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Right. I was planning on purchasing a pair of Neuspeed ARB's to fit before LM in June.

However, I read a thread a couple of weeks ago that said the front arb was too big - over sized - to begin with and that just changing the rear would suffice tobalance things out.

IIRC the thread was about the Whiteline rear arb kit. Now I had a look at the spec of these and they are smaller section than the Nuespeed ones (and the oe ones). Are the Whiteline ones to be fitted to cars without rear arbs?

I would really appreciate some advice on this as I know nothing.
 

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Hi,

In my opinion the front bars on the mark 4 is more than heavy enough so only a rear arb has to be added. The reason for the smaller diameter of the Whiteline bar is that it is also shorter. Stiffness of an anti roll bar is governed by 2 things. The thicker the bar the stiffer and the shorter the bar the stiffer. The Whiteline bar is shorter than the others and therefor is made in a smaller diameter. This obviously saves weight. The Whiteline adjustable rear bar can be compared in stiffness to other makes of solid anti roll bars of 24-30mm. Hollow bars need a much bigger diameter to get a similar roll stiffness.

Cheers
 

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Also, a lot of people change the front bar not to gain in stiffness or increase the understeer but simply to overcome the driveshaft clearance problem with bigger hoops on the replacement front anti roll bars...........the rear is defo the way to better handling though......can't recommend the whiteline one enough....[;)]
 

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I think the best overall balance is a standard front ARB...uprated with Powerflex bushes.....ADJ droplinks to sort out the clearance issues..(If not going ultra LOW)....and a 25mm rear ARB....Neuspeed or alike.....this setup does everything you need and dosen`t break the bank....also is easy to fit it all.... doesn`t require you to drop the front subframe like fitting a BIG hoop ARB does......[:D][Y]
 

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Hi Mitch,

I have never looked at the bars with larger hoops. Surely this makes the bar longer though? A longer bar reduces the stiffness a lot (just see what the difference is with your rear Whiteline bar, adjustment of approx. 2cm can make a neutral car into an oversteering car). I would expect that about 2cm increase in length on both sides would need an increase of 2mm in thickness to have the original stiffness.

Cheers,

Job
 

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its relative to the strength/spring of the material used in the bar. Thickness + length are not the only factors to consider in the design of an arb. In additionan off the shelf non adjustable rear bar might be gret for some and rubbish for others. If you are that concerned about over/understear then leave the front alone and get an adjustable rear bar, sp
Yes [Y]
end some time on a track tuning the roll to yourdesire.
 

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I think the best overall balance is a standard front ARB...uprated with Powerflex bushes.....ADJ droplinks to sort out the clearance issues..(If not going ultra LOW)....and a 25mm rear ARB....Neuspeed or alike.....this setup does everything you need and dosen`t break the bank....also is easy to fit it all.... doesn`t require you to drop the front subframe like fitting a BIG hoop ARB does......[:D][Y]
I would advise against this. Fitting one to the rear only will cause the car to oversteer more, whereas fitting a full kit will transform the car, dialling out any understeer. I was amazed when I had got the eibach kit fitted

Plus you can't compare the oem front bar to the one in a kit, the difference is night and day
 

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Most anti roll bar munufacurers use a heat treated 4340 or similar type of material (spring steel). Most of these have similar spring characteristics. The difference between materials seems to be mainly regarding maximum stress rather than rating.

Only when very expensive material like titanium etc. is used will there be a completely different rating.

I was incorrect in saying that there are only 2 things that influence roll resistance created by an anti roll bar. There are several other things like lever arm effect, pre-tension, mounting strength etc.

I totally agree that on the Mk.4 only a rear bar is needed. A stiffer front bar results in less traction and more understeer. I have tried most combinations and found that an adjustable bar gave the best balance and the highest G before ESP intervention.

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A stiffer front bar only increases understeer when a matching rear bar isn't fitted. As I already said, fitting an uprated rear bar without the front will increase oversteer. Simple physics.

I get no understeer and traction is increased because there is less weight being transferred onto the wheel when cornering. I'm sure others on here with a similar setup would agree.
 

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I think the best overall balance is a standard front ARB...uprated with Powerflex bushes.....ADJ droplinks to sort out the clearance issues..(If not going ultra LOW)....and a 25mm rear ARB....Neuspeed or alike.....this setup does everything you need and dosen`t break the bank....also is easy to fit it all.... doesn`t require you to drop the front subframe like fitting a BIG hoop ARB does......[:D][Y]
I would advise against this. Fitting one to the rear only will cause the car to oversteer more, whereas fitting a full kit will transform the car, dialling out any understeer. I was amazed when I had got the eibach kit fitted

Plus you can't compare the oem front bar to the one in a kit, the difference is night and day
I would say a standard front ARB (23mm)....mounted with powerflex bushes..(very similar if not identical to poly "KIT" bushes)... and using ADJ droplinks...(which are solid mounted)....would be very close to an aftermarket front setup.....yeah of course having say a 28mm rear or a 25mm ARB adjusted to hardest setting together with a standard front setup is gonna increase oversteer....thats obivious.....eliminating some of the flex up front however and not over doing it by going to hard/firm at the back is the key to a good balance....

If wanting to go LOW....45-50 mm +... etc then an aftermarket front ARB is required anyhow.....and most people fit them for that exact reason....the clearance gain making more of a difference than the handling side of things where the gains are smaller...

I bet if the MK4 didn`t have a "FAT" driveshaft and clearance problems then people prob wouldn`t even bother with changing the front ARB at all....(unless the car was for regular track use maybe).....am sure they would just uprate the standard front setup.....

.
 

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A stiffer front bar only increases understeer when a matching rear bar isn't fitted. As I already said, fitting an uprated rear bar without the front will increase oversteer. Simple physics.

I get no understeer and traction is increased because there is less weight being transferred onto the wheel when cornering. I'm sure others on here with a similar setup would agree.
The front suspension frequency is already slightly to high on a 2wd Mk.4 compared to the rear suspension frequency (4motion does need uprated front bar as well as uprated rear).

A thicker front bar WILL unload the inside front wheel more when cornering. The rear bar will counter this to a certain extent. There are lots of cars that benefit from an uprated front bar (like the 4Motion) but in my opinion the 2WD Mk4 n does not need more front roll resistance (which increases the total front frequency), only extra rear. Adding a rear bar does not create oversteer per se, only too much rear roll resistance will create oversteer. That is why an adjustable rear bar is ideal to be able to adjust for a neutral chassis, because spring and shock rates have a direct influence on the balance of the car.

I do realise that handling balance is a personal thing and preference varies from person to person. Some people like a bit of understeer, some a bit of lift-off oversteer and some just plain neutral. What is an understeering car for 1 person can be a neutral handling car for another, all depending on their driving style, e.g. acceleration of steering, braking into corners etc.

An thicker front bar might work very well for you. But my opinions are not quite as subjective. Besides my personal preference (neutral with a touch of lift off oversteer) the suspension geometry and rates are quite clear. Or I might have been doing the wrong thing over the last 20 years as a suspension engineer:)

Try a 2wd Mk4 on road tyres with an adjustable rear bar fitted and a standard front bar. You might be surprised.
 

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I have a rear neuspeed arb fitted and set to medium stiffness - I've
also fitted some bilstein b4 dampers with some eibach -30mm springs. I
had all this lot fitted together - the difference I've noticed between
this set up and the standard GTI set up is quicker turn in, more
front end bite and generally better grip. However the downside for me
is that in the wet the handling is a touch twitchy and pushing too hard
or lift off in a corner corner (in the wet) WILL provoke oversteer to
the extent that once I had to opposite lock. This happened at slow
speeds (-30mph) on a small roundabout when I was actually testing the
limits. In fact I can quite easily get the car to shimy sideways in the
wet. As a result I find I have to be quite gentle with steering and
throttle inputs in the wet (btw, I run 18" RS4 reps with F1s with are
only 1 month old). Before had these bits fitted I just had a lot
of understeer.

After reading all the above I may consider fitting an upgated front arb (if I don't sell first).
 

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I have a rear neuspeed arb fitted and set to medium stiffness - I've also fitted some bilstein b4 dampers with some eibach -30mm springs. I had all this lot fitted together - the difference I've noticed between this set up and the standard GTI set up is quicker turn in, more front end bite and generally better grip. However the downside for me is that in the wet the handling is a touch twitchy and pushing too hard or lift off in a corner corner (in the wet) WILL provoke oversteer to the extent that once I had to opposite lock. This happened at slow speeds (-30mph) on a small roundabout when I was actually testing the limits. In fact I can quite easily get the car to shimy sideways in the wet. As a result I find I have to be quite gentle with steering and throttle inputs in the wet (btw, I run 18" RS4 reps with F1s with are only 1 month old). Before had these bits fitted I just had a lot of understeer.

After reading all the above I may consider fitting an upgated front arb (if I don't sell first).
Try the different settings on the rear bar.....(I take it your on the middle hole of a 25mm bar?)...going softer may dial out the oversteer a touch.....
 

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yea, I'm on the middle hole - i always thought that making the rear
stiffer than the front increased oversteer? i knew guys who
deliberately fitted softer front shocks to their 205 gti's to increase
oversteer...
 

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I think I'll take your advice and try the softer setting..... probably
doesn't help that I have new F1's on the front and part worn dunlop
sports on the rear
 

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Yeah try out different setups mate......as people said above it all down to how YOU like the car to handle....not what others THINK the best setup is.....is easy to fall into the "follow the crowd" trap.....when you ask alot of people why they carried out a certain mod they stay..."cause thats what everyone does"....don`t get me wrong good advice/opinions are great....providing the the info given is exactly what you are also looking to acheive...[Y].

have fun finding your perfect setup,

Nick
 
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