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MG Midget and Sprite Technical - bent rear axle

Ive had trouble since getting the car with oil in the brakes on the LHS, RHS no trouble at all.
I even went to double bearing hubs and sealed for life bearings to try and solve it, but today, whilst investigating my axle noise , found the brakes full of oil again...

Beginning to despair... and swear....

The noise in my axle was not infact the diff, but the inner bearing of the two from the LHS hub which had given up and become very rough, after less than 1000 miles.

Just by chance i noticed that when turning the hub, with the half shaft inserted but not screwed down, a gap appears at the back between the hub and halfshaft face.

Further investigation shows that , if you measure from the top of the wheelstud to the half shaft with the stud at the forward position, then rotate half a turn and measure at the same place there is half a mm difference.

The half shafts are new, and i checked them with a square and seem true.

I re-attached my old standard hub and got the same measurements.

So if the axle is bent on the LHS and with everything bolted up tightly then there would have been excessive load on the inner bearing which would explain why it failed so quickly. And also would explain why the standard arrangement leaks also due to the seal constantly flexing.

I bought a new main bearing with double seals, managed to get a new oil seal which fits in the place of the inner bearing on my double bearing hubs so now it only has one bearing as standard, used lots of RTV and bolted everything up tight again.

Not expecting it to last long though.

If my axle is bent, what can i do...?






Andy Phillips (frankenfrog)

Thinking about it, there are signs of accident damage,, there is only one mounting for an ARB, the LHS mount isnt there, and the A-arm was all bent and had been welded also..
So maybe the axle was bent in a collision ?
Andy Phillips (frankenfrog)

strip down and straighten it, or replace, seem the only options.
Glad it's not a problem with the diff that came from me!
David Smith

Axles can bend perhaps as a result with an impact with a kerb or similar.I had a similar issue with a axle and took it to Mallock racing. They used to use A series axles and had a long steel shaft which was turned to just fit in the hubs ends. If if fitted straight through all was well. If not the axie was tube was straightened using a large mallet or similar until the rod could slide cleanly through. Mine was straightened this way and all was well. Is it possible to do some thing similar?

Bob Beaumont

For no more then a complete axle assemble cost on ebay...

Id just replace the entire thing and be done with it...rebuild it before installing

Once something is bent, and wears it just keeps wearing other parts...

Check your wheel and see if its bent

Prop
Prop and the Blackhole Midget

And of course the wheel is wobbling also, and the brakes must be compromised probably been pushing the wheel cylinder in and out etc
cheers Rod
R W Bowers

Prop do you have any idea how much it costs to ship something as big and heavy as an axle casing to Thailand?
David Smith

We check ours for straight after welding by supporting each end in a V-block and rotating the whole housing, using a dial indicator to measure any run-out.
We use the shrinking effect of red heat after cooling to achieve straightening, but a press or a suitable mallet could do the job.

Over the length of the seal area, zero runout is preferable, but less tha 2 thou over this distance seems to be OK.


Paul Walbran

Thanks for comments... if i lived in uk, or America, then i would just get a new one, but i would have done that a while ago already instead of grafting mitsubishi brakes on as i have (they work great by the way except when full of oil..)

Dave, ive still got 4 years left on the warranty you gave me with the diff.... ;)


Pauls method of straightening seems easy enough, i have some vee blocks, and a mallet, and access to a press if i need it, and i can borrow a DTI gauge from work, so i'll give it a go.
Ive heard of people doing it with heat before, Paul could you explain a bit more.. ?
Do you just heat one side of the casing to red then let it cool down ? or do you have to quench it ?
Then the heated side shrinks to smaller than before pulling the casing around a bit towards the heated side ?

The steel rod method makes sense too, is the diff left in position during this procedure ? or was there some dummy diff inserted with holes the same diameter as the ends of the chassis?

It'll be new year before i'll be able to get time to do this.. have to put up with it till then
Andy Phillips (frankenfrog)

Andy, yes, just as you describe. We don't quench it. Heat to a red hot spot about 15mm wide then work in a line (rather than a very wide patch) along the side you want to shrink. Try an inch first and see how much effect it has and then go more or less heated length from there as required. If it overshoots, then it's back to the other side ...

With welding (which I know isn't the case here) I find that the first weld pulls it the most by a substantial amount. So generally, if welding a bracket or whatever on, I run a dummy weld, about 1/4 the length of that needed for the bracket, down the other side of the axle first to bend it the other way. That leaves the exle requireing only a bit of final tweaking.
Paul Walbran

Where do they actually bend? Is it just the short section after the flange, or further back along the length towards the diff casing?
Lawrence Slater

It seems its more of the casing up to the diff housing. I was amazed when Mallock straightened mine how easily it moved.
Bob Beaumont

How about frequent hard bottoming out against the bump stops? I wonder if that could cause it over enough time.
Lawrence Slater

heard of people straightening land rover axles by running a line of weld along the inside of the bend. My LR axle has a massive bit of angle iron welded to the bottom of it that seems to keep it straight.

It's interesting that it is even possible under normal driving, it looks like such a strong thing. Is there a way to check it's straight without taking it all apart?
Rob Armstrong

I think spridget axles are very lightweight compared to others...

I bought a mitsubishi lancer one from the scrapyard to get the brakes off it , they had to get the forklift/crane to get it to my truck, then it was very difficult for me to move it around in the garage...

it weighed more than my engine block.

My spridget one i can just lift and move around no problem
Andy Phillips (frankenfrog)

Thailand ???

Sorry about that andy... I didnt pay that close atten to your location

At the risk of thread drift, how did you get a car into or find a midget in Thailand....thats a lottery feat if there ever was one.

Back on thread... considering im willing to try almost anything once, im not so sure id be willing to try my hand at sausage making, and really, im not sure I want to learn how axle straightening sausages is made....that is just insane

Im wondering if broken rear axles are a result of the housing being flexed if there this easy to bend

Prop


Prop and the Blackhole Midget

Bob, does Mallock still offer that service? I haven't been to their place in years (last time to pick up a Lola in 1982 or 83). I've welded loads of brackets onto my axle case and hope it's not bent - but it likely it might be - and so it would be handy to know.
Nick Nakorn

Nick to be honest, I don't know, it was a few years ago when I used that service. My post was really to illustrate that axles bend relatively easily and that the long rod used by Mallock was one solution!

They must still maintain the older cars for customers so that chances are they can help. Worth a call perhaps?
Bob Beaumont

This thread was discussed between 22/11/2014 and 24/11/2014

MG Midget and Sprite Technical index

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