EN24 driveshafts
Turbo Mini Forums

Bit off the topic of Minis but I have just splashed out on a pair of EN24 half shafts for the rear axle of the turbo A35.

I notice that where they are reduced slightly in diameter just before the splined section which enters the diff, the step is quite abrupt between the two diameters.

My limited understanding is that this could create a notch effect so that failure is likely to occur at that point.

I am proposing to smooth out this step, spreading the change of section over say 25mm, Does anyone think this will have any beneficial effect ?

Lastly, is tufftriding the shaft a good idea, to add strength ?.

are vyou saying the shafts are plain old en24, i would have thought they needed to be case hardedned in some way or another at least,


carl

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Not sure if they are case hardened -will go out tomorrow and see, but I would guess that only the splines will be hardened.

Just found out someone else is making them from EN30 and hardening them - at the same price I paid !!

Any thoughts for me on the notch effect idea ?. Or the tufftriding ?.

i reckon it depends how sharp the change is, if theres a radius i wouldnt worry overly,

I thought tufftridings main benifit was from a wear point of view, anyone?

how about cryo treatment?

heat treating it to the specification below should be sufficient, if it hasn't been already.

http://www.westyorkssteel.com/EN24.html

what diameter is the notched section and whats the max engine torque?

Edited by longy on 1st Feb, 2011.

1972 998 TURBO SLEEPER

I have determined that they are heat treated but have not been able to establish to what level.

The shaft is 26mm in diameter and the reduction is 0.5mm,not much, but there is no appreciable radius. The producer says they never break here, only on the splines !

As to the max torque its a 1275 engine with a Turbophil head,MG NA cam and will be running a GT1752 at 15psi min
Megajolt (natch) and gas flowed exhaust manifold - one RC40 silencer on a 52mm exhaust, so whats the best guess ? I am hoping to match the Metro van at 150+bhp and how much torque ?.

Match for how much longer though Dave? Changes are a foot

Think we currently have a guestimated 170 curlly wurlys

With that spec I think you will absolutely muller our metrovan power-wise dave.

I'm going for AT LEAST 160curlywurlies at 15psi

If something is worth doing, it's worth doing half of.

im working on a shaft at the moment that made from EN19 hardened, with an maximum OD of 30mm and thats running 500Nm, so im sure this notch will have no effect

1972 998 TURBO SLEEPER

On 1st Feb, 2011 apbellamy said:

On 1st Feb, 2011 longy said:
im working on a shaft at the moment

1972 998 TURBO SLEEPER

From a strict engineering point of view a generous radius is required to improve fatigue life (just like crankshafts).

Notches or sharp corners just aren't acceptable in anything subject to fatigue (alternate, reversed loadings like a crankshaft).

But if they are absoulutely perfectly machined concentric the only fatigue loading will be torque - most drive shafts suffer fatigue failure from bending loads because they are never perfectly concentric or straight (I could quote one classic example from my industry...)

But if the supplier isn't too worried about leaving a sharp corner he may not be too concerned with it being concentric/straight.

Schrödinger's cat - so which one am I ???

Thanks everyone, once again my background knowledge has been increased.
I will try to improve the "step" and polish it out and then we will see how much abuse they can take.

Point taken Andy, I will always be one step behind, but I think I will have to accept that I can only go so far

If something is worth doing, it's worth doing half of.

Regardless of speed, the A35 will always look nicer than the only metro van in the world......

^^^ Agreed!

If something is worth doing, it's worth doing half of.

Aw shucks guys you are making me embarassed

Hi David,just seen this,I think the reasoning is that undercut splines produce stress raisers and relieving the shaft so that they are proud reduces this.It's a well known mod amongst the midget racers (little fast people) :cool:

'Where does the engine go?'

Edited by minimole23 on 4th Feb, 2011.

As far as I am concerned its all a bit academic now as I have sold them and am having some better(?) ones made in heat treated EN30.