Taper attachment

[magicniner]

The (bevel) gears on the end of the halfshafts

Half-shafts don't have gears on the ends, they have splines, these fit into sockets in the differential, half-shaft splined ends are not driven directly by any gear.

 

[British Steel]

I sit corrected... So power is transferred to the halfshafts from the diff, via a gear carrier with the bevel gear at its inboard end, and the stress raisers are the cuts for the splines, I take it? So the spline effectively goes into a gear...? Wouldn't be a diff' otherwise?

Dave H. (the other one)

 

[mickri]

Lots of confusion on the parts in a midget rear axle. Here is a parts diagram.



The axle haft shafts, #29 or #30, have male splines on the inboard end. These splines fit into the gear, #20, which has female splines. Because of flex in the axle housing the upper edge of the outer edge of the gear, #20, bears on the splines of the haft shafts. This creates a stress point on the haft shafts and the half shafts typically break at this point. The haft shafts rarely fail at the flange on the outer end of the haft shaft. When you growlerize the haft shaft as described in a previous post the outboard end of the gear no longer bears on the haft shaft eliminating the stress point.

 

[magicniner]

This photo makes it easy to see both the relationship between shaft and gears and also the differential function
The author's arrow is pointing at the gear with which the shaft engages.

 

[mickri]

I am going to order a coupler nut from McMaster Carr later today. I looked at the lead screw again and as best as I can tell without an acme thread gage is that the lead screw is 1/2 x 10 tpi LH. If I am wrong on this would someone please let me know. My lathe is a craftsman 12x36. I have some 1/2" StarBoard on hand which I will use for the end plate StarBoard is polyurethane plastic that I have used on my boats. If this taper attachment works to my satisfaction I will replace the StarBoard with steel. I am going to use a 3/4" shaft and will turn down one end to 1/2" to fit into the coupler nut. I will drill and tap the coupler nut and the shaft for a screw. Either 1/4x20 or 10x24. The other end I will turn down to 3/8 and thread for a 3/8x16 nylock nut. This will leave a shoulder on the shaft for the wheel to fit against when tightened with a nut. I have a piece of 3" diameter aluminum on hand and will make a wheel out of this.

So that's my plan of action at this point. I could use some help on the math to calculate the diameter of the wheel.

 

[Tozguy]

Back in the 60s I used to carry a spare half axle in the boot of my Bugeye Sprite because they were not very strong and sometimes had to change it at the side of the road to get home again. Then I shoehorned a 1500 engine into the Sprite. The rear axle splines were cut off and a stronger spline from a scrapped transmission was welded on. I had it done and don't know which transmission the stronger splines came from but they never broke after that.
Growlerizing makes sense to avoid concentrating stress at the end of the spline but does it make the axle stronger?

 

[mickri]

When MG went to the 1275 cc engine in 1967 they also changed the steel in the half shafts from EN7 to EN17. I have put a 1969 rear axle in my midget so I have the stronger half shaft. From what I have read on the various midget forums is that it was not that the axles weren't strong enough but were too stiff. Growlerizing allows the haft shaft to flex a little and eliminates the hard stress point. A late model haft shaft is supposedly good for 100 hp or a little more. Growlerizing increases this to around 150 hp. I am going to swap a toyota engine with 75 to 90 hp which I might modify up to around 100 hp.

 

[Tozguy]

Sounds like you are having fun. Makes me wonder why the factory did not pick up on concept and 'Growlerize' OEM axles at some point.

 

[mickri]

I don't know if growlerizing was known during the production run of these cars. Also these cars were low end price point cars and growlerizing would have required extensive machining adding to the cost of these cars. The original bugeye sprites had round rear wheel arches which allowed owners to fit much larger wheels and tires. This contributed to haft shaft breakage. Rumor is one of the reasons MG changed to the square rear wheel arch was to prevent owners from doing this. It was cheaper to change the stamped steel rear fenders than to make stronger half shafts.

 

[Tozguy]

The principal behind Growlerizing is not new. It has been used extensively for bolts and screws in high stress situations like connecting rod bearing caps and cylinder head screws for a long time now.
In post no.27 there is mention of upgrades by the factory and by then the R&D types must have known about that option.