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MG MG Y Type - Rear Axle - Questions?

After failing the MOT due to a small amount of oil weeping out of the halfshaft flange onto rear brakeshoes, I replaced the shoes with some spare I had, it then sailed through the MOT, but as I drove home into my garage I heard a clunk (I think it was a clunk) and thought nothing of it untill this weekend when I started her up and put it into gear and there was no drive?
The propshaft was turning but untill I dismantle the diff I am assuming a halfshaft has snapped!

1/ Is there any where that sells new halfshafts other than NTG?

2/ what gasket material will stop the oil weeping from the flange?

3/ I am told that if I pour petrol over the contaminated shoes and set fire to them it will clear the oil. is there any other method of cleaning oil from contaminated shoes without having the safety issues associated with petrol? (I want to keep my eyebrows!)

Any answers will be greatfully recieved.
stephen randle

You don't saay whether you have a YA or a YB. They have totally different rear axles.

Clive Evrall
J.C. Evrall

Hi Clive thanks for your reply I have a very early YA
stephen randle

Stephen,

Try the MG Octagon Car Club.

http://www.mgcars.org.uk/octclub

They list half shafts, plus many useful parts.

Richard
R E Knight

Stephen, I am having similar problems with rear axle oil on the brake shoes, but I have found it is the hub seals that are the problem, not the gasket.

I have fitted new seals but offset their mounting position to ensure the lip runs on a clean surface of the axle - you can do this as the new seals are only 8mm thick, while the originals are much thicker.

It does sound like you have broken a half shaft. If you were closer you could have one of my dozen or so spares. I have hoarded them since buying my first Y in 1991, but have never broken an axle since starting my "I'll need that one day" collection of half shafts.

This of course means I will in the near future break an axle as I have tempted fate by revealing my strategy to the universe. I'm pretty sure that is one of Murphy's Laws of Nature.

Tony
A L SLATTERY

Tony, thanks for your comments, I will certainly check this when I dismantle the axle, but the oil was definately around the halfshaft flange.

Richard, I did check the Octagon club web site, but if I fit a second hand one I will need to ensure I have one that came from the same side as the broken one because they twist, but at the moment I do not know what has broken.
But a new halfshaft can be fitted either side. at least thats what I am thinking.
stephen randle

Stephen

If you jack the car up at the rear - both wheels off the ground and turn one in any direction normally the other will rotate in the opposite direction when the car is in neutral. If it does not, then you have a broken half shaft. Welcome to the club.

Yes you can fit a second hand one but you need to determine which side is which. To do this, simply lay the new (second hand) shaft with the wheel hub outer most as if you were going to fit it. The look closely at the splines. You will be able to detect signs of loading or strain against one side. This is in the forward direction. If the shaft you have has the loading pointing to the front of the car then you guessed right and it is for that side. If it is pointing to the rear it is for the other side.

How to fix?
You will clearly need to pull both shafts out (the broken one all the way, the good one can rest inside the axle.

Get an axle set of gaskets from either the MGOCC or NTG as you will need to replace both. Also, get a differential plate cover gasket too and some Hypoid 85W/140 oil. I would recommend Penrite - it is spendy but it is going to last a long time and Penrite does a great job.

Drain the axle (this will take a couple of days as the oil is nasty and thick. If you get bored you can use a propane gun to gently warm the axle and the oil in it ... just remember though you have a petrol/gas tank above you too so dont go too mad.

Once you have most of the oil out, you will need to undo all the nuts on the studs holding the differential on. Pull that out and stick it in an old washing up bowl with some parrafin/Kerosine in and thoroughly wash off all the old oil and all the metal debris. Examine the crown and pinion for damage and hope/pray that the gear teeth are OK. Look at the main bearings too. If the seal at the front is begining to weap then now is a good time to replace that too.

Now inside the axle case you will need to pick out the remains of the stub of the old half shaft and again thoroughly wash out the axle case with parrafin/kerosine. If you leave any shrapnel behind it will get into the crown gears and ruin them so be very thorough.

Once everything is cleaned out and good, then use a straight edge and clean all the surfaces of the differential, the house, both of the half shaft flanges (check your new one for true running too and machine out any warping that may be on it. Remove all rust if any from it having been stored.

Check all flanges for true and clean, then refit the differential and the axles. You will need to "feel and float" the ends of the half shafts into their splined receivers. Dont rush this. If it is frustrating - walk away and come back later. It wont be done by itself, but you need to just keep playing until they slot in. If you want to help them a little then put some of the new oil on the receivers and on the ends of your half shaft splines.

As all good manuals - reassembly is the reverse of dismantling. Stick everything back togther again, put the sump plug back in the axle case and fill with Hypoid 85W/140 to the correct level.

If you fit new ones from the MGOCC they do not need to be assessed for sides as they can do either - it is only second user ones you need to worry about loading on. In an emergency even that can go by the board but it is not a permanent fix as reversing the loading does not make the problem go away - it makes it worse and they will snap like carrots if over stressed ... it is a get you home fix only.

Link to the MGOCC is http://www.mgoctagoncarclub.com/index.htm

Good luck Steve

Paul
Paul Barrow

Steve,

I had a snapped driveshaft but like you I was lucky to have it happening only a few hundred yards/meters from my house, after completing 300 miles of spirited driving in the Swiss Alps!

As a warning to "hoarding Tony" this only happened after purchasing a spare pair on eBay. Apparently my car thought it fitting to reward my distrust by breaking the shaft! After that I bought a spare dynamo from the same seller and promptly the dynamo on my car gave up the ghost..... Of course I have now reverted to buying only non-vital parts from this seller.

If you buy a used pair, you always have the proper replacment and a spare for the next time.

I didn't completely dismantle the back axle. I took out both driveshafts to determine which one was broken and to gain access to the broken spline that was still in position in the differential.
I pushed out the offending piece with a long bamboo (fishing)rod until it came to a stop at a ridge at the end of the axle. After some hard thinking I came up with a "broken spline removal tool" that I still carry in the toolbox. It consist of a small length of PVC pipe that is used to guide electrical wires in the house. Through the pipe I looped the thin inner cable from a bicyclebrake. The result was not unlike the rods that dogcatchers use to control rabid canines.

You can loop the wire over the broken spline and pull it tight against the PVC pipe, after that you have perfect control over an otherwise hard to remove part.

After draining the oil I filled it with Dieselfuel and ran the engine with the wheels off the ground, thus flushing all the old oil and debris. I repeated this twice and filled up with Pentrite single grade 140 back axle oil. I wasn't aware that there's a suitable multigrade available.

Now indeed is the time to renew the driveshaft oilseals. I use a thin layer of silicone gasket to help the flange gasket.

I've had good results with boiling oiled up brakeshoes in a strong "St.Marc"-solution. "St. Marc" is a product used for degreasing house surfaces prior to painting.
Willem vd Veer

Thanks Paul & Willem and every one else for the usefull tips, which after reviewing other threads seems to be the norm for this site. long may it continue!

I hope to have a look at my axle over Easter and then get the required parts. but if there are new half shafts available I would certainly get one in.

Are YB halfshafts different?
stephen randle

Hi Steve

Yes the Y/YT axle is completely different to the YB. The YB has a hypoid differential.

Paul
Paul Barrow

Just a little tip to add to the excellent advice already given. When re-assembled carry out another oil change after a few miles, there may be a few small fragments you missed. In driving never let either of the rear wheels lift off the ground, if this does happen immediately press the clutch. Its the shock load that gets the splines, I can say that I have in past really loaded the shafts but by obeying that principle never broken one since. As for oil in the brakes as advised new oil seals should do the trick but for years I ran the diff at low oil level and cornered much more sedately so that the oil remained in the bowl, this also ensured that the wheels remained on the terra-firma. Its a habit which I have got into and it stops the passengers getting car sick! Bryan
B Mellem

Excellent and a great note Bryan - thanks.

Paul
Paul Barrow

Long ago when I was visiting the Motor Show in the days when all the foreign cars were grouped in the corner of the hall, I was looking at the MG stand lusting over a MGBGT when I got into conversation with a young member of the sales staff [they were engineers then] and it was he who told me what the fault was with the drive shafts on the YA. In the old days he said if anything broke then they just beefed it up but often this just transferred the problem elswhere. The YA half shafts were too thick and rigid to absorb shock loads, what they should do is act as tortion bars and wind up under extreme loading and unwind progressively. It was he who told me to keep the wheels on the ground and be careful with the clutch. This I found sound advice. The YB however has benifited from this new uderstanding in transmission loads, its a pity no one has produced a more modern shaft for the YA/YT. Bryan
B Mellem

Bryan

The MG Octagon Car Club have - see http://www.mgcars.org.uk/imgytr/links.shtml#Half Shafts - YA/YT

The prices may now be somewhat out of date but they do a new set.

This is also covered on http://www.mgcars.org.uk/imgytr/halfshaft.shtml.

Paul
Paul Barrow

Stephen, a few years ago we broke a YA half-shaft and had difficulty in finding a replacement. We cut the YA half-shaft and welded on about 6" of a TC half-shaft to the inboard end. The welding was done at a hot-rod shop and has not given any problems. I think TC half shafts are available in an improved grade of steel. They are relatively inexpensive and readily available. The TC half-shafts have the same inboard spline as the YA.
Cheers, Hugh Pite
H.D. Pite

Thanks for all the feedback!

Brian, I think in my case this may have started when on the rolling road having the brakes checked, I do however use the clutch to keep up with modern (UK) driving/traffic as much as I can
stephen randle

I broke a half shaft on my YA once. I drive it "fast and furious", well hard any way! It is a car and my view is it enjoys it. I have no fear of breaking another as I now have a little hoard of originals (3 for each side!) to work through and as someone else said earlier, it probably wont happen now!

Not sure I would want to go down the route of welding a stub on there though, but each to their own Hugh.

I checked up on Paul's references there and those Octagon ones would be a tempting spare to have ... after I use up my third set of spares.

Good luck Steve and keep rollin'

CG
Corry Grainger

Corry You are a tear away, in the 1950s&60s everyone drove Y types like that. Keep it up! Bryan
B Mellem

Just to let every one know I have now fitted a new halfshaft from Octagon Car club. it is the composite type where the shaft and hub section are joined.

The broken part was pushed out using 15mm copper water pipe.
I flushed the diff as suggested above but the most difficult bit was putting oil into the diff! I found using a pump oil can with a rubber tube done the job.
Anyone know a better way?

The interesting thing is the axle is now quieter, which looking at the broken part shows marks just before the twist starts which could be where any noise could start.

Stephen Randle

Hi Bryan

Yes that is exactly where they go! Fun thing to have in your black museum!!

A fellow from the US has also just asked for a half shaft so it looks like it is the seasonal thing to do now! Sadly the MGOCC will not ship to the US or Canade so I am having to find a circumnavigation around that whereby we can avoid the 20% VAT.

How much did you pay please (ex shipping) if it isnt a rude question please Bryan?

Paul
Paul Barrow

Paul,
I have sent you an email with the information you requested.
Steve.
Stephen Randle

Just arrived home 2 hours ago from a 1600km round trip to Newcastle for the MG Car Clubs of Australia National Meeting over Easter in the YT.

I did my best to break an axle on a number of occasions by powering uphill through 1st gear towing the Y-Trailer, but sadly I am still an axle breaking virgin.

A L SLATTERY

Provided you are actually rolling, not so much torque is being exerted on the splines when you double declutch and change into low gear and power up.

I broke mine after have a great thrash around the local area in the New Forest in Hampshire UK where we lived at the time. Everything was fine until I came up to a Stop sign at a + intersection.

I physically stopped. When I went to move off it was as if the clutch had let go as there was a bump ... and nothing. Checked clutch levers/actualtion etc. then called the recovery truck. I was less than one mile from home and on the flat. But that last load up from standing start was when the axle decided that was it and went.

Paul
Paul Barrow

You YB owners will never know that quiet contemplative moment when the engine's running, its in gear, and the clutch is home, and you are stationary ahead of a long line of traffic. Then someone taps on the window and says "that car should be in a museum and you with it" Bryan
B Mellem

There seems to be a weakness in either the design, material, or both in YA half shafts. For what it is worth I used to be a buyer for a military vehicle manufacturer and one type of item that I was concerned with was torsion bars, which were very highly stressed on extremely fast light tanks.

To guard against them breaking part of the supplier's process was to pre stress them by twisting them and letting them go to predetermined levels (twice) and then part numbering the finished bars to identify them for fitting to either the left or right of the vehicle (they looked identical but had different part numbers). They were also protected with a special epoxy paint along their length to avoid them being subjected to rust or being scratched. I was told that a light scratch would mean that breakage in service would occur very shortly.

To manufacture half shafts to those standards would not be practical for an ordinary road car but one thing that would improve service life would be to have the half shafts SHOT PEENED. THIS PROCESS HAS NOTHING WHATSOEVER WITH SAND BLASTING, VAPOUR BLASTING, SHOT BLASTING ETC. BUT INVOLVES SMALL METAL BALLS BEING PROJECTED AGAINST THE GROUND SURFACE OF THE LENGTH of the bars to relieve stress on the surface and to close up any microscopic imperfections which could spread and cause failure. It was essential that the bars would be fitted on the correct sides or they would be in danger of snapping.

It seems possible that used half shafts would have been stressed in service so if they are replaced on the wrong side of a car they would be in danger of failure.

I am no engineer but perhaps some of you out there who are would care to comment? Hope this helps.

Clive Evrall

J.C. Evrall

Clive,

I fully agree that these shafts are weak and that used shafts should only be used on the right side (that is the side it was formerly fitted). Shot peening would be a good idea, my problem is that I now have to find out what the Dutch translation is and find a shop that can do it.....

Some 20 years ago a Dutch TD driver tested his remanufactured TD driveshafts by putting lines of white paint along the length of the shaft. After some use he was appalled by the twist in the shaft.
Through the supply chain via England he ended up with the German manufacturer. As an engineer he asked why the wrong material and wrong treatment were used. The answer was that his original quote included a suitable higher grade but that the buyer didn't want to pay so much and asked for lesser quality....
The TD driver then ordered a batch of good quality shafts which stayed straight in the "white line test". This shows that the material of the shaft makes a big difference. I don't think the design is really the fault.
Willem vd Veer

The problem of the Y/YT half shafts is only related to the original ones. Modern reproduction shafts aremade to a much higher standard and grade of material. the original fault was not so much in the "design" as in the "material specification" of the metal used. In fairness though to the original designers/speciication they were never intended to last 70 years (the design is a late 1930s one) or be subjected to freeway speeds. That said, the breaking of half shafts was a problem that even plaqued the early history of our cars and was a contributory factor to their replacement with the YB hypoid axle and shafts.

If you are replacing a half shaft with a second hand one, or you take both half shafts out you should only replace them in the same side that came out. Determing which "hand" is very easy as I mentioned earlier: you just look at the stress winding of the spline and if you cannot see that, then look for "loading" wear marks on the leading edge of the spline where the differential has loaded against the spline.

Paul
Paul Barrow

Good Evening Paul and Willem

I was interested to read both of your comments.

After the war steel was rationed in the U.K. and it might well be that M.G. had to make the best of a bad job and use an inferior grade of material since that would be better than nothing at all.

In more modern times I suspect that a manufacturer of good quality cars would probably use EN 24 heat treated to 'T' range (55 tons tensile) to the best of my remembrance. A more modern description would be 817m40T, which is basically the same steel but the BS970 steel specifications changed their numbering system back in the 1970s. 'T' after the description of a steel specification indicates that it has been heat treated to 55/60 tons tensile, again to the best of my recollection. Does anyone know what specification was used to make the YA halfshaft?

The surface treatment of a steel really does affect it's reliability in that if cracks and other surface imperfections are present they can spread causing eventual failure. Normally I doubt if axle shafts on an ordinary car would be shotpeened but it might be a practical solution to prevent failure in what does seem to be a problem with the YA.

I must point out that the above remarks are open to correction by a metallurgist or suitably qualified design engineer, but shot peening is not an uncommon process, should be cost effective, and may well help.

Clive Evrall
J.C. Evrall

Hi All you broken halfshaft men!!
You have never had it so good, or easy!!spare a thought for the poor old pre 52 sit up and beg Ford owners,a broken shaft for them means torque tube and axle removed from car,split axle in two and remove broken end!! reason the differential gears are part of the halfshaft.Im very glad i own a YB.
John Jebb UMG624
JC Jebb

This thread was discussed between 11/04/2011 and 03/06/2011

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