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Billet Stub Axles vs. Turbo Stub Axles


02tom

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Well, I messed up one of my stub axles getting it off the car.  The splines have some pitting anyway which is way it took so much to get it off, so maybe this was no great loss, but it has me seriously considering upgrading to the billets axles that Ireland sells.  There was some (unconfirmed at this point - links no longer work) talk of the billet stub axles breaking back in 2003 or so, but haven't seen or heard problems since.  While I've come to consider these, which are hopefully overkill for a street car, I'm also looking at the turbo stub axles and it looks like cost-wise it's about a wash.  The turbo bearing inner diameter is 30mm vs. the 28mm standard issue.  The turbo pieces will cost more in the end if I have to buy them through Walloth Nesch, and pay VAT and probably some additional charges from converting funds I'd imagine.

 

Here's how the turbo pieces are in reference to interchangeability per realoem.com:

 

Turbo Stub Axles:
33 41 1 111 092   Turbo Stub Axles   x2    specific to turbo                              $158.39
33 41 1 119 994   Turbo Bearings     x2    specific to turbo and E21                $109.25
33 41 3 404 161   Bearing Seals        x4    non-specific: all '02 and E21           included
07 11 9 945 270   Split Pin                 x2
33 41 1 111 094   Spacer Sleeve       x2    specific to turbo and NK 2000 NLA  $38
33 41 3 404 109   Spacer Sleeve       x2    2002, TII - does not fit Turbo         
33 41 3 704 135   Drive Flanges        x2   specific to turbo and NK 2000          $232.84
___________________________________________________________________
Don't absolutely need:
33 41 3 404 150   Crown Nut              x2   non-specific: all '02, E21 & NK
33 41 1 118 731   Shim                        ?   non-specific: all '02, E21

 

So, at the bare minimum, the parts add up to right around $1000, except that doesn't include VAT (possibly $159) and you don't get the space sleeves you need, or know what kind of shims you'd require.  The billet stubs seem like they'd be less of a hassle with shims & space sleeves and I have the hardened Tii Drive Flanges 33 41 1 101 848 already.

What am I missing here, if anything?

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What are you doing with the car? Are you running a Turbo or big HP engine? Are you running big tires, slicks? Is this your track toy or street car? I have run many 2002 race cars on stock '02 rear axles and in over 35 years I have only had one fail. (GT3 car on Slicks) There was a change in the metallurgy about 1972 and they got a lot stronger (the one that failed on me was a early axle). I don't see a need to run

aftermarket axles but if you feel better spending that kind of money you should go right ahead.

BTW I have seen a couple of the aftermarket Billet axles fail in vintage racing within the last 15 years or so.

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I guess I should have clarified: Street driven s14 car in the works, probably won't be too much more HP over a stock s14, but I don't know how that's going to turn up yet.  Maybe just a new set of stock axle would be fine.  I just think with the wider tires and the rough roads around here, eliminating a potential weak link would be good.  It's an early '72 car also, so there's possibly another reason to renew both axles at this point.

 

Were the billet axles that failed on 2002's?  And being billet axles, they probably aren't that old to begin with I'd guess. 

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as another data point....

 

i put new normal 02 stub axles in my car when i started working on it 4 track seasons ago.  with normal 02 trailing arms.  they are still in one piece.  as most folks know, they see a bit of abuse in my car.

 

you don't need to spend more money for your build and use of the car on stub axles.

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I'm having trouble understanding why people go ape over something called billet. Billet only means it was turned from heavy bar (with a lot of machining time and so costly) and the metallurgical grain structure is inferior to a forged and turned hub and so, can actually be a weaker part.  Billet to me is a buzzword that those who do not understand how things are made get happy owning something made from a billet.

If "billet" has been reinvented, then it's different than what I was taught in machine design class.

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Sure, its marketing. This is why I was interested in the turbo axles also - not enough information about the manufacturing process of the billet axles that are offered or the previously reported failures of the aftermarket stub axles. I thought the were machined from 4130 chromoly from previous group buys, but there's no info in the current listing as to specifics.

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Years ago (2003-2004, wow, how time flies!), I put together two group buys on the FAQ for aircraft quality 4030 billet stub axles and they were absolute works of art.  I used a company called Summers Brothers and I have no idea if they are still in business.  I have a stroker S14 powered car with sticky tires and so this was an important upgrade for me given the fact that the wheel can part ways with the car in the event of a half-shaft failure.  Mine have never missed a beat and they still looked brand new when I pulled them out for inspection last year when we had the car apart.  As far as I know, everyone who was in on the buy was thrilled with the finished result and lots of them went to racing teams (Skidmark, etc) .  In the end, over 60 FAQers received axles from the buy...I still have a spare set in my office serving as bookends!  They're definitely "overkill" for a stock or mildly modified car, but anyone with a car approaching 200 hp should definitely consider this, especially if he/she does autocrosses or club racing events.

 

COOP

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If you're modifying the car, you can also use 320 trailing arms.  They are a bit longer,

and they have fixes for all the problems that the 2002 hubs and stubs figured out over the years.

 

I don't know what their ultimate yield strength is, but they're a big improvement especially over the early 2002 version.

 

The late 2002 version proved to be pretty bulletproof in my experience, but I never made massive torque...

 

t

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 They're definitely "overkill" for a stock or mildly modified car, but anyone with a car approaching 200 hp should definitely consider this, especially if he/she does autocrosses or club racing events.

 

COOP

oh oh....i have north of 200hp, run sticky r-comps, and have logged over 3,000 very hard track miles on my normal 2002 stubbies......

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oh oh....i have north of 200hp, run sticky r-comps, and have logged over 3,000 very hard track miles on my normal 2002 stubbies......

 

Well hopefully you'll continue to be safe and sound.  I'm sure you know what you're doing and perhaps the billet units are overkill (which I'll take simply for the peace of mind).  My original inspiration for putting the group buy together 10 years ago was Jeff Ireland who recounted some stories about failed stock stub axles resulting in catastrophic failure/wheel departures on the track...He was the one who cautioned me against running the stockers on my car and so I took it from there. 

 

COOP

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As another data point, I've seen a couple of new and used stock axles fail in person while snapping photos of dedicated track 2002's from some of the corner stations at Button Willow.  Unfortunately I've never caught any on camera.

 

Got a good chuckle at the "marketing" comment regarding the axles because I can relate on many shiny bits I see in fancy aftermarket catalogues.  However, this particular instance is a case of holding back plenty of applicable "marketing" speak (much of which would make an engineer foam at the mouth) in an attempt at trying NOT to oversell something to someone.  The general idea is "You'll know when you need them, if you have to ask....then...."

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If you're modifying the car, you can also use 320 trailing arms.  They are a bit longer,

and they have fixes for all the problems that the 2002 hubs and stubs figured out over the years.

 

I don't know what their ultimate yield strength is, but they're a big improvement especially over the early 2002 version.

 

The late 2002 version proved to be pretty bulletproof in my experience, but I never made massive torque...

 

 

t

 

 

I had looked at 323i arms as an option briefly, but stopped looking at them when it looked like they required flaring the fenders.  Same bearings and shaft diameter as the turbo units FWIW - if the 320 stubs could be shortened and the grooves machined further in, they could work on the '02 arms

Years ago (2003-2004, wow, how time flies!), I put together two group buys on the FAQ for aircraft quality 4030 billet stub axles and they were absolute works of art.  I used a company called Summers Brothers and I have no idea if they are still in business.  I have a stroker S14 powered car with sticky tires and so this was an important upgrade for me given the fact that the wheel can part ways with the car in the event of a half-shaft failure.  Mine have never missed a beat and they still looked brand new when I pulled them out for inspection last year when we had the car apart.  As far as I know, everyone who was in on the buy was thrilled with the finished result and lots of them went to racing teams (Skidmark, etc) .  In the end, over 60 FAQers received axles from the buy...I still have a spare set in my office serving as bookends!  They're definitely "overkill" for a stock or mildly modified car, but anyone with a car approaching 200 hp should definitely consider this, especially if he/she does autocrosses or club racing events.

 

COOP

 

I remember your group buy back then and would have like to have bought some then, but I wasn't to the point of seeing the need for them at that point.  If you do a search, you'll see some anonymous posts referring to some failures of the stub axles being attributed to possibly 'first run' issues - none of which was confirmed as far as I can tell.  May have been a different manufacturer too for that matter.  There were even some posts linked from the FAQ to Skidmark Racing's site about it that are gone.  I just thought I should ask some questions before I went any further and I like the discussion that's happening so far.  The billet stub axles on Ireland's site don't say what they're cut from, and I had thought maybe Summers Brothers was making them - and still from 4030 chomoly.

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