sat Aug 05, 2017 1:58 am
Be careful, are you sure you are talking about hub units?

These things

http://www.skf.com/binary/30-147232/457284.pdf

As you can see, tightening the axle nut merely compresses the female spline, it does nothing much to the bearing preload.
Those SKF production hub bearing units are a very elegant piece of engineering. If you look closely at the one shown in the SKF document, you'll see that the axial preload on the back-to-back angular contact ball bearing set is provided by a swaged flange at the inboard end of the shaft. Imagine how hard it is to get a consistent axial bearing preload in a mass production process using this approach.

I had to replace one of these integrated hub bearings on my '02 Chevy truck front end a while back. The cost for a GM replacement part, including the ABS sensor, was $180. Can't imagine how they manufacture an assembly like this including bearings, seals, shaft, housing, wheel studs, ABS sensor, etc. for that price.
"Q: How do you make a small fortune in racing?
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henry
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Re: Bearings and drag reduction

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riff_raff wrote:
Sun Aug 06, 2017 4:41 am
Greg Locock wrote:
Sat Aug 05, 2017 1:58 am
Be careful, are you sure you are talking about hub units?

These things

http://www.skf.com/binary/30-147232/457284.pdf

As you can see, tightening the axle nut merely compresses the female spline, it does nothing much to the bearing preload.
Those SKF production hub bearing units are a very elegant piece of engineering. If you look closely at the one shown in the SKF document, you'll see that the axial preload on the back-to-back angular contact ball bearing set is provided by a swaged flange at the inboard end of the shaft. Imagine how hard it is to get a consistent axial bearing preload in a mass production process using this approach.

I had to replace one of these integrated hub bearings on my '02 Chevy truck front end a while back. The cost for a GM replacement part, including the ABS sensor, was $180. Can't imagine how they manufacture an assembly like this including bearings, seals, shaft, housing, wheel studs, ABS sensor, etc. for that price.
If you can buy it retail at $180 the manufacture cost, at the gate, will be considerably lower. When I made small individual components in bulk for the motor industry the ratio of factory gate price, in bulk, to individual component spares department retail was 20, 30 or more. Admittedly small components incur disproportionately high handling expenses, but spares retail prices are much, much higher than factory costs.
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godlameroso
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Re: Bearings and drag reduction

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Greg Locock wrote:
Sat Aug 05, 2017 6:57 am
That's not what I'd call a hub unit. See the previous post.
You're right, as I stated Honda doesn't use hub units, the bearing is pressed into the knuckle/upright, and the hub is then pressed into the bearing.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee

Greg Locock
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Re: Bearings and drag reduction

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On mountain bikes we called them cartridges.They still have the advantage that so long as they are torqued up to spec the bearing preloads are not negotiable as you are just compressing the two inner races against each other.

At one point with taper rollers I was speccing 1.4 Nm, about 1 lb ft, for the front hubs, as the problems with heat were so great. That is one case where taper rollers (which are generally brilliant) was the wrong choice, we should have used ball bearings.


Funnily enough i was using hub units pressed into an aluminum spindle, and guess what, they were coming loose enough to make a graunching noise because of the brake heat (and a bit of a stuff up by the designers on hole sizes given the low stiffness of aluminium).

Jolle
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Re: Bearings and drag reduction

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Greg Locock wrote:
Sun Aug 06, 2017 11:38 pm
On mountain bikes we called them cartridges.They still have the advantage that so long as they are torqued up to spec the bearing preloads are not negotiable as you are just compressing the two inner races against each other.

At one point with taper rollers I was speccing 1.4 Nm, about 1 lb ft, for the front hubs, as the problems with heat were so great. That is one case where taper rollers (which are generally brilliant) was the wrong choice, we should have used ball bearings.


Funnily enough i was using hub units pressed into an aluminum spindle, and guess what, they were coming loose enough to make a graunching noise because of the brake heat (and a bit of a stuff up by the designers on hole sizes given the low stiffness of aluminium).
the big difference between two wheeled and three/four wheeled vehicles is the vector of force. On a bike its always through the centerpoint, never from the side. My city bicycle has the same bearings for 30+ years, while in my freight bicycle (three wheels) needs new bearings each year.

Greg Locock
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Re: Bearings and drag reduction

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On mountain bikes they are used in the bottom bracket, ie on the cranks. I don't think they are used in the wheel hubs. Yes I can believe a trike gets through wheel bearings (and wheels at a guess).

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MrPotatoHead
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Re: Bearings and drag reduction

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MrPotatoHead
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Re: Bearings and drag reduction

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I found this interesting image from a recent F1 car that shows a little of what's going on inside the upright:

Image

riff_raff
riff_raff
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Re: Bearings and drag reduction

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The uprights shown use a pair of angular contact ball bearings with steel balls and races, thermoplastic retainers, and fluorocarbon elastomer (viton) shaft seals.
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A: Start with a large one!"

thisisatest
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Re: Bearings and drag reduction

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Greg Locock wrote:
Mon Aug 07, 2017 10:29 pm
On mountain bikes they are used in the bottom bracket, ie on the cranks. I don't think they are used in the wheel hubs. Yes I can believe a trike gets through wheel bearings (and wheels at a guess).
On bicycles, including mountain bikes, radial cartridge bearings are used in hubs as well. A couple companies use angular contact cartridge bearings on their hubs as well as their bottom brackets, but radial bearings are still dominant.

Greg Locock
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Re: Bearings and drag reduction

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Interesting, thanks.