Rear hub holder

[mr mugello]

Torquing up the rear hub by using the brake . Is it ok to do it this method ok if you don't have the holder to hand.

[Adam_Winstone]

More a road-side make do technique, rather than an advised way of doing it... but it is a very typical 'make do' that works. I don't think that it should be readily recommended though.

Adam

[mr mugello]

Can distortion damage be caused by brake method to layshaft or hub just out of interest ?

[Adam_Winstone]

Not sure, hopefully neither, however I don't like the idea that applying the brake is trying to stop the hub from rotating AND applying pressure to stop the hub from pulling onto the layshaft. Therefore, what torque are you actually measuring when using the brake as a method of stopping rotation? For this reason, I would question the accuracy of any torque figure that you might hope to fit it to.

Yes, it can work. Yes, it does work. Is it best practice?.... No.

Adam

[mr mugello]

Best I get a holder made up then. Thanks for good advice.

[lammydave]

Best I get a holder made up then. Thanks for good advice.

martin at just lambretta has some for sale


http://www.lambrettaspareparts.com/page33.htm

[Warkton Tornado No.1]

Torquing up the rear hub by using the brake . Is it ok to do it this method ok if you don't have the holder to hand.

Even if I had access to a rear hub holder, I cannot think why I would choose to use it. I can’t recall ever seeing one in use, either & I think it’s fair to say that ‘I’ve been around’

To my way of thinking, the only components under any load when utilising the brake as the torque resistance are the shoes themselves. So, if they cannot hold the hub whilst torque is applied, then that would ring alarm bells to me!

I certainly wouldn’t remove a wheel to fit a tool in its place as the time involved, lack of stability & general inconvenience far outweigh any possible advantage.

[Adam_Winstone]

WT1... for someone who is so keen to do things properly, your response above surprises me... you're so lazy!

[ian i.o.w]

J B fabrication on Facebook does one I have one and found it good and useful

[Warkton Tornado No.1]

WT1... for someone who is so keen to do things properly, your response above surprises me... you're so lazy!

I'm pleased that you state an opinion on what I have said...

Hmmm. Not a case of being 'lazy'

More a case of thinking it through & application of sound engineering principles.

Would I countenance holding the hub against, say, a flywheel holding tool? No, never, would be my response.

What I do to tighten & loosen hubs is a very common practice, particularly within sporting circles & kills two birds with one stone.

[Adam_Winstone]

^... WT1, I thought you would like that and was kidding about the 'lazy' bit.

"More a case of thinking it through & application of sound engineering principles.", OK, talk me through this then... when setting the rear hub nut to torque down the hub, if you're applying the rear brake, what are you actually torquing to, the shoes's ability to stop the rub rotating or the nut's torque setting to the layshaft? If looking at it from engineering basics, why introduce a factor that influences additional resistance to an assembly that is meant to be torqued to represent the tightness of nut on layshaft? In the same way that you should never undo a rear hub nut to allow a locking plate hole to align with the threads for the grub screw, as it releases pressure on the cone (initially torqued tighter) and can result in it subsequently coming loose, why would you apply a brake that resists the hub from pulling onto the layshaft (as well as rotation of) and assume that the torque setting remains constant once you release the pressure that the brake is applying to the hub? If the action of the brake simply exerted force in one direction then fair enough, however, the application of brake also applies force as a lateral restraint to hub movement. Considering that the whole ideal of the torque setting is to apply a known range of lateral force of nut - against hub - against cone - against layshaft, anything you do to alter these lateral loads (like apply a twin shoe'ed brake assembly to resist rotational movement but at the same time resist lateral movement) will totally throw that torque setting out of accuracy.

As I suggested previously, "Yes, it can work. Yes, it does work. Is it best practice?.... No.", which still stands.

Adam

[mr mugello]

Best I get a holder made up then. Thanks for good advice.

martin at just lambretta has some for sale


http://www.lambrettaspareparts.com/page33.htm

Thanks

[Warkton Tornado No.1]

^... WT1, I thought you would like that and was kidding about the 'lazy' bit.

"More a case of thinking it through & application of sound engineering principles.", OK, talk me through this then... when setting the rear hub nut to torque down the hub, if you're applying the rear brake, what are you actually torquing to, the shoes's ability to stop the rub rotating or the nut's torque setting to the layshaft? If looking at it from engineering basics, why introduce a factor that influences additional resistance to an assembly that is meant to be torqued to represent the tightness of nut on layshaft? In the same way that you should never undo a rear hub nut to allow a locking plate hole to align with the threads for the grub screw, as it releases pressure on the cone (initially torqued tighter) and can result in it subsequently coming loose, why would you apply a brake that resists the hub from pulling onto the layshaft (as well as rotation of) and assume that the torque setting remains constant once you release the pressure that the brake is applying to the hub? If the action of the brake simply exerted force in one direction then fair enough, however, the application of brake also applies force as a lateral restraint to hub movement. Considering that the whole ideal of the torque setting is to apply a known range of lateral force of nut - against hub - against cone - against layshaft, anything you do to alter these lateral loads (like apply a twin shoe'ed brake assembly to resist rotational movement but at the same time resist lateral movement) will totally throw that torque setting out of accuracy.

As I suggested previously, "Yes, it can work. Yes, it does work. Is it best practice?.... No.", which still stands.

Adam

The way that I tighten the hub nut is totally reliant upon application of the back brake. That much you must surely agree....

The torque applied to the nut is resisted by applying the brakes & the brakes are either operated in such a scenario via the pedal or, say, a ring spanner applied to the brake lever that is splined to the hub.

When you say:

"when setting the rear hub nut to torque down the hub, if you're applying the rear brake, what are you actually torquing to, the shoes's ability to stop the rub rotating or the nut's torque setting to the layshaft?"

Both are achieved. Surely you can see that? What would happen if the hub wasn’t constrained in some way via the brake or some kind of holder?

The answer is nothing, unless you were to use an ill-advised impact gun for tightening.

Somehow, you appear to be thinking that the mechanical means by which the hub is constrained has differences between the two types discussed.

The reality is that there isn’t, other than the brakes shoes may not grip if there is some inadequacy. In that instance, the desired torque will not be achieved.

Hence my expression “killing two birds with one stone”

The rest of your response is to my mind, a case of complicating what is a simple arrangement.

I could agree with you were we discussing the varying methods of tightening the clutch centre nut, where I would advocate the use of a proper holding tool rather than a jammed in screwdriver, but, again, I can assure you that the torque applied would be the same.

[Adam_Winstone]

^... sounds good but hasn't convinced me one bit as stopping the hub from rotating by use of the correct tool applies load in one direction only, whereas application of the brake applies resistance to both rotation and lateral movement. A side loading adds to a directional loading so convinces me that any measured torque figure will be incorrect and if you don't accurately know what figure you're working to then you may as well leave the torque wrench hanging on the toolboard and use a lump hammer and ring socket, which is how it is shown on the Innocenti assembly line film shown on TV many years ago (Classic Marques?).

Well, please feel free to post any supporting evidence that you may choose to add but I've said all that I can be bothered to and have, so far, read nothing to convince me otherwise...

"Yes, it can work. Yes, it does work. Is it best practice?.... No."

Adam

[Fast n Furious]

The amount of lateral resistance that the brake shoes have on the lateral "in movement" of the hub are negligible once the cone has started its grip. The shoes would probably just move in a little on their pivot pins and then there's permissible flex in the hub its self.
So..... Torque up in stages and release and apply the brake with every step. Da Dah.

[Adam_Winstone]

^... that would certainly help to negate any issue caused by applying the brake and stopping the lateral resistance and throwing implied torque readings out. You're also right F&F to be considering this in terms of lateral movement, indicated by commenting that this really only becomes an acceptable method once the cones starts to bite (lateral movement allowed for by sequential application of brake, release, reapplication).

Remember that I've not said this doesn't work... quite the opposite:

""Yes, it can work. Yes, it does work. Is it best practice?.... No."



Anyway enough time spent on semantics and difference of opinion.... mr mugello, how are you getting on with your rear hub?

Adam

[mr mugello]

Well, I agree with what you say. Friction free movement of no brakes applied is best method. My scoot is being restored and after posting a couple of pics it was pointed out because I had yet to fit lock washer, due to nut fully tightened yet, don't forget to use the correct tool, from a local friend. Never used one before . My original rear hub inner brake surface is not 100% smooth and so I thought this might be the cause. I am guilty of using a long screwdriver for flywheel holder in my youth, , but never ever dream of doing it now, probable reason kept shearing crankshafts ! Now what about the issue of resting a hub holder against a crankcase whilst torquing ? is this a no no ?

[CHRIS in MARGATE]

Rear brake every time when the engine is in the scooter. When it's on the bench; that's different.
I like hearing my wife say "can I take my foot off now?"

[Adam_Winstone]

^... agree 100% that there are times when this is the only method available and I too have used it over and over again, although involving my wife normally complicates matters. On the bench the holding tool works a treat, especially when pulling the layshaft home for shimming the gearbox, and now in most cases (for the sake of 4 nuts) will fit the holding tool, rather than applying the brake, if the bike is at home and the holder is available. I consider this to be 'best practice'.

It seems like most of us have used the rear brake method, and continue to do so, but it is not my first choice for the reasons that I've outlined.

Adam

[Warkton Tornado No.1]

^... agree 100% that there are times when this is the only method available and I too have used it over and over again, although involving my wife normally complicates matters. On the bench the holding tool works a treat, especially when pulling the layshaft home for shimming the gearbox, and now in most cases (for the sake of 4 nuts) will fit the holding tool, rather than applying the brake, if the bike is at home and the holder is available. I consider this to be 'best practice'.

It seems like most of us have used the rear brake method, and continue to do so, but it is not my first choice for the reasons that I've outlined.

Adam

Just to draw my own line under the debate & merits of the two principal methods of hub tightening.

As some clarification, I am advocating the use of using the rear brake as a means of holding the hub for torquing of the hub nut when the lay-shaft has been ‘set’ correctly relevant to the gearbox shimming procedure (0.003 – 0.011”)

Under such circumstances , it is my belief that any ‘lateral side loading’ is inconsequential/unlikely to affect the procedure of tightening the hub nut as there will be compliance laterally (as stated above) as well as the inevitable compliance of the friction surfaces themselves allowing for ‘creep’ if necessary.

If in doubt, then the torquing (using the rear brake) should adopt an ‘on-off ‘ procedure to ensure that lateral loading cannot be excessive, if such a condition could actually occur. I doubt that it can & I’m only paying lip service to it.

Unfortunately, I accept that this (civilised) debate can only ever be conclusive were there back to back tests in laboratory conditions. In the absence of such a luxury, the two main camps should agree to disagree.