Technical Panda Cross rear hub nut torque setting

[mikerf]

Well, changing the rear disks on my Cross has turned into a real ball ache. Passenger side changed ok aside from the usual issues of getting to all the bolts but the driver side was a bit of a disaster. Basically, the 2 hex head bolts holding the calliper carrier were seized solid and, eventually after a lot of heat and much pressure, the hex holes rounded off. To cut a long story short, I had to remove the hub nut, take off the hub and even then, with easy access to the 2 offending bolts I had to drill through them and use more heat and a stud extractor to free them. I now just have to put the whole lot back together.

However, I have no idea what pressure the hub nut needs torqued up to or if it needs backed off or not. I do know it was f tight and a lot of effort to remove.

Can anyone advise what the hub nut needs tightened to please?

 

[A3jeroen]

Really, really tight. I think we (normal 100HP) did them up to 250Nm when we changed bearings.

gr J

 

[koalar]

Well done is sorting out the rounded bolts

280Nm

Nut

M22 x 1.5

28

most people will not have a torque wrench that go that high though.

 

[mikerf]

Thanks, Guys.

Koalar, you're probably correct. I do have 2 torque wrenches. 1 smaller range and a bigger one for the really tight buggers but I'm not sure even that goes up to 280Nm. Fortunately, the guy a couple of units along from mine has every tool you can possibly think of. That's where I borrowed the massive breaker bar and socket from to undo it.

 

[A3jeroen]

We used the same stuff (breaker bar) to do them back up.

gr J

 

[portland_bill]

One of these https://www.machinemart.co.uk/p/040215238/ it can be set to beep at the desired torque setting.
And one of these. https://www.machinemart.co.uk/p/clarke-pro230-1-2-drive-breaker-bar/

 

[DaveMcT]

I did mine to 150 ftlbs (200Nm) with my ordinary torque wrench then took it to a garage friend who took it to 280Nm. It was basically as tight as I could take it without hammering it tighter. The next time, I used the torque wrench followed by 600mm breaker bar to the same level - basically it's pulled up solid. The nut has never come loose - which is fortunate.

 

[A3jeroen]

Would it really matter wether it's 275 Nm or 285? Like Dave says:as long as they don't come loose.

gr J

 

[portland_bill]

Would it really matter wether it's 275 Nm or 285? Like Dave says:as long as they don't come loose.

gr J

It is likely that there is a tolerance, as unless torque wrenches are accurate initially, or regularly calibrated, there will be differences.
However, getting to test data to see if destructive tests have been done to find the max tolerances, might be difficult. If the spec is 280, and my torque wrench says it is at 280, I'm happy. If the spec is 280, I would not be setting it anywhere else.

 

[koalar]

Would it really matter wether it's 275 Nm or 285? Like Dave says:as long as they don't come loose.

gr J

probably not

4450D11 ONE REAR WHEEL HUB, LH OR RH - R+R WITH WHEELS REMOVED FOR VERSIONS WITH ABS - Fiat - PANDA - eLearn - 4CarData

shows 220Nm

and

4450 HUBS AND WHEELS - Fiat - PANDA - eLearn - 4CarData

shows 280Nm

 

[dac69er]

ive just done them up as tight as i can with a standard breaker bar. done 100s of thousands of miles with various cars using this method and never had an issue.

i wouldnt worry yourself too much about it, as long as its bloody tight, you will be fine

 

[DaveMcT]

Back in the 1980s, I had an Austin Mini front wheel all but fall off - the CV joint fractured. These CV joints had a 1 inch dia (approx) threaded end with a castle nut which and split pin to retain the wheel hub. The whole lot sat within the wheel bearing.

One very cold night, my wheel came loose. Thankfully I was going very slowly and lost drive before I lost the wheel. The threaded end had literally sheared off the end of the CV joint. It takes minimal side loads, so the reason had to be over-tightening, aggravated by the severe cold making the metal more brittle than normal.

Moral - do the nuts up tight but when you have repair manuals giving different torque values - go for the lower number. Excessive tightening adds no value.

 

[Myusername]

On previous cars I've just done then up "really tight." Always seemed to work for me.

 

[portland_bill]

Back in the 1980s, I had an Austin Mini front wheel all but fall off - the CV joint fractured. These CV joints had a 1 inch dia (approx) threaded end with a castle nut which and split pin to retain the wheel hub. The whole lot sat within the wheel bearing.

One very cold night, my wheel came loose. Thankfully I was going very slowly and lost drive before I lost the wheel. The threaded end had literally sheared off the end of the CV joint. It takes minimal side loads, so the reason had to be over-tightening, aggravated by the severe cold making the metal more brittle than normal.

Moral - do the nuts up tight but when you have repair manuals giving different torque values - go for the lower number. Excessive tightening adds no value.

The usual problem with Mini, and the other BMC FWD vehicles using the same system, was usually the nut not being tight enough. There was a dished spacer behind the nut that centred the drive flange, but being dished, it exerted outward force, especially if just a little slack. Usually the wheel bearings would fall apart as a result, taking hub, drive flange, disc (or drum) and CV joint with them. Always expensive. I was sent a pile of bits once as evidence for a warranty claim against failed bearings, having only lasted a week or so. The castle nut showed clear evidence of being tightened with a chisel. Difficult to achieve any meaningful torque that way.

 

[koalar]

. These CV joints had a 1 inch dia (approx) threaded end with a castle nut which and split pin to retain the wheel hub..

.The threaded end had literally sheared off the end of the CV joint. It takes minimal side loads, so the reason had to be over-tightening, aggravated by the severe cold making the metal more brittle than normal.

Moral - do the nuts up tight but when you have repair manuals giving different torque values - go for the lower number. Excessive tightening adds no value.

I find it hard to believe the end sheared off due to over tightening

I doubt its even possible to over tighten a 1 1/8 nut with a breakers bar most people have.

I don't know why it failed.

 

[DaveMcT]

It was a clear brittle fracture. We will never know for sure but my suspicion is that over tightening could have started a crack and the severe cold was enough to finish the job. The threaded end had two split pin holes and a six point castle nut. The issue was mechanics forcing the nut to pin the hole they could see rather than the next usable alignment.

 

[koalar]

It was a clear brittle fracture. We will never know for sure but my suspicion is that over tightening could have started a crack and the severe cold was enough to finish the job. The threaded end had two split pin holes and a six point castle nut. The issue was mechanics forcing the nut to pin the hole they could see rather than the next usable alignment.

1 1/8" threads are normally good for 400nm I doubt you would be anywhere near that, hot or cold weather. Moving to the next hole from 80nm

 

[vexorg]

I've had similar discussions with peopl ein the past about over torquing a driveshaft nut, you uually struggle to get it tight enough with brute force never mind over tighten. I'd say to anyone, "show me it be overtightened and sheared"

 

[DaveMcT]

1 1/8" threads are normally good for 400nm I doubt you would be anywhere near that, hot or cold weather. Moving to the next hole from 80nm

I get your point but I have seen people hammering axle centre nuts to get the spit pin into place. It's one thing to fore another 1/12/th of a turn to reach the next castle/hole alignment but a whole different matter to bash it around 1/6 of a turn when it's already as tight as it can go.

It's academic on the Panda but I was trying saying there's no need to go mad with the breaker bar. Take it until it's tight and stake the nut. It won't come loose. I go 100% on the torque wrench then add the remainder with the breaker bar. It moves less than 1/2 a flat but clearly solid and tight.