AlexD Posted February 12, 2009 Author Report Share Posted February 12, 2009 So the final verdict is in. In essence the new collar gear / spline gear that FEO sent was identical to the old one. The part is made of manganese steel which is typically used in applications that require high ductility ("bendyness") and impact resistance. As before, this seems an odd materials choice for the application to start with. Transmission parts of this sort are usually rated in terms of hardness using the Rockwell scales. Specifically, most gears for this type of application are on the "C" scale, usually in the middle. This part didn't even rank on the C scale and both the old and new part ranked at 60 A. Here's it straight from teh horse's mouth "They are about 60 Rockwell A scale (HRA). This is pretty soft. The hardness of most hardened steel and other hard alloys start just above this hardness level. We usually use the Rockwell C scale (HRC) for heat treated steel (quenched and tempered). Typical hardness of average material of this type is in the 30 to 40 HRC range. (Equivalent to 65 to 70 HRA) The A scale ranges from 20 to 92 HRA."In English this means that they expected a part of this nature to be hardened steel, which is more normal for gear types and links in transmissions, but this didn't even manage to rank on the scale used to rate the hardness of tempered steel. I.e. it's soft metal.As far as hardening the part, it is just not possible. I asked why and was sent the picture below. This is a picture of the crystalline structure of the metal itself. The steel crystals (yes, steel is actually a crystal) are the dark sections and the alloy section is the lighter coloured material. The alloy used in this part is not hardenable but the steel is. However, this would not yield an improvement overall since there is such a high percentage of alloy materials in the part. It was explained to me like this "It's like putting marbles in play-doh, you can make the marbles as hard as you want, but if you can't change the play-doh it will still fall apart just the same." So if the part was more steel than "play-doh" then we could harden, but as it is we can't. On to the next part!Old part, 100XOld part 250XNew part 100XNew part 250X Link to comment Share on other sites More sharing options...
pm2000541568908310 Posted February 12, 2009 Report Share Posted February 12, 2009 So the final verdict is in. As far as hardening the part, it is just not possible. I asked why and was sent the picture below.OK I give...where's Waldo? -mk Link to comment Share on other sites More sharing options...
AlexD Posted February 13, 2009 Author Report Share Posted February 13, 2009 And here's the latest info in on the angle gear fresh in:Both collar gears are low carbon steel with come manganese, heat treating may be possible, but the difference will be very slight (as stated before). Unfortunately with this material you could end up trading hardness for something that fractures more easily. Not the best solution. It appears the new collar gear part has a nitride surface coating that the old collar gear does not have. This coating covers just the gear tooth area of the gear and has a much higher harness equivalent to "very hard steel." This is likely done to prevent wear and maintain sectional thickness. I.e. if the collar teeth wear there is less bulk to resist the sheer forces on the teeth, so if you reduce wear you increase the durability against wear induced sheer forces only. If the inner material isn't strong enough to begin with, and wear of the teeth is not the causal factor, then this coating won't really help, BUT, it does seem to indicate that Volvo thought there was a problem with wear and failures on this part and has done something to change the durability of the part in their eyes. The engineer at BAE would like to see a collar gear that has had use but had NOT failed to examine. When the gear fails it destroys any evidence of wear. Not sure how easy that will be to accomplish. Below you can see pictures of the old and new gear, on the new you can clearly see the nitride coating, on the old gear you see what looks like some sort of odd layer but that is just machining distortion from the angle gear input shaft and the collar gear grinding on one another. Bottom line: The rumor mill of an improved part appears to be true, but as to whether or not it solves the problem is still an open ended question. If the part is failing due to wear on the teeth, then this part helps the situation. If the part fails because the teeth were not strong enough in the first place, then it doesn't make a difference. Old GearNew GearOld GearNew Gear Link to comment Share on other sites More sharing options...
so_calR Posted February 14, 2009 Report Share Posted February 14, 2009 Wow!! Great scientific approach to this issue Alex, this seems to be how you approach all your items (i.e. Air Filter Shootout). This may have been stated earlier, but is this piece designed to fail like this on purpose? It seems like an odd metal to use for a part that will see much abuse so the only logic I can put behind it is that it's a failure point to protect something much more expensive or damaging to the car. Is there anything else that connects, runs in unison with, or dependent on the "Collar" gear that would warrant a failure point? Link to comment Share on other sites More sharing options...
AlexD Posted February 14, 2009 Author Report Share Posted February 14, 2009 Wow!! Great scientific approach to this issue Alex, this seems to be how you approach all your items (i.e. Air Filter Shootout). This may have been stated earlier, but is this piece designed to fail like this on purpose? It seems like an odd metal to use for a part that will see much abuse so the only logic I can put behind it is that it's a failure point to protect something much more expensive or damaging to the car. Is there anything else that connects, runs in unison with, or dependent on the "Collar" gear that would warrant a failure point?This has been suggested, but I think the fact that Volvo decided to apply a harder coating to the gear indicates that they think there was a wear issue. I am being sent a used but not broken collar gear from someone on swedespeed,com and we'll take a look at that to see how the collar gear wears. If the gear wears and as a result of the wear (and subsequent weakening of the teeth due to wear) then the new coating on the gear could help that. If the old gear shows stress feactures on the teeth themselves then we know the material is too soft and is breaking anyway. In essence, we just need to run more tests to be sure but it looks like a stronger collar gear is not a bad idea at this point. Link to comment Share on other sites More sharing options...
geoguy Posted February 14, 2009 Report Share Posted February 14, 2009 There must be some Swedish engineers sipping vodka & laughing their a$$es off, looking at all this forensic materials-science effort that is being expended on their humble driveline component . . . Who knows, you & Rob may be adding to Volvo's understanding of this problem! - Mark Link to comment Share on other sites More sharing options...
Big Will Posted February 14, 2009 Report Share Posted February 14, 2009 I truly think this would be worth sending to Volvo. This seems like a good analysis on the part and even if Volvo wouldn't care to comment it could only help them. Link to comment Share on other sites More sharing options...
Tzantushka1568908311 Posted February 14, 2009 Report Share Posted February 14, 2009 Alex,To continue from Mark's comments - I imagine that the Volvo Engineers (and their component suppliers) are either doing what Mark described - OR - feverishingly scribbling down all your notes!Just to add some further light, your guys are spot on. In a former life, we used to Nitride certain steels to improve the surface wear characteristics - without having to utilise very expensive and exotic alloyed steels. Nitriding is indeed a quick fix and alternative to other methods of hardening and surface hardening.You analysis confirms a few things we know or suspected:Everything is built to a priceHence, the type of material that has been selected by Volvo or their component suppliersThe 'collar gear' has been designed as more of a safety deviceRather than being engineered for heavy duty reliability, which...Is probabaly intended as the designed weak point for the drive train.Volvo and their component suppliers are probabaly aware that *IF* the collar gear was NOT designed as a failure component - then, the cost of dealing with other driveline components that fail (transmission, Haldex, etc) under warranty would be far greater...Let's be honest making cars is all about keeping factories running and making money.The reality is that most modern car manufacturers run very comprehensive economic models that assess the eceonomic affect of technical changes.And this is one of them.The funny thing, if that Volvo had used a better clutch slave cylinder then they would probabaly have lower warranty costs.But we know the strategy dealing with this one... Get the component supplier to suck it up, and try and pass the rest of the cost to the dealer consumer - as the clutch is a wear & tear item Again, thanks Alex for your efforts.Trent Link to comment Share on other sites More sharing options...
AlexD Posted February 14, 2009 Author Report Share Posted February 14, 2009 Trent,The very fact that Volvo decided to improve the collar gear, and that the TFSC80 equipped Rs use a collar gear rated with 50% more torque capacity seems to indicate that even Volvo felt this part was too weak. According to Rob, nitride coating is a fairly expensive coating since it must be applied by plasma, so this part is considerably more expensive to make than the previous part (even the quality of the machining is better on the new part) all this would seem to indicate that Volvo knew this part was a problem and tried to fix it. If it was intended to operate as a "fuse" in essence, then they would have left well enough alone.In addition to the failure of the collar gear, the design of this component is also a problem. The way the collar gear mates to the transmission and collar gear leaves a great deal to be desired, only a small portion of the gear's teeth mate with the input / output shaft teeth, this is evident in Soupandspoon's (from swedespeed,com) collar gear that shows considerable wear on the teeth. Here's an illustration of the problem. Link to comment Share on other sites More sharing options...
Chilled man Posted February 14, 2009 Report Share Posted February 14, 2009 Just dropped of a collar gear at the machine shop here to see what they recomend and such . Does anyone know the Volvo Price on these ? Since the machine shop says guestimate around $250 for one in SS Link to comment Share on other sites More sharing options...
AlexD Posted February 16, 2009 Author Report Share Posted February 16, 2009 OK, we need to volunteers to help donate to this cause, we need to buy one more collar gear, the new one used on the 06-07 Rs with the automatic transmission. I'm thinking we should be able to get a number of guys between here and swedespeed,com to chip in $5-$10. Who's willing? Reply here and I'll get the details back to you when we get enough volunteers! Thanks! Link to comment Share on other sites More sharing options...
so_calR Posted February 16, 2009 Report Share Posted February 16, 2009 OK, we need to volunteers to help donate to this cause, we need to buy one more collar gear, the new one used on the 06-07 Rs with the automatic transmission. I'm thinking we should be able to get a number of guys between here and swedespeed,com to chip in $5-$10. Who's willing? Reply here and I'll get the details back to you when we get enough volunteers! Thanks!Are you going to set up a paypal for that, or should we send checks??BTW, count me in for $10, its a cheap investment for the knowledge that will be gained from it.Lemme know where to send the cash.-Mike Link to comment Share on other sites More sharing options...
geoguy Posted February 17, 2009 Report Share Posted February 17, 2009 I'll contribute to this worthy cause . . . let me know how much & where it needs to go.Great entertainment value, btw, with all these amazing images that Rob is providing for you. What produces those images, a scanning electron microscope? - Mark Link to comment Share on other sites More sharing options...
AlexD Posted February 17, 2009 Author Report Share Posted February 17, 2009 I'll contribute to this worthy cause . . . let me know how much & where it needs to go.Great entertainment value, btw, with all these amazing images that Rob is providing for you. What produces those images, a scanning electron microscope? - MarkSome were from the SEM but most were from the high powered stereo optical microscope. Apparently BAE would have charged almost $5,000 for the work hes done so far. Yikes! Pity he doesn't get paid like that LOL Link to comment Share on other sites More sharing options...
AlexD Posted February 18, 2009 Author Report Share Posted February 18, 2009 We're up to $65 as of 4:00 PST. The gear cost $96 including shipping and of course the last one was around $80 if we want to help cover the cost of that I'm sure FEO won't mind (he paid for the last one) Link to comment Share on other sites More sharing options...
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