UPDATE! Half shaft and hub modification - other options.

Post by **PHUQ** » Fri Dec 19, 2014 10:08 am

Do you have any more info on them David? I assume standard bearings etc. and it's just a beefed up shaft (probably easy enough to do with materials selection/ heat treat/ improved machining etc).

david painter · Post by **david painter** » Fri Dec 19, 2014 10:33 am

On a Caterham the tyres are much more likley to be wider and very sticky, possibly even slicks. Not the standard 165, 185 road tyre and without a LSD as found on most Marinas. Meaning when a marina is driven hard it will tend to spin the inner rear wheel, as the weight transfer makes this corner of the car light. This will tend to wind the half the haftshafts up as the wheel suddenly grips. Most halfshaft that I have seen break tend to be at the spline where it goes into the diff. You can usually see whre the splines have been twisting. Shafs that break at the other end is often due to the way the wheel bearing has been changed by using heat rather than a press to change the wheel bearing thus changing the structral integraty of the metal in the halfshaft, possibly dropping it in a bucket of water to cool it quickly making it very hard. Dropping the clutch is just as likley to rip the lining off the clutch plate or ripping the centre out of it, as break a halfshaft.

Dave

Post by **balmy** » Fri Dec 19, 2014 10:34 am

Just a beefed up shaft as far as I know.
Want me to be the forum tester?

Let's face it-if they survive my hooligan driving then they should be ok

Post by **PHUQ** » Fri Dec 19, 2014 12:35 pm

I dunno, the factory ones haven't gone pop yet...

But yeah, gowaaan, treat yourself, tiz the season and all that...

Post by **balmy** » Fri Dec 19, 2014 1:08 pm

I have broken half shafts before. Twice. Maybe three times. And munched a couple of gearboxes. In a standard 1.3

But can't lunch the TC ones. Yet.

Will do something about half shafts promptly. Getting the head done soon. Hopefully a Peter Burgess one.

Post by **PHUQ** » Fri Dec 19, 2014 2:22 pm

Yeah, but you were young and foolish then. Now you are old and, ah, erm... yeah, how come you haven't broken any yet?!

I suspect the control of the material and the machining at the factory was probably none too clever, I wouldn't be at all surprised to find that some shafts are virtually bombproof whereas theoretically identical ones have all the torsional rigidity of a nice mature cheddar. It only takes a small difference in heat treatment, a slight sharp edge (or even localised tempering back from the frictional heating of a blunt tool) from a machining op., or a slight shift in core material properties batch- to- batch to cause fairly significant changes in strength.

Martec · Post by **Martec** » Fri Dec 19, 2014 4:31 pm

How many people have had a broken half shaft?

It has taken me 40 years to find someone who had a lower trunion collapse (both), but he never greased them.

So is the 'broken half shaft' a myth?

In 167,000 miles over 46 years I have had 4 axles and 6 diffs, but never a broken half shaft???

I once contacted 'Caterham' and asked what they did to recondition the marina axles they used at the time and why they got away with the greater power than the marina could put out. Replacement bearings and far less weight of the car was there answer.

Brian

Post by **balmy** » Fri Dec 19, 2014 4:41 pm

I'm er'ing on the side of myth with both gearbox and rear axle. Sure I snapped two axles many years ago but have no idea if it had oil in / bearings where good etc etc.

So far my TC is pushing out 40% more torque than standard and no problems....... Yet.

Post by **MarinaCoupe** » Fri Dec 19, 2014 5:08 pm

The AOX rally car boys snapped their near side half shaft at the splined diff end, on a Tarmac stage at MIRA and that was with a tuned 1.3 engine.

david painter · Post by **david painter** » Fri Dec 19, 2014 5:28 pm

Did AOX have an LSD at MIRA
Dave

Post by **MarinaCoupe** » Fri Dec 19, 2014 5:59 pm

I don't think so, it was only their second outing. They've converted to a 10cwt van axle now with a gripper LSD.

david painter · Post by **david painter** » Fri Dec 19, 2014 7:29 pm

I suspect the failure was caused by the wheel spin on inner wheel when axle goes light then suddenly grips as the weight goes back on putting full engine power throgh that shaft. Speaking of AOX did anymore come of the quick steering racks
Dave

Post by **MarinaCoupe** » Fri Dec 19, 2014 8:36 pm

No unfortunately it all went dead, I'm not sure that they have rallied AOX in a twelve month.

Chicken Hawk · Post by **Chicken Hawk** » Fri Dec 19, 2014 9:41 pm

Be interesting to find some stronger rear axle components just for piece of mind when having a play around....saying that if munched through 3 diff's,2 gearboxes and snapped a prop shaft over the years but never done a half shalf...

Post by **balmy** » Tue Jan 06, 2015 6:51 pm

david painter wrote:On a Caterham the tyres are much more likley to be wider and very sticky, possibly even slicks. Not the standard 165, 185 road tyre and without a LSD as found on most Marinas. Meaning when a marina is driven hard it will tend to spin the inner rear wheel, as the weight transfer makes this corner of the car light. This will tend to wind the half the haftshafts up as the wheel suddenly grips. Most halfshaft that I have seen break tend to be at the spline where it goes into the diff. You can usually see whre the splines have been twisting. Shafs that break at the other end is often due to the way the wheel bearing has been changed by using heat rather than a press to change the wheel bearing thus changing the structral integraty of the metal in the halfshaft, possibly dropping it in a bucket of water to cool it quickly making it very hard. Dropping the clutch is just as likley to rip the lining off the clutch plate or ripping the centre out of it, as break a halfshaft.

Dave

I need to make a decision soon. Just halfshafts ( much cheaper option ) or the rakeway kit. Any opinions?

Dave-point you make above. Thinking about it-I guess an lsd could help-stops the sudden change in half shaft speed when spinning and then suddenly gripping and maybe snapping? Is that what you mean?

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