Front Hub Bearings preload.

[Deleted]

Can anyone explain to me why the LH thread is on the off-side? Turning the nut clockwise will undo it so, in theory, the direction of the wheel going forward is trying to undo the nut.........................isn't it?! I know that can't happen because of the two safeguards in the design but I would appreciate if someone could explain. 

[Deleted]

Sept 11, 2014 16:14:54 GMT @resurgam said:

Can anyone explain to me why the LH thread is on the off-side? Turning the nut clockwise will undo it so, in theory, the direction of the wheel going forward is trying to undo the nut.........................isn't it?! I know that can't happen because of the two safeguards in the design but I would appreciate if someone could explain. 

Sorry, I just accidentally removed my original post about preload and fitting bearings because I didn't want to repeat it all again to ask the question and I couldn't see a reply tag.

[eisdielenbiker]

Hi,
I hope that I wont mix up things but this seems the original post. I have copied it to my local harddisk as it seemed very interesting to me:

Have just replaced the bearings in the O/S front hub. Had a test drive and have returned with four wheels.

In fact, the bearings were in perfect condition despite the overheating issue a few years back. The grease was poor and had turned into a thick dark oily substance. As I had the new bearings I went ahead and renewed them. Here are a few tips for those interested.

First, put the races in the fridge the day before. It will make a difference.

Second, make sure the housings in the hub are absolutely clean.The races are a tight fit.

Third, when you drive the races in make sure you have a suitable driver and a big hammer! A small hammer can do a lot of harm. You need to be assertive.

Fourthly...............................

The w/s manual is a bit vague when it comes to setting any preload and doesn't actually mention any. It just describes the setting of the end float.The problem with missing the preload is this is that the bearings might not be seated properly.

On a timken tutorial I discovered, the following process is recommended . On our cars just use the key washer and the outer nut to set the preload. YOU WILL STILL NEED TO SET THE END FLOAT AFTERWARDS.

Tighten the nut to 50 ft lbs whilst turning the rotor.

Slacken one complete turn.

Tighten to 10 to 10 ft lbs whilst turning the rotor.

Slacken a quarter turn.

This will then ensure the bearings are seated ready to set the end float as per the manual. This took me some time as every time I tightened up the outer nut my end float disappeared! I ended up with about 5 thou.

[Deleted]

Sept 15, 2014 6:48:32 GMT eisdielenbiker said:

Hi,
I hope that I wont mix up things but this seems the original post. I have copied it to my local harddisk as it seemed very interesting to me:

Have just replaced the bearings in the O/S front hub. Had a test drive and have returned with four wheels.

In fact, the bearings were in perfect condition despite the overheating issue a few years back. The grease was poor and had turned into a thick dark oily substance. As I had the new bearings I went ahead and renewed them. Here are a few tips for those interested.

First, put the races in the fridge the day before. It will make a difference.

Second, make sure the housings in the hub are absolutely clean.The races are a tight fit.

Third, when you drive the races in make sure you have a suitable driver and a big hammer! A small hammer can do a lot of harm. You need to be assertive.

Fourthly...............................

The w/s manual is a bit vague when it comes to setting any preload and doesn't actually mention any. It just describes the setting of the end float.The problem with missing the preload is this is that the bearings might not be seated properly.

On a timken tutorial I discovered, the following process is recommended . On our cars just use the key washer and the outer nut to set the preload. YOU WILL STILL NEED TO SET THE END FLOAT AFTERWARDS.

Tighten the nut to 50 ft lbs whilst turning the rotor.

Slacken one complete turn.

Tighten to 10 to 10 ft lbs whilst turning the rotor.

Slacken a quarter turn.

This will then ensure the bearings are seated ready to set the end float as per the manual. This took me some time as every time I tightened up the outer nut my end float disappeared! I ended up with about 5 thou.

Thanks for restoring that. Much appreciated. I could just add that the hub could always be gently heated in the oven to make the job even easier.

Did any one have any idea as to why a LH thread is on the O/S? In otherwords, the rotation of the wheel would try to unscrew the nut.

[enigmas]

Goodness, l almost got a headache reading through that. If the grease has gone black and runny the bearings would have overheated. I don't think anyone needs to be so anal about fitting and setting up wheel bearings, but hey, each to their own obsessions. OCD anyone! Just ensure that there's some free play when you tighten the nut/key/pin and all the other over engineered paraphernalia holding the wheel to the stub axle. Also, don't use big hammers for anything other than carpentry! If something is overly tight find the problem...most likely a burr or something similar. Then linish the hub carefully. If you feel the urge to use a hammer, it's definitely chill out time. Take a break and have a coffee/tea or brew and wait for the adrenaline to subside.

As for the left hand thread on the offside (RHD) front wheel stub axle...if you are driving forward and for some strange reason the lock pin and it's keyed restraining lock plate sheared off and allowed the stub axle nut to rotate...it would tighten, not loosen.

[Deleted]

Sept 15, 2014 9:19:17 GMT enigmas said:

Goodness, l almost got a headache reading through that. If the grease has gone black and runny the bearings would have overheated. I don't think anyone needs to be so anal about fitting and setting up wheel bearings, but hey, each to their own obsessions. OCD anyone! Just ensure that there's some free play when you tighten the nut/key/pin and all the other over engineered paraphernalia holding the wheel to the stub axle. Also, don't use big hammers for anything other than carpentry! If something is overly tight find the problem...most likely a burr or something similar. Then linish the hub carefully. If you feel the urge to use a hammer, it's definitely chill out time. Take a break and have a coffee/tea or brew and wait for the adrenaline to subside.

As for the left hand thread on the offside (RHD) front wheel stub axle...if you are driving forward and for some strange reason the lock pin and it's keyed restraining lock plate sheared off and allowed the stub axle nut to rotate...it would tighten, not loosen.

Yes, they certainly did overheat and can still remember the smoke and smell! There's a very steep and long descent approaching Exeter from the West on the A38. It's called Haldon Hill. During the descent, my o/s caliper heated up and the rusty piston inside expanded and the rest was fairly predictable! To my shame it took me six years to get around to the recent change but the old bearings are in perfect condition and had no visible signs of wear. The inner one was the original SKF.

I think you might have misinterpreted my use of the hammer! My Late Father always reminded me that a lot of damage can be done with a small inadequate hammer. Once the correct driver had been selected for the race, it was a question of driving it home with the correct amount of force with the minimum number of blows. I've seen YouTube videos of people using tiny hammers and hitting the races about 50 times! That's bad but I agree, a big hammer in the hands of a Gorilla is not good engineering practice.

Sorry to be a bit dim on the LH thread but I don't understand.If the wheel is turning clockwise on a LH thread, won't the tendency be for it to unscrew?  

[enigmas]

You're viewing the wheel from the driver's side. Walk around the car and stand in front of the OS wheel (literally). If the car is moving forward (that's to your left) the OS wheel is turning anti-clockwise. A left hand thread tightens anti-clockwise. You confusing it because of you orientation. Think of a clockface. Viewing it from the front, the hands turn clockwise. View the clock from the back (no you can't see the face) and the hands turn anti-clockwise.

Check that your wheel bearings aren't 'blued' from over heating. If they're blued the case hardening is compromised.

If the bearings got that hot on the descent you describe also look at the discs, you may have hot spots (blued sections on these)

[djm16]

Tapping v wapping!

Very occasionally a bearing race will go in nicely for me when cooled. Usually what happens is that it heats up to binding when part the way down. At that point it is OK IMHO to use the right sized drift and use a heavy hammer gently, and sometimes less than gently (thinking of the collar on the rear half shafts).

More commonly though the race does not start in the hole square. I then eye ball it carefully and straighten it up with gentle taps from a pin hammer. It often will not stay square either, so I then repeatedly tap with a pin hammer in an X pattern until it is straight and moving. Then revert to the heavier hammer.

[Deleted]

Sept 15, 2014 22:44:17 GMT enigmas said:

You're viewing the wheel from the driver's side. Walk around the car and stand in front of the OS wheel (literally). If the car is moving forward (that's to your left) the OS wheel is turning anti-clockwise. A left hand thread tightens anti-clockwise. You confusing it because of you orientation. Think of a clockface. Viewing it from the front, the hands turn clockwise. View the clock from the back (no you can't see the face) and the hands turn anti-clockwise.

Check that your wheel bearings aren't 'blued' from over heating. If they're blued the case hardening is compromised.

If the bearings got that hot on the descent you describe also look at the discs, you may have hot spots (blued sections on these)

Thanks and I understand what you're saying but I still don't get it although I know that I'm wrong! Regardless of orientation, the drivers side wheel (RHD) in forward motion is turning in a clockwise direction so, if the O/S nut was on loose with no locking, it would be undone because it would undo by the clockwise motion of the wheel.

The old bearings weren't blued but I replaced them anyway. The disc also survived but both discs need replacing anyway due to corrosion.

[enigmas]

if the O/S nut was on loose with no locking, it would be undone because it would undo by the clockwise motion of the wheel.

Only in reverse.

Forget about what the DS wheel is doing! I'll sign off now. Hopefully another scribe will sort this conundrum for you. It may come to you in your sleep. I'm off to bed.

[Deleted]

Sept 16, 2014 13:42:20 GMT enigmas said:

if the O/S nut was on loose with no locking, it would be undone because it would undo by the clockwise motion of the wheel.

Only in reverse.

Forget about what the DS wheel is doing! I'll sign off now. Hopefully another scribe will sort this conundrum for you. It may come to you in your sleep. I'm off to bed.

All I can say is that one doesn't have to be too bright to be me!!  We're not a cross purposes re the wheel are we? I'm talking about the DS wheel on RHD cars.

[Ken Nelson]

I realize that opening up this question is akin to waking sleeping dogs, but I have just finished regreasing the front hubs on my MGA and shortly after doing this job on my Rover P5. I noted that each workshop manual contradicts the other about the thread direction on the front stub axle nuts. The Rover manual states the Left-hand thread nut goes on the Right hand side of the car and the Right-hand thread nut goes on the Left hand side of the car. My MGA manual states exactly the opposite thing. Both cars are set up as the manual states, but it would seem that one way is incorrect. However, the Rover uses tapered front bearings and the MGA uses flat ball bearings. Is this what causes the difference in the setup?

[Phil Nottingham]

Rover did swap sides over as the thread direction in late P4s and P5s. So the answer is no not really!