Broken axle shaft

Mick70RR · Post by **Mick70RR** » Mon Jul 27, 09 2:08 pm

Few pics of the broken axle shaft. This happened on the start line on Saturday, first run.

Ivor · Post by **Ivor** » Mon Jul 27, 09 2:17 pm

Just been looking at this with my metallurgist and he reckons that apart from the obvious twists in the spine, the black granulation in the centre shows that the shaft has been weakened internally for a long time and the strength in the shaft has only been provided by the outer circumference and that centre pip...which by rights means that a sound set of 8 3/4 shafts should be able to handle 600 horse easily.

Well that's what I think anyway!

I don't think you need a Dana yet Mick...

Dave999 · Post by **Dave999** » Mon Jul 27, 09 2:42 pm

keep that and flog it to someone who wants a shortend axle

half the jobs done and you found the weak bit

Dave

Pete · Post by **Pete** » Mon Jul 27, 09 2:55 pm

Sorry to hear that Mick - now you know why 4 speeds are called "Parts breakers"! They will find the weak spot in any transmission set up.

Were they stock or Mosers/Strange??

Anonymous · Post by **Anonymous** » Mon Jul 27, 09 2:56 pm

Bad luck Mick , you can see where the splines twisted , time for some aftermarket shafts & slicks.

Mick70RR · Post by **Mick70RR** » Mon Jul 27, 09 3:21 pm

Just ordered a pair of NHRA approved shafts from Dr Diff. These were stock shafts Pete, like Ivor said, probably been weakened for a long time.
Unfortunately, I had to drop the carrier to get the splined piece out, I tried with a strong magnet but it wouldn't come. Once I got the carrier out and tapped the thrust block it fell onto the bench. Gave me a chance to look over the new ring and pinion I fitted a few months ago and it all looks good.
This is one of the reasons I have been reluctant to run slicks but the BFG drag radials are just as grippy when they have a bit of wear on them.

Pete · Post by **Pete** » Mon Jul 27, 09 3:34 pm

If they are stockers then they have done pretty well over 39 years.....time for them to have a rest..

andyrob · Post by **andyrob** » Mon Jul 27, 09 3:38 pm

join the club mick, bust your car on the first run

lots of standing about talking Bananarama! & drinking for the rest of weekend for me
3 years in row ive bust a car @ the nats

Mick70RR · Post by **Mick70RR** » Mon Jul 27, 09 3:44 pm

First time I have ever had to be recovered Andy, guess I've been lucky. 3 years in a row, I'd call that bad luck.

Ivor · Post by **Ivor** » Mon Jul 27, 09 3:46 pm

andyrob wrote:join the club mick, bust your car on the first run lots of standing about talking Bananarama! & drinking for the rest of weekend for me
3 years in row ive bust a car @ the nats

I reckon you do it on purpose Andy!

Mick70RR · Post by **Mick70RR** » Sat Aug 08, 09 1:47 pm

Fitted the new shafts this morning.

Green68 · Post by **Green68** » Wed Aug 12, 09 8:39 pm

Hi Mick,

Seen this alot lately with 30 spline shafts!

I think time is catching up with these old parts?
Modern tyres are very grippy, and the old shafts can't take it!

I'm gonna be going with 35 splines with my 4-speed, just in case?

Better luck next time out!!!

P500.

Mick70RR · Post by **Mick70RR** » Wed Aug 12, 09 8:49 pm

These are Yukon shafts, induction hardened 1541h steel alloy, about 25 percent stronger than stock shafts. Just hope they're up to the job.

35 spline shafts would be nice but what do you use for a suregrip? I've only seen spools available for the 8 3/4 with 35 splines.

Green68 · Post by **Green68** » Wed Aug 12, 09 9:24 pm

Hi Mick,

Here lies the problem,

STREET or STRIP???

30 splines and a locker for the street and 35 splines/spool for the strip!

That's the dividing line I believe

4-speeds are a Bitch, they bust everything Wussy!!!

P426.

ps why do ya think Mother Mopar fits DANA's