DwayneGorniak Posted August 29, 2008 Share Posted August 29, 2008 I posted this topic on Protech just to see what kind of ideas and opinions it would bring. There are a few old dogs in our dealership that have this theory that 75W140 Synthetic is the main cause of all the F-150 differential bearing failures. I have worked in other dealerships that have had this same theory. My theory is that it is just a crappy manufacturing issue. So here's my question: If 75W140 synthetic is the main cause of the bearing failures, then why don't we see this problem on the Superduty's being that they use the same fluid? I have heard the age ole arguement where techs say: I use 80W90 on diff overhauls and have no comebacks. But I come back at them with: I use 75W140 synthetic on my diff overhauls and never have a comeback. So, what do ya all think? Quote Link to comment Share on other sites More sharing options...
Shlep Posted August 29, 2008 Share Posted August 29, 2008 I tend to agree with the manufacturing issues causing most of the failures, with customer abuse or neglect being the other factors. I've used 75W140 in all my toys since the early 90's and I've never had a bearing issue or any other failure that was caused by anything other then abuse on my part /forums/images/%%GRAEMLIN_URL%%/shrug.gif Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted August 29, 2008 Share Posted August 29, 2008 75W140 is a CAFE thing.... You could use 80W90 in any of these diffs and no one would be the wiser.... Differential bearing failure rings a bit of a bell.... I see a lot of R&Ps being replaced and they come with bearings. I see a lot of bearings getting replaced that shouldn't.... (I also see the odd bearing that someone has returned to service and shouldn't). Some of the deal may be with where bearings are sourced.... but I'm having a hard time because I see my guys replacing R&Ps... If a bearing hasn't had a catastrophic failure, a ring and pinion? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted August 29, 2008 Share Posted August 29, 2008 "Blackstone said my last differential sample was good and since I was using synthetic I could go 500,000 miles!" /forums/images/%%GRAEMLIN_URL%%/sick.gif Over the last 5-6 years I saw probably several hundred full axle overhauls on Jeeps in my shop. Dana axles. One tech commented that if you didn't service the diffs every 15-20 thousand miles the bearings fell apart. Not sure what lube they used but I certainly would not blame the oil. The general consensus was that there was a quality issue with the axles. I have to agree with you fellers for the most part but I recall Ford introducing synthetics to our light trucks on the diesel equipped units. Both rears and transmissions. I assumed that the synthetics being a better lubricant were intended to provide added protection under the presumed higher loads these vehicles were intended to see. Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted August 29, 2008 Share Posted August 29, 2008 If you use amsoil or BG fluids you will NEVER have a problem /forums/images/%%GRAEMLIN_URL%%/hahaha.gif Quote Link to comment Share on other sites More sharing options...
Rickster42 Posted September 2, 2008 Share Posted September 2, 2008 Dwayne, I had the exact same argument on protech a couple of years ago. I`ve seen no failures after o/haul with 75w140 either, and my main point was if Ford specs that oil for that diff, and I install something else and have a problem... I would be standing beside myself in blame... I took quite a bit of heat for it and had alot of fun responding to the pro 80/90w crowd. Quote Link to comment Share on other sites More sharing options...
DwayneGorniak Posted September 3, 2008 Author Share Posted September 3, 2008 I sure don't see the pro 80W90 crowd responding this time. I didn`t get to see your post a couple of years ago. Must have been busy. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 3, 2008 Share Posted September 3, 2008 I sure don't see the pro 80W90 crowd responding this time. I didn`t get to see your post a couple of years ago. Must have been busy. You aren't reading close enough, Dwayne - some idiot redhead wrote <75W140 is a CAFE thing.... You could use 80W90 in any of these diffs and no one would be the wiser....> The state of the art of modern hypoid gear oils is the API service classification GL-5... covers most every hypoid gear lube you are likely to run across including synthetics (including "true synthetic" PAO base stocks as well as "semi synthetic" hydro-cracked petroleum base stocks ). All gear oils contain extreme pressure additives.... A consideration.... If a gearset manufacturer recommends anything meaningful, it will be regarding the API classification. Putting a GL-5 spec lube into a gearset that recommends GL-4 can get you into a world of trouble.... Dabbling with the viscosity index isn't going to mean a whole bunch... Case in point.... At one point in time, the 8.8 Ford diff came with GX 80W90 as factory fill.... This gave way to GX75W90 and eventually to GX75W140... with Ford respec'ing fluid requirements to the 75W140 viscosity index oils.... Yet - the 8.8 FRONT axle in my girly-boy truck still specs 75W90.... 2002 F SooperDoody WSM specs SAE 90 for a front axle fill..... As long as you are using a GL-5 lube.... who cares? Hmmmm.... there seems to be some confusion.... Bottom line.... You could use 80W90 in any of these diffs and no one would be the wiser - as long as it bears the API classification GL-5... However - we are trained factory techs and we follow the recommendations of the engineers.... right? Taking some convoluted thinking a step or so further.... Lets click on over to the online 2008 WSM.... <GASP> Dang, Elmer.... jes' look at all 'em motor oils fur the 6.4.... 0W30 - 5W40 - 10W30 - 15W40.... Mah God.... yud think that one o' them'd get yer motor blowed up reel gud.... But it isn't the viscosity index of the lube that matters.... Whatever the viscosity grade of the oil may be, the package must bear the API classification of CJ-4.... And even Ford admitted that running a CI-4+ oil isn't going to "blowed 'im up...". Getting back to the diff..... It is my understanding (and I will state that I have not found any empirical evidence) that one or both synthetic gear oil base stocks will not EMULSIFY moisture well... even with the addition of dispersants... If push comes to shove, I will keep a customers truck at "factory spec".... But I can't see myself recommending $100 worth of oil for the axle on a $400 truck.... The 80W90 crowd is alive and well... but if they are smart, they will bow to the engineers.... Will 80W90 kill a diff? Nope.... Will a gearset manufacturer use "incorrect lube" as a lever if his gearset goes south... Oh, yeah.... Word to the wise.... learn what all that crap on a lubricant package means.... CJ-4 speaks volumes.... GL-5, ditto.... even grease- NLGI EP-1... EP-2... I recall an EP-Arctic but that could be an Esso Petroleum thing.... Can a lithium grease be EP2? Can Molydenum disulphide grease be an EP1? Do we need to think outside the box? Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted September 3, 2008 Share Posted September 3, 2008 I agree with what is being said....Now my question....What about the Friction Modifier, of which I used to call Posi additive, is there something special about it??? Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 3, 2008 Share Posted September 3, 2008 The term friction modifier pretty much says it all.... The first thing to remember is that a differential clutch pack is simply a wet clutch - not much different from a clutch or band in an automatic trans and not much different from the clutch on most motorcycles. Now.... as the speed DIFFERENTIAL between the driven and driving members of the clutch pack approach zero, they get into a stick-slip-stick-slip situation. The skunk oil addresses this.... Got a LS diff that chatters during low speed turns? Before you replace the clutch packs, check the break-away torque. If this is adequate, simply add more friction modifier, make some tight figure 8s and re-assess. FWIW, friction modifier was the big difference between type A and Type F trans fluids (we were always told that using the wrong fluid would kill a trans.... something I never did see. Before the advent of B&M Trick Shift, we would replace Type A with TYPE F in hopes of crisper shifts ). Quote Link to comment Share on other sites More sharing options...
slim Posted September 4, 2008 Share Posted September 4, 2008 I always found it funny that we added friction modifier to these locking diffs. These guys want their big bad 4x4 to drive like a car 99.9% of the time, until they run off the road and get stuck. Then they complain about one wheel spinning while the other is barely moving, then their locking diff is broken. It's a no win situation for most customers. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 4, 2008 Share Posted September 4, 2008 Slim.... right there is one of the big misconceptions.... These aren't "locking" differentials... they are "limited slip". Quote Link to comment Share on other sites More sharing options...
DwayneGorniak Posted September 5, 2008 Author Share Posted September 5, 2008 You aren't reading close enough, Dwayne - some idiot redhead wrote <75W140 is a CAFE thing.... You could use 80W90 in any of these diffs and no one would be the wiser....> I was referring to the Protech massage board replies Jim. I guess you still can't view that though, not that that matters. I'm not really pro 75W140 or pro 80W90 though. I was just simply getting at the fact that you can't really blame 75W140 for all of our bearing failures when it seams to perform pretty well in other aplications. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 5, 2008 Share Posted September 5, 2008 Dwayne... stated that way, we appear to be saying the same things, anyway... I will say that I must have misunderstodd the intent of some statements.... *like that's never happened to me before.... riiiiiight). As for message board.... it is probably a better place without the likes of me darkening it's hallways... Quote Link to comment Share on other sites More sharing options...
Shlep Posted September 7, 2008 Share Posted September 7, 2008 As for message board.... it is probably a better place without the likes of me darkening it's hallways... I disagree Jim, while others may have been offended by things said, you gave alot of good advise and tips on doing things right. Besides who else would call Ralph a "wiener" /forums/images/%%GRAEMLIN_URL%%/rofl.gif Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 7, 2008 Share Posted September 7, 2008 There ain't a day goes by that I don't piss at least one person of in a royal fashion.... occasionally, it is my boss (how's that for job security?) /forums/images/%%GRAEMLIN_URL%%/smirk.gif. Irreverance comes naturally for me but sometimes I work a little bit harder at it than I might need to... For Ralphy-boy and his prissy little namby-pamby "Ooooh, the workshop manual didn't tell me common sense was required" thinking - I would hope that, in my absence, someone would step up to the plate and remind anyone that refuses to take their top extremity to work with them that they are wieners. Good techs will rarely make wieners look good... but wieners will make good techs look like.... well, like wieners.... Quote Link to comment Share on other sites More sharing options...
mchan68 Posted September 17, 2008 Share Posted September 17, 2008 Slim.... right there is one of the big misconceptions.... These aren't "locking" differentials... they are "limited slip". I think where the confusion lies, is in the fact that Ford calls their "locking" differentials "TRACTION-LOK", leading many to believe that they are locking units while those in the know, know very well that they're not. Generous Motors OTOH, have always used "Posi-Traction", which appears to be the more commonly used jargon for all makes. And what those "Torsen" differentials.....? Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 18, 2008 Share Posted September 18, 2008 Toyoda-Koki (no, not toyota) is the current owner of the Torsen diff. A marvelous differential, they are still far from the "best in every case".... This distinction could very well go to the the down and dirty welded spider gear. Back when it was Zexel Torsen, there was some really good tech stuff (even some animations) on the web site.... Toyoda hasn't seen fit to be so generous with details. It's been a long time since I last visited the place and some of the details have gone a bit sketchy. You can check out http://www.jtekt.co.jp/e/products/drive03.html Quote Link to comment Share on other sites More sharing options...
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