I broke a couple of early type axle shafts when I was running fully locked
spider gears. Once I switched to an LSD and the axles pictured above, no problems. I have wondered if the limited slip gives the whole system a little give an protects the axle?
I snapped an axle while racing yesterday in my Montreal. It happened on the fastest corner of the track at about 140km on corner exit.
At first I thought I had been hit from behind, and it was a scary ride for 150 meters in the gravel trap, as with the car raised in the front it sort of surfed the gravel trap instead of digging in and slowing down.
This is the second snapped axle, last time it was the right hand side and the damage to the car was real bad, this time it was the left with minor damage.
I've fitted a 105 shaft one at the track from another racers spare to get me "mobile" to allow me to get the car on and off the trailer. The 105 ones are an inch shorter than the Montreal ones and only just engage into the LSD about 5mm (So I run the risk of stripping the splines if I attempt to drive it)
My problem is that if I get another Montreal one (most likely only second hand) It will be 40 yrs old and I'll run the risk it breaking again, and this time perhaps I won't be so lucky, and a concrete wall might not be as forgiving as a gravel trap. So does anyone know of an axle shaft manufacturer who is currently making billet 105 ones so I can have some new ones made up to the slightly longer length that the Montreal requires?
Many thanks Frank. I'll keep them in mind. At this stage I'm thinking of having some billet ones made up out of 4140 which will be much stronger than the standard cast ones, so I'll let you know if I have no luck.
Just a question.... Are the pictures you posted of the Montreal ones? As my axles are threaded and have a castellated ring nut to secure the bearing onto the shaft, I’ve not seen this on 105 ones so presumed this to be peculiar to the Montreal.
For new axles, talk to Moser Engineering (in Illinois) or Mark Williams (in Colorado. They happily do customs.
The stock axles are most certainly NOT cast, they are forged.
4140 is not a bad alloy selection for axle shafts, but is NOT necessarily the best.
Induction hardened shafts are likely the best way to go.
The REAL solution, especially for racing, would be to convert the rear wheel bearings to a 3/4 floating design--peek at an MGA rear for an example of this design. It removes the full alternating stress (due to vehicle weight, cornering loads, etc.) from the outer end of the shaft (EXACTLY where yours broke) and thus solves the problem.
The 3/4 floating design is a lot lighter and simpler than the classic full floating design, and almost entirely as reliable. And, just as with a full floater, the wheel bearing(s) run in gear oil, NOT grease. Another good thing about it.
Any tech inspector/racing organization that objects to such a conversion in any way deserves nothing more or less than a summons and complaint !!
Your break is a classic fatigue failure, and endemic to semi floating axles, particularly in racing applications.
Glad you had an angel riding on your shoulder (TWICE!!!!). It's not at all uncommon for the rear wheel/tire to roll its way out of the wheel well and pitch pole the car over the opposite corner. Many racers have died this way !!
I wouldn't take a GIFT of a used axle for this application, particularly where there's a past history of failures !!
Have a 2 liter axle resplined to the smaller 105 spline size.
Simple as well, convert to a 2 liter LSD Diff.
I build 105 sized LSD units by machining 2 liter LSD carriers to match bearing & ring gear positions of the 105 smaller unit. Then welding up the splined ends of the 105 axles and re-splining to fit the larger 2 liter drive splines which fit the LSDs units.
Precisely. And the ID of the inner race of the carrier bearings for the 2 liter axles is also much larger than it is in the earlier axles. hence my comment. Boring the carrier from an early axle to accept the late axle shafts would tend to leave the bearing seats on the carrier on the thin side.