I agree with 92. The grain structure suggests the shaft has been hardened all the way through. In reality, the heat treatment should only be there to prevent wear on the surface - as it was, it was always going to be too brittle.

Ben is right. Its torsional overload leading to brittle fracture. Must have been heated too much or something to get brittle like that.. I studied this sort of thing at uni too

then again.. the guy I got my shafts done ( same as Ben's) said there is no way to built bullet proof axles for this application since the CV joint size of the mini is the biggest restriction from making up beefy drive shafts.

When I got my shafts.. I thought.. jeez they are kinda puny .. but thats the way it has got to be unfortunately..

Ben is also correct in saying the overall shaft should be smaller than the spline itself otherwise it will just crack at the edge.

Slider Engineerin'g recommendation was to somehow fit bigger uprights so bigger CV's can be used.. I dont know how that is ahievable though.. something to think about ( maybe getting bearing with more bore to suit CV's of other vehicles???

i had very similiar problem and your right next was the gearbox i just dont pop the clutch every time i drive it seems to be working so far

I'm pretty sure Austin Maxi C/Vs will fit a Mini hub, these have a bigger size spline inside.
Would probably need to get from UK or NZ though, as we never got em in Oz.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I used morris 1300 auto/morris 1500 CV's same spline size for drive flange but has a bigger bell on the cv so uses a bigger shaft spline same size as an austin 1800. The only problem is the CV shaft/spline that goes into your bearings and drive flange is 3/8" longer so requires a spacer to be fitted.
Josh I could probably some shafts made by slider if you wanted.

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4efte powered Clubman
supercharged 998 race car

Thanks for the offer Ben, I'm getting some quotes now if it doesn't work out i'll let you know

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Starlet Conversion:
http://www.ausmini.com/forums/viewtopic.php?t=15484

I wonder whether the use of a half shaft (equalising shaft) could have reducing the chance of this happening? Although, I have not seen any of the 4EFTE conversions use a half shaft yet. Everybody must love torque steer

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-Alan
I blame my dad for my love of minis. I think I was conceived in the back seat of one
I also blame my Dad for me being 6' 1" - not really the optimum height for driving a Mini.

A certain type of Hyundai CVs fit mini swivel hubs. David Rosenthal showed me when I was down at his workshop once. We tested them and they fitted nicely, he said they were from an "Elantra" maybe, but definitely not "Excel". I forgot to check if the splines were larger though - my guess is they probably are.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T