A Little Treat for the Z

For the M Powered Z3 derivatives

Moderator: Gazza

Post Reply
User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

A Little Treat for the Z

Post by Mike123 » Fri 02 May, 2014 23:40

Having owned the Z for coming up to 9 happy years and 80k miles I must admit to casting my eye around for a replacement.

I looked at a number of candidates, a 911, SLK55, SL55, M3, M6, Z4M, and Z4 35i, but none of them really did it for me. A C4S 997 Cab came closest, but it meant a chunk of money, and in some ways I still preferred the Z. I thought about a younger Z3M, and there have been some interesting low mileage ones for sale recently, but I'm a bit fussy about colour - Imola red is by far my favourite, and the two tone interiors are a bit sudden for my taste.

So the Z will have to put up with me pushing its limits for another couple of years, at least. :twisted:

To make up for this, I've decide to give it a little treat - I liked the handling improvement from Bilstein B6 rear shocks at about 60k miles, so I've ordered a complete set this time, and will fit some replacement Rogue mounts at the same time. I looked at KW coilovers, but don't really want to lower the car or reduce the ride quality, which I think is pretty good for a small performance car.

I saved about 20% by buying them from Germany - mk-fahrwerkstechnik.de - worth a look if anyone's looking for German parts.

If anyone wants to try out the B6 rears, they've only done about 35k, so are in good nick - we can sort out a cheap deal. 8-)

t-tony
Joined: Sun 21 Feb, 2010 23:17
Posts: 352

  Z3 roadster 2.0
Location: torksey lock

Re: A Little Treat for the Z

Post by t-tony » Sat 03 May, 2014 00:55

I bought my car which had already had K&W suspension all round and the car handles really well with what I would call a firm rather than hard ride. Unfortunately I can't compare it with the original figment. It is lowered but by how much I'm not exactly sure and has wider than original wheels and tyres.
"Knowledge and experience are not always the same"

User avatar
Davejue1
Joined: Sun 22 Sep, 2013 08:25
Posts: 1249

  Z3 roadster 2.8
Location: Mansfield

Re: A Little Treat for the Z

Post by Davejue1 » Sat 03 May, 2014 10:08

Pleased your keeping your Z. I think after nine years and the way you lovingly talk about it you'd regret it once it had gone. :)

Cheers
Dave
Image

"Growing old is mandatory, growing up is optional!"

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2119

  Z3 roadster 1.9

Re: A Little Treat for the Z

Post by Del » Sat 03 May, 2014 11:33

Only ever heard great things about Bilstein B6. I've used B4s in the past and looked at B6s but the price jump from B4 to B6 is substantial. They are also supposed to be very tough and last for ages - therefore would be a good buy with just 35,000 miles under their belt.

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Sat 03 May, 2014 12:20

I've been pondering fitting H&R anti-roll bars at the same time.

I actually don't mind a bit of roll - I think it's part of the feel of the approaching limits, and don't plan to do any more track days, but the Z does tend to scrape the door handles a bit:

Image
Image

Does anyone have direct before and after experience of them?

User avatar
BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2221

  Z3 roadster 1.9

Re: A Little Treat for the Z

Post by BladeRunner919 » Tue 06 May, 2014 17:30

Mike123 wrote:
I saved about 20% by buying them from Germany - mk-fahrwerkstechnik.de - worth a look if anyone's looking for German parts.
Wow, that site really is cheap. Eibach springs for my M44 come to £160 delivered, instead of about £220 from UK suppliers! :shock:

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Wed 07 May, 2014 23:08

No answer to my question about H&R anti-roll bars here, but there's a lot of opinions on the ZCoupe site, mostly strongly in favour of the change. :rtm:

I like the existing handling balance and ride quality for fast road driving, so any sort of modification carries a degree of risk, but the Z is due for a refresh. I'm confident about the Bilsteins, but they won't deal with the roll issue.

I've decided just to replace just the front bar (H&R 28mm) - the main roll problem appears to be the front end - see the pics above. The theory is by reducing the front roll there will be less tendency to understeer, hopefully without making the back end too twitchy, but if you're anywhere near me on a fast wet corner please leave me plenty of room! :shock: :shock:

There's a risk of unbalancing the car, but I can always add the equivalent rear, or revert to the original front bar if I don't like the feel. It may create more stress on the chassis, the open roadster is obviously more flexible than the coupe, so there may be some new creaks and groans, but I can probably live with those if the handling is improved.

Should be all fitted next week, I'll report on the outcome.

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Mon 19 May, 2014 16:53

Bilstein shocks and H&R AR bar fitted, and wheels realigned last week.

Weather perfect over the weekend, as ordered, to see if I've improved or ruined the car.

Initial report (dry roads only):

The ride is no harsher, which is really good news! :) :)
The front roll has been dramatically reduced, making the car much more neutral entering corners - no obvious understeer, but I'll find out more on slippery roads.
It hasn't made the back end more lively, but again not fully tested yet.
As expected, it's more stable under heavy braking on undulating roads, with less front end dip.

I'll need to find an opportunity to test it to the limits, but I'm very happy with the initial feel.

The original OEM AR bar, and the 35k ish miles rear B6s are available if anyone is interested.

692DPG
Joined: Sun 09 Mar, 2014 19:30
Posts: 87

  Z3 roadster 2.8
Location: Lancashire

Re: A Little Treat for the Z

Post by 692DPG » Sat 24 May, 2014 08:37

Mike -sounds like the result is positive based on first experience. I've always found uprated ARBs to improve any car as the standards items are always a compromise to a broad range of driving styles and comfort preferences.

Looking forward to the outcome of your full analysis as I plan to use my Z3 2.8 for a track day or two and want to make some sensible tweeks enhance the experience.

Cheers, Dave
1997 (R) BMW Z3 2.8 Roadster - weekender
Hell Red/Imola Red/Black Z3M leather - 2 door, manual
2007 (57) BMW M3 Coupe - inbetweener
Melbourne Red/Black leather - 2 door, manual
2012 (12) Mercedes C Class AMG Sport Estate - daily
Iridium Silver/Black leather - 5 door, Manual

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Mon 02 Jun, 2014 08:10

An update.

Having driven the car after the mods for a few weeks, I've got to know it better.

The car is tighter, more composed, and feels more planted in all circumstances. It has more rubber on the road, and carries 5-10mph additional speed through corners.

There are no surprises in the wet - yes, it's still possible to keep the right foot planted and slide the rear, but it's not snappy. I was initially concerned that only stiffening the front roll bar would make the car tail happy, but the balance feels right - the turn in is quicker, but the main difference is the significant reduction in roll-based understeer.

Have I improved it? Slightly mixed feelings. The car definitely handles better, and the ride is still fine, which is what I set out to achieve.

Is it a better driver's car? That is less easy to answer. It's easier to drive fast, A to B times are certainly quicker, and there's satisfaction from smooth cornering lines, and carrying higher speed through corners, but....

..............it may have lost a little of the 'killer' edge that has excited me over the years. :shock:

I don't think I'd want to go back, though. Maybe I'm getting old! :roll:

User avatar
Brian H
zroadster sponsor
Joined: Tue 16 Dec, 2008 19:55
Posts: 2502

  Z3 roadster 3.0i

Re: A Little Treat for the Z

Post by Brian H » Mon 02 Jun, 2014 16:11

I just changed both front and rear ARBs on my 3.0i Mike along with the rear ARB links (fronts changed not too long ago), the first real test was Cadwell Park earlier this year. The car does feels a lot tighter/flatter though the bends, the ARBs have reduced the body roll feel dramatically whilst driving the car and as you stated this does allow faster cornering. A great modification IMO.

swamper
Joined: Thu 13 May, 2010 18:14
Posts: 1866

  M roadster S50
Location: Mossley

Re: A Little Treat for the Z

Post by swamper » Sun 15 Jun, 2014 17:23

I thought the way the ARB works it's the front ARB that keeps the rear from rolling and visa versa?

Sent from my HTC One using Tapatalk
the badness makes me do it...!

Image

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Sun 15 Jun, 2014 22:28

I think you mean that the reduced front roll increases the rear grip, due to the inside rear wheel staying in touch with the tarmac. It's a diagonal force - the outside front wheel takes the initial turn in load - see the pics above - lifting the inside rear, creating initial understeer, then oversteer as rear grip is lost due to less rubber contact.

Subjectively, the main difference with the stiffer front ARB is definitely a 'flatter' front end, less understeer, and improved stability right through the corner.

Previously I had to take a very late turn in point to neutralise the understeer, which potentially destabilised the car in slippery conditions - exciting, but not the quickest technique - but better than understeering into the hedge! :shock:

Now the cornering speed is quite noticeably higher because I can take the conventional 'racing line' - much smoother overall, and happier passengers, although they do have to get used to the faster entry speed. :twisted:

swamper
Joined: Thu 13 May, 2010 18:14
Posts: 1866

  M roadster S50
Location: Mossley

Re: A Little Treat for the Z

Post by swamper » Mon 16 Jun, 2014 19:32

its my next mod mick thats why im trying to get my head round the effects of the stiffer ARBs.
im running B8s at the minute with H&Rs and its sitts a lot more flat than OE and with no understeer at all...im just worried that the thicker ARBs might push it into oversteer ...

stay away from them edges bud....it puts a dent in the pocket :lol:
the badness makes me do it...!

Image

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Mon 21 Jul, 2014 16:34

Having decided not to change the springs at the same time as the shocks to avoid stiffening the ride, I have just managed to break a rear spring on Dartmoor's pretty lanes :head:

So a set of H&R progressive springs on the way from Germany, and suspension out again. :cry:

I've read good reports, just hoping I keep my fillings! :roll:

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Thu 31 Jul, 2014 15:37

H&R springs went on today.

First surprise - stated to lower the car 30mm, actually raised the car by 2mm! :shock:

I'm actually really pleased, living in a town with many speed humps, and enjoying back roads (often with green stripes down the middle!), I nearly went for the frighteningly expensive OEM springs, but decided to risk the H&Rs. If you're thinking of these with the idea of slam dunking the car on to its wheel arches I would reconsider. I believe it will settle to slightly lower than original with a bit of enthusiastic cornering! :twisted:

The ride is the best it's ever been, which is good for a short wheelbase sports car, a noticeable improvement over the rusty (one recently broken) original OEM springs. Handling is significantly better than ever - the combination of B6 Bilsteins, H&R front ARB and the new springs has done the job. I wouldn't want it any better, but it's been reworked for fast road use, not track days.

In the last few months I have been considering alternatives, and driven a few options, but none that inspired me.

Now it's sorted all thoughts of changing it are out of the window.

therealdb1
Joined: Tue 25 Jun, 2013 22:47
Posts: 234

  Z3 roadster 2.0

Re: A Little Treat for the Z

Post by therealdb1 » Thu 31 Jul, 2014 16:15

Generally a thicker front ARB will increase the 'push' i.e. give you more understeer. This can be beneficial under certain circumstances like flowing fast bends since it gives more confidence that the car will not swap ends and reverse into a lamp-post or hedge.
Most road cars are set up with understeer deliberately built in because they are not being driven by racing drivers who have the awareness and reactions to catch an oversteering car! This is how the crazy rule about putting brand new tyres on the rear of a FWD hatchback and leaving the old ones on the front (which does all of the steering and braking) came about.
In my racing days we used to fine tune the car to the circuit by changing the front and rear ARB rates since you can pretty much balance out the understeer / oversteer to suit the nature of the track. Heavier front for stability, heavier rear for better turn in (controlled oversteer). We very rarely changed spring rates as too soft and the car hits the bump stops and too stiff and the thing bounces all over the place like a pogo stick. Changing the ARB should make very little difference to the ride quality unless you go for some extremely stiff thing that does not let the springs function correctly.
Unfortunately, as with many things in life, suspension is quite a complex compromise of handling, ride, confidence, and driver ability. The best advice is to change only one item at a time to see what effect it has and set the car up how you like it. I've seen good drivers take on other people's cars and look like rank amateurs who should have their competition license rebuked it really does make that much difference. Ok a slight exaggeration but you get my drift!
Suspension tweaking can be fun but it can also be frustrating. How many times do you hear F1 drivers with their professional backing quoting car set up as the reason for a poor qualifying performance?

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Fri 08 Aug, 2014 10:14

OK, so the suspension is sorted, and I'm back in love with the car. :D

Last job, sort out the worn leather driver's bolster and give the seats a lick and spit - booked into http://autoretrim.co.uk/ next week - have a look at the Wheeler Dealers clip on the website (no alcantara for me thanks! :oops: ).

Would a ///M logo embroidered on the headrests be too bling? Probably - it's a bit Porsche/ Type R - what do you think?.

User avatar
Davejue1
Joined: Sun 22 Sep, 2013 08:25
Posts: 1249

  Z3 roadster 2.8
Location: Mansfield

Re: A Little Treat for the Z

Post by Davejue1 » Fri 08 Aug, 2014 12:39

I don't think it would look bling at all and I don't long bling! If you go ahead please post a pic after. :)
Image

"Growing old is mandatory, growing up is optional!"

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Thu 14 Aug, 2014 17:37

Decided against the logos, but just picked the Z up after seats, door cards, and interior trim refurbished to 'as new' condition by Dave at http://autoretrim.co.uk/.

Great bloke, excellent, friendly service, and he knows his stuff! 8-)

If you're in the Midlands area with a tired interior this is the guy to talk to.

I'll post some pics when it stops raining!

Off to Prodrive Kenilworth on Saturday to see if the new suspension is as good on track as it is on the road. :twisted:

User avatar
Mike123
zroadster sponsor
Joined: Tue 21 Mar, 2006 14:34
Posts: 323

  M roadster S50
Location: Leamington Spa

Re: A Little Treat for the Z

Post by Mike123 » Mon 25 Aug, 2014 08:49

Final piece of the jigsaw:
Image
A beautiful replacement steering wheel made and fitted by Jack at Royal Steering Wheels.

http://royalsteeringwheels.com/

Slightly thicker rim. I did consider perforated side sections as an option, but went for the closer to OEM as shown.

That's it now. End of treats.

I may get round to some pics, but too busy driving it at the moment! 8-)

Really happy with the result! :sunny

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests