it would be really interesting i think to have a drive of various people's set-ups on a closed circuit - most of the time it's hard gauge how people's changes have affected the car, as a lot of the discussion is opinion and description. Without much experience of motor racing as a driver i find it hard to understand the changes people have made. I guess also what may be good improvements for the road for someone who lives in Dorset, maybe different to someone who lives in London.
///M Rod Bearings, Vanos Bolts & Motor Mounts
- Thread starter tomscott
- Start date
exdos said:ChawenHalo said:
Why are you getting so "miffed" by my opinion? If you don't agree with me, that's perfectly fine by me; I won't take umbrage
On the AC Schnitzer website here: http://www.ac-schnitzer.de/en/bmw-cars/about-us/development/suspension/ there are a few quotes which I happen to agree with, based on my own experience of the ACS Racing suspension on my Z4MC and other adjustable suspensions:
"The philosophy is simple: "Better fast than hard". This quote would really be nothing special if it did not come from a famous person - a racing driver who has been responsible for suspension development at AC Schnitzer for decades. A man who has every curve on the "North Loop" stored in his popometer, and whom the trade press like to call the "Suspension guru from Aachen": Manfred Wollgarten. With this simple sentence, he expresses our entire suspension philosophy in a nutshell. "The car must in principle handle as well as standard"; and he is convinced that "Forgiving load change responses and gentle understeer on the limit are important - in the end AC Schnitzer customers are not professional racing drivers. Our suspension can handle both country roads and tracks equally well. For sporting drivers who often go to race tracks we offer special racing suspensions. As the damper compression as well as the sway bars are adjustable the handling of the car can be modified."
"Only when a set-up has achieved optimum results under all conceivable driving and race conditions, and combines sports handling with maximum suspension comfort, can it be offered for sale as an AC Schnitzer sports or racing suspension."
So it would appear that AC Schnitzer reckon that it's possible to have both suspension comfort and handling, be it on public roads or on track and that's exactly as I've found is the case with both the ACS Racing suspension on my Z4MC and KWV3 (with front coilovers) on my Z3MC. The beauty of adjustable suspension lies in the "adjustability", but to benefit from this feature you must experiment with different settings to find the best settings for the circumstances and then adjust appropriately when circumstances require the changes. Until you have a series of different settings for different circumstances logged for reference then you won't be getting the best from adjustable suspension. My "Ring" settings are terrible on public roads because they're too stiff.
I'm not miffed by your opinion in particular Exdos but by the general idea you guys are pushing that OEM is rubbish.
That's a famous line from ACS and I wholeheartedly agree that hard suspension does not equal necessarily faster. But they don't claim softer than or more comfortable ride than OEM either.
Was their suspension kit developped specifially from their ACS4 Sport and "Profile" concept for the Z4MC?
What I've lost in day top day driving comfort (probably 15%) I know I've gained in wheel and body control, mechanical grip, precision and feel. I accept the trade off. On track I'll be able to stoffen up further in under 20 secs and 9 clicks away (well, times 4).
ChawenHalo said:
If the OEM suspension was the only suspension available for the Z4MC, then I can tell you, I wouldn't own the car because I find the ride to be jarring and I get a stiff neck and shoulders from driving it on the A&B roads all around my home. I genuinely find the Z4MC's suspension that bad and I've been in a few of them and I find they're all the same.
From my reading of many of those that defend the stiff OEM suspension, they claim it has to be that way because its so "focussed" and a "real drivers's car" but how many of those "real drivers" want to take their cars on track to exploit that focus? I do and that's where I also find the front suspension way too soft. As a staunch defender of the OEM suspension, why have you now ditched it in favour of an aftermarket kit? Because you find the car is a bit "out of focus" on the track?
I've found only advantages of fitting adjustable suspension, except for having to lie on the floor to adjust it when necessary, and that's no big deal.
I've absolutely no idea of how ACS produced its ACS Racing for the Z4MC, all I know is that they found 14mm and 16mm F&R springs to be a better solution than 11mm and 19mm F&R springs.
Thought I would give my 10ps worth! With not having driven a Z4M or indeed a Z4 my experience of the car is zero, but I have had many other cars that I have swapped the suspension systems on so I feel I can add something to the debate.
I agree that OEM suspension is indeed the best compromise between comfort and handling from the factory but and it is a big BUT (I cannot lie) it is made to a price. So BMW engineers made the best setup they could within the bean counters allowance, by swapping out 2k worth of suspension it is going to be better in every area if that is what you want. Manufacturers Would love to put KW suspension on from the factory on all their cars im sure but just imagine how much that would cost!
I agree that OEM suspension is indeed the best compromise between comfort and handling from the factory but and it is a big BUT (I cannot lie) it is made to a price. So BMW engineers made the best setup they could within the bean counters allowance, by swapping out 2k worth of suspension it is going to be better in every area if that is what you want. Manufacturers Would love to put KW suspension on from the factory on all their cars im sure but just imagine how much that would cost!
exdos said:
This being the case why did BMW purposely design the car in such a way, they are not a bunch of amateurs, do we have any facts on the oem compression and rebound figures on the dampers and how they compare front to rear? Was the set up perhaps something to do with the US market, where they expected to sell most of these?
I sold mine as I didn't want to spend more money upgrading the suspension but to be fair to our Euro cousins their roads are far better suited to the cars set up and as such it is likely that they will have less issues with the stiffness at the rear.
daz05 said:
Personally, I think that the Z4M's OEM suspension is the way that it is because its predecessor, the Z3MC, has suspension which is far too soft, which makes that car extremely "lairy", particularly in the wet and BMW wanted the Z4M to have a better reputation with improved handling manners, which it does. As you know, many owners claim that the Z4M has a tendency to understeer and the Z4M's rear geometry of negative camber greater than at the front and a fair amount of toe-in is also commensurate with the suspension being set up to resist oversteer (the characteristic tendency of the Z3M).
BMW engineers are far from a bunch of amateurs, but the fact is, aftermarket suspension suppliers all produce their kits for the Z4M with F&R springs which are of a much closer spring rate match than the Z4M's OEM suspension, and they can't all be wrong, can they?
john did you see this thread thats just popped up on pistonheads....
s85 v10.. 50k miles.....
Rod bearing shells... again... for a long while these have been issues with numerous ///M engines.... wonder why they keep running into this issue... insufficient lube or high oil temps... or both???
http://www.pistonheads.com/gassing/topic.asp?h=0&f=181&t=1311592&mid=48052&nmt=Rod+Bearings+at+50K+miles
s85 v10.. 50k miles.....
Rod bearing shells... again... for a long while these have been issues with numerous ///M engines.... wonder why they keep running into this issue... insufficient lube or high oil temps... or both???
http://www.pistonheads.com/gassing/topic.asp?h=0&f=181&t=1311592&mid=48052&nmt=Rod+Bearings+at+50K+miles
I've just taken a look. It looks to me as though its a clearance issue, the same as the early S54 problem. When the engine gets hot, the metal in the bearings and the cranskshaft expand against each other, reducing the space for oil to lubricate the surfaces causing metal to metal contact and thus wear.Beedub said:
The fact that this is happening in engines much later in their lives than was the case with the early S54s, would suggest to me that they've probably a few microns more clearance than the early S54 bearing shells but still not enough for proper lubrication at all times.
I totally ignore the variable redline indicator on the tachometer on the Z4M, because it shifts the redline to 8000rpm way faster than the oil temperature gauge comes up to temperature and I reckon it takes about 6 miles of driving at no more than 3000rpm to bring the oil up to working temperature.
You'd expect BMW would've learned its lesson on the bearings in its high-revving engines by now.
a340driver
Member
teamemmenracing said:what can you say .....
stuff wears out in proportion to how you use it
25 track Days ...... ????? thats probably about 100,000 miles worth of "normal use" wear .....
Blimey you 're right
These are high performance cars with high costs when things go wrong. Overall it's still a bargain.daz05 said:I just don't get it why go to the trouble of fitting such a fast steering rack, creating such a stiff chassis and then sticking stupidly soft springs at the front to ruin everything they had tried to achieve.
It would appear from the general reaction on this forum that most owners think the OEM suspension is great and criticising it is like swearing in church, so I suppose BMW has satisfied its target market. So why should BMW go to any more trouble in providing something better? They made the car safe with the geometry so the car doesn't have a desire to swap ends. Job done.
I had OEM springs in my car for only the briefest of times, but it was long enough to get to know the car and find the front end frighteningly floaty at extremely high speed. I changed to Eibachs with significant improvement in handling, some improvement in body pitch and roll, and resolution of the high speed front end vagueness. However, the car continues to pitch and roll more than I would like and I have been unable to abolish the understeer inherent to the Z4 despite geometry changes, spacers, a strut brace and sticky tyres. I use mine as a track car side by side with my Westfield so perhaps I'm expecting too much of a car with nearly three times the mass, but this is my motivation for buying KW Clubsports. If mine were a road car only, I would be happy with Eibachs (and less aggressive camber settings) but I couldn't have tolerated the OEM set up.
I'd rather swap ends and crash backwards into a tree than understeer and see it coming thanks
exdos said:
I'd rather swap ends and crash backwards into a tree than understeer and see it coming thanks
exdos said:daz05 said:I just don't get it why go to the trouble of fitting such a fast steering rack, creating such a stiff chassis and then sticking stupidly soft springs at the front to ruin everything they had tried to achieve.
It would appear from the general reaction on this forum that most owners think the OEM suspension is great and criticising it is like swearing in church, so I suppose BMW has satisfied its target market. So why should BMW go to any more trouble in providing something better? They made the car safe with the geometry so the car doesn't have a desire to swap ends. Job done.
Haha exdos. That made me smile
I think most of us who don't track their cars just don't need to spend the extra cash to upgrade the suspension. I did 400 miles of hooning in the Lakes recently with others on here and had a blast. Only occasionally did I think about poor damping at the rear. The majority of the time though the car felt great being thrown about on those roads. But we were generally keeping to all speed limits so perhaps by some standards we were driving in a restrained manner. I accept that drivers who track their cars regularly, or those more experienced at high-speed driving than i, may see more fault than I can though.
I also think that some people expect too much of a stock M (not directing this at you exdos, just a general observation). We should remember that M cars are NOT in the same category as Porsche GT cars (except in the case of the M3 GTS perhaps) which was over £100k.
OG, No offence taken.original guvnor said:
I think my criticism of the OEM suspension is taken out of context by some. Overall, I am very impressed by the Z4MC and I don't have any problem admitting that it is a better car than the Z3MC, of which I am a huge fan. 
But I know from first-hand experience that by fitting decent aftermarket suspension BOTH cars can be transformed into something much better. OEM cars are what they are because they're made to a price for a specific target market, but spending a couple of grand on properly set up adjustable suspension makes your car feel and handle like it's worth 20 grand more. For me, it's been a great investment. 8)
Those of us who really want something different than standard and are prepared to tinker will always find a way to getting something better from what we've got; it's human nature. 8)