Axle Nut - What does it hold together?

Pulseammo · 5 Feb 2012 at 12:28

I'm wondering if someone can put this into idiot terms for me - if you removed the axle nut from a VW Polo what would fall off the car?

When I say axle nut it's the nut right in the centre of the wheel which is covered by a plastic cap (the one that says VW on it).

I've tried to find this information on google but I can only find that it holds the wheel to the axle but there are other bolts around the wheel as well, would the wheel fall off removing the axle nut alone though?

Thanks in advance if anyone can help!

Firestar_3x · 5 Feb 2012 at 12:30

The Driveshaft to the hub and the hub to the carrier.

If the nut comes off you stand a real chance of the wheel bearing and thus hub coming away from the carrier and your wheel with the hub and disk departing from the car.

Simon · 5 Feb 2012 at 12:30

Driveshaft would fall out of the hub. No power

Pulseammo · 5 Feb 2012 at 12:42

Quick replies! Thank you very much!

I'm still a bit confused though. Would the wheel actually slide off with just that one nut removed then (what I think Firestar is saying)?

Or would the wheel just stop receiving driving force meaning only one side of the car would be remain driving the car forwards, which I would assume would make the car turn (what I think simon is saying).

Thanks again also, sorry for the follow up questions. I'm really no good with all of the terminology.

Lopéz · 5 Feb 2012 at 12:47

No, the wheel doesn't fall off, there is the wishbone and the strut holding in place too.

Driveshafts have play in them to allow them to extend slightly when you turn the wheel. If the hub nut is missing, there is nothing to hold the end of the driveshaft in place, and eventually it will pop out.

This won't make the car turn - most cars have open differentials, so when one side loses drive, so does the other. So you would not be able to move.

rodenal · 5 Feb 2012 at 12:47

Its unlikely to fall off completely but you would find a horrible horrible vibration as the whole hub moved about and as said already fair old chance the driveshaft would disconnect itself giving you no drive.

In short do not drive without it under any circumstances

Pulseammo · 5 Feb 2012 at 12:47

Actually I think I might be following:

Is the hub the disc behind the wheel that the wheel bolts onto.

So the axle nut is the thing that holds the hub to the axle.

So if you remove the axle nut the hub is now free to move about with the wheel still attached to it, so all that's holding the whole thing in place is stuff like the suspension?

Edit: oh more replies, reading.

Lopéz · 5 Feb 2012 at 12:54

Pulseammo said:
Actually I think I might be following:

Is the hub the disc behind the wheel that the wheel bolts onto.

So the axle nut is the thing that holds the hub to the axle.

So if you remove the axle nut the hub is now free to move about with the wheel still attached to it, so all that's holding the whole thing in place is stuff like the suspension?

Edit: oh more replies, reading.

Yep that's pretty much it.

Hub is the bit behind the disc. Has your wheel bearing in it, and your brake caliper bolted to it. It's essentially held in place by the lower suspension arm, the track rod arms and the damper.

Behind the hub is the driveshaft (FWD * 4WD cars) This transmits drive from the differential to the wheels. Unless you have a mechanical LSD if one of these breaks or comes loose, you will have no drive at all. The driveshaft is held in place at the hub end by the hub nut (which is what you are talking about) No nut means the driveshaft will vibrate, knock, and eventually it'll probably come out or snap off at the end, leaving you stranded.

Screwed (or not) to the hub is the disc. Bolted through the disc into the hub is the wheel (this is why you don't need to screw the disc to the hub, the wheel holds it all together)

Pulseammo · 5 Feb 2012 at 12:58

Ok I think Lopéz and Rodenal have cleared up the rest of it for me

.

Don't worry, no driving is intended without the nut! More just curiosity of how the whole thing is held together.

Thanks again for the replies, extremely helpful people here!

Firestar_3x · 5 Feb 2012 at 12:59

Lopéz said:
No, the wheel doesn't fall off, there is the wishbone and the strut holding in place too.

Driveshafts have play in them to allow them to extend slightly when you turn the wheel. If the hub nut is missing, there is nothing to hold the end of the driveshaft in place, and eventually it will pop out.

This won't make the car turn - most cars have open differentials, so when one side loses drive, so does the other. So you would not be able to move.

Doesn't the hub nut compress the wheel bearing between two washers (one each side) which sits between the carrier and the wheel hub? The wheel is bolted to the hub, if it wasn't then it wouldn't rotate.

Granted it would be unlikely to come away but without the wheel nut the hub (number 6) could indeed come away from the car.

dalin80 · 5 Feb 2012 at 12:59

Hub bolt also holds the wheel bearing outer-races under load, without that the bearing can come apart if enough play is put through them which can cause the wheel to come off still attached to the drive flange, I have only seen this once in a decade though. The drive shaft can also tip if it slides out too far destroying the teeth it grabs onto and can also damage the differential in the same manner.

Behind the wheel is the brake disc which mounts onto the flange (that some manufacturers call the hub) which mounts onto the hub (which some manufacturers call the knuckle). The hub/knuckle is held in place by the lower arm and shock absorber.

Lopéz · 5 Feb 2012 at 13:03

Firestar_3x said:
Doesn't the hub nut compress the wheel bearing between two washers (one each side) which sits between the carrier and the wheel hub? The wheel is bolted to the hub, if it wasn't then it wouldn't rotate.

Granted it would be unlikely to come away but without the wheel nut the hub (number 6) could indeed come away from the car.

Yep, if the bearing seperated you'd lose the whole lot - the inner section of the hub and the wheel. Your brake line might hold it on a bit

EDIT

No it wouldn't (your brake line hold it on, that is), I must be on drugs. The caliper is bolted to the other section of the hub, the knuckle side. Durr!

Lopéz · 5 Feb 2012 at 13:07

dalin80 said:
Hub bolt also holds the wheel bearing outer-races under load, without that the bearing can come apart if enough play is put through them which can cause the wheel to come off still attached to the drive flange, I have only seen this once in a decade though. The drive shaft can also tip if it slides out too far destroying the teeth it grabs onto and can also damage the differential in the same manner.

Behind the wheel is the brake disc which mounts onto the flange (that some manufacturers call the hub) which mounts onto the hub (which some manufacturers call the knuckle). The hub/knuckle is held in place by the lower arm and shock absorber.

While I remember, have you ever come across a wheel welded to the hub?
I've only seen one, a mate bought a Maestro. The wheel trims hid the fact that some lunatic had welded the wheel to the flange....

Liampope · 5 Feb 2012 at 13:11

Lopéz said:
No, the wheel doesn't fall off, there is the wishbone and the strut holding in place too.

The wishbone and strut aren't connected to the wheel/hub though, are they! If you really were to remove the hub nut and go driving, the only thing that will stop the wheel coming off is the brake caliper being in the way round the disk. But if you really were driving at some speed in this curcumstance, the vibration/rocking/movement of the loose wheel/hub could feasably break the caliper off/apart and then the wheel would fall off.

Not recommended

Lopéz · 5 Feb 2012 at 13:13

Liampope said:
The wishbone and strut aren't connected to the wheel/hub though, are they! If you really were to remove the hub nut and go driving, the only thing that will stop the wheel coming off is the brake caliper being in the way round the disk. But if you really were driving at some speed in this curcumstance, the vibration/rocking/movement of the loose wheel/hub could feasably break the caliper off/apart and then the wheel would fall off.

Not recommended

Well, they are but it's via a bearing. And as we discussed above, if that bearing seperates under load then yes you are in serious bother. Hopefully the immense knocking noises would give you a bit of a hint

Firestar_3x · 5 Feb 2012 at 13:16

I must admit you made me do a second take on what i originally said, thought i was going mad for a moment

Lopéz · 5 Feb 2012 at 13:28

My fault, I didn't really word myself brilliantly. I blame the temporary change from Coke Zero to normal Coke, it's blown my head.

dalin80 · 5 Feb 2012 at 14:11

Lopéz said:
While I remember, have you ever come across a wheel welded to the hub?
I've only seen one, a mate bought a Maestro. The wheel trims hid the fact that some lunatic had welded the wheel to the flange....

Never deliberately, we have had to cut a wheel of a fairly new passat (06 If memory serves) as it had welded itself via corrosion to the flange, two of the wheel nuts had also become one with the metal requiring a new front flange and bearing.

Lopéz said:
Hopefully the immense knocking noises would give you a bit of a hint

With some customers you never know, they don't notice that the engine is about to drop a piston via the big end that is only attached through force of habbit yet they will come back the next day to complain about a squeak in the door that it didn't have before you changed the number plate.

kaiowas · 6 Feb 2012 at 12:33

On my first MR2 the tip of the driveshaft broke off (no idea how) with the hub nut attached. When stripping everything down it became apparent to me that the brake caliper was the only form of positive location stopping the wheel, hub and disc all departing the car :eek: