Bad grounds destroy your wheel bearings - Where is Sid when you need him
07-12-2005, 12:43 AM
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Bad grounds destroy your wheel bearings - Where is Sid when you need him
I **** you not, there was a "thread" on the e-mail list last week about how bad grounds can damage/destroy bearings throughout the vehicle. The discussion got pretty heated at a few points as well, but the lister, a fellow from my neck of the woods named Bruce who works in the automotive and industrial bearings trade provided plenty of evidence to back it up, including references to various TSB from a few automakers. Would it be bad form/against the charter to post some of the content here? I thought it was an interesting read.
07-12-2005, 01:03 AM
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I missed the post in question but I've seen ungrounded static electricity take out huge bearings and bushings very quickly in large wind generators. Sealed bearings are more prone than open type bearings. It can form a type of fretting corrosion and pit as well as embrittle the rollers if enough current tries to bridge the gap. I have a hard time appyling the problem to wheel bearings though, I would like to see the thread to understand the circuit.
07-12-2005, 01:15 AM
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OK, hope this isn't a no-no. I will edit out most of the BS messages and focus on what Bruce had to say since it was the most informed commentary
It started with this:
Then:
And after people were really nasty to him he posted (note that others offered more supporting info) :
It started with this:
FYI, bad grounds also destroy wheel bearings.
Electricity WILL find a ground, and if the closed circuit in your automobile is compromised, it will simply find a ground through the suspension, wheel bearings, and tires.
If that happens, tiny micro-sparks travel from the rolling elements to the races, causing microscopic pitting in the races. It doesn't take long for those microscopic pits to get larger and larger and start spalling, etc., and wheel bearing failure. It can easily happen in under 10k miles.
Electricity WILL find a ground, and if the closed circuit in your automobile is compromised, it will simply find a ground through the suspension, wheel bearings, and tires.
If that happens, tiny micro-sparks travel from the rolling elements to the races, causing microscopic pitting in the races. It doesn't take long for those microscopic pits to get larger and larger and start spalling, etc., and wheel bearing failure. It can easily happen in under 10k miles.
I don't blame you [for being sceptical] ... people constantly talk to me like I have brain damage when I try to explain the phenomenon. NOBODY EVER believes it.
From my experience in the field, I'd say 99% of bearing failures are misdiagnosed by well-meaning but not well-informed folks who also don't believe bad grounds ruin wheel bearings. Come to think of it, I'd have to say I have NEVER seen anyone outside the bearing industry ever correctly diagnose a grounding induced failure. I'll have to think about that.
Of course, as a guy who made a very nice living for quite a while running a company that manufactured automotive wheel bearings, you could say bad grounds have been very good to me. Especially all those thousands and thousands of Omni/Horizon wheel bearings we sold because Lee Iacocca's engineers saved a couple bucks on ground wires. We literally were running those bearings 24/7 and couldn't keep up with demand, even after Chrysler had a big TSB announcement and started recalling cars to install more grounds. I even had one do-gooder engineer on staff who wanted to put a notice in the bearing boxes, notifying customers about the fix. I sure put a stop to that (does it make me a bad guy?).
In fact, I've seen studies by all world's largest bearing manufacturers, and everyone points to bad grounds as right around the third most-common reason for automotive/light truck wheel bearing failure. The first is installer error, of course. The second is accident/driver inflicted damage, and the third is bad grounds. Contamination and dragging brakes and old grease and flooding and etc. all come later.
Yes, we do a ****-poor job in the bearing industry of explaining these most common reasons for bearing failure in automobiles and light trucks. The heavy truck and industrial applications get a lot more of the attention and tend to do better with diagnosis. Part of that has to do with the very high cost of a bearing failure in a piece of production equipment or an over-the-road truck. With cars and light industrial equipment, they often don't get the attention. Not a snipe at anyone, just my experience.
I ran a little Google search, and here's the first hit it came up with regarding bad grounds ...
http://www.tomorrowstechnician.com/tt/t2100322.htm
See "Story 4"
Which DOES bring up another bad ground failure which I totally forgot to mention, and that's transmission bearings. And that includes clutch release bearings. But tranny bearing failures are, thankfully, less common than wheel bearing failures. With transmissions, you see damage to the gears (particularly pinion gears) before you see bearing damage. The loading is higher on the gears, damage is exacerbated by the forces at work.
PLEASE check out the various bearing company web sites; they all have excellent technical information areas, even though some are hidden or at other URLs. SKF, Timken, NSK, NTN, INA/***, and several other bearing manufacturers have sections on their web sites dealing with how to identify particular bearing failures, and then determine their causes. Definitely worth visits, and they do a better job explaining the bad ground situation with pictures, etc., etc. Here's one of the Timken TechTips links, written with the semi-trained technician in mind:
http://www.timken.com/industries/aut...ssue2-2005.pdf
(see electric current on page 2) Note that Timken gives two versions ... pitting and fluting. In fact, we rarely see bad-ground pitting in cars and trucks, it's virtually all seen as fluting.
It's not limited to cars, however. Another I dealt with was (industrial) bearing failures in the conveyor system used in the Neon power steering assembly line. Out of the blue one day, DaimlerChrysler notified us they were billing us $30,000 an HOUR while the line was down due to repeated bearing failures. I sent our guys up there and in about fifteen minutes they identified stray grounding through the bearing races as the cause (bad maintenance of the conveyor drive system). After that, they were SO nice, we showed them a couple other problem areas for free.
Not so free was when an inadequate chassis ground on a huge rotating telescope drive system damaged the high-precision bearings AND forced them to disassemble the entire observatory to get the darn things out of there. Our guy told me the electrical connections for this big powerful motor were just tiny little wires, and they were all held in place with drywall screws. Nice.
Here are a few other non-bearing-company resources:
http://www.gaussbusters.com/ppm93.html
(that one has a nice long list of reading material which should satisfy your desire for documentation) In fact, the fine folks at gaussbusters make most of their living from bearings ruined by bad grounds.
http://www.allpar.com/cars/desoto/suburban-1951.html
Here's a guy who found out when he honked his horn, the ground wound its way through the steering gear box, and the pitting erosion caused it to wear oddly.
But like I say to everyone, please DON'T believe me ! Do your own research via those bearing manufacturer sites. You'll learn a lot more there than I can put into an email. (Disclaimer: I did write some of the stuff that shows up on Timken, SKF, Minebea and INA/*** technical sites, and maybe a couple others, but I don't remember ever writing anything about electrical damage, so it'll all be non-Bruce resources; my foci tend to be OEM installation, mechanical failure diagnosis, and cost/performance analyses).
From my experience in the field, I'd say 99% of bearing failures are misdiagnosed by well-meaning but not well-informed folks who also don't believe bad grounds ruin wheel bearings. Come to think of it, I'd have to say I have NEVER seen anyone outside the bearing industry ever correctly diagnose a grounding induced failure. I'll have to think about that.
Of course, as a guy who made a very nice living for quite a while running a company that manufactured automotive wheel bearings, you could say bad grounds have been very good to me. Especially all those thousands and thousands of Omni/Horizon wheel bearings we sold because Lee Iacocca's engineers saved a couple bucks on ground wires. We literally were running those bearings 24/7 and couldn't keep up with demand, even after Chrysler had a big TSB announcement and started recalling cars to install more grounds. I even had one do-gooder engineer on staff who wanted to put a notice in the bearing boxes, notifying customers about the fix. I sure put a stop to that (does it make me a bad guy?).
In fact, I've seen studies by all world's largest bearing manufacturers, and everyone points to bad grounds as right around the third most-common reason for automotive/light truck wheel bearing failure. The first is installer error, of course. The second is accident/driver inflicted damage, and the third is bad grounds. Contamination and dragging brakes and old grease and flooding and etc. all come later.
Yes, we do a ****-poor job in the bearing industry of explaining these most common reasons for bearing failure in automobiles and light trucks. The heavy truck and industrial applications get a lot more of the attention and tend to do better with diagnosis. Part of that has to do with the very high cost of a bearing failure in a piece of production equipment or an over-the-road truck. With cars and light industrial equipment, they often don't get the attention. Not a snipe at anyone, just my experience.
I ran a little Google search, and here's the first hit it came up with regarding bad grounds ...
http://www.tomorrowstechnician.com/tt/t2100322.htm
See "Story 4"
Which DOES bring up another bad ground failure which I totally forgot to mention, and that's transmission bearings. And that includes clutch release bearings. But tranny bearing failures are, thankfully, less common than wheel bearing failures. With transmissions, you see damage to the gears (particularly pinion gears) before you see bearing damage. The loading is higher on the gears, damage is exacerbated by the forces at work.
PLEASE check out the various bearing company web sites; they all have excellent technical information areas, even though some are hidden or at other URLs. SKF, Timken, NSK, NTN, INA/***, and several other bearing manufacturers have sections on their web sites dealing with how to identify particular bearing failures, and then determine their causes. Definitely worth visits, and they do a better job explaining the bad ground situation with pictures, etc., etc. Here's one of the Timken TechTips links, written with the semi-trained technician in mind:
http://www.timken.com/industries/aut...ssue2-2005.pdf
(see electric current on page 2) Note that Timken gives two versions ... pitting and fluting. In fact, we rarely see bad-ground pitting in cars and trucks, it's virtually all seen as fluting.
It's not limited to cars, however. Another I dealt with was (industrial) bearing failures in the conveyor system used in the Neon power steering assembly line. Out of the blue one day, DaimlerChrysler notified us they were billing us $30,000 an HOUR while the line was down due to repeated bearing failures. I sent our guys up there and in about fifteen minutes they identified stray grounding through the bearing races as the cause (bad maintenance of the conveyor drive system). After that, they were SO nice, we showed them a couple other problem areas for free.
Not so free was when an inadequate chassis ground on a huge rotating telescope drive system damaged the high-precision bearings AND forced them to disassemble the entire observatory to get the darn things out of there. Our guy told me the electrical connections for this big powerful motor were just tiny little wires, and they were all held in place with drywall screws. Nice.
Here are a few other non-bearing-company resources:
http://www.gaussbusters.com/ppm93.html
(that one has a nice long list of reading material which should satisfy your desire for documentation) In fact, the fine folks at gaussbusters make most of their living from bearings ruined by bad grounds.
http://www.allpar.com/cars/desoto/suburban-1951.html
Here's a guy who found out when he honked his horn, the ground wound its way through the steering gear box, and the pitting erosion caused it to wear oddly.
But like I say to everyone, please DON'T believe me ! Do your own research via those bearing manufacturer sites. You'll learn a lot more there than I can put into an email. (Disclaimer: I did write some of the stuff that shows up on Timken, SKF, Minebea and INA/*** technical sites, and maybe a couple others, but I don't remember ever writing anything about electrical damage, so it'll all be non-Bruce resources; my foci tend to be OEM installation, mechanical failure diagnosis, and cost/performance analyses).
<snip>I am talking about bad ground in terms of an errant electrical path to the (-) terminal. You know, errant as in not as designed by the auto manufacturer but as induced by time / wear / error.
For those of you who have some shred of sense in your brains (rather a fewer of you than I used to believe, unfortunately), some other information to answer questions I got in various emails:
- 300mV in a car/light truck is still too high; quick death for automotive-sized tapered roller and ball bearings. We know 100mV will create (minor but) observable damage in one revolution, so I'm guessing right around zero is quite nice ;-)
- To people who emailed and got to the stage of thinking about grease dielectric. Yes! Wheel Bearing + grease = Capacitor YES! Someone finally suggested high dielectric protects bearings, even in bad ground situations, by keeping that ground going somewhere/anywhere else. Take a cigar! Oh, how my heart swells; I am proud of you. Sadly, in a Real World wheel bearing, grease dielectric performance degrades to crap very quickly, for a long, boring set of reasons. NASA has some nice stuff that holds its dielectric, but the cost is -cough- high.
- Yes, there are bearing-failure-related ground problems being sorted out right now. I really shouldn't comment on any of them, sorry.
Okay, I'll now pitch a softball out to all you earth = ground people who were so condescending in your emails, (I'll assume you were just having a bad day):
- Ford has TSBs out on most of its recent vehicles, using rear wheel hub assemblies (TSB 97-18-4 is an example, old enough to be on the Internet), if a customer complains about static on the AM radio. Turns out (usually rear) bearings aren't cleanly conducting rear tire / pavement - induced static electricity to the chassis. Brand new, the grease dielectric stops the juice getting through, but (as above), grease degrades. And so, gradually, that static electricity starts arcing across the bearing races to get to the chassis ground (electricity's will to live is amazing, eh?). Symptom = customer complains about AM radio buzz. Solution = add a little ground strap thingie between the hub and axle stub. SYMPTOM IGNORED = every spark is another step in DESTROYING THE REAR WHEEL BEARINGS! (industry secret: we sell more Ford rear wheel hub assemblies than statistics say we should, and we ain't killin' no Golden Goose). Don't you think it's interesting Ford can issue a series of TSBs for AM radio buzz, but ignore the fact that the reason for the buzz is that the wheel bearings are being arc-welded to death?
For those of you who have some shred of sense in your brains (rather a fewer of you than I used to believe, unfortunately), some other information to answer questions I got in various emails:
- 300mV in a car/light truck is still too high; quick death for automotive-sized tapered roller and ball bearings. We know 100mV will create (minor but) observable damage in one revolution, so I'm guessing right around zero is quite nice ;-)
- To people who emailed and got to the stage of thinking about grease dielectric. Yes! Wheel Bearing + grease = Capacitor YES! Someone finally suggested high dielectric protects bearings, even in bad ground situations, by keeping that ground going somewhere/anywhere else. Take a cigar! Oh, how my heart swells; I am proud of you. Sadly, in a Real World wheel bearing, grease dielectric performance degrades to crap very quickly, for a long, boring set of reasons. NASA has some nice stuff that holds its dielectric, but the cost is -cough- high.
- Yes, there are bearing-failure-related ground problems being sorted out right now. I really shouldn't comment on any of them, sorry.
Okay, I'll now pitch a softball out to all you earth = ground people who were so condescending in your emails, (I'll assume you were just having a bad day):
- Ford has TSBs out on most of its recent vehicles, using rear wheel hub assemblies (TSB 97-18-4 is an example, old enough to be on the Internet), if a customer complains about static on the AM radio. Turns out (usually rear) bearings aren't cleanly conducting rear tire / pavement - induced static electricity to the chassis. Brand new, the grease dielectric stops the juice getting through, but (as above), grease degrades. And so, gradually, that static electricity starts arcing across the bearing races to get to the chassis ground (electricity's will to live is amazing, eh?). Symptom = customer complains about AM radio buzz. Solution = add a little ground strap thingie between the hub and axle stub. SYMPTOM IGNORED = every spark is another step in DESTROYING THE REAR WHEEL BEARINGS! (industry secret: we sell more Ford rear wheel hub assemblies than statistics say we should, and we ain't killin' no Golden Goose). Don't you think it's interesting Ford can issue a series of TSBs for AM radio buzz, but ignore the fact that the reason for the buzz is that the wheel bearings are being arc-welded to death?
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07-12-2005, 01:25 AM
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Thanks for posting that Michael...It makes perfect sense and I don't doubt his statements one bit. Where I work we spend thousands every year just maintaining carbon brush contacts for nothing more than shunting stray current around oil cooled bearings on large motors. When you have 14- 88,000 HP pumps in just one plant, grounding and stray current electrolysis is serious business.
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07-12-2005, 01:30 AM
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Damn.... Does that mean the NA's weak Ring and Pinion gear is not weak, and that it is the often bad grounds that these 944's have which is eating away at the R&P!!! lol, kidding.
07-12-2005, 09:28 AM
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Yeah, this was a known deal in the "Team Shelby" days (mid-80's) when the guys were racing Charger Turbos in SSA among other things. You can believe that we added grounds to our trusty GLH-S Omni before it ever hit the track 
Brian
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07-12-2005, 10:31 AM
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That may be one of the most enlightening posts I've read here on the board... thank you VERY much for posting this. What he says DOES make perfect sense... and I have to suspect that IceShark's upgraded groundstraps might help alleviate this. Anyone have any input on that?
Lynn
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07-12-2005, 11:45 AM
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Originally Posted by 109er
That may be one of the most enlightening posts I've read here on the board... thank you VERY much for posting this. What he says DOES make perfect sense... and I have to suspect that IceShark's upgraded groundstraps might help alleviate this. Anyone have any input on that?
Lynn
Lynn
