Another anti roll bar question

mercules

Registered User
Couldn't find anything for my exact question so hopefully someone has done this and can shed some light.

I have a S4 with sports diff and the rear ARB is 16mm from what I've read. I want to get a uprated one but they come in twos and I already got a H&R front on a good price off a member from here.

My question is has anyone swapped the 16mm one for the non sports diff 21.7mm one? I can pick them up cheap £40 used with everything but new bolts.

I saw the 034 rear but I'm not paying £300 for a metal bar unless it's night and day over stock S4 21.7mm one.

Thanks

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Dippy

Registered User
I can't answer the question but I wonder why our cars have the 16mm bar. I can only imagine that it is because the sports diff prevents a thicker one being fitted?
 

mercules

Registered User
I've read it's because it makes comfort mode more soft?

I've just bought this morning a RS5 rear sway for cheap so trying it out. Could prove a nice cheap mod for us "smart" savers.

Someone said RS5 22.5mm fits a S5 and then someone else said a stock S5 21.5mm fits a S4.

See where I'm going

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forty3

Registered User
034 arb made a big difference to my S4 when pushing hard through long bends. It definitely helps to tame the cars desire to understeer.

I don't have sports diff tho so not sure what difference, if any, an uprated one would make on your car.
 

mercules

Registered User
034 arb made a big difference to my S4 when pushing hard through long bends. It definitely helps to tame the cars desire to understeer.

I don't have sports diff tho so not sure what difference, if any, an uprated one would make on your car.
I have a friend who is lucky enough to have had a new shape merc C63s and he can drive. We went for a small trip in my car and I took a long corner at very good speeds and he was so amazed I didn't slide out comparing to his Merc that following couple weeks he PX it for a R8 V10 plus.

He mentioned 50% of the decision was based on the grip you get from AWD compared to RWD. I think anything over 400hp on RWD struggles to put power down in the first couple gears.

I have noticed driving the S4 on a hard pulls the back does feel like it wants to come out if I can control that a slight bit more I'd be happy. I also wished the super sports seats were more hugging as I find I'm sliding all over the place when driving on twisty roads.

But then I say to myself it's a near 2 ton estate car sort your life out haha



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Dippy

Registered User
someone else said a stock S5 21.5mm fits a S4.

The p/n for a 2013 S4 21.7 mm rear bar is 8K0 511 305 AB
The p/n for a 2013 S5 21.7 mm rear bar is 8K0 511 305 AB
 

mercules

Registered User
The p/n for a 2013 S4 21.7 mm rear bar is 8K0 511 305 AB
The p/n for a 2013 S5 21.7 mm rear bar is 8K0 511 305 AB
So if the RS5 bar is said to fit the S5 on Audizine then I'm on to a winner.

Will update once it comes and I fit it.

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mercules

Registered User
It's here!
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mercules

Registered User
Just confirming 8k0511305s 22.5mm rear bar from RS5 fits fine on b8.5 S4.

It cost me £60quid from eBay breakers.

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mercules

Registered User
How does the handling compare over stock? Is it a noticeable difference on long bends?
I had Eibachs fitted and moog solid front and rear end links at the same time. Although I can't comment purely on the rarb performance the car feels more planted and corners I've taken it made the back less twitchy. Before on stock one I did notice a few times under load cornering you'd get a little twich and the diff would kick in now I've not had it happen in a week since it's been fitted.

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Deckard

Registered User
I was about to order a 034 rear sway/arb but Awesome have stopped stocking 034 for some reason and everyone else, including 034 are out of stock. I agree £330 for a bar is a lot lot lot of money but this seems a very popular upgrade.
 

Deckard

Registered User
thanks, I'll call them tomorrow, they have a terrible website :)
 

forty3

Registered User
thanks, I'll call them tomorrow, they have a terrible website :)

Get yourself on the S4 owners group on Facebook. Mark of Brotek runs it and always answers messages.

The arb is a lot of money but worth it if you want to drive beyond the point when the car starts to understeer as it helps bring the back end around at the point when you'd normally start sliding.
 

GarethS4

Registered User
I have just bought a set of eibach arbs and have been told by several people not to fit the front bar and only fit the rear .what is the reason for this could someone explain please .
 

jdp1962

Grumpy Old Man
It depends on what you're trying to achieve in the handling department. Uprating the rear antil roll bar increases rear roll stiffness which, on its own, reduces understeer. Uprating the front-anti roll bar increases front roll stiffness which, on its own increases understeer. Uprating both at the same time will probably cancel out any changes to the level of understeer, but improve overall roll resistance. There may, though, be a stiffer, jigglier ride.
 

Cerbera9

Registered User
Just replacing the rear roll bar helps turn in and reduces understeer.

Replacing both keeps the ratio between the front and rear overall increase the roll stiffness keeping the car flatter through sweeping bends etc.

I installed both front and rear H&R roll bars and i'm very happy with the handling. The front H&R is adjustable so set this on the softer setting which is still stiffer than standard. This way you get the best of both worlds as the ratio front to rear has changed reducing understeer and helping turn in and overall the car is flatter than standard through the bends.
 

GarethS4

Registered User
Just replacing the rear roll bar helps turn in and reduces understeer.

Replacing both keeps the ratio between the front and rear overall increase the roll stiffness keeping the car flatter through sweeping bends etc.

I installed both front and rear H&R roll bars and i'm very happy with the handling. The front H&R is adjustable so set this on the softer setting which is still stiffer than standard. This way you get the best of both worlds as the ratio front to rear has changed reducing understeer and helping turn in and overall the car is flatter than standard through the bends.
Really what I’m looking to stop is the way the car feels like em how would you explained it very boaty as in on say a longer corner rolling sort of .sorry I’m not doing a very good job here am I lol.i want it to feel planted with little or no roll without going to the extremes of changing shocks ect as I don’t want it to hard as it’s my daily .the car just moves about far to much when being pushed on a bit .i do have eibach springs already so was hoping the arbs cut out a good bit of that roll I’m on about .
 

mercules

Registered User
Really what I’m looking to stop is the way the car feels like em how would you explained it very boaty as in on say a longer corner rolling sort of .sorry I’m not doing a very good job here am I lol.i want it to feel planted with little or no roll without going to the extremes of changing shocks ect as I don’t want it to hard as it’s my daily .the car just moves about far to much when being pushed on a bit .i do have eibach springs already so was hoping the arbs cut out a good bit of that roll I’m on about .
I'm much less roll now with both arbs and springs. What tyres you using too?

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Cerbera9

Registered User
Really what I’m looking to stop is the way the car feels like em how would you explained it very boaty as in on say a longer corner rolling sort of .sorry I’m not doing a very good job here am I lol.i want it to feel planted with little or no roll without going to the extremes of changing shocks ect as I don’t want it to hard as it’s my daily .the car just moves about far to much when being pushed on a bit .i do have eibach springs already so was hoping the arbs cut out a good bit of that roll I’m on about .
Do you have Audi Drive Select?
 
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