DaveMcT said:

Except of course for the ARB, the 169 axle is identical to the 2015 500

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Is it not 2" wider ?

Wet weather handling depends on rear wheels following the dry line fro front to some extent.

This is a critical dimension as it affect the cars handling and will make the car understeer more. Not that you will notice it unless you push the car on a race track. However god forbid the car is in a serious accident were someone is injured and the reason why is full investigated ?

A car that just when you need the most spears off in a straight line is not a nice feeling even if its only into a gravel trap. I wouldn't like to do it into a pedestrian, oak tree or on coming vehicles.

koalar said:

Is it not 2" wider ?

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Not being rude but did you read what I said?

Yes the 500 axle is 2" wider but the difference is entirely in the stub axle brackets. Everything else is identical to the 169 axle. Except for those brackets and of course the ARB.

You "could" widen a 169 axle by adding metal to the brackets. You "could" narrow a 500 axle by taking metal out of the brackets. The job would need professional standard fabrication skills but far easier than trying to widen the wheel arches.

My 100HP on standard springs and 195 tyres is far more likely to go backwards into a hedge than my wife's 1.2 with 155 tyres. The 500 axle and 500 springs are more compliant so the back end stays planted. Mine skips from bump to bump. Shocks on both cars were in good condition.

DaveMcT said:

Not being rude but did you read what I said?

Yes the 500 axle is 2" wider but the difference is entirely in the stub axle brackets. Everything else is identical to the 169 axle. Except for those brackets and of course the ARB.

You "could" widen a 169 axle by adding metal to the brackets. You "could" narrow a 500 axle by taking metal out of the brackets. The job would need professional standard fabrication skills but far easier than trying to widen the wheel arches.

My 100HP on standard springs and 195 tyres is far more likely to go backwards into a hedge than my wife's 1.2 with 155 tyres. The 500 axle and 500 springs are more compliant so the back end stays planted. Mine skips from bump to bump. Shocks on both cars were in good condition.

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Why use an axle that's equivalent to adding 25mm wheel spacers
Why would adding 25mm wheel spacers not increase the understeer and effect wet weather handling
Why not use the correct axle they are easy to obtain

Insurance premiums. Just one company.
Turbo/Supercharging 132%
Transmission or Gear change 63%
Exhaust changes 26%
Air Filter 25%
Wheel arches 41%
Complete body kit 57%
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Light changes 12%
Tinted windows 16%
Replacement of seats 27%
Roll Bars/Roll Cages 41%
Dashboard changes 16%
Uprated brakes 36%
Suspension 25%
Alloy wheels 8%
LPG conversion 15%
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Air conditioning 13%
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Intercooler Upgrades 23%
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Specialised paintwork 15%
Stripes & badges 9%

How does widening the rear track induce understeer in a FWD car exactly?

Using your own logic of making the tyres run on wetter road would cause oversteer, not understeer.

The spring and dampening rates make a far greater difference to compliance, predictability and handling than the track width.

Bengie said:

How does widening the rear track induce understeer in a FWD car exactly?


Using your own logic of making the tyres run on wetter road would cause oversteer, not understeer.

The spring and dampening rates make a far greater difference to compliance, predictability and handling than the track width.

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The logic is fine and correct wet and dry are two different things.



In the dry you have reduced the weight transfer on the rear axle by a huge amount

making the difference between the font and rear greater than Fiat intended which is already set for mild understeer

setting up something like a stock Porsche for a particular track track you are adding normally around 8 10 12 or 15mm wheel spacers.

here we are talking 25mm here



on a completely wet road we aren't talking about weight transfer. but again by moving 25mm you increasing the chance of the back overtaking the front.


I was lucky enough to be in the pits for a round of the European cart championship. The weather changed only a couple of minutes before they were due on the track. They had a choice change the rear track or put full wet tyres on but not both. They went for the track and lapped everyone up to 2nd place including those on full wets.


If you don't believe adding 2" to the rear axle affects the handling thats fine by me.

If you don't inform the insurance company that you have modified your car thats fine by me


But because it "feels" better doesn't mean it safe. I not saying its not safe. I would have to be tested by an expert in all conditions. Just by changing the worn out shock for new will make it feel better also

I can understand when axles were hard to come by to fit an alternative thats also fine by me

whether its safe. I don't know. Would I risk it. No.


However now axles are easy to come by and cheap now. I don't see why you would want to preform a major modification and not do it properly


Fiat and Ford changed the front suspension and track to match the wider rear. Take a look at where the front drop links attach to the strut especially at the angle they are completely different

the suspension has to be taken as a complete system. Changing one aspect will have a knock on effect.

Bengie said:

How does widening the rear track induce understeer in a FWD car exactly?

Using your own logic of making the tyres run on wetter road would cause oversteer, not understeer.

The spring and dampening rates make a far greater difference to compliance, predictability and handling than the track width.

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interesting First post

are you looking to replace the axle ?

the maths if you want it https://racingcardynamics.com/weight-transfer/


something like a formula Ford can't be tuned much this way as the track width will already at or close to the max under the regs so yes you will be tuning via springs, dampers

I’m not interested in changing my axle the slightest, I happened upon this thread looking for something else but I am intrigued why you posted a link about weight distribution that specifically says that changing the track makes very very little difference at all and thats on a highly focused race car compared to a cheap shopping car like a panda.

From my limited personal experience of track days and fast road driving I’ve seen only positive experiences with changing wheel offset or using spacers to widen the track, admittedly these changes were on cars with coil overs, poly bushes and uprated ARB’s

Bengie said:

I’m not interested in changing my axle the slightest, I happened upon this thread looking for something else but I am intrigued why you posted a link about weight distribution that specifically says that changing the track makes very very little difference at all and thats on a highly focused race car compared to a cheap shopping car like a panda.

From my limited personal experience of track days and fast road driving I’ve seen only positive experiences with changing wheel offset or using spacers to widen the track, admittedly these changes were on cars with coil overs, poly bushes and uprated ARB’s

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have a word with the Clio drivers they usually run 25mm Eibach hubcentric spacers on the FRONT ONLY to dial out the factory safety understeer

Ok, that’s changing the axle in question on a totally different car and as you’ll be aware there’s a lot more going on with the front axle of a FWD car than the rear, especially when it’s a solid rear axle.