Solid prop shaft donut ???

[Scullies]

What are your thoughts on a solid prop shaft donut?

I got this made, its about 20mm smaller in diameter than the OEM one. Reused the steel inserts from the OEM donut, so the drive shaft bolts don't eat into the the aluminium.

Reason : OEM one was starting to fall apart and the solid one will allow a bigger DP through the tunnel

 

[Andrew@A.L.D]

Why is the OEM one rubber? Never thought about it or looked into it?

 

[<tuffty/>]

Front or rear? Front will definitely need to be flexible to move with the engine... Rear maybe not so much but there is still some flex...

Dunno mate tbh... Props of old had universal joints for a reason... personal opinion is there needs to be a degree of flex...

<tuffty/>

 

[Scullies]

I assume its rubber to absorb some of the rotational force, there is also another rubber donut at the heldex end of the prop shaft and the bearing carrier in the middle of the shaft.

I have seen a few TTRS guys on the forums, complaining that the oem rubber ones don't last long in their tuned cars.

 

[Scullies]

Front or rear? Front will definitely need to be flexible to move with the engine... Rear maybe not so much but there is still some flex...

Dunno mate tbh... Props of old had universal joints for a reason... personal opinion is there needs to be a degree of flex...

<tuffty/>

I don't think the front one has any flex as the prop shaft flange bolts into one side and the output of the transfer box bolts into the other side of the donut. the rubber in these is pretty stiff.
I have noticed that the prop shaft can be extended or compressed a bit. I think the flex part is near the center bearing carrier.

 

[StaceyS3]

Will definitely need something in there to allow a degree of flex other wise are stopping the engine from rotating or changing angle at all

Like the thinking and direction of thought though as like you say can run a bigger DP

I've been looking into making some adjustments to the chassis/floor pan to achieve the same goal but prop doughnut will be easier

 

[<tuffty/>]

partially rotational take up but also engine movement... the centre CV of the prop is fixed to the chassis but there is a degree of 'plunge' available to take up engine rock and being a CV of course it will allow the front section of the prop to pivot...

The doughnut on the transfer box needs to have a degree of flex to allow it to pivot too... if your solid one is for the transfer box end then I think you will just end up bending the prop putting it out of balance of worse case shearing the transfer box off

If you re-worked it to have a CV on the end then that would work... they did this for the drive shafts on the Lotus 7 (saw it on wheeler dealers )

Would require the three point part of the prop to be reworked to accept a spline (and be rebalanced of course)

<tuffty/>

 

[<tuffty/>]

Think about it.... the engine rotates back on the mounts... having a solidly fixed 'pole' sticking out the back of the gearbox is going to do what when the engine rotates?

It does flex a little... this will need to be factored in...

You want to see a 1.8t on std mounts on the dyno mate... engine near enough leaps out the bay...

<tuffty/>

 

[Scullies]

yeah, I have seen them rocking away even the tfsi are bad. Mine is almost welded in now, I basically drive a big yellow vibrator

I can't imagine the prop shaft flexing that much in those standard mounts. Someone needs to fit a gopro under the car and video the front section of the prop

 

[<tuffty/>]

bolt the front part of the prop to something solid and see how much articulation is there

<tuffty/>

 

[Scullies]

The center of the prop shaft also has a locating slot that slides over the pin on the output flange on the transfer box

This is the read haldex end but the front looks the same

Failed OEM donut

 

[<tuffty/>]

Fit it and let us know what breaks

<tuffty/>

 

[snowy]

The transfer box's on 02J's are known to crack due to the forces applied by the prop

The 02M transfer boxes have been significantly reinforced to cope

That's with the stock flexi prop and shock bushing

Without that bushing I'd expect you'd crack the transfer box eventually

The chances of this happening would be greatly reduced by firmer engine mounts, subframe mounts etc etc

 

[snowy]

Cheaper that the doughnut fails that the transfer/haldex box cracking open

 

[Scullies]

Fit it and let us know what breaks

<tuffty/>

OK
I have a quattro TT now, it might be converted to fwd shortly

 

[Scullies]

I had a brain fart.

The TT has stock engine mounts, so I will remove the dogbone and put a camera under the car. Then rock the engine, should be able to record prop shaft flex

 

[ayfreetee]

I'm surprised nobody does a poly bush for these props , I think they would be a big seller.

 

[snowy]

You should have patented that idea

 

[Andrew@A.L.D]

I know a few people that would make one of these