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GTA Roll Bars vs Eibach Bars?

Hi All,

Really debating at the moment whether or not to buy the Eibach roll bar kit for my 156, although I am not sure if the Eibach kits really live up to the price - 311.99 delivered with VAT direct from Eibach.

I need a new front bar for my 2.5 V6 either way and am interested in upgrading the bar, so thought maybe the GTA bars are perhaps nearly as good, and they also cost a little less than the Eibach kit, has anyone got any advice on this?

Many Thanks,
Tony.
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I had a 1.6 Twinnie 147 and I went through this quandry myself, I chnaged the ARBs for GTA ARBs and was very impressed with the increased stability, My original review is here.

https://www.alfaowner.com/Forum/tunin...s-upgrade.html

I have done a similar thing on the GTA but gone from standard GTA ARBs to Eibach and found the difference in a same order as going from standard on the twinnie to GTA ARBs.

Pascs also has some experience with different ARB setups on his 156s so good idea to get some input from him.


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I'd go for the GTA bars, but make sure you do front and rear to keep the balance.
If you just change the front it will make it understeer more.
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If you are going to change the ARB's then I'd recommend going for the Eibach's if you can afford it - the change is not huge but the car is definitely flatter through the corners......also the rear Eibach is 'adjustable' so in theory you can alter the setup to give more or less rear stiffness

If you dont have a good set of dampers then I'd recommend you do this first as a change in dampers has a far bigger improvement than a change in ARB's

The GTA bars are only 1-2mm thicker than standard and the Eibach's are 4mm thicker than standard so there is quite a significant difference

156 2.5 V6 24v, Cosmos Blue Metallic, Tan Leather, 17 GTA's, 225/45 Michelin PS2's, Full Zender body kit, GTA Headlights, Eibach springs, Koni FSD's, Eibach Anti-roll bars, Ferrari 360 Brembo calipers, DS2500 pads, Squadra ECU, 45mm Intake Runners, Carbon Intake, Dan & Wizard exhaust

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Thanks for all of your replies.

I have the adjustable Koni Sport Kit (yellow dampers and blue lowering springs). Not sure how these compare to the Eibach/Koni spring and damper setup, although compared to what I had (standard springs and dampers) is a vast improvement, so Koni shocks and springs coupled with the Eibach bars would be a good choice you think?
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The Koni kit is pretty low right -40mm ? how do you find that?

I'm very happy with the Eibach bars, you'll need to fit new genuine front drop links at the same time
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I feel the Koni setup is pretty good really, I think it is -30mm, and has the benefit of being adjustable. I haven't touched this yet as the ride is still quite hard, but not spine breaking!

Thanks for your advice, I think I may go with the Eibach bars and I will fit new drop links at the same time. May I ask though, why genuine drop links?
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I bought a set of non genuine Alfa drop links and the ball joint sticks out about 5mm more than the genuine ones. This is fine for normal ARB's but the Eibach's being a bit thicker or something, cause the non genuine ball joint to run very close to the suspension and appear to knock / rub against it.

Also I think non genuine ones can have a dubious quality and the Eibach's do put more force through the drop link
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Hang on, that is exactly the problem that I have. One of my droplinks (nearside I think) is actually rubbing on the front suspension fork. So maybe this could be my problem? I can, with extreme pressure, move the anti roll bar from side to side, about 1/2 inch - would this be normal? The anti-roll bar I have has been fitted to the car for around a year and has covered hardly any mileage, so my thought in the roll bar bushes wearing out maybe wrong, as I have pattern droplinks (made by Firstline I believe).

Maybe if I was to try buying some genuine Alfa Romeo links and fit them prior to changing the bar, would this be an idea ???

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I can, with extreme pressure, move the anti roll bar from side to side, about 1/2 inch - would this be normal?
It should not move from side to side.
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Another OEM part that has failed then!
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I'd go for the GTA bars, but make sure you do front and rear to keep the balance.
If you just change the front it will make it understeer more.
I have concerns about the balance of the Eibach ARBs for a 156 SW 1.9 JTD16V. Those bars were for sure developed for optimal performance for a GTA which is more heavy at the front. The Eibach ARBs have 4mm more both at front and rear than the original ones. Isnt 26mm too much for a 1.9 JTD. I want less roll but also want the car to understeer less (which i already worked on raising the front tyres pressure a bit to decrease understeer, but i prefer to do this the right way with some arbs).

I'm with Bilstein B12 Pro Kit suspension and as some probably already know this suspension change the rake angle of the car. The rear gets a different front / rear height ratio than the original suspension. With B12 the rear gets lower in comparison to the front and that means that there is more weight on the rear, making the front lighter and of course making the rear more planted but the front gets more understeer. I want to reverse this effect a bit, so i'm worried that keeping the F/R stiffness ratio wouldnt work so well on a 1.9JTD due to the engine being lighter than the one on the GTA.

In the case of installing GTA ARBs the front as a 1mm improve and the rear 2mm improve meaning that the rear will get stiffer, which also means that the car will get more oversteer in comparison to the original setup.

Which are your thoughts about these variables?
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If you have a Bilstein B12 kit, for a SW, I'd make up some spacers for the bottom of the rear springs to raise them 15mm from the strut spring perch. I think simply making spacers from a fibreglass paste should be strong enough. Just make a few drainage channels in the bottom. That should sort the aerodynamic angle of attack.

As the SW is heavier at the rear, use the holes for the rear ARB closer to the bushes. The JTD has more weight at the front so won't be significantly different from the V6. (the V6 is heavier overall but the JTD has a greater forward weight bias). The handling should be balanced at that as the variable rate rear coil springs should effectively self adjust the handling. As with any kit, the greater the roll angle, the greater the understeer effect. Therefore, if the rear is too loose in the wet or greasy roads, fit the rear ARB links to the outer holes.
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If you have a Bilstein B12 kit, for a SW, I'd make up some spacers for the bottom of the rear springs to raise them 15mm from the strut spring perch. I think simply making spacers from a fibreglass paste should be strong enough. Just make a few drainage channels in the bottom. That should sort the aerodynamic angle of attack.

As the SW is heavier at the rear, use the holes for the rear ARB closer to the bushes. The JTD has more weight at the front so won't be significantly different from the V6. (the V6 is heavier overall but the JTD has a greater forward weight bias). The handling should be balanced at that as the variable rate rear coil springs should effectively self adjust the handling. As with any kit, the greater the roll angle, the greater the understeer effect. Therefore, if the rear is too loose in the wet or greasy roads, fit the rear ARB links to the outer holes.
So in your opinion i could stick with the Eibach ARB and just change from the softest to hardest setting according to driving conditions? I will have to change the front ARB for sure because mine got bent in a very hard pot-hole. We've take some time to find out what is making the front lean more to the left side than the right side, till the moment i've got the idea to unlink the ARB to see if the height gets leveled. And... surprise, it gets fully leveled, linked the droplinks again and it got uneven. So i will have to change it. Considering the labour cost i find out that is a good idea to make the upgrade of course with front and rear to keep everything balanced.

I have another concern that is the Xenon headlight leveling pieces. Hope the new ARB doesnt mess with those.

Raising the rear end seems a great idea.

The other issue with the Eibach ARB is that some guys seem to lose grip in tight corners. The thing is... how tight are those corners...? I love to do some twisties. My concerns is that i end up with a FWD car that gets much less progressive in terms of throttle control during corners.

Thank you for your input
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On my 2.4 JTD I use GTA front anti roll bar and Eibach rear anti roll bar on the hard setting. It drives wonderfully on the narrow, bumpy roads of Cumbria. No understeer at all.
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There was a question on here about the bracket for the Xenon self levelling. Apparently the Eibach front ARB doesn't have it but I think that some drilled and bent stainless steel and a stainless steel motorcycle exhaust clamp would sort that.

Yes, @Pud237 , I'd expect no understeer with that set up. That said, the torque of the JTD is why the Q2 was created as it will always be able to spin the inner wheel.
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Yes I have Q2 on it as well, and 17" GTA wheels with 225/45/17. Everytime I drive it the grip & nimbleness blows me away. Feels like it has the grip of a 159 and the handling of a TS.
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Originally Posted by Fragoso View Post
I have concerns about the balance of the Eibach ARBs for a 156 SW 1.9 JTD16V. Those bars were for sure developed for optimal performance for a GTA which is more heavy at the front. The Eibach ARBs have 4mm more both at front and rear than the original ones. Isnt 26mm too much for a 1.9 JTD. I want less roll but also want the car to understeer less (which i already worked on raising the front tyres pressure a bit to decrease understeer, but i prefer to do this the right way with some arbs).

I'm with Bilstein B12 Pro Kit suspension and as some probably already know this suspension change the rake angle of the car. The rear gets a different front / rear height ratio than the original suspension. With B12 the rear gets lower in comparison to the front and that means that there is more weight on the rear, making the front lighter and of course making the rear more planted but the front gets more understeer. I want to reverse this effect a bit, so i'm worried that keeping the F/R stiffness ratio wouldnt work so well on a 1.9JTD due to the engine being lighter than the one on the GTA.

In the case of installing GTA ARBs the front as a 1mm improve and the rear 2mm improve meaning that the rear will get stiffer, which also means that the car will get more oversteer in comparison to the original setup.

Which are your thoughts about these variables?
You should read the following as yours is a SW. Your issue is the rear springs, thats whats causing your low rear ride height. https://www.alfaowner.com/Forum/alfa...l#post17427601 (suspension upgrade)
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With B12 the rear gets lower in comparison to the front and that means that there is more weight on the rear, making the front lighter and of course making the rear more planted but the front gets more understeer.
Lowering the rear ride height (relative to the front) won't cause the rear end to carry significantly more weight. Don't be confused by the fact that forward acceleration causes rear end squat as well as rearward weight transfer, the two aren't inextricably linked, rather they are two somewhat seperate affects of the acceleration.

Statically raising or lowering one end of a car relative to the other will move weight (represented by the CG of mass) forward or rearward, but only to a relatively small degree (even if the change in relative ride heights were to be quite substantial). It will be measurable in single digit millimetres, and of itself I can't see that this small change in static longitudinal weight distribution will have a significant effect on the handling or steering etc.

Out of curiosity (and to quantify my assumptions...) I made a CorelDraw diagram. According to the diagram, if we assume a chassis with a wheelbase of 2595mm (156 sedan wheelbase), with a CG height at 600mm (about the same as the top of the tyres, generally a reasonable rough approximation of CG height), and a 60% forward weight bias determining the longitudinal CG location (typical FWD), then a 30mm lowering of rear ride height causes the CG to move backward by only 7mm (note that the CG also lowers by 12mm). This represents only a 2.7% change in the front / rear static weight bias (with a 30mm rear ride height lowering).

This is not to say that changing relative front / rear ride heights won't affect handling and steering, but I can't see that it would be as a direct result of altering the longitudinal weight distribution so slightly. The change in CG height will be more significant, as will the associated change to the height of the rear vs front geometric roll centres.

Lowering the rear GRC (as will occur with a reduction in rear ride height, quite possibly significantly more than the actual decrease in ride height), will decrease geometric rear roll stiffness, so will reduce lateral weight transfer at the rear (while causing lateral WT to increase at the front even if front roll stiffness is unaltered). This will tend to increase understeer, especially initial understeer because geometric weight tranfers are 'instant' as opposed to 'mechanical' weight tranfers which are 'slow' ('geometric' being the % of weight transfer which occurs via the suspension geometry, and 'mechanical' being the % of WT which occurs via the springs and ARBs).

IMO it is probably counter productive for the rear ride height to be reduced if the front ride height isn't (likely to be understeer inducing, as well as degrading responsiveness to steering inputs and change of direction), so I do agree with you that you should try to avoid it happening. I just don't agree with the notion that it is a product of any change in static weight distribution...

Regards,
John.
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You should read the following as yours is a SW. Your issue is the rear springs, thats whats causing your low rear ride height. https://www.alfaowner.com/Forum/alfa...l#post17427601 (suspension upgrade)
The rear is higher than the front. Its just the ratio that changed and i'm okay with that in fact, aesthetically i like it this way and supposedly the Eibach ARBs should work optimal with my suspension, as said by Eibach (if that is credible enough), now the thing is, all of this should work "optimal" on the car they tuned, which i think should be the GTA. But i think i will go with the Eibach.

The rear height even when i carry people and luggage is still okay. The B8's with the springs can handle the added weight. But most of the time i drive alone and when i'm with the family just carry my kid and sometimes the dog, so a max of 50kg at the back.

I'm a bit off to change the rear springs.

At this moment there isnt much understeer, its quite balanced. I use to feel understeer with the original tyre pressures. 2.4 Front and 2.4 Rear with the 215/45/17 on Toyo Proxes T1 Sport. Now i'm with Continental Premium Contact 6 (great btw) and since i've raised the front tyres pressure the understeer gone and the car is now balanced. I just need to change the front ARB because mine just got bent, so i'm considering upgrading both front and rear, but dont want to end up with a car that is less fun to drive. At this moment the car has a progressive handling and very good throttle control to lift off on the limit. My concern is to lose that and ending up with a car that refuses to loose the rear or with a car that oversteers too easy.
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Lowering the rear ride height (relative to the front) won't cause the rear end to carry significantly more weight. Don't be confused by the fact that forward acceleration causes rear end squat as well as rearward weight transfer, the two aren't inextricably linked, rather they are two somewhat seperate affects of the acceleration.

Statically raising or lowering one end of a car relative to the other will move weight (represented by the CG of mass) forward or rearward, but only to a relatively small degree (even if the change in relative ride heights were to be quite substantial). It will be measurable in single digit millimetres, and of itself I can't see that this small change in static longitudinal weight distribution will have a significant effect on the handling or steering etc.

Out of curiosity (and to quantify my assumptions...) I made a CorelDraw diagram. According to the diagram, if we assume a chassis with a wheelbase of 2595mm (156 sedan wheelbase), with a CG height at 600mm (about the same as the top of the tyres, generally a reasonable rough approximation of CG height), and a 60% forward weight bias determining the longitudinal CG location (typical FWD), then a 30mm lowering of rear ride height causes the CG to move backward by only 7mm (note that the CG also lowers by 12mm). This represents only a 2.7% change in the front / rear static weight bias (with a 30mm rear ride height lowering).

This is not to say that changing relative front / rear ride heights won't affect handling and steering, but I can't see that it would be as a direct result of altering the longitudinal weight distribution so slightly. The change in CG height will be more significant, as will the associated change to the height of the rear vs front geometric roll centres.

Lowering the rear GRC (as will occur with a reduction in rear ride height, quite possibly significantly more than the actual decrease in ride height), will decrease geometric rear roll stiffness, so will reduce lateral weight transfer at the rear (while causing lateral WT to increase at the front even if front roll stiffness is unaltered). This will tend to increase understeer, especially initial understeer because geometric weight tranfers are 'instant' as opposed to 'mechanical' weight tranfers which are 'slow' ('geometric' being the % of weight transfer which occurs via the suspension geometry, and 'mechanical' being the % of WT which occurs via the springs and ARBs).

IMO it is probably counter productive for the rear ride height to be reduced if the front ride height isn't (likely to be understeer inducing, as well as degrading responsiveness to steering inputs and change of direction), so I do agree with you that you should try to avoid it happening. I just don't agree with the notion that it is a product of any change in static weight distribution...

Regards,
John.

Well that makes total sense to me now. A very deep view into the subject, never considered the geometry factor in question. I haven't confirmed in depth that the front / rear height ratio has changed, since i haven't noted the height before the modification.
Plus, there's another variable on this issue that i didnt mentioned before. I've powerflexed the rear end some days after the suspension upgrade. It was part of a maintenance solution and i'm pretty happy with the feel plus already passed two years and fortunately the rear camber is still the same today as it was the day i've made the bushings maintenance. The powerflex bushings on the rear turned it more precise, stiff and grippy. It could be this that is making it less grippy at the front in comparison. One thing is fact, i feel more understeer in initial turn and less after the initial turn. Plus with the 2.4 bar F / R not only the front lacks response as the tyres get chewed pretty easy. My last Toyos got totally bald on the interior in 8000/9000kms while the center still almost new. Now with 2.6 front and 2.4 rear the new Conti are wearing evenly and the initial turn in understeer almost gone.

Supposedly this B12 should work fine and the rear / front measures are according to what is expected after installation. So thinking once again about it, it could be the rear powerflex stiffening everything up influencing on the geometry response between back and rear. I have planned to powerflex the front as well considering that i'm so pleased on the effect and compliance on the rear. I might have another reason to do it now.

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I haven't confirmed in depth that the front / rear height ratio has changed, since i haven't noted the height before the modification.
Just keep in mind that lowering the rear ride height also lowers the rear GRC, and this can impact handling and steering response. When lowering I think it's generally advisable to ensure the rear lowering is no greater than the front lowering, or less than the front lowering. I would always keep lowering ambitions modest, as lowering usually messes with the geometry in ways that may not be obvious.

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Plus, there's another variable on this issue that i didnt mentioned before. I've powerflexed the rear end some days after the suspension upgrade. It was part of a maintenance solution and i'm pretty happy with the feel plus already passed two years and fortunately the rear camber is still the same today as it was the day i've made the bushings maintenance. The powerflex bushings on the rear turned it more precise, stiff and grippy.
I've fitted custom made rear lateral control arms on my 147. These are based on Toyota Corolla and Camry rear control arms, and eliminate the relatively soft Alfa control arm bushes (note that my cars' 'original' rear control arms appeared to be in good condition, but may have been aftermarket and not OE, and there is some suggestion that at least some aftermarket rear arms have problematically softer bushes than OE arms). Each control arm is a hybrid of half a Camry arm and half a Corolla arm (one or both shortened to suit the length required for the Alfa). The Camry arms use a spherical bearing at the outer end (factory part, fully weather sealed etc). The Corolla arms have rubber bushings, but much stiffer than the Alfa bushings. So, each hybrid arm has a spherical outer bearing and a fairly stiff rubber inner bush. The arms are also tubular, eliminating the flimsy 'U' shaped Alfa arm stamping. A search on this forum for 'Camry' and / or 'Corolla' should find a more in depth description. These arms were a huge improvement in rear end stability, probably similar to what you have achieved with fitting poly bushes (maybe better, can't really say).

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It could be this that is making it less grippy at the front in comparison. One thing is fact, i feel more understeer in initial turn and less after the initial turn. Plus with the 2.4 bar F / R not only the front lacks response as the tyres get chewed pretty easy. My last Toyos got totally bald on the interior in 8000/9000kms while the center still almost new. Now with 2.6 front and 2.4 rear the new Conti are wearing evenly and the initial turn in understeer almost gone.
Personally I've found that very high tyre pressures work very well to sharpen up the handling and steering response (what most people would probably regard as 'excessive' pressures...). The pressures I'm using are substantially higher than you are using (arrived at with a lot of experimentation). The down side is harshness, but the car is much more fun to drive.

My cars' steering response is good with some toe-in, and the tyre wear is very even across the treads. Toe-out will promote inner edge wear (when negative camber is also present). I'm using 3mm of toe-in both front and rear, and prefer the steering feel of toe-in compared to toe-out (which I find makes the car a bit 'wandery' without really improving turn in response, despite what seems to always be said regarding toe-out...).

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Supposedly this B12 should work fine and the rear / front measures are according to what is expected after installation. So thinking once again about it, it could be the rear powerflex stiffening everything up influencing on the geometry response between back and rear. I have planned to powerflex the front as well considering that i'm so pleased on the effect and compliance on the rear. I might have another reason to do it now.
Softer bushings in the rear control arms adversely affect steering response, as well as handling 'precision'. Also, when the bushes are laterally loaded the bushes in the frontward control arms (front arms of the rear suspension) compress more than the bushes in the rearward control arms. This is because the arm geometry laterally loads the frontward arms more heavily than the rearward arms, not because the bushes in the front arms are softer, all eight bushes in the four arms are same stiffness (many cars also use softer bushes in the front arms compared to the rear arms). This creates a passive steer effect which induces rear toe-in when cornering. This passive steer is understeer inducing (i.e. 'stabilises' the handling by inducing understeer...). The softer the bushes the greater this affect will be.

I have standard bushes in the front suspension lower control arms. I'd like to try stiffer bushes (poly being the only practical option for this), but it's a lot of expense for something which may cause more trouble than it's worth...?

Regards,
John.
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