C Streit

I recently discovered mine was sheared off just past the splines on the rear stub axle... Wondering why it happened....

Derrick B.

Unfortunately, I cannot help you with the why's and how's beyond speculating that some type of corrosion (chloride stress corrosion cracking?) weakened the stub.

I can, however commiserate.

The summer of '85, two young lads are overjoyed at the chance to drive Dad's 1969 Lotus Elan drop head coupe in the afternoon sun. My brother and I made it a half a block.

The passenger side axle broke right by the rubber donut that acts as an "add lightness" version of a U-Joint. We pushed the car home (I guess that light weight is good for a few things after all). As I wasn't accelerating hard with all 115bhp at my disposal, I don't think it was too much power that caused the failure.

Good thing my younger, more trustworthy borther was with me to corroborate my story. I could have been a dead man. Honest Dad, I don't KNOW how I broke the Lotus's axle in two!! :-)

Do you have a picture for the metallugists on the list?

C Streit

Here's a crappy picture... I've added some dots for reference. The outer dots define the axle where it narrows for the castellated nut. The inner dots show where it is clear the axle was pulled and broke in tension. Between the two looks like it's sheared. My guess is a crack propogated from the outside edge, then finally enough strength was lost as it got deeper untill it pulled off in tension.

I guess I'll magnaflux them every year...

<img src="http://forums.pelicanparts.com/uploads/csPICT0005.JPG" alt=" - " />

Steve Weiner-Rennsport Systems

Hi Chris:

Sorry to see that pic,.....I'm familar with that situation, myself.

Those pieces are rather stressed from shock loads and any tiny nick in the machined surfaces or a stress riser will start the process and a crack will propagate.

On race cars or high-powered street cars, I do magnaflux them every year. Porsche finishes these with a VERY hard surface treatment but any nick or imperfection can trigger a failure.

Derrick B.

Thanks for posting the picture. I hadn't realised the amount of tension that the stub undergoes. What else do you magnaflux annually?

C Streit

Good question. I don't know but I will be checking these and probably the fronts annually now... Of the many things I'd have drop off the car during a race, the wheels are WAY down the list... (Right above the drivers seat.)

Jerry Forthofer

About seven years ago I had one break on my track car as I exited turn one at Road America. Pretty exciting!!

The car was a 1982 911SC narrow body with a turbo motor and turbo half shafts. I had not magnafluxed the half shafts, but obviously should have.

CamB

The summer of '85, two young lads are overjoyed at the chance to drive Dad's 1969 Lotus Elan drop head coupe in the afternoon sun. My brother and I made it a half a block.

The passenger side axle broke right by the rubber donut that acts as an "add lightness" version of a U-Joint.

Wow. The only car I know of to break an axle is an Elan +2. The freaky bit is that it had been converted to proper CVs and axles - they weren't even dodgy Lotus parts anymore!!!! But still, the ghost of Colin Chapman made it break...