Not that the M needs them, but cant find anyone that makes an aftermarket setup. I will be polybushing mine, but did wonder if anyone has played with larger bars, and if it made it understeer (front bar) more or oversteer (rear bar). I went H&R on the M3, but on the CSL the stock bars were spot on. Suppose as the Z4M weighs less, then they are good anyway, although the CSL is lighter still, and with a 30.8mm front and 22.5mm rear does perform very well.
Uprated anti roll bars?
- Thread starter chris
- Start date
See http://www.z4-forum.com/forum/viewtopic.php?f=9&t=39936&p=607837&hilit=h&r+arb#p607837
Personally I don't get this thing that people have about understeer: it's not necessarily all down to the suspension and set up of the car but also down to driving technique. If you've ever driven a go kart on slicks in the wet, then they understeer like mad if you don't apply the throttle when you turn the steering, but if you apply too much throttle the kart will oversteer into a spin, so the diference between over/understeer is all down to technique in the same prevailing conditions with the same set up.
Personally I don't get this thing that people have about understeer: it's not necessarily all down to the suspension and set up of the car but also down to driving technique. If you've ever driven a go kart on slicks in the wet, then they understeer like mad if you don't apply the throttle when you turn the steering, but if you apply too much throttle the kart will oversteer into a spin, so the diference between over/understeer is all down to technique in the same prevailing conditions with the same set up.
I had read that, but no one has said if it makes the car better. If isn't realise the Z4M comes with the 27mm front bar anyway, so I've got some power flex black bushes, and see how that goes.
As I said, on the road I have found very very little roll, well nothing I would want to get rid of. Just going to see how she behaves on track. May end up with a set of KW V3 or clubsport coilovers instead
As I said, on the road I have found very very little roll, well nothing I would want to get rid of. Just going to see how she behaves on track. May end up with a set of KW V3 or clubsport coilovers instead
exdos said:Beedub said:
Untrue:
considering that photo is is on semi slick tyres, cornering on a hairpin at a very considerable speed, i call that very little body roll..... with your progressive springs on the front, you probably felt the need to update the ARB...
Lets not forget uprated Arbs pull out the mounts on this car, the stock bars are more than enough and the tiny amount of roll left isn't unwelcome for numerous reasons.
how about this pic, even tighter corner, and serious forces at work....
looks pretty good to me... bone stock ARB and clubsports :evil: :evil: :evil:
Each to their own but imo they simply aren't needed, i haven't once experienced anything that would lead me to replace them,Hell its cheap enough and easily to do so. The stock mounts points are very weak, unless a welded reinforcement is in place this will pull out, when an upgraded bar is used with uprated coil overs.
heres another on a tightening radius corner thats taken at 65-70mph....
looks pretty good to me... bone stock ARB and clubsports :evil: :evil: :evil:
Each to their own but imo they simply aren't needed, i haven't once experienced anything that would lead me to replace them,Hell its cheap enough and easily to do so. The stock mounts points are very weak, unless a welded reinforcement is in place this will pull out, when an upgraded bar is used with uprated coil overs.
heres another on a tightening radius corner thats taken at 65-70mph....
Byron,
As you know, I very much like the technical side of cars, and in doing some calculations of the Z4M's geometry for my own use, I'd previously used the photo I posted to calculate that in that instance there is 2.3 degrees of bodyroll. Personally, I think that this could be reduced by ARBs and I think you'd notice the difference.
In the case of my Z3MC, I fitted KW coilovers and thought that I'd eliminated lateral bodyroll, then I fitted uprated ARBs and they certainly made a significant difference and reduced the body roll some more.
I share your concern for the weakness of the front mounting points, but I think that my addition of a 6mm shim between the chassis and the mount addresses this problem.. If it doesn't., then a repair which beefs up the mounting points will certainly solve the problem. From the photos that I've seen of my Z4MC on track, with uprated ARBs, I get 1.6 degrees of bodyroll, even though the springs are progressive.
As you know, I very much like the technical side of cars, and in doing some calculations of the Z4M's geometry for my own use, I'd previously used the photo I posted to calculate that in that instance there is 2.3 degrees of bodyroll. Personally, I think that this could be reduced by ARBs and I think you'd notice the difference.
In the case of my Z3MC, I fitted KW coilovers and thought that I'd eliminated lateral bodyroll, then I fitted uprated ARBs and they certainly made a significant difference and reduced the body roll some more.
I share your concern for the weakness of the front mounting points, but I think that my addition of a 6mm shim between the chassis and the mount addresses this problem.. If it doesn't., then a repair which beefs up the mounting points will certainly solve the problem. From the photos that I've seen of my Z4MC on track, with uprated ARBs, I get 1.6 degrees of bodyroll, even though the springs are progressive.
exdos said:
always nice to read your replies.... i simply must stress i have never once experienced anything that would lead me to replace the bars, otherwise id simply do it, but if i did, id have to do a proper welded reinforcement to the mounts, i would not be satisfied with the shim option, luckily i don't need to worry on this level as i feel the stock bars are doing what i need.
Surely 0.7 degrees is minimal. And I would want to know the extra speed that you would get, as some roll is obviously good, and you don't want the car too stiff! or the trade off is the car will just be unpredictable, well to some extent.
Plus with weak bushes, then that will be a part as well. From how it handles, I would say that it's on par with the CSL, well with uprated springs.
If more speed can be had, then I'm all up for that
Plus with weak bushes, then that will be a part as well. From how it handles, I would say that it's on par with the CSL, well with uprated springs.
If more speed can be had, then I'm all up for that
chris said:Surely 0.7 degrees is minimal. And I would want to know the extra speed that you would get, as some roll is obviously good, and you don't want the car too stiff! or the trade off is the car will just be unpredictable, well to some extent.
Plus with weak bushes, then that will be a part as well. From how it handles, I would say that it's on par with the CSL, well with uprated springs.
If more speed can be had, then I'm all up for that
if i fitted uprated ARB the roll would mostly be less still than 1.6 degrees as i run a track biased coil over setup..... the tiny roll i experience is more than welcome and does not hinder progress at all.
The angle of bodyroll is an indication of the difference in loading of the outside tyres versus the inside tyres, therefore the greater the angle of bodyroll the greater the difference in loading and the nearer the outside tyres are to being overloaded and then losing grip. At the same time the relative unloading of the inside tyres means that these tyres are not providing all their potential grip, so overall, a car cornering with lateral roll, is not achieving maximum grip. As such, 0.7 degrees of additional lateral bodyroll, is significant. When lateral bodyroll is reduced, you get more feedback through the seat of your pants from the car from noticing the "slip" on the tyres (I.e. sliding) because the car remains flatter.chris said:Surely 0.7 degrees is minimal. And I would want to know the extra speed that you would get, as some roll is obviously good, and you don't want the cara too stiff! or the trade off is the car will just be unpredictable, well to some extent.
Plus with weak bushes, then that will be a part as well. From how it handles, I would say that it's on par with the CSL, well with uprated springs.
If more speed can be had, then I'm all up for that
Whether you have coilovers or a progressive spring is irrelevant. If the spring rate of your coilovers permit, say 2 inches of spring compression of the outer suspension at a given speed when travelling around a bend of a given radius, whereas a progressive spring permits only 1.5 inches of compression in the same circumstances, then the coilover would permit more lateral bodyroll. Increasing the spring rate, rather than using uprated ARBs will also reduce lateral bodyroll of both coilovers and progressive spring suspension systems.Beedub said:
You might think that the your present set up doesn't hinder your progress, but if you're looking to improve your sprint times, then I would suggest that you'd most likely gain from reducing lateral bodyroll, and in your case, fiting front springs of a higher spring rate would be a place to start, without the potential downside of uprating ARBs.
Yes, I do a few days at The Ring every year. I have a heavily modded Z3MC and my Z4MC is modded in the suspenion dept.chris said:
I like minimal toe-in at front and rear on any suspension and negative camber at the front to match the angle of max bodyroll as my starting point and it often finishes at this too.
Chaps, much though I'd love to join the debate, life is busy at the moment and I don't have time to write a proper response. I'll let some pictures describe my experience:
Car entirely OEM:
2012 - Eibachs, OEM dampers, OEM strut brace:
2014 - KW Clubsports, H&R ARBs, OEM strut brace + countless other mods:
Car entirely OEM:
2012 - Eibachs, OEM dampers, OEM strut brace:
2014 - KW Clubsports, H&R ARBs, OEM strut brace + countless other mods:
Hi Chaps,
I am another one that is in support of uprated ARBs on the Z4MC. I run them with KW v3s, I track my car and have experience of running the KWv3s with and without the uprated ARBs.
With the ARBs There is a noticeable reduction in body roll car has perfect neutral, confidence inspiring and predictable handling. With a set of semi-slick tyres it really is a surprise for people in much more exotic machinery.
The proof of there effectiveness is how much more evenly my tyres wear now with them fitted. Just about to do my 4th day on the same set! Granted I did have a rather damp day at Thruxton but previously i would destroy the outer shoulders in a single day. Granted more camber would help but I am running -2 degrees already.
I did a lot of research on the strength of the arb mounts and had discussions with exdos around the increased stiffness the H&R ARBs would provide. The problems most people seem to encounter is when they run the CG ARBs which are massively stiffer than the H&R ones. I found some info about using an epoxy resin to weld the shims exdos mentions on the other z4 forum. I chose to do this, so far no problems I was only under the car the other day and no signs of stress what so ever.
I am another one that is in support of uprated ARBs on the Z4MC. I run them with KW v3s, I track my car and have experience of running the KWv3s with and without the uprated ARBs.
With the ARBs There is a noticeable reduction in body roll car has perfect neutral, confidence inspiring and predictable handling. With a set of semi-slick tyres it really is a surprise for people in much more exotic machinery.
The proof of there effectiveness is how much more evenly my tyres wear now with them fitted. Just about to do my 4th day on the same set! Granted I did have a rather damp day at Thruxton but previously i would destroy the outer shoulders in a single day. Granted more camber would help but I am running -2 degrees already.
I did a lot of research on the strength of the arb mounts and had discussions with exdos around the increased stiffness the H&R ARBs would provide. The problems most people seem to encounter is when they run the CG ARBs which are massively stiffer than the H&R ones. I found some info about using an epoxy resin to weld the shims exdos mentions on the other z4 forum. I chose to do this, so far no problems I was only under the car the other day and no signs of stress what so ever.