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Tailshaft Bolts Snapped

Posted: Sun Mar 11, 2018 2:00 am
by Mattspies
Hi Guys

First post from Australia...

Was driving a few mornings and went to overtake a car and halfway through I heard a ping and what sounded like a pinball machine in the back.. 😳
Got under the car and saw this... 2 Tail shaft bolts were missing. Towed to Porsche and the bolts actually snapped off....
Covered under warranty with a new Differential and Driveshaft with upgraded M10 Bolts
Early model Macans has M8 bolts which now have been revised and M10 bolts are now the normal...
I think this should have been a recall on all early models with this design fault.

Re: Tailshaft Bolts Snapped

Posted: Sun Mar 11, 2018 6:00 am
by Guy
Good morning and welcome to the Forum!

Well I had to Google 'tailshaft' but now I know that you are talking about the 'prop shaft' it is quite disconcerting. Did you take a photo? Also, when you say 'early model' what years are you talking about? What year is yours?

(EDIT: I just had a look at the US forum and there's a couple of threads reporting missing bolts, plus a couple of photos.)

Re: Tailshaft Bolts Snapped

Posted: Sun Mar 11, 2018 6:46 am
by Nuclear Nick
That does sound like a significant design shortfall, if the bolts are being overstrained in normal service and failing as a result. Clearly the fix is not just to change the bolts as it sounds like the drive flanges will not accommodate that, hence the replacement of diff and driveshaft. Unless of course they were damaged in the event.

I wonder if this vehicle has been subjected to unusually heavy loading perhaps? Major off roading, serious towing, many launch control starts? While such things might cause the failure, and it might therefore mean that the vast majority of cars don't suffer such a failure, it doesn't excuse a design fault. But it's interesting that a mod seems to have been introduced at some point.

Re: Tailshaft Bolts Snapped

Posted: Sun Mar 11, 2018 2:41 pm
by Mattspies
Mine is 2015 model and I did take pics of the two missing bolts and the aftermath of when it was fixed.
I’m not sure how to post pics on this forum though... Apparently models 2016 and above have this issue fixed with the larger M10 bolts.
I don’t have Chrono so no LC although it did happen when I went to overtake and it kicked down applying load at that time.

Re: Tailshaft Bolts Snapped

Posted: Thu Mar 15, 2018 8:55 pm
by Bigboyrolo
Mattspies wrote: ↑Sun Mar 11, 2018 2:41 pm Mine is 2015 model and I did take pics of the two missing bolts and the aftermath of when it was fixed.
I’m not sure how to post pics on this forum though... Apparently models 2016 and above have this issue fixed with the larger M10 bolts.
I don’t have Chrono so no LC although it did happen when I went to overtake and it kicked down applying load at that time.
There you go, I had copied it off your fb page, pleased to see you on here.

7A2841AE-D2B4-4D59-A3F7-56B85F27C588.jpeg


Re: Tailshaft Bolts Snapped

Posted: Sat Apr 01, 2023 5:51 pm
by JulesMacan
I know its 4 yrs later, but i have a 2015 Macan S with chrono (but have never used launch control), and ive had the exact same issue today! Under the same conditions. Except mine is long out of warranty (I'm the 2nd owner, only had it 18months). Have a terrible feeling this will cost me a fortune! :/

Interestly, the same two bolts gave way...
If theres any chance of getting it done not at my cost, id love to hear it!

@matspies any reason they couldnt just get 2 new bolts? High strength ones perhaps?

Re: Tailshaft Bolts Snapped

Posted: Mon Apr 03, 2023 10:41 am
by Tim92gts
JulesMacan wrote: ↑Sat Apr 01, 2023 5:51 pm I know its 4 yrs later, but i have a 2015 Macan S with chrono (but have never used launch control), and ive had the exact same issue today! Under the same conditions. Except mine is long out of warranty (I'm the 2nd owner, only had it 18months). Have a terrible feeling this will cost me a fortune! :/

Interestly, the same two bolts gave way...
If theres any chance of getting it done not at my cost, id love to hear it!

@matspies any reason they couldnt just get 2 new bolts? High strength ones perhaps?
Those heads are often associated with high grade bolts so could be the best they can get.

Going up a bolt size is a big step in strength.

Re: Tailshaft Bolts Snapped

Posted: Mon Apr 03, 2023 10:46 am
by Tim92gts
JulesMacan wrote: ↑Sat Apr 01, 2023 5:51 pm I know its 4 yrs later, but i have a 2015 Macan S with chrono (but have never used launch control), and ive had the exact same issue today! Under the same conditions. Except mine is long out of warranty (I'm the 2nd owner, only had it 18months). Have a terrible feeling this will cost me a fortune! :/

Interestly, the same two bolts gave way...
If theres any chance of getting it done not at my cost, id love to hear it!

@matspies any reason they couldnt just get 2 new bolts? High strength ones perhaps?
Those heads are often associated with high grade bolts so could be the best they can get.

Going up a bolt size is a big step in strength.

Re: Tailshaft Bolts Snapped

Posted: Mon Apr 03, 2023 5:53 pm
by Col Lamb
Just getting out the broken bolts is a sizeable job in itself.

There are dozens of grades of high tensile steel from which Porsche could have chosen and looking at the image they choose poorly or the bolts supplied were not up to spec if this is the case then yet another black mark against Porsche for their questionable QA procedures. It is a very simply test rig to test to destruction sub-contractor supplied components like a bolt.

Re: Tailshaft Bolts Snapped

Posted: Mon Apr 03, 2023 8:25 pm
by Nuclear Nick
It may not have been the bolts at fault, incorrect assembly could result in the bolts being over torqued leading to subsequent failure.