Bike Forums - Brinelling

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Quote:

Originally Posted by Mr_Wrench (Post 16540389)

I welcome you to try it my way, although you'll need a plumbing wrench and a shop rag to get it tight enough.

If this isn't a troll, it's the worst mechanical advice I've ever seen on this forum.

What is the point of using bearings if you are going to mash them like that? Stupidest thing I have ever heard. Exactly how much of the time does he ride no hands I wonder. Not saying his method helps, which I can't believe, but why is it so damn important in the first place.

The quickest "fix" is to remove the front brake caliper and loosen the stem, then spin the fork a rotation or two until you find a smooth spot. That will reposition the ball bearings relative to the cups.

Quote:

Originally Posted by FBinNY (Post 16519796)

OTOH the hazards of such headsets are greatly exaggerated. They're rarely noticeable when riding and even bikes with fairly severe indexing headsets still ride OK. However, they may be harder to ride no hands.

I would've agreed six months ago (except I'd say will be harder to ride no hands), if it wasn't for a bike I came across... riding it back to the workshop from the customer's workplace was a bit scary. I thought I'd given the bike the once-over before I hopped on it, but the handling was so spooky (with my hands on the bars!) I thought it must've had a bent frame or something. I was surprised to discover the culprit was an indexed lower headset bearing, although perhaps the fact it was an internal cartridge type for a 9/8" steerer contributed to a greater effect than I'm used to.

We didn't have a replacement in stock so I gave it some WD40 (it felt tight with rust) and temporarily reinstalled it, and with better preload adjustment the indexing was gone altogether.

But before that, it was well dodgy. Although of course, the owner was oblivious, having become accustomed to it gradually.

'82 Peugeot in the French rounding down standard (fractional) diameters for tubes, etc.
to be even Metric sizes, era?

which continues to be problems for parts since the rest of the world is not using entirely French standards..

They did want the Prime Meridian , to be Paris. rather than Greenwich England.

I informed my friend of my researching and opinions on this site and he agreed with me and is going to try to fix this problem. I stressed the fact he may have a hard time finding new parts. Thanks for all the input.

Quote:

Originally Posted by IthaDan (Post 16540452)

Jesus Christ.

I hear he used loose balls and pre-loaded his headsets just so.

.
....I sense this thread has legs.:popcorn

Does anyone have any advice on the proper rag and plumbing wrench to use ?

Quote:

Originally Posted by 3alarmer (Post 16552340)

.
....I sense this thread has legs.:popcorn

I thought it was about heads.

The indexing is caused by dents (brinelling) in the lower cup and cone races. Said dents are caused by (1) impact forces which cause the balls to dent the races and (2) wear resulting from the fact that the balls repeatedly move back and forth in one place because a headset does not rotate in complete revolutions but cycles back and forth in a narrow arc. A properly built and maintained headset bearing setup should not have dented races; dented races should be replaced with new ones. If there are 24 balls in the lower complement there will be 24 dents in each race. Rotating one race by (1/2 x 360/24) degrees will only result in 48 smaller index points, not a good solution. By the way, a ball bearing setup should be adjusted to have only a slight preload. Excessive preload only contributes to the denting process.

Quote:

Wrong again. It will only stay that way a few bumps until the balls slide back into the dents.

Quote:

Originally Posted by CroMo Mike (Post 16552584)

Excessive preload only contributes to the denting process.

..you see this sentiment posted all the time here, and in fact at least one regular, dddd, is adamant that this is the case.
I personally, preload headset bearings, and it seems to work for me. Maybe I just have a good feel for it.

I think maybe the phrasing "excessive preload" is just vague enough to render such information meaningless. Anyway: Brinelling

Quote:

Brinelling is a material surface failure caused by Hertz contact stress that exceeds the material limit. It usually occurs in situations where there is a load with a lot of force that is distributed over a relatively small surface area. This failure is caused by just one application of a load great enough to exceed the material limit. Brinelling typically results from a heavy or repeated impact load, either while stopped or during rotation. It can also occur from a heavy load remaining on the bearing for a length of time in a stopped position. The result is a permanent dent or "brinell mark." In bearings, the brinell marks will often be in evenly-spaced patterns along the races, resembling the primary elements of the bearing, such as rows of indented lines forneedle or roller bearings or rounded indentations in ball bearings. It is a common cause of roller bearing failures, and loss of preload in bolted joints when a hardened washer is not used.

Avoiding brinelling damage

Engineers can use the Brinell hardness of materials in their calculations to avoid this mode of failure. A rolling element bearing's static load rating is defined to avoid this failure type. Increasing the number of elements can provide better distribution of the load, so bearings intended for a large load may have many balls, or use needles instead. This decreases the chances of brinelling, but increases friction and other factors. However, although roller and ball bearings work well for radial and thrust loading, they are often be prone to brinelling when very high impact loading, lateral loading, or vibration are experienced. Babbitt bearings or bronze bushings are often used instead of roller bearings in applications where such loads exist, such as in automotive crankshafts or pulley sheaves, to decrease the possibility of brinelling by distributing the force over a very large surface area.

A common cause of brinelling is the use of improper installation procedures. Brinelling often occurs when pressing bearings into holes or onto shafts. Care must usually be taken to ensure that pressure is applied to the proper bearing race to avoid transferring the pressure from one race to the other through the balls or rollers. If pressing force is applied to the wrong race, brinelling can occur to either or both of the races. The act of pressing or clamping can also leave brinell marks, especially if the vise or press has serrated jaws or roughened surfaces. Flat pressing plates are often used in the pressing of brearings, while soft copper, brass, or aluminum jaw covers are often used in vises to help avoid brinell marks from being forced into the workpiece.[SUP][2][/SUP]

...by far the simplest solution, in the absence of a new, correctly sized headset for your French bike is
to pull out the caged bearings (if indeed, that's what's in there), and replace them with the same sized
new balls placed in the races loose, which increases and redistributes the number of contact points, because
there are now more bearings required to fill the race.

If what's in there is already loose bearings, this is not an option.

While folks call this type of damage Brinelling, this isn't the process that causes the damage.

Most headset "brinellng" is actually "false brinelling" or fretting. It isn't that the balls are driven into the material making small crush dents. It's a form of abrasive wear or fretting which is common in stationary bearings. Basically the lubricant is squeezed out from between the balls and races by the repetitive impacts or vibration. Since there's little or no movement to re-wet the point of contact, the direct metal contact wears spots into the races. One tipoff that it's fretting and not brinelling is visible to the naked eye.

If brinelled, the contact dots would be highly polished, whereas a careful examination of the races shows the dots to have a dull etched look. If one takes it to the next level and does destructive testing breaking the races, a brinelled race would show some compression under the dimples, but fretted races wouldn't.

The classic example of false brinelling is damage to newly delivered cars shipped by rail. The vibration caused damage to front wheel bearings, and case were delivered with dead bearings despite having never been driven more than a few miles.

BTW- it's impossible to brinell an headset when riding on air filled rubber tires. It might be possible if the headset were loose, where there was the impact of the moving fork, but a properly adjusted headset wouldn't have that movement.

All the above is simply to correct misconceptions, but has nothing to do with the OPs probelm of needing a new headset.

Quote:

Originally Posted by FBinNY (Post 16552727)

Thank you for a well written explanation. The terminology commonly used has always confused me.

Self centering steering bearings, whether due to brinelling or fretting corrosion, can lead to a dangerous speed wobble. While we cyclists generally do not go fast enough to bring this about it does happen.

If you have ever had a hands-off-the-bar front end shimmy, you've experienced the natural destabilizing forces that can lead to speed wobble. Dented steering head bearings pump energy into the destabilizing forces which can, when everything is right (or wrong) bring on a full-force speed wobble -- you can't steer when this occurs and you will crash.

Replace the bearings and fit a roller set instead of balls, if you can, as they carry more load, are much more resistant to denting and should last much longer. Be especially sure that the new bearings are adjusted carefully. There must be no free play and yet no significant rotational friction.

Joe

Quote:

Originally Posted by a77impala (Post 16549806)

The simplest fix was already mentioned - replace the caged bearings with loose ones so you can fit an extra ball or two in there and that way the balls can no longer line up with the damaged points in the race. Although it's been stated that this is a temporary fix, I've found that it can frequently last for many years and/or thousands of miles and can certainly outlast the life of the original caged bearing.

High speed steering shimmy is another issue and I haven't found it to be correlated with the indexed steering of false brinneling.

Quote:

Originally Posted by catmandew52 (Post 16636635)

When in doubt, throw it out!

French Metric Bicycle Parts 24.0mm post, 24mm post, 22.0 stem, 25.0 headset 14mm pedal etc at Yellow Jersey

and

Headsets French Thread 25 mm x 1.0 - Harris Cyclery bicycle shop - West Newton, Massachusetts

if the the headset in the last link will work, and, i admit i know next to nothing about french bicycle specs, then this is all that is necessary, IMO, you need. $4 at Sears. order online and pickup for free at you local Sears store. 30 second Google find with "headset race 26.4". easy-peasy.

am i missing something? i really want to know, because when i had an "indexed" headset, i just bought a new crown race and was done with it.

Quote:

Originally Posted by hueyhoolihan (Post 16637001)

...I think, but am not certain, that the headset in that link is designed to adapt a more modern fork
to use in a French bike.....IOW, it has a crown race to fit what you can buy now in a fork , but the
rest of it will fit the different head tube dimensions typical of French standards.

And brinelling is not always limited to the crown race..........so yeah, it's more complicated.

..............LOOK HERE

...sometimes, you can coax the 26.4 onto your 26.5 fork seat, sometimes you have to mill it down a hair.