Technical Wheel bolt torque settings

[CamperDoctor]

I’m trying to find accurate data on wheel stud torque settings. I can find loads of opinions but haven’t been able to find anything official yet. I have a 2024 X250 L3H2 panel van running 225/75 R16 tyres on Fiat 16 inch 5 stud alloys. The wheel studs are stamped 4F and are M16 bolts. This would generally point to a maxi chassis but I’m almost certain it’s a light (single rear leaf spring, V5 etc).
I’ve been advised to set the torque covering a range from 140-185NM.
FYI this is a new vehicle and checking the torque settings revealed two bolts at 95NM! And the rest between 160 and one off scale (200NM) on my torque wrench!

 

[rayc]

I though the Light Chassis had larger hubs and brakes etc at the 2024 uplift? Can you confirm the PCD is still 118?

 

[jackwhoo]

180nm for m16 bolts

 

[Reg 65]

I’m trying to find accurate data on wheel stud torque settings. I can find loads of opinions but haven’t been able to find anything official yet. I have a 2024 X250 L3H2 panel van running 225/75 R16 tyres on Fiat 16 inch 5 stud alloys. The wheel studs are stamped 4F and are M16 bolts. This would generally point to a maxi chassis but I’m almost certain it’s a light (single rear leaf spring, V5 etc).
I’ve been advised to set the torque covering a range from 140-185NM.
FYI this is a new vehicle and checking the torque settings revealed two bolts at 95NM! And the rest between 160 and one off scale (200NM) on my torque wrench!

It cannot be an L3 H2 panel van and 6.36 metres long
If its an L3 H2 panel van it will be 5.98 m long and could be on either the light or heavy chassis
If it is 6.36 m long panel van it will be L4 H2- like a motorhome or H3 like an ambulance - and will be the heavy chassis like mine.
I have an idea there was a 6.36m on the light chassis but it was only for motorhomes and not sold as a panel van.
I read somewhere the M16 wheelbolts should be 133 lb/ft and recorded it in my book - I can't remember where I got this figure from but have been using it for 15 years with no problems
L3 and L4 wheelbase is identical, all the extra length of the L4 is behind the back axle.

 

[jackwhoo]

180nm = 133 lb ft roughly

 

[CamperDoctor]

It cannot be an L3 H2 panel van and 6.36 metres long
If its an L3 H2 panel van it will be 5.98 m long and could be on either the light or heavy chassis
If it is 6.36 m long panel van it will be L4 H2- like a motorhome or H3 like an ambulance - and will be the heavy chassis like mine.
I have an idea there was a 6.36m on the light chassis but it was only for motorhomes and not sold as a panel van.
I read somewhere the M16 wheelbolts should be 133 lb/ft and recorded it in my book - I can't remember where I got this figure from but have been using it for 15 years with no problems
L3 and L4 wheelbase is identical, all the extra length of the L4 is behind the back axle.

Sorry my mistake, it’s the L4H2 (6.36m - the bigger rear overhang ) - yep it’s a Panel Van conversion from Auto-Trail.
I’m reasonably sure it’s a light chassis as just looking under at the rear suspension it clearly has single leaf springs.

But (factory fit) it certainly has 225/75 R16 tires fitted. And the wheel bolts have just measured at 16mm thread outside diameter - so M16.
But I’m now going to measure the PCD because apparently a light chassis has a PCD of 118mm whereas a maxi has 130mm PCD (for wheel bolts)

I’m favouring your figure on 180NM for the torque setting. It appears to be the most common response when searching. I’ve totally discounted anything below 140NM (as some people quote) because this is just stupidly loose. And 200+ just feels like stud breaking realms.

 

[CamperDoctor]

I though the Light Chassis had larger hubs and brakes etc at the 2024 uplift? Can you confirm the PCD is still 118?

Just measured the wheel bolt PCD and it’s 130mm on my 2024 Ducato L4 (6.36) H2 - sorry got mixed up with the L3-L4 in my original post.
Just removed wheel bolt and rechecked my measurements of the wheel bolt size and it’s certainly 16mm thread outside diameter. Threaded length is 23mm, overall bolt shank length is 30mm. It’s also stamped with 4F on the end if that means anything to anyone.

 

[Reg 65]

Sorry my mistake, it’s the L4H2 (6.36m - the bigger rear overhang ) - yep it’s a Panel Van conversion from Auto-Trail.
I’m reasonably sure it’s a light chassis as just looking under at the rear suspension it clearly has single leaf springs.

But (factory fit) it certainly has 225/75 R16 tires fitted. And the wheel bolts have just measured at 16mm thread outside diameter - so M16.
But I’m now going to measure the PCD because apparently a light chassis has a PCD of 118mm whereas a maxi has 130mm PCD (for wheel bolts)

I’m favouring your figure on 180NM for the torque setting. It appears to be the most common response when searching. I’ve totally discounted anything below 140NM (as some people quote) because this is just stupidly loose. And 200+ just feels like stud breaking realms.

I have had 2 with the Heavy Chassis and both came with single leaf springs. The double leaf was an extra cost option.

 

[CamperDoctor]

I have had 2 with the Heavy Chassis and both came with single leaf springs. The double leaf was an extra cost option.

Ok that’s useful to know. Up to now I’d assumed single or double leaf springs was a definitive differentiator for light and maxi.
My ratings plate says 3500kg, 1- 1960kg, 2 - 2000kg, 3- 0kg. Am I right in saying if it was a maxi chassis the front and rear axle figures would both be over 2000kg?

 

[jackwhoo]

@Reg 65

Hi, do you know if seval is now (2024 on) fitting the light chassis with heavy chassis hubs /wheels/brakes?

Cheers
J

Just to make it even more difficult to distinguish light/heavy !

 

[Jockstrap]

@Reg 65

Hi, do you know if seval is now (2024 on) fitting the light chassis with heavy chassis hubs /wheels/brakes?

Cheers
J

Just to make it even more difficult to distinguish light/heavy !

I have just been through this with Auto-Trail (don't know) and email confirmation from Fiat they will not tell me!
As above my 2022 Ducato is light chassis max 3,500kg. The hubs, wheels and brakes are heavy chassis and the tyres fitted were 116 load.
I've changed wheels and tyres, and still comply with user manual specs.
Fiat again in email advised me to go to a Fiat Professional garage and have the garage check the fitting.
I have also confirmed with Fiat that in the event of a puncture I should follow the user manual procedure. When I removed the factory fitted wheels the effort required went from mouse to guerilla on steroids on every wheel.

Please stop advising a torque setting which is not specific to the vehicle. Not helpful.

 

[jackwhoo]

I have just been through this with Auto-Trail (don't know) and email confirmation from Fiat they will not tell me!
As above my 2022 Ducato is light chassis max 3,500kg. The hubs, wheels and brakes are heavy chassis and the tyres fitted were 116 load.
I've changed wheels and tyres, and still comply with user manual specs.
Fiat again in email advised me to go to a Fiat Professional garage and have the garage check the fitting.
I have also confirmed with Fiat that in the event of a puncture I should follow the user manual procedure. When I removed the factory fitted wheels the effort required went from mouse to guerilla on steroids on every wheel.

Please stop advising a torque setting which is not specific to the vehicle. Not helpful.

Hi Jock,

Fiat spec torque wheel bolts m16 for Ducato is 180nm



The chassis plate max of 3500kg does not definitively mean it's a light chassis
Some heavy chassis are "plated down " to a gvw of 3500 for a variety of reasons /countries/ driving laws. Other heavy chassis are plated gvw 4000kg

 

[CamperDoctor]

Wow this is mental that it’s so difficult to definitively pin down (a) what van model you have (b) what is fairly critically important information. I guess part of the issue is particular to my case, in that my van is supplied via Auto-Trail as a camper van conversion. And as Jack in part mentioned, that Auto-Trail either don’t know what they ordered….? Or they don’t want to say. Either sounds poor / or as I’m beginning to realise as expected.

An interesting spot is that my Fiat (official) rating plate actually puts the max gross weight at 3510KG which I guess is an issue for the UK and license types. EG you wouldn’t be able to drive it without a C1 category on your license. Auto-Trail on their “Second stage conversion” plate drop the weight to 3500KG. Hopefully this is an official change and not just a rounding error .

A few of you have said “the manual says…” but in my manual it gives a range that says “ it depends on the variant of base vehicle you have”.

I’m going to visit a Fiat professional dealer tomorrow and ask (a) what is my vehicle/variant - yep at face value this sounds a stupid question (b) can they check the wheel bolt torque settings, and if yes can they show me how they know what value they are going to use. To this last question I have a horrible feeling they’re going to say, they just use a windy tool and crank it up tight.

 

[jackwhoo]

Its is 180nm for m16 wheel bolts

If the mam or gvw on the plate is over 3500kg it is the next mot category up from cars/light vans.

 

[jackwhoo]

Ok that’s useful to know. Up to now I’d assumed single or double leaf springs was a definitive differentiator for light and maxi.
My ratings plate says 3500kg, 1- 1960kg, 2 - 2000kg, 3- 0kg. Am I right in saying if it was a maxi chassis the front and rear axle figures would both be over 2000kg?

From the fiat online drivers handbook

Maxi versions maximum rear axle load 2400kg

 

[CamperDoctor]

From the fiat online drivers handbook

Maxi versions maximum rear axle load 2400kg

By the way if your plate box 3 is 0kg it appears your vehicle is prohibited to tow anything- worth keeping in mind.

Sorry I may have confused thing’s slightly. I have two ratings plates, one official vehicle manufacturer from Fiat quoting
3510KG. Max vehicle gross weight
6010KG. Max train (vehicle plus braked trailer) weight
1960KG. Front axle max
2000KG. Rear axle max
(traditional metal plate)

Then a second plate (sticker) called the Second Stage Conversion plate added by the Motorhome converters. This states:
3500KG. Max vehicle gross weight
6000KG. Max train weight
1960KG. Front axle max
2000KG. Rear axle (1) max primary axle
0KG. Rear axle (2) max. Tag axle

Remember most Motorhome converters can take cab only variants from Fiat and then bolt on an Alco chassis at the rear. This comes with the added option on some vehicles of tag axles variants (second axle and wheels for added load support).
I don’t have a tag axle vehicle as I’m totally Ducato van based but Auto-Trail only have one sticker, hence they remind you of the lack of a second set of rear wheels by saying you can’t carry any load on it.

My tow capacity is still defined by the 6000KG limit.

Yes the discrepancy of 10KG in the figures is as seen on the plates and as previously mentioned is probably due to down-plating to meet UK non C1 licence needs?

 

[Reg 65]

Ok that’s useful to know. Up to now I’d assumed single or double leaf springs was a definitive differentiator for light and maxi.
My ratings plate says 3500kg, 1- 1960kg, 2 - 2000kg, 3- 0kg. Am I right in saying if it was a maxi chassis the front and rear axle figures would both be over 2000kg?

In that case you must have the light chassis - the heavy chassis has axle weights of 2100kg front and 2400kg rear
If it was a panel van it would have been sold new as a heavy chassis
Only the converters could get the L4 with the light chassis.
Unless things have changed recently
Whatever, with M16 bolts the torque should still be 133 lb/ft (sorry I'm still on feet and inches)

 

[jackwhoo]

Good it has been plated down so no c1 licence required and you don't have to get a commercial (class7?) Mot

 

[Communicator]

Its is 180nm for wheel bolts same for m14 or m18

If the mam or gvw on the plate is over 3500kg it is the next mot category up from cars/light vans.

That's interesting. Fiat eLearn for my x244 gives 160Nm for M14 studs, and 180Nm for M16 studs. The figures are not given in the data section, but I have found them quoted in a "procedure".

 

[jackwhoo]

That's interesting. Fiat eLearn for my x244 gives 160Nm for M14 studs, and 180Nm for M16 studs. The figures are not given in the data section, but I have found them quoted in a "procedure".

Oh no I will have to re-check