standard or 4.5 diff.

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squizzel
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standard or 4.5 diff.

Post by squizzel »

The rear axle in my 1971 traveller has cracked the casing and blown the diff. I have the option of a guaranteed used standard one from a 1969 saloon. ( which i think is a straight swap with the traveller). Or a rebuilt 4,5 axle and diff. Its had a pin welded on for a pan hard rod ( that isn't needed).
It also has new saloon springs so they need changing for the 7 leaf traveller ones. Which one is the better for a standard traveller?
Also have an option for a complete rear axle including drums from an MG midget / sprite, with a 3.9 : 1 diff. will this fit, and are the moggy brake shoes / cylinders the same or do they need specifically the midget ones?
Thanks
Last edited by squizzel on Tue Nov 19, 2019 6:17 pm, edited 1 time in total.
myoldjalopy
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Re: standard or 4.5 diff.

Post by myoldjalopy »

If its a standard 1971 traveller, the diff off a 1969 saloon will be the same as the one you had (4.22) so you might as well use like for like.
squizzel
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Re: standard or 4.5 diff.

Post by squizzel »

Thanks for the quick reply
Is the axle casing a straight swap as mine is scrap.
Thanks
ManyMinors
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Re: standard or 4.5 diff.

Post by ManyMinors »

I'm not sure how a cracked axle can "blow a diff" but if you're saying that you must replace the whole axle including the diff and the only options are using an axle from an earlier Minor 1000 (4.55:1 ratio) or that from an MG Midget, you'll have to use the axle from the Minor. An axle from an MG Midget will not fit. The track is narrower on a Midget although the 3.9:1 diff WILL fit a Minor 1000 axle and indeed is very sought after.
If you use the axle from an earlier Minor 1000 with the 4.55:1 diff and wish to fit a 4.22:1 or 3.9:1 diff into it you will have to alter the axle to accomodate an oil filler plug as this is within the diff casing of the 4.55:1 differential but within the axle casing on the later cars...... If you simply fit the whole axle assembly then you will have a car you can use perfectly well although your overall gearing will be a bit lower of course.
philthehill
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Re: standard or 4.5 diff.

Post by philthehill »

A photograph of the axle damage would be appreciated so that other owners can be a aware of possible problems and take action as necessary.

Is the damage at the spring seat? That is a known corrosion hot spot. If bad -the spring seat can break off the axle casing.

I would recommend changing the axle casing/diff like for like. The 4.5 and 4.22 filler plugs are in different places and whilst the diffs are interchangeable in the casings the 1098cc diff requires the axle casing with the filler plug in the rear of the axle banjo otherwise it is very difficult to fill the axle with oil.
The 4.55 diff has the filler plug in the alloy diff housing and can be fitted to the 1098cc axle casing giving two filling points.

The MG Midget axle casing is too narrow for the Minor.

myoldjalopy
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Re: standard or 4.5 diff.

Post by myoldjalopy »

squizzel wrote: Tue Nov 19, 2019 6:21 pm Thanks for the quick reply
Is the axle casing a straight swap as mine is scrap.
Thanks
Yes, if you have the axle and diff from the 1969 saloon......
squizzel
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Re: standard or 4.5 diff.

Post by squizzel »

Yes the axle casing has cracked by the u bolt for the spring. It dumped the oil on my way home from work, i didn't know as it was ok when i started home, ( no oil visibly on the works car park). Almost home it went with a bang and is now knocking really bad. I have had a quick look underneath and the prop shaft seems ok, but the play in the diff is like there's a couple of teeth missing from one of the gears. I can get it in the air tomorrow and have a good look.
I was just wondering if i am replacing the axle if there was a better option as a straight swap, as i don't have the time to mess about with it really. Plus i am working outside.
The standard axle and diff has a guarantee and i can have it for £90, if i fetch it. The complete 4.5 is a rebuilt axle, i:e new drums, bearings and a rebuilt diff, but its £295.00 if i fetch it.
liammonty
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Re: standard or 4.5 diff.

Post by liammonty »

All the above points are excellent, but you haven’t said if you are concerned about altering the drive ratio on your car - if you put the 4.55:1 diff in with your 1098, it will feel really low geared. Maybe this wouldn’t bother you, but I would find it very frustrating running out of revs at a lower speed than with the standard set up.
squizzel
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Re: standard or 4.5 diff.

Post by squizzel »

Yes that would be a bit of a pain. I will go with the standard axle. Just got to confirm that it is the diff that's gone, I did look in the dark but it seems to have loads of play. I will get it up on stands in the morning.
Thank you all for your help, i really appreciate it.
myoldjalopy
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Re: standard or 4.5 diff.

Post by myoldjalopy »

Both 'philthehill' and I have suggested (and 'liammonty' has hinted) that it will be best to replace like for like and as you can get that for £205 less than the other set-up, its a no-brainer, really.......
squizzel
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Re: standard or 4.5 diff.

Post by squizzel »

That's what i am going to do, i'll stick with the standard diff.
Thank you all for your input and advice.
Declan_Burns
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Re: standard or 4.5 diff.

Post by Declan_Burns »

See how much you get get the Midget axle for. You could just keep the diff and sell the rest on and maybe cover some of your costs. The 3.9 diff would be a great improvement.
Regards
Declan


Regards
Declan
ManyMinors
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Re: standard or 4.5 diff.

Post by ManyMinors »

I had mis-understood the initial post which I thought read that there was a standard diff on offer rather than a complete axle. I agree that if a complete axle of the correct type fitted with a 4.22:1 diff is available then that is the best option.
I also agree with Declan that a 3.9:1 at the right price is well worth acquiring. As I said earlier, these are very sought after.
I still don't understand how the cracked axle has caused the diff to fail though??
Edward1949
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Re: standard or 4.5 diff.

Post by Edward1949 »

ManyMinors wrote: Wed Nov 20, 2019 4:14 pm
I still don't understand how the cracked axle has caused the diff to fail though??
Maybe run dry after total oil loss through crack?
ManyMinors
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Re: standard or 4.5 diff.

Post by ManyMinors »

Maybe - but seems unlikely during one short journey :-?
philthehill
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Re: standard or 4.5 diff.

Post by philthehill »

I suspect that the oil has been leaking out from the crack/damage at the axle spring seat bracket for some time and the axle case was already empty of oil when you were parked at work. It finally gave up the ghost on your way home. If there is no oil the diff will soon fail.

As I said above the axle spring seat brackets which are welded to the axle casing are a well know dirt trap; and if not regularly cleaned out will soon rust the axle spring seat bracket away from the axle casing with accompanying damage to the axle casing. It is not unknown for the axle casing to collapse in the area of the axle spring seat bracket when the corrosion has been left to its own devices.

Prevention of rust around the axle spring seat bracket is a must.

myoldjalopy
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Re: standard or 4.5 diff.

Post by myoldjalopy »

One would expect a diff running without oil to be very noisy, thus alerting you to the problem.................at least, that has been my experience on one occasion, but the diff certainly didn't break.....it hadn't run completely dry.
squizzel
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Re: standard or 4.5 diff.

Post by squizzel »

O k so an update on this problem.
I do have a crack in the axle case around the nearside spring seat due to corrosion, although it is very small at the moment. There is a fair amount of oil on the underside of the body, but none on the floor where its parked and the diff was 1/2 full of oil when i checked it yesterday. There is no whining noise, but there is an excessive amount of backlash in the diff, this isn't what is causing the loud knocking though.
I have been away for just over a week so the car has been parked up on the drive, and it seems someone has tried to pinch the alloy wheels off the car. The knocking was the rear wheel loose.
So i have managed to get a really good rear axle case from a traveller, it has a 4.22 diff but that is unknown if its good or not. Its cost me £30 and the fuel to collect from 40 miles away, so completely worth it for the case. I intend cleaning it up and painting it, while i do this i can strip the diff and give it a service, also i can keep an eye open for a 3.9 diff if one comes available and rebuild it with that in is an option.
I am certain it will hold out until the weather is a bit better, as i currently shouldn't be pulling axles out of cars, i have a torn rotator cuff muscle and am due for an operation in January. I would have done it if necessary, but its really not advisable at the moment, plus i won't be able to drive for 12 weeks anyway.
I would like to thank you all for your input and advice i really appreciate it.
IslipMinor
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Re: standard or 4.5 diff.

Post by IslipMinor »

If you are anywhere near Oxford, we have a full-length 'stand in' depth pit, with lights, air etc., that you are welcome to use. It's warm and dry too!

Assuming the replacement axle is near to a 'straight swap', then 1/2 day's work should see it done, but allow 1 day to be sure!
Richard


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