Morris Minor Forum

Who or what is WSM please Sir

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Had a bit more time to collect references
That aircraft site has this to say about doing up fasteners.

Many fastener manufacturers now also recommend a "torque-turn" technique, as used for years on new sparkplug installation, oil filter installation, or when setting up hydraulic valve lifters. Use a torque wrench to some set torque, say, 30 lbs-ft; then add 60 degrees of turn. Of course, each assembly, and each application, has its own spec.

The Fred in a shed hammer and chisel method is a hands on "torque-turn" technique.
"Torque" it up until it needs a summat wi' a bit of grunt,
then turn it 45 degrees.

There's a section in the same article about tightening wheel bearings.
It tells how over tightening bearing retaining nuts causes damage.
Compression forces on the inner part of the wheel bearing could make the inner shorter and fatter.
Which will reduce the thickness of the lubricant layer.
With "ugh nasty" results.
The section is headed Spindle/Axle Nut Life Cycle Service Deficiencies

http://www.aviationtoday.com/am/repairstations/Bolts-Shear-and-Tension-not-Torque_33732.html#.VcsXCrVS8SU
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If you decide to tighten to a high torque Johnnyboy,
may I suggest you get yourself a pair of new nuts

Threads fatigue.

Some washers too while you are at it

"Wear and Tear

Bolts, nuts and washers, like all mechanical devices, wear out. Washers wear out with a single application of clamping force. These are the softest parts of the assembly, and their deformation is a calculated part of proper assembly. Never reuse washers in critical applications. Nuts, as well, are designed to wear faster than bolts. Though most of us will reuse nuts as long as some lock action seems to be working, nuts are not as strong in their second and subsequent uses as in their first. Bolts are meant to last the longest and can be re-used, as long as they do not exceed certain mechanical and environmental parameters. Bolts that have experienced overheating, over-torque, or that have been subjected to bending, have had their threads bottomed, or have visible damage, should be replaced out of hand."

http://www.aviationtoday.com/am/repairstations/Bolts-Shear-and-Tension-not-Torque_33732.html#.VcsXCrVS8SU
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Edited 1 time(s). Last edit at 2015-08-12 08:38 AM by 0123.

WSM = forum shorthand for Work Shop Manual.

John F. Quilter
Eugene, Oregon USA

Thanks John
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G’day all
Would like to bring to your attention a case of rear axle failure. There are parts suppliers here and in the UK supplying rear hub gaskets which are up to 0.035 inch (0.89 mm.) thick. In the Minor workshop manual, the rear axle section page HH5 it is clearly stated that the hub bearing should protrude beyond the face of the hub and paper washer by .001 to .004 inch (.025 - .102 mm.) with the bearing fully pressed into the hub. This assures that the bearing is gripped between the abutment shoulder in the hub and the driving flange of the axle shaft. Using a gasket of the thickness of those being supplied goes nowhere near allowing the clamping the outer race of the bearing as required, and this would allow the outer race to move around and cause flexing of the axle and its driving flange, probably leading to failure as depicted in the link supplied. Although it cannot be shown that the failures indicated in the link were associated with the bearing not being clamped I know where I would be placing blame for these failures, especially as in the case of the breakage a new quality bearing was fitted which had only travelled 5000 miles. There seems to be no definitive thickness to the gasket that I was able to find but there are several references to 0.008 inch. My approach would be to make the gasket thickness as required to meet the specification of the bearing protruding by .001 to .004 inch. It should be noted that if the bearing is clamped between the hub and its gasket and the axle flange the portion of the gasket outside of this clamping is thinner than the gap, which would possibly allow oil leakage. I suspect that this was the reason for later modifying the hub to have an O ring for positive sealing. I will be removing my axle shafts and carefully checking this bearing protrusion. There is one benefit of such a failure that being the shaft is easily removed and the diff centre does not have to be removed for cleaning out swarf.
Cheers Bob
http://morrisminorowners.co.uk/viewtopic.php?f=14&t=9310

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G,day all
I have removed my axles and measured the bearing protrusion beyond the hub alone and it was 10 thou one side and 9 thou the other. The seals and seal surfaces on the ends of the housing were perfect. The paper washers in the area where they had been compressed by the wheel nuts was 15 thou both sides. This means the outer race of the bearings was short of being gripped between the hub and axle flange by 5 thou one side and 6 thou the other. One bearing had quite a lot of free play, the other seemed OK. This is after a little over 2500 miles on the new bearings. Rather than take any chances I fitted new 6207 2RS bearings, used the same Dow Corning High Vacuum grease to initially lubricate the seals as was done before and the void between the seal and bearing was ½ packed with Castrol HTB grease which is my preferred bearing grease. I made paper gaskets from 7 thou material which would give a protrusion from the hub and gasket of 2 thou one side and 3 thou the other which complies with the workshop manual. I am not concerned about the gaskets being a little short of filling the gap between the hub and axle flange – the O rings will take care of this. After seeing the axle failure in my previous post I gave the matter some thought and decided to fit two brand new old stock EN 17 axles I had in my spares box. They were covered in surface rust so I bead blasted them and found the wording very shallow and probably rolled onto the shafts ‘REGENT 146 MADE IN ENGLAND’. My understanding is that standard Minor axles were EN8 which has an ultimate tensile strength of 700 MPa as against 1130 MPa for EN17. The moral of the story is to be very cautious of the thickness of gaskets used. It is imperative to grip the outer bearing race between the abutment shoulder of the hub and the driving flange of the axle. When tightening the hub bearing retaining nut I used a 46 mm. 3/4" drive socket with a bar about 15 inches long. It was tightened to what I would say was a sensible though tight figure probably about 80 to 90 lbs/ft. - certainly no where near the 150 or so lbs/ft. which has been mentioned. You may note that I used 6207 2RS hub bearings. They are fitted with nitrile lip seals both sides and are charged with the correct quantity of grease to last for the design life of the bearing. Being properly sealed they will not allow any diff oil to pass through them. However it is important to half pack the viod between the seal and bearing with grease to allow for lubrication of the seal, which would normally be done by diff oil passing through a conventional open bearing.
Cheers Robert

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Edited 1 time(s). Last edit at 2015-08-20 12:08 AM by BLOWNMM.

Nice comprehensive explanation of your repair. I have never seen an axle shaft break in the location yours did. BTW, I am told that used axles should always be fitted in the side they were removed from so that years of torque stresses are not reversed in the new installation. Also inspect the splined ends to see if any initial twisting is starting to occur. The same LH/RH fittment applies to torsion bars I am told.

John F. Quilter
Eugene, Oregon USA

My truck is the one in the link, from earlier. In repairing mine I used new nuts and washers. they were torqued up dry.

Hi Guys
John – the axle failure was not in my car but from a guy in New Zealand. He posted the pics on the Morris Owners Forum in the UK. When I assembled the axles the hub bearing retaining nut the thread and the face in contact with the tab washer were lightly oiled to prevent galling or pickup. The nuts and tab washers were new. It is definitely true that axle shafts and torsion bars take on a set and become handed. They should never be installed on a side opposite to which they came from. Almost invariably leads to failure with axles and sagging suspension requiring re-setting. There was no problem with the splines on the axles I fitted as they were brand new old stock EN17. The reason for fitting them was because of having travelled over 2500 miles with poorly fitted hubs, almost certainly allowing flexing between the axle shaft and its driving flange. A bit of food for thought re the link in my post of August 18. That axle failure occurred after 5000 miles from when a new bearing was fitted. The circumference of a 520X14 tyre is 73.04 inches or 6.0866 feet. Having travelled 5000 miles at 5280 ft. per mile this would add up to 26,400,000 feet travelled. Divide this by 6.0866 and the wheel had rotated 4,337,379 times. Even if say the flexing was minimal at one thou it is not hard to understand a failure after that many revolutions with the axle flange flexing in relation to the shaft! I do suspect that flexing may well be more than one thou. You may also note that I used 6207 2RS hub bearings which have a nitrile lip seal both sides and are charged with the correct quantity of grease to last for the design life of the bearing. They do not allow anything to pass through them and this is why it is important to 1/2 pack the void between the seal and bearing to lubricate the seal which would normally be done by diff oil passing through an open bearing.
Cheers Robert

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Edited 1 time(s). Last edit at 2015-08-20 12:17 AM by BLOWNMM.

Hi guys
0123 – I will answer your questions in order of presentation. The effect of tightening a fastner without lubrication is to have a reduced torque due to the friction from the unlubricated threads and bearing surfaces of the nut/bolt head. Google for ARP fastner catalogue and have a good read. The reason for using new nuts and tab washers was because some clown had previously removed and replaced the nuts with a chisel and hammer. As for the lock tabs it is normal practice to use new ones. As for the need for retaining the outer seal on the bearing, the reason is just as I stated in my post – it is there to retain the prescribed quantity of lubricant to last for the design of the bearing.
Cheers Robert

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