Rear Axle Failure

[gcmak]

Judging by the lack of information I've found in forums and in groups for the Supra, I wanted to ask if anyone else has broken their OEM axles on stock power.
A related post that is somewhat helpful: https://www.supramkv.com/threads/broken-axle-after-mods.9168/

My axle failed similar to the one in the video in the post above, but I have an untuned Supra, running OEM size tires on OEM rims and OEM rear suspension.
The failure occurred under WOT acceleration around ~40mph. I was able to safely pull over and get a tow. No other vehicles were near me at the time.

Supra is currently at the dealer and I am told they need to have this evaluated by Toyota.
Happy to update this thread with more details and/or the final outcome once I have the information.

LINK TO POST WITH RESULTS

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[gdi2290]

Thanks for keeping us updated on this

 

[Davidr3]

Interesting, I haven't done research on if Toyota uses BMW's axles but it's likely they do. On my N55 335i I broke my axle on stock power too. But that car was rated at 306 HP.

 

[gcmak]

Interesting, I haven't done research on if Toyota uses BMW's axles but it's likely they do. On my N55 335i I broke my axle on stock power too. But that car was rated at 306 HP.

Thanks for chiming in.
All of this gets into a mechanical and technical realm beyond my education and experience. I venture to guess most/all of the drivetrain on the Supra is identical to that found on the high-end Z4. What components that Z4 shares with the BMW line-up, I am unsure of.

May I ask how your axle failed and what was the outcome of the fix? I am curious how Toyota will handle this, but would be helpful to know how BMW did it for a 335i too.

 

[gdi2290]

If its common for bmw then this is another thing toyota never has but bmw does. (Just like oil consumption issue). This also means Toyota will be forced to fix it until they realize its a bmw thing

 

[Davidr3]

Thanks for chiming in.
All of this gets into a mechanical and technical realm beyond my education and experience. I venture to guess most/all of the drivetrain on the Supra is identical to that found on the high-end Z4. What components that Z4 shares with the BMW line-up, I am unsure of.

May I ask how your axle failed and what was the outcome of the fix? I am curious how Toyota will handle this, but would be helpful to know how BMW did it for a 335i too.

My axle failed just from a low gear pull (I believe it snapped in 2nd out of the 8 gears on that car) Fortunately the car was under warranty so it was just replaced, oddly enough I was not the only one and on bimmerpost several users had similar encounters. There's always a possibility of breaking other things when the axle goes, I believe my dealer was worried I had broken my diff too but that was okay in the end.

Edit: I'd like to add my car was full at the time passenger wise, so i'm not sure if extra weight specifically in the back plays a part?

 

[Davidr3]

If its common for bmw then this is another thing toyota never has but bmw does. (Just like oil consumption issue)

Definitely likely this is a BMW issue and not a Toyota issue. We'll see if more cases pop up.

 

[gcmak]

My axle failed just from a low gear pull (I believe it snapped in 2nd out of the 8 gears on that car) Fortunately the car was under warranty so it was just replaced, oddly enough I was not the only one and on bimmerpost several users had similar encounters. There's always a possibility of breaking other things when the axle goes, I believe my dealer was worried I had broken my diff too but that was okay in the end.

Edit: I'd like to add my car was full at the time passenger wise, so i'm not sure if extra weight specifically in the back plays a part?

Thanks. I think having the extra traction in the rear is a contributing factor but it's not great to hear that it's a somewhat common bmw issue - which might mean they were trying to design the axle with as little overhead as possible. That said, if the axle is weak, it should reduce the likelihood of shock and damage to the parts up and down the Axle (differential, torque tube, wheel hub assembly etc.).

When the dealer contacted me this morning and didn't get back to me for the rest of today, my concerns have grown about this not being covered. As I understand, if it's just the one axle, the part itself is ~$800 and the labor could be over 4 book-hours...which translates to a whole lot of money. Really hoping my SA/Dealership is in my court. I was not doing a standing burnout, for example.

 

[Loco38SUP]

They should cover it 100%, hopefully you removed the drag radials before arriving at the dealership. ?

Seriously though you must have hooked up good to snap an axle on stock power.

-RJM

 

[Escapist]

I wonder if this is the reason why BMW insists on sticking with the relatively narrow 275's even on M cars and ups to a still modest 285 for some of the competition models.

 

[gcmak]

They should cover it 100%, hopefully you removed the drag radials before arriving at the dealership. ?

Seriously though you must have hooked up good to snap an axle on stock power.

-RJM

I stuck with the stock tire sizing and wheels because I do like the handling characteristics but I find any 300tw unable to safely handle the power. The slip is both fun and maybe by design to minimize stress on hardware. So I am using a 200tw tire but it is completely street legal and within all the specs to be run on the Supra

I wonder if this is the reason why BMW insists on sticking with the relatively narrow 275's even on M cars and ups to a still modest 285 for some of the competition models.

The compound matters a lot. Get a 200tw tire and it changes how the car really handles. It’s an odd feeling to get used to - grip - instead of always counter steering haha.

 

[zrk]

They're going to blame the radials if they're still on there. These axels like to break. I know of axels snapping on drag radials with a modest tune on an 11.5 second car (at the drag strip).

 

[Mason]

Yup, gotta get the reinforced axels when you put better tires on, especially if you race digs

https://titanmotorsports.com/produc...graded-2020-gr-supra-axles-by-driveshaft-shop

 

[Cptnslo]

I saw that video, it’s interesting he snapped the bearing cage. If it was just that you can normally pull a cage out of a trashed car and put it in along with the bearings and a new boot but it heavily depends on cost and availability. That’s mildly concerning if the axles can snap on stock power. I’ve been down the track 8 times this season on the last 2 test and tune days on factory tires and wheels and I have major traction issues but no axles yet (knock on wood)

 

[zrk]

I saw that video, it’s interesting he snapped the bearing cage. If it was just that you can normally pull a cage out of a trashed car and put it in along with the bearings and a new boot but it heavily depends on cost and availability. That’s mildly concerning if the axles can snap on stock power. I’ve been down the track 8 times this season on the last 2 test and tune days on factory tires and wheels and I have major traction issues but no axles yet (knock on wood)

Once you solve the major traction issues (a good tire + a good launch) you're cringing as you're building boost while the tree lights up. My best pass of the season (low 11s) I was absolutely terrified. Once I saw my 60' I packed it up for the season until my built axels showed up. STILL WAITING, NORRIS/P2UNED/DSS.

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