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MG Midget and Sprite Technical - Diff doubts

Probably a bit premature concern this, - I need to do a little investigation tomorrow.
But, thinking of the diff and /or half shafts,
With car in gear and one rear wheel lifted off the ground I have a lot of 'lash' at the wheel rim. I mean around 6" which seems really excessive!

I just wonder if I have a broken half shaft? But if that were the case wouldnt the wheel rotate 360 degrees, rather than just this 20 or so degrees. Unless it has broken, but there are lose bits jamming the planet gears. Any thoughts?
GuyW

Badly worn thrust washers behind the planet gears/sun wheels?
Dave O'Neill 2

Could be that Dave. I have replaced them on that dif before. Oddly though, I have never had a broken half shaft so not too sure what to expect. If for example one had broken and the splined end bit got lodged somewhere where it shouldn't be.
GuyW

Does it lock up at the end of the 20 degree rotation? Or if you keep going does it turn the prop shaft?

If broken, even if it left a chunk in the gears, the shaft/wheel would rotate freely.

Sounds to me like a lot of 'lash', for what ever reason, rather than a broken shaft.



anamnesis

That's what I thought - if the halfshaft has broken then surely the wheel would keep turning?
Bill B

Worn splines on the halfshaft?
I have some spare halfshafts (2 pairs) and a diff gear that the shafts engage into. One pair of shafts is a very loose fit in the gear with lots of rotational movement, looking at the splines there is lots of wear. The other set of shafts are a really snug fit into the gear with no play - ironically these are the older shafts!
On my car I also have quite a bit of rotational free play, although not as much as Guy has. But after 64 years and 110k miles I guess you would expect some wear!
Les Robinson

Hmm! Just tried again and lash at wheel rim is down to about 1&1/2" . Quite happy with that!

So what was the difference, you all ask!
Third, not first gear selected. Or maybe it was even 5th! I did warn it was a bit premature. Leaning in through the passenger window as no room to open the door, to put it into gear in the dark, not quite accurate enough! Sorry!!


On a happier note car fired up for the first time in 6 months since engine went back in. Other than waiting to fill the carb and pump a bit of oil round with the plugs removed. It then started literally on the first compression stroke! That engine has always been a good starter!
GuyW

When's drive it again day then Guy?

anamnesis

Fair while before that Anam. I only really took the engine out to refresh the engine bay. Cleaned it all down, some welding and then repaint. But the car needs a complete external respray. Brakes will want a rebuild too I think as its been standing that long! Project car really,but quite hard motivating for it. I seriously thought about parting it out as it has a lot of 'special" components that individually make up to quite a lot, quite likely more than the complete car! Problem is there is little interest this far north, very few Spridgets within a 50 mile radius. Digits on one hand sort of numbers.
GuyW

Isn't this your Sprite that you've had for ages? I guess now you have the frog on the road, motivation does become an issue.

I'm certainly glad now I've decided not to get another 'classic'. My single Sprite is enough.
anamnesis

Yep, 'bought' (it was free) in 1989. It was 18 years old and had 17 successive owners, so was well run in by then. PO had it stored for 3 years to be used as a parts donor car, but that never happened.
GuyW

When the halfshaft was broken you would be able to drive as all traction is lost
Im an expert as Ive busted 3 halshafts before upgrading the rearaxle...
A de Best

If you find you have worn spider gears and you cannot find a good set locally, I have good ones which I could post to you. Not sure what a reasonable price would be but guessing about $150 Australian might be about right. I think they are not available new.
The ones I have are in sets (wired together) removed from diffs (about 40) I converted to suit MG TCs many years ago. They come with the dished small thrust washers but not the big flat washers because the latter were used in the conversion. Because I converted so many diffs, and many were Morris Minor (mostly not driven hard) there is a number of good sets to select from.
I will check this site over the next few days in case you are interested.
Bob Schapel
South Australia
Bob Schapel

Thanks Bob. I dont think I need any as its not so long since I rebuilt this diff anyway. Well not long in mileage at least!
But I do remember you mentioning this before and thinking it would take a good while to find homes for that many sets, one pair at a time! I wonder if you could strike a deal with one of the major spares suppliers. Moss, or perhaps more likely with the MGOC ?
GuyW

I had to make them thinner to fit

Flip Brühl

This thread was discussed between 07/05/2025 and 11/05/2025

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