CARDAN SHAFT (propshaft) BOLT FAILURE

45bvtc

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The Audi 2.0 TT (MK2 quattro) employs a cardan-shaft with flex couplings that is connected to the 3-pin input flange to the Haldex coupling with three M10 bolts. The RS3 uses a similar arrangement with three similar M10 bolts.

1) A standard 2.0 TT develops 350Nm (258 lbf ft) of torque @ 1600 to 4200 rpm

2) A standard RS3 develops 450Nm @ (331 lbf ft) of torque @ 1600 to 5300 rpm: that's 28% more torque through those same three M10 bolts.

3) A stage 1 ECU upgrade for the RS3 is claimed to produce 447 lbf ft of torque "throughout the power band": that's 35% more torque than a standard RS3 and 73% more than a standard 2.0 TT (through those same three M10 bolts).

Something here has to give, you'd think. Photographic evidence of a current failure shows that ALL 3-bolts have sheared at the connection of the (cardan-shaft) rear flex coupling to the 3-pin input flange to the Haldex.

Now, good engineering practice would have the load being transmitted across the shank/major diameter of a bolt, but in this application the load is being applied across, or very close to, the root diameter of the thread, and this may well be the issue as the shank diameter of an M10 bolt is 10mm (10.0/9.7), but its minor thread diameter is only 8mm (8.3/7.9 according to tables): that's a 25% reduction.

So think on if you have an uprated ECU in your RS3, especially if you've alternative sticky and/or oversized tyres, and enjoy launch control, as it could well prove expensive.

Just my own thoughts and sums mind, feel free to disagree

In the meantime I'll not be using launch control on my standard ECU controlled RS3.

Hope this helps...
 

Rrobson

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If it were me, I would be doing one of two things if it was a real concern.

1. Replace all the related bolts with cap heads (harder)

2. Removing the prop shaft and drill everything to m12 and use cap heads

You could even use normal 8.8's but use the ones that aren't threaded all the way down so the torque is applied to the whole size of the bolt
 
T

T-800

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Perhaps the answer is to avoid using launch control at all if you have your RS 3 re-mapped ?
Also if you up rate the bolts and something else goes 'bang' what's the likelihood Audi aren't going to honour any warranty ?

I suppose this is a risk people are going to have to take when remapping an RS 3 and I bet the re-map companies won't be interested in making people aware of this disaster waiting to happen.

And it is a disaster waiting to happen.... Imagine that shaft bouncing around underneath and hitting something in the road it shouldn't

I mean come on guys, the RS 3 is no slouch from a rolling start is it.
 

desertstorm

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There are possibly many other weak points in the whole drive train. The manufacturer will have specified the parts for the expected loads. They may have actually designed that part of the system as a weak point to fail and protect other parts of the transmission.
The problem with launch control is the dynamic loads that will be present in the drivetrain, these will be far in excess of the normal steady state torque loads seen.And the values will depend on so many variables.
Thats why on a lot of cars there is a limit , I believe something like 200 on some models and these are recorded by the ECU.Get to the limit and the feature is disabled.
Fitting uprated bolts or larger bolts will probably move the point of failure to another component which could well be a lot more costly.The shaft appears not to become detached when the bolts fail.

http://m.vagoc.co.uk/vb/showthread.php?t=12201&showall=1

Karl.
 

45bvtc

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Discussing the cardan shaft bolt failure issue with my Audi dealer this afternoon he went on to tell me that any Audi car submitted for a warranty issue is first has its ECU checked (with Audi GmbH) for modification and that any car with a modified ECU falls outside of any warranty arrangement made with Audi UK and/or Audi GmbH.

So any of you guys with second or third hand cars may want to have the integrity of your cars ECU checked by your Audi dealer; obviously those that have had their own ECU modified already know...
 

PaulRS3

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While a standard feature, that should be fit for purpose on a standard car, I have no interest in trying Launch Control.

Knowing the pampered, low mileage , well cared for history of my car, I doubt the previous owner did either.

The car is no slouch, I prefer to get the car rolling, then progress, which is sympathetic to the clutches, drive train and tyres.

I won't be giving Audi any cause to void my warranty, and will happily remain standard, it's just not worth the risk.
 

PaulRS3

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If they break while in warranty, Audi can pick up the tab.

Out of warranty, i might feel different, or have the bolts replaced at service intervals.
 
T

T-800

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On the Audi experience day in May this year during the pre-driving briefing the instructor Frank Schmickler mentioned about launch control on the various cars and how it's repeated use wasn't very good for the cars mechanical health....

I don't launch and never feel the need to... As I've said above its plenty fast enough from a rolling start.

We were flooring the R8 at the experience in the ABS manoeuvre and to be honest the R8 just chattered it's wheels a very uncomfortable experience ! In the end it was easier to get the R8 rolling and then put foot to the floor....

You've got to give these cars some mechanical sympathy.
 

45bvtc

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OK, so I corresponded with MTM (Motoren Technik Mayer GmbH, is a German car tuner and small manufacturer based in Wettstetten) today to ask if they'd had any issue with standard and/or modified cars and they replied:

"we know, there is an update regarding the launch control from Audi for the RS3 cars. Do you know, if his car has this already? If not he can expect maybe also a new cardan shaft.

My opinion is also not to put better screws in, because if this is stronger there, you destroy mabye the rear Haldex…

From Audi are no stronger ones available."

Several of us here have already made this same point i.e., because if this is stronger there, you destroy mabye the rear Haldex…

Note: MTM were one of the first to offer performance modifications for the RS3
 
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Mr_Freeze

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If you were to put a m10 bolt into a vice with the thread facing up, then drop a 1/2 thick steel plate down on top with a 10mm hole in it, then hit the plate with a large hammer to try shear the bolt, the odds are you won't do it the first time. Now if you repeat the hitting several times more with the same brute force, you may get to see the bolt stretch or twist just before is shears off.

This is what I fear is happening to the bolts on launch and the one reason I don't launch mine no more.

If people aren't uprating the bolts, they could up the maintence schedule to include replacing the bolts on a frequent basis. This should help reduce fatigue and the chance of stress/shear breaks.
 

Kelza

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We drive with 12.9 bolts in the propeller shaft, everything else is original VW.
 

dbm

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Interesting comments from MTM. I seem to recall that you can buy MTM tuning parts at Audi dealerships in Germany? Or is it ABT?

I'm another one who doesn't feel the need for launch control on my standard car, or the need to modify it in general. I have been down that road in the past (with an 8L S3) but that just raised the performance of the original car to comparable to a TTS, so a very different proposition from updating the RS3 which is already so capable. And when I did modify my S3 only £800-ish was spent on "performance" and over £4k on handling, brakes and cooling in an effort to produce a more balanced package.

I would support the right of people to modify their cars, but I also support the right of Audi to say "sorry, you went beyond the design parameters" and decline warranty work if things go wrong. In regard to standard cars failing - things break. Mechanical sympathy is important for longevity of systems and so driving hard when cold or repeated launches are going to reduce the life of your vehicle.

I bought an extended warranty for my car when the original one expired. It was less than £500 for another year of peace of mind and well worth it to me.
 

45bvtc

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We drive with 12.9 bolts in the propeller shaft, everything else is original VW.


This chart will help explain that John:


bolt strength.JPG
 

45bvtc

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Yes, I know the three cardan shaft to Haldex flange bolts that have failed are 12-point high strength bolts but the chart above is just to differentiate between the strengths of standard 8.8, 10.9 and 12.9 hex-head bolts, and no more... :kissmyrings:
 

billyali86

Registered User
The Audi 2.0 TT (MK2 quattro) employs a cardan-shaft with flex couplings that is connected to the 3-pin input flange to the Haldex coupling with three M10 bolts. The RS3 uses a similar arrangement with three similar M10 bolts.

1) A standard 2.0 TT develops 350Nm (258 lbf ft) of torque @ 1600 to 4200 rpm

2) A standard RS3 develops 450Nm @ (331 lbf ft) of torque @ 1600 to 5300 rpm: that's 28% more torque through those same three M10 bolts.

3) A stage 1 ECU upgrade for the RS3 is claimed to produce 447 lbf ft of torque "throughout the power band": that's 35% more torque than a standard RS3 and 73% more than a standard 2.0 TT (through those same three M10 bolts).

Something here has to give, you'd think. Photographic evidence of a current failure shows that ALL 3-bolts have sheared at the connection of the (cardan-shaft) rear flex coupling to the 3-pin input flange to the Haldex.

Now, good engineering practice would have the load being transmitted across the shank/major diameter of a bolt, but in this application the load is being applied across, or very close to, the root diameter of the thread, and this may well be the issue as the shank diameter of an M10 bolt is 10mm (10.0/9.7), but its minor thread diameter is only 8mm (8.3/7.9 according to tables): that's a 25% reduction.

So think on if you have an uprated ECU in your RS3, especially if you've alternative sticky and/or oversized tyres, and enjoy launch control, as it could well prove expensive.

Just my own thoughts and sums mind, feel free to disagree

In the meantime I'll not be using launch control on my standard ECU controlled RS3.

Hope this helps...


1 of the bolts on mine sheared, 2 were still holding but bent out of shape. Warped the prop shaft in the process so whole shaft had to be changed. Car was 7 months out of warranty however Audi were very helpful, covered cost of parts whereas I paid for labour.

What have I learned? Over enthusiastic launch on a dry day with MPSS all round is a no no....
 

45bvtc

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NOT good billyali86 but great information nontheless.

With exactly the same observations i.e., "over enthusiastic launch on a dry day with MPSS all round" and the TTRS having less kerb weight @ 3320lbs than an RS3 @ 3803lbs.

Says it all really...

These Audi RS3/TTRS cars are best when rollin', rollin', rollin'... :yahoo:
 

MBK

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Hello chaps, it's been a while. I think it's worth remembering our bias for listening to the unusual story, more people will be talking about a failure than a car with no problems. I launched my RS3 before and after remap many times on Conti and wide, sticky MPSS tyres. It was the RS3 party piece, the shock and awe for passengers was worth it. I also agree with all the other comments that if you don't want to place the car under excess stress, don't launch it. If you map it be honest and accept the costs that might follow. There is no real need to launch, less than 0.4s to sixty when I tested it...several times. Launch is silly but at the same time wow it's fun! You can judge me for that if you want I don't mind. I buy cars to drive them on road and then to the limit on track, though I will never share as openly about that after my experience with the RS3 (or more accurately keyboard warriors) for a number of reasons. Just my opinion but I don't think the odd launch is going to lead to some catastrophic failure and if it's a standard car, within warranty there isn't much to worry about is there?
 

45bvtc

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Already reported to own dealer and Audi Customer Services, John; both verbally (telephone) and in writing.

Audi UK state categorically that there are NO updates for uprated cardan-shaft bolts.

Strongly suggest everyone writes and lists there own concern to Customer Services at Audi UK if only to have the issue logged should their own RS3 and/or TTRS suffer failure.

customer.services@audi.co.uk

I still maintain these 10mm dia. bolts are shearing across the 8mm root dia. of the thread where the full side load is being applied. It isn't the fault of the bolts, it's the application, and there Audi are at fault. Drive dowels, spring, sleeve, or otherwise are required...
 

45bvtc

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Look at it this way:
BOLT.jpg

And it's the same at gearbox end too...
 

PaulRS3

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There would appear to be a common denominator here.

read between the lines... :rolleyes:
______
Remap
______

For example The RS6/RS7 seems to manage ok with massive 560bhp and 700 Nm because they have been designed for it.
 

Broken Byzan

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The joint mounts into recesses so the load is there not on the bolts. The bolts don't share the rotational force till they are loose . Till then all they do is hold the parts into line
 

PaulRS3

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I wonder if the TT RS plus uses the same bolts, as the plus effectively has an Audi mild remap from factory.


TT RS plus:

Power boosted by 20PS to 360PS, torque up by 15Nm to 465N
Top speed increased from 155mph to 174mph,
Coupe 0-62mph down to 4.1 seconds with S tronic transmission (from 4.3)


 
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T

T-800

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This is the image for the RS6 propshaft it says the bolts are M8 x 48
image.jpg


The TTRS seems to use a mix of M10 x 48 & M10 x 18
 
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45bvtc

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The joint mounts into recesses so the load is there not on the bolts. The bolts don't share the rotational force till they are loose . Till then all they do is hold the parts into line

I think you maybe right. I have seen one photograph that shows the coupling sleeves locating into individual but shallow recess in the driven flange.

But for the time being I'm going to chase customer services at Audi UK and see if they can give us all some assurance that the current arrangement is suitable for purpose and that the already known failures are not to be expected.

I think it also important to remember that the "Standard model equipment" for these cars included "7-speed S tronic® transmission with launch control system" so where owners have been using launch control and failure has occurred then the regular use of launch control cannot be used by Audi as a reason for failure.

Standard model equiipment Capture.JPG




 

45bvtc

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I wonder if the TT RS plus uses the same bolts, as the plus effectively has an Audi mild remap from factory.

TT RS plus:
Power boosted by 20PS to 360PS, torque up by 15Nm to 465N
Top speed increased from 155mph to 174mph,
Coupe 0-62mph down to 4.1 seconds with S tronic transmission (from 4.3)


All of which suggests Broken Byzan is correct by suggesting 'loose' bolts, I like the reasoning...
I don't often suggest :audibash: but I do think we should all be writing to: customer.services@audi.co.uk
 

Kelza

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Audi must know there's a problem ,so they should have a solution ,before more props go bang !
 

DAYTONA 500

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Ive had 3 different brand new or nearly new S&RS Audis in the last four years{all models have had and still are having issues} and I've come to the conclusion that Audi's are riddled with problems throughout the whole range of cars and Audi don't give a $h1T,they deny the problems exist and try to fob you off ,I've had a case open for 6 weeks for a well known and media reported serious software issue that affects a number of models other than mine and theres still no solution.
 
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45bvtc

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Audi must know there's a problem ,so they should have a solution ,before more props go bang !

So here's a revised drawing with recess location - thanks to Broken Byzan:
BOLT2.jpg

And here's what I'll be doing - post warranty - if Audi don't:
BOLT3.jpg
 

45bvtc

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Just checked my bolts at the specified 60Nm - Broken Byzan made me do it...

And thanks to Sean - Veneeringman - for the specific data; it's always good to give credit where credit's due... :thumbs up:
 

45bvtc

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What's bolts are they john ,they look longer ?


They will be longer, John; with the full 10mm diameter all the way through. I can't understand why VW/Audi would drill and thread (threaded holes cost 4x that of a drilled hole anyway) a flange with the inherent weakness therein, however. But first I need to know the strength (UTS) of an original bolt before deciding on a suitable cap/Torx head bolt - and self locking nut. As you know I'm more than prepared to do my own thing.

That said, I've just had a telephone call from Audi UK who've said they are indeed looking into the cardan-shaft bolt concerns I raised yesterday (in writing) and that the issue for me (and non-modified BLUEY) is now logged. Also, my concerns and suggestions have been carried forward for technical review in Germany.
 

45bvtc

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