P2 AWD "Collar" gear analysis

[AlexD]

Update:

-Collar gear #3 (TF-80SC models) is under the knife today, hope to see results shortly. (Thanks FEO from Swedespeed!)

-Two used collar gears (pre-nitride coating) are on their way to me from generous swedespeed,com donors. (Thanks!)

-Part number 30783419 which by all indications should mate the M66 transmission to the stronger 1,5000nm angle gear it on its way from Europe. If anyone wants to donate to that cause, you can paypal to my at adykes@coit.com

[AlexD]

Latest update from the TF-80SC collar gear that just arrived: the part that is used in the 2006-2007 Rs equipped with the TF-80SC automatic transmission AND the XC90 V8/3.2 and the new S80/V70/XC70/XC60 is considerably harder than the part used on the AWD P2 cars including our Rs. This is especially telling since the angle gear in the 06-07 GT models has the SAME rating as ours, this means that the suggestion that the collar is a shear can finally be put to rest and we can safely pursue a custom part.

Also: Today the used but not broken part from Jeff from Swedespeed has arrived and will be in the lab tomorrow for analysis. This part is pre-nitride coating and will tell us the failure mode of the existing part and whether or not the nitride coating will actually experience less wear. Stay tunned for detailed cross sections.

[AlexD]

Additional info: The material on the collar gear used on the 2004-2007 MT Rs and the 2004-2005 GT Rs has a tensile strength of about 110,000lb/sq inch, the part used on the 06-07 GT equipped Rs has a tensile strength of 351,000lb/sq inch.

[Tzantushka1568908311]

Additional info: The material on the collar gear used on the 2004-2007 MT Rs and the 2004-2005 GT Rs has a tensile strength of about 110,000lb/sq inch, the part used on the 06-07 GT equipped Rs has a tensile strength of 351,000lb/sq inch.

Er... Just a slight difference

[shimon340]

looking forward to updates on the nitride coated part....

Are you able to identify the base material used in the XC90 V8 etc part? Rather than go the stainless steel route as proposed on swedespeed (itself questionable hardness, brittleness checks need to be done on the proposed material), could one not get collars made from the XC90 V8 etc material? That material seems up to the job and also doesnt need a nitriding of the surface?

regards

S

[Chilled man]

4140 Heat treated steel

or

301 SS

both can be had for less then $400 the steel for alot less.

And alex , I should be sending out the collar next week might even have two for you

[AlexD]

So, news from the worn, but not broken collar gear:

As you can see in this pic, the core metal is the same as the 1st generation gear

The gear Soupandspoons sent did NOT have the nitride coating so this is the 1st gen part. It is apparent with the picture below that that wear is the key failure mode not an overload of the gear teeth. This is evident by the lack of grain flow in the core area near the teeth, the grain flow at the edge of the teeth, and lack of stress cracks within any part of the gear.

Lastly, the new part used in the TF-80SC equipped vehicles has been case hardened. The core metal is about the same strength as the other collars, but the case hardening strengthens a considerable portion of the gear. You can see the case hardened section is on the right, core on the left. The chemistry of the new part is similar to the old part:

C 8%+/- 1.06

Cr 1.17+/- 0.18

Fe 90.76 +/- 1.06

According to Rob, 4140 would lean toward a similar chemistry but there are a few more elements present in that alloy, 4140 has good toughness, impact resistance, BUT, it would have to be machined in the annealed condition and heat treated after being machined.

[Chilled man]

So suggestions on metal ?

So I can get some quotes from my machine shop guys.

[AlexD]

From Swedespeed:

Well, the question would be: can they machine the material and then have it case hardened? If so, then that would be the best option.

Quote the SS part, since that doesnt have to be treated after cutting, and quote the case hardened part only if they can get the annealed metal and then case harden after cutting.

[AlexD]

OK, part number 30783419 has just arrived. This is the part that is used in the 2009 XC7- D5 AWD with the M66 manual transmission (EU only) The good news is this part appears to be a totally different material, and it appears on the surface to be a direct fit part for the R. I'll know more hopefully tomorrow when I can get it compared to the existing collar gears in the lineup.

[AlexD]

Updates from the other side of the Volvo world:

3/15/09

On the matter of the D5 part, this looks like a good match so far. Please remember we are still waiting on complete test results back, hopefully by the end of next week we will have the hardness, cross sections, and detailed measurements of everything done.

On the D5 gear I can say the following at the present time: 1 the inner diameter is roughly the same, since the calibrated instruments to measure this were checked out at the moment, a simple ruler test was all that was done, it appears to be the same. 2 the length of the splines on the input and output sides of the collar appear to be identical, as is the ring that attaches the collar to the transmission. 3The overall dimensions of the gear are slightly shorter length wise, but this does not appear to be a large deal since the teeth themselves are the same, the old collar had a large area where the teeth were shaved down to a bevel, no doubt to make assembly line fitment easier, this area is much shorter on the D5 collar. 4 the D5 collar gear *appears* to be case hardened, we await the hardness tests and cross sectioning for a final verdit.

Keep in mind a few factors:

1. The D5 part mates to a 1500nm rated angle gear, this would explain a stronger part and why they didn't bother to shift this down to a model that was supposed to end in 06 but got a temporary stay of execution. The 1500lb unit is used in the 08+ XC70 D5 and will NOT fit in a P2 R.

2. The D5 collar us a EU only part, it does appear that it can be ordered in the USA, but I cannot say that it will always be available via a US dealer.

3. If this part fits, it's about $80 plus shipping, so it's the cheapest option vs. a custom made gear/

4. The D5 collar does not address the poor fitment issue, so long term the wear would not be as ideal as a better fitting part, but it could well last a decent amount of time, say 100K+ miles.

5. If it all works out, the D5 collar is available now and there's no need to wait for a custom gear or some uncertain outcome of a class action suit.

6. Keep in mind that no matter how much you beg your dealer, they will not install anything other than the Volvo spec part for your R is you are under warranty. So, no real hope of having that under warranty R break and get the D5 part instead.

7. If you don't like number 6, and the D5 part is a good fit, the best thing to do instead of suing is to ask VCNA nicely to make that part the replacement part for all Rs under warranty. I think a letter writing campaign would be a much less combative way to start this process than a suit.

3/20/09

OK boys and girls, the news is IN. We don't have cross sectional photos yet, but the hardness tests have been done. The ogiginal part came in at an HRA of 60 (surface and core) the D5 part comes in at 59 for the core and a 65.3 for the surface, this part has been case hardened. This is not a linear scale, so this represents an increase in tensile strength of about 33% which is a decent increase. Overall it is still considerably softer than the part used on the TF-80SC equipped vehicles which has an HRA of 70 and an approx tensile strength about 2x higher than the D5 part and almost 3X higher than the original part used on the R.

The conclusion has to be that the D5 part seems to be an improvement in terms of wear characteristics, according to the materials guys at BAE the part should wear considerably slower than the original part. Since wear is the mode of failure, this is a benefit.

In terms of finding the absolute best part, the D5 falls short in terms of dimensions, the fitment of the teeth is the same as the stock gear therefore the mating characteristics would be the same.

If you want an improved part that will last longer than stock, get the D5 part

If you want the best part available, better fitment, etc, then we're still looking at a custom part.

We should get a victim/volunteer to pop a D5 gear on their R at some point.

[Rob1568908302]

What a fantastic project writeup Alex... ! A+

[Dutch1568908322]

Just a question that popped into my mind....how does the strength of the splines fitting into the collar compare to both the new and older collars? Does strengthening the collar now put the splines in the position of the fail point? And so on down the food chain so to speak.

[AlexD]

Just a question that popped into my mind....how does the strength of the splines fitting into the collar compare to both the new and older collars? Does strengthening the collar now put the splines in the position of the fail point? And so on down the food chain so to speak.

Yes and no. The concern about having the same part just get harder would be that right now the collar gear is what wears. The failure is not a sudden sheer, but rather gradual wear because the fitment of the part is such that there is play an the teeth pull apart and clank together again. So if you make the collar gear harder than the input/output shafts without making the fitment better, you could start to wear the shafts. Now, of course the shafts are much harder so even if this was the case failures would take much, much longer than they do now, but it is a concern. If you had a part that fit better, (see the diagram further back on this thread), then you reduce this risk.

[Geordie Bob]