’Club Sport’ Conversion

Hi Guys,

Here's one for the track days boyz out there. With the onset of the Z4 I thought it was time to consider what I want to do with my newly acquired Z3M Roadster. I was reminded in Crail just how much I enjoy track days & the Roadster is a hoot.. too much power for an old fashioned chassis.. lovely! I'm also enjoying the improved acoustics from my GruppeM ram air kit.

If we were to agree a 'Club Sport Package' using the new CSL as our template.. what would we go for? Ultimately any package has to stand up on various grounds.

1.Integrity

2. Cost

3. Drivability & Flexibility

4. Performance

5.Distinctiveness & Identification

6. Insurance & Warranties

The monikier could then be translated across the range of M cars.. something that club owners would recognise at better driving days. The skills are out there. Someone such as CA Autotech can fabricate carbon fibre and have already produced a CSL style roof for the E36. Now there's no reason that a similar approach cannot be used for other M cars.

To kick this off (& I appreciate that ideas and opinion will vary here) I propose for the Z3M Roadster & Coupe the following;

Schnitzer sports suspension & strut brace

Brake Upgrade

Lightweight flywheel

CA Autotech carbon front splitter, head cover and rear lip spolier.

Rogue Octane or Schnitzer Quickshift

GruppeM ram air induction

Superspeed or Gruppe M quad-exhaust

Schrick 284 Camshafts?

ECU Upgrade?

For the Coupe a carbon roof could be developed while a rear carbon bootlid could be developed for the Roadster though of course the issue with most Ms is front end weight not rear. Carbon bonnets are also available but this does complicate matters. The end result is NOT  to have a stripped out racer.. for that we simply strip out the car and voila. What we are talking here is a CS special that is a better compromise between road and track. Thoughts, suggestions, support and advice all greatly welcome. This is as much a basis of a fantasy league-type discussion as it is a serious proposal to the M fraternity.

Best

M Blur

Therein is the problem. t's all too easy to go extreme and just ditch everything out of the car but then that loses the balance between driveability and trackability. The car has to be enjoyable at 1/10th, 6/10ths & as much as 10/10ths. That means it's at home burbling along the back roads as it is on the track. Anyone can gut a car for the track - I'm talking 'intelligent lightening' that doesn't change the aesthetics of the car too such a dramatic state. As I said the plan is to eventually get a RS for hard core action.

What I'm talking about is a definitive set of mods than can tighten up the M without losing it's quality and comfort.. It's all in the balance.

So too make this easier.. let's seperate the mods into 2 distinct lists. The full-on track day car..  let us call is the 'RS' - stripped to the bone and a packing serious power & a softer 'CS' that has been only on the Atkins diet briefly but still wants to be just that little bit sharper, that little bit more the CSL than the standard car.

In both instances let us set an imaginery budget of £3000. As was rightly pointed out it's not all about power as handling, braking reliability tend to be far more important on the track. Let's list & debate the generic modifications of both conversions and their order.

The 'CS' may for example need to up the power as it cannot drop as much weight.

The 'RS' can be more dramatic & aim for better weight distribution and handling.

Come on guys.. a little imagination and see where it takes us..

Aye but at the sake of the long-legged ability of the 5-speed ZM. There's something quite amazaing about a wee car that can pull in third from 30 well into 3 figures without pausing for breath.

Wouldn't lowering the diff ratio also place additional pressure on the other mechanicals?  Is there an optimum ratio to give the balance or is the standard the best compromise?

Can anyone recall what % lsd the ZM runs? This seemed to work well @ Crail http://www.newtongrove.demon.co.uk/bmwcc/meets/2003/oct/ though oversteer I got last night on a dark damp road with Baz in the passenger seat was less welcome.. sorry about that Baz.

Jon

M BLUR wrote: Aye but at the sake of the long-legged ability of the 5-speed ZM. There's something quite amazaing about a wee car that can pull in third from 30 well into 3 figures without pausing for breath. Wouldn't lowering the diff ratio also place additional pressure on the other mechanicals?  Is there an optimum ratio to give the balance or is the standard the best compromise? Can anyone recall what % lsd the ZM runs? This seemed to work well @ Crail http://www.newtongrove.demon.co.uk/bmwcc/meets/2003/oct/ though oversteer I got last night on a dark damp road with Baz in the passenger seat was less welcome.. sorry about that Baz. Jon

The US M Coupe boys (most of whom have the S52 engine with only 240 bhp) have experimented with going for a 3.23, 3.46 or 3.64 differential, but I fully agree that if the M is to be used in normal driving conditions the standard 3.15 is a very good compromise - though I have contemplated having a 6 speed gearbox from an E36 Evo put in for that over-drive 6th.

As for LSD  it is 25 %.

25% LSD - That's what I thought it was & certainly makes for a good compromise for road & track. A 3.23 Diff would certainly work and probably still be ok for road though not sure it's worth the outlay (?) for the increment.

When I've driven the 6-speed I find the lower ratios are not as well spaced as on the 5-speed, which seems well mated to the engine. The 6th gear only seems handy as an o/d if you intend to do some serious 3 figure numbers.. and unless you are heading into Europe....? A better upgrade would be a good short-shift kit. It's a shame SMG was never made available.. that could have made the M Coupe a real track-day star.

Did the M Roadster/Coupe ever get fitted with TC. If not then why do BMW keep quoting that it does have it in their adverts. I've certainly not detected any TC cutting in to spoil the fun.

Thanks Lancelot..

This is a bit more like it. Anyone else want to chip their 10p in???

Who would you recommend for the arb? My choice would be a wide diamond shape set up but this isn't possible on the ZM. An adjustable arb would seem the best way to adapt the setting from road-to-track. Carbon fibre would look very CSL but not even CA Autotech produces one though I've noted Schnitzer have shown cf struts in brochures/website but I can't find prices or product codes.

Who would you recommend for wheel & tyre choice? Compos/Avons?

Will E36 evo wheels fit the ZM?

I already have Schnitzer sports suspension, which does seem to have had the desired effect although it's far from track-stiff. For the RS Schnitzer racing suspension would be the comparable upgrade. I of course refer to Schnitzer though any good quality set up would do. I refer to it as it's what I've used, it's recognizable & can of course be fitted by BMW. I of course appreciate thet there may be superior systems out there.

CA Autotech refer to a rear camber change for the ZM - has anyone had this? I assume it's to increase negative camber to reduce oversteer.

I would probably agree with everything bar the glass, which in the case of the M Roadster there is very little anyway.

For the RS it could mean taking the power hood out of the Roadster in favour of the the Spyder conversion & tonneau cover. A cf roof for the M3 is already available through CA Autotech and I'm sure they could develop one for the ZMCoupe. For the Roadster a fly screen could be substituted for the front windscreen as long as a lid was worn. Not sure what it would look like though and this again compromises the looks of the car.

As to cam change then there's no reason why this couldn't also be dropped into the CS albeit at a less aggressive profile. E.g. ther CS could run Schrick 284s while the RS runs 286s with perhaps revised throttle linkages. Re-map would then be different and perhaps the RS would run a convertable cat-back system that could be switched back when on the road. Ultimately I would see the difference between CS & RS being weight, roll cage etc etc rather than power though cam and diff' differences would alter how each car delivers its power, each suited to their different task.

Of course the problem with lightening a car is a) weight distribution & b) the effect on roadholding/suspension that has been calibrated for a particular weight. Does anyone have any experience of this?

Has anyone tried a good old fashioned balance/blueprint of the 3.2? I see Hartge supply alternative cranks & pistons for the S14/S25. Anyone try these? Is the M3.2 head as flowed as possible? I assume along the way there has been concessions made. Is it the ECU that returns such a high mpg for a 300bhp+ engine?

What about flywheels - a lightened multi-mass wheel can have a huge impact on throttle response & modern ones are not always as lumpy as in the old days. What about the propshaft?

Best

Hi M Blur,

Your suggestion of a CS is very very well thought .. Basically, you're very right !

Your list;

1. Schnitzer sports suspension & strut brace
2. Brake Upgrade
3. Lightweight flywheel
4. CA Autotech carbon front splitter, head cover and rear lip spolier.
5. Rogue Octane or Schnitzer Quickshift
6. GruppeM Ram air induction
7. Superspeed or Gruppe M quad-exhaust
8. Schrick 284 Camshafts?
9. ECU Upgrade?
10. For the Coupe a carbon roof

I basically have most of the essential parts but not quite exactly the same:

1. H&R Coil-over with 250lbs Eibach spring cos the car have basically no weight in the rear for the M Roadster
2. AP 4Pot Front and 4 Pot Rear
3. Gp.A Flywheel and Twin Plate Clutch
4. RevoZport designed fibre glass front bonnet, bumper and splitter for special cooling to brake, exhaust manifold, intake and oil cooler
5. I reckon the original stick is rather short so I kept it original
6. Don't really like the idea of cone filter instead I've modified the original airbox to accomodate a 3" cold air duct direct from the kidney grille and original brake duct (This is an amazing DIY job) VERY efficient !
7. RevoZport Twin Exhaust instead of the quart pipe, it improves torque all the way, but it's rather loud tho.
8. Schrick 284 Camshafts done and installed, very good massive torque
9. Custom ECU program from RevoZport with improved lift-off throttle to fit the 284 cams.
10. I've tried using 3.64, 3.73 and 3.91 final drive and I found that with the 284 cam, the 3.91 works much better and efficient. However, you do need to install a rear diff cooler as it's very hot back there. (That's what I'm gonna do these few weeks)
11. Reinforcement to the final drive is STRONGLY recommended as it's a very flimpsy thing.

With all these, I'm getting well over 400NM of torque on wheels ! It's the torque that amazed you .. not really the HP.

Thanks Kliss,

Car sounds absolutely lovely! I'm glad to hear that the 284s with the ECU remap does the trick. I'm tempted to leave the standard exhaust even if it is a bit restrictive.

If we presume for a second that most Roadster owners have either a) sorted the suspension or b) are dead - and that most have likely fitted an induction kit (i.e. me). If we set a budget at 3K - what would be your next move within that budget... brakes?

Do you recommend any wheel/tyre packs for track work...?

Baz,

Aye it was a laugh.. looking forward to some proper sideways action next year!!