Technical 500 wheel bolts torque values??

[stevehg]

Did a quick search before posting, both on here and google and I get differing values. This forum throws up 85Nm for both alloys and steels, google throws up from a US forum, 85Nm for steel and 100Nm for alloys, with the source quoted as a workshop manual.

500 Owner manual suggests 'fasten the bolts completely in a criss cross fashion' - ever the helpful doc!

So what is it for alloys, 85Nm or 100Nm - anybody know the definitive answer?

I'm inclined to take the 100Nm value, as I'm used to torque value for Land Rover vehicles and they too suggest a higher value for alloys than steel. (130Nm vs 110Nm in that case).

Cheers

Steve

 

[grimwau]

Hi Steve, I have always used 96Nm on all my 500s (only ever had alloys) as this was a figure that I was told when researching back in 2008.

Never had a wheel fall off yet.

 

[RobW]

https://www.fiatforum.com/500/193517-wheel-bolts-torque.html

 

[stevehg]

Thanks for the quick reply and confirmation.

P.S. I like your 595 - I tried to persuade my wife to get one when she bought her 500, as there were three available in the dealership. She liked the interior but not the look of the front end, so I had no chance justifying almost £6K difference on a better interior.

 

[ELL4EVER]

Thanks for the quick reply and confirmation.

P.S. I like your 595 - I tried to persuade my wife to get one when she bought her 500, as there were three available in the dealership. She liked the interior but not the look of the front end, so I had no chance justifying almost £6K difference on a better interior.

Did you tell her it comes with 160bhp and a whole lot of extras?

 

[stevehg]

No, it would have been pointless

Now if during the winter it pre-warmed the cabin before she got in, she would have bought it instantly! A whole different set of buying priorities

 

[twinairturbo]

I torque them up to 120NM

 

[varesecrazy]

I torque them up to 120NM

why..??

have you read the threads about new hubs in warranty period..??:bang:

 

[twinairturbo]

When you work on a lot of cars it's varies from 100-130NM so I meet in the middle also i I thinks it feels safer mentally

What's this about hubs in warranty period?

 

[varesecrazy]

https://www.fiatforum.com/punto-evo/337301-front-hub-stripped-threads.html

admittedly the GM series run finer pitch bolts,
but why tighten ANY tighter than it's designed for?,

Charlie

 

[twinairturbo]

https://www.fiatforum.com/punto-evo/337301-front-hub-stripped-threads.html

admittedly the GM series run finer pitch bolts,
but why tighten ANY tighter than it's designed for?,

Charlie

Thanks for the thread, will slacken and re-torque hehe

 

[bgunn]

When you work on a lot of cars it's varies from 100-130NM so I meet in the middle also i I thinks it feels safer mentally

What's this about hubs in warranty period?

The paradox is, by tightening bolts past their designed yield point, you're actually more likely to lose a wheel because they'll break (or the threads will pull), than if they were at the manufacturers torque rating.

 

[jrkitching]

The paradox is, by tightening bolts past their designed yield point, you're actually more likely to lose a wheel because they'll break (or the threads will pull), than if they were at the manufacturers torque rating.

Absolutely. You are far more likely to have problems from overtightening than undertightening and if in doubt, this is one of those occasions when less is more.

The manufacturer has to build in a significant safety margin to compensate for the increased hysteresis if there is any corrosion on the threads.

If you keep the bolts greased (controversial but it has some significant advantages), then the hysteresis is much reduced and you need to use a significantly lower torque setting to achieve the required clamping force. Since FIAT (along with most other manufacturers) don't publish torque settings for greased bolts, I use 2/3rds of the lowest published dry torque setting (and even this may be more than is required).

Do this at your own risk, but I've never had anything come undone in service in the past 40 years. The only caveat is that you should degrease, clean & relubricate the bolts each time they are removed and refitted.

What you absolutely must not do is grease the bolts and then tighten to the published values - you'll seriously overstrss the threads and risk taking the bolts past their elastic limit.