Broken Sprite axle

[Michael Oritt]

A few weeks ago at VIR I broke an axle at the differential. I could not drive out the stub as it was severely twisted but I had a spare differential and two axles with me and was able to complete the event.

Attached is a shot of what was eventually pressed out of the differential--this is a Winner's Circle axle though its age is unknown and of the old pattern with the bolt in the end of the flange. The WC axle on the other side had about a half-spline of twist, no doubt from the shock of this one's breaking. BTW I had inspected both axles just prior to the event when I changed from 4.2 to 4.5 differential. They both appeared fine.

I'm not complaining--just sharing fun racing experiences.

 

[aeronca65t]

Yep....broken Sprite axles! Part of the joy!

What's interesting (to me, at least) is that you broke the splined end.
I've seen this happen (in fact, I saw Chris_S's car do this at Pocono), but in over 10 years of street and racing (with over 125 hours of track time), my Spridget has never broken one at the inner end. I've broken well over a dozen at the outer end (three last year at the BeaveRun/Pittsburgh Vintage event). Probably because I'm only pushing about 70 HP and mostly running skinny (185) DOT race tires.

I had one break about 1" inside the outer hub last year at the track. Couldn't figure out how to get it out! Then I got the idea of drilling into the broken end with a #7 drill and tapping it 1/4-20 TPI (I borrowed the tools from Chris Shoemaker). I was able to thread a 1/4-20 bolt into it and pull the axle out with a Vise-Grip. Now I always bring a 1/4-20 tap and drill to events!

Just to be on the safe side, check your axle housing.....they bend like a banana and it's hard to find a truly straight one. This can lead to axle failure.

Are you running a limited slip?

 

[ChrisS]

As Nial said, I broke them in the same spot, although mine were stock axles; I've since upgraded to WC competition axles. I suspect that the autocross starts did the initial twisting and then they just happen to fail at Pocono. I've got a 5:38 for autocross that I'll run this weekend but I'm going to pull the WC axles and run stock. I can't see putting my good axles through the jack rabbit starts. If I break one or two so be it, autocross is only $25 and 45 minutes away, the track days cost a lot more and I'd hate to waste another one.

How were your axles to get out? I had to weld a nut to the flange and use a slide hammer to get these out. The remaining spines were so chewed up that I couldn't get them past the boss for the differential bearing.

 

[Michael Oritt]

Nial--my differentials (all ratios) are welded.

Chris--looks like we should get our axles together! I had no problem getting the axle out though it must have just cleared through the housing as the stub is probably 1/16" bigger in diameter from having been twisted up like a stranded rope.

I was at Carlisle last Friday and at the WC I showed him the piece that is in the picture--got a chuckle but no offers of replacements, etc. We discussed the concepts of switching sides to "untwist" axles and cutting grooves, etc. but he did not think much of either idea.

I agree that a bent housing could be involved here and I hope to find a cheap one online somewhere and put it in a jig, etc.

 

[bugimike]

The joys of Spridget ownership!! I have been through three axles over the years. Never broke one at the flange end though, all three were as shown above!! /bcforum/images/%%GRAEMLIN_URL%%/eek.gif

 

[Biff]

Michael,

Do not swap sides. Once they twist they are shot. Switching sides to untwist them will only result in them snapping now instead of later. When they twist the metal takes a set and when reversed they are weaker.

 

[DrEntropy]

Metallurgically speakin' the steel is being embrittled by being "work hardened". Reversing the stress nearly guarantees fracture. About the same as 'wiggling' the tab off'n an aluminium beer-can. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif


...scampers back to th' hovel...

 

[bugimike]

When mine went, the broken ends looked like they had "shattered" or "crystalized". Nasty little slivers!!

 

[mrsprite]

Well, I'm sort of happy that I'm not the only one snapping these things! I've broken 3 axles on my Bugeye in the past 6 months......2 at the splines and the other one at the hub.

 

[DART]

You Sprite/Spridget racers are going to have to upgrade the rears when you drop those V8's in. /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif