Suspension / Handling Mods

[MGR]

It seems this question comes up a lot and so I thought it may be good to get a list of things that people have done, their opinion on if it was worth while and what sort of focus the mods have - i.e fast road, track day etc

Mods maybe make this a sticky ?

[Chris]

I know I wont be the only one to say this but ARB's are by far the best pound for pound handling mod you can do.

Anything else after that is up to the size of your wallet and the type of driving you do.

[h4pry]

Mods maybe make this a sticky ?

Good idea Mike.

Hopefully this thread will provide a good overview from different owners. Sticky'd for the mo.

[h4pry]

Personally I really get tired of a "too firm ride" on UK roads. Having spent last week in France the roads were an absolute dream and perfectly suited to my car. After 10mins of returning to the UK I felt "jarred" again.

I have the ACS set-up on my car and am considering going back to OEM for a while prior to deciding what package is best for me. I am almost 100% sure that KWV3 is not for me though. Having said that many owners report superb findings with the KW's.

The majority of the time my car us used for fast road use with a couple of track days / visits to the ring per year.

[Chris]

Personally I really get tired of a "too firm ride" on UK roads. Having spent last week in France the roads were an absolute dream and perfectly suited to my car. After 10mins of returning to the UK I felt "jarred" again.

I have the ACS set-up on my car and am considering going back to OEM for a while prior to deciding what package is best for me. I am almost 100% sure that KWV3 is not for me though. Having said that many owners report superb findings with the KW's.

The majority of the time my car us used for fast road use with a couple of track days / visits to the ring per year.

Paul, possibly not the best place to put this being a sticky and all, but we should try to organise another meet very soon where you can come out in a few peoples MC's with different KW setup. I personally find mine firm but rides the small bumps really well, much less jarring than the ACS setup I had previously!

[h4pry]

Paul, possibly not the best place to put this being a sticky and all, but we should try to organise another meet very soon where you can come out in a few peoples MC's with different KW setup. I personally find mine firm but rides the small bumps really well, much less jarring than the ACS setup I had previously!


Hey Chris, you're right we should organise another meet soon deffinately. You don't fancy a trip to the ring then?

I've driven an MC with KWV3's, but also admit that the topic is completely subjective...Just not for me that's all. I'd be interested in a go in your car though if you feel the set-up is that good.

Suggestions people on moving the thread to GD or technical to get more airtime?

[ghibbett]

I know I wont be the only one to say this but ARB's are by far the best pound for pound handling mod you can do.

Obviously the ARB is there to help prevent roll, but what else do people find it affects. How does it affect the ride of a std car etc etc?

[c_w]

Obviously the ARB is there to help prevent roll, but what else do people find it affects. How does it affect the ride of a std car etc etc?

It does detract the ride slightly, in that you can feel it pulling from side to side if you hit one wheel on a bump; basically it makes the low speed ride a bit lumpier on lumpy roads.

[c_w]

Budget Fast Road / Track Brakes

- Good/new OEM floating 2-piece discs (from BMW dealer or EuroCarParts)

- EBC Yellowstuff pads (www.ebcbrakesdirect.com)

- Cooling ducting fed on to the back of the brake disc guard "inlets" (got the neoprene ducting hose off ebay and used some 1" length sections of 3" diameter exhaust pipe to create the flanges for the hose to attach which were welded on the disc guards. The hose on mine is routed along the ARB and around the arch liner - with a little cutting - and fed into the side of the exisiting brake ducts in the bumper (cut hole to suit hose diameter), with the factory holes in the arch liner blocked off so all air fed into the bumper air ducts is forced through the new brake duct hosing)

Total cost: circa £315 (inc. new discs, pads, hosing, clips)

[MGR]

ACS Road suspension kit

There is no issue with rubbing and it does not need any modification in terms of spacers etc. The quality of the kit seems very high.

The look of the car is improved as it looks much lower and more agressive.

General impression is that the ride is medium to poor despite the rear being quite soft but just about acceptable for daily use.

Seems to reduce body roll a bit over the OEM kit and provide a bit more body control. Both are still quite poor in the grand scheme of things though (compared to some other perfomance cars).

The main minus for me about this kit is the ride height. For the roads in the area where I live its simply too low. You can work around it to some extent but some speed bumps provide real issues.

Ferodo 2500 brake pads

noisy, very dusty, no problems in operation but not used on track.

[c_w]

Subframe "bush" inserts

These are essentially 4 pieces of curved plastic that are inserted in to the rear subframe bushings. Usually for sale on ebay (U.S.) or you could try and make some yourself.

Benefits:
Increases straightline stability hugely IMO.
Less lift-off / power-on torque reaction

Disadvantages:
Bit more transmission noise and NVH

[c_w]

Anti Roll bar droplink strengthening

Unfortunately the Z3M isn't as well made underneath as we'd like to hope and all brackets and connections are on the edge of their design envelope IMO. So if you've fitted stiffer H&R roll bars then IMO it's a good idea to strengthen the droplink brackets on the trailing arms as they're very flimsly, bend very easily and it's not unknown for them to break away eventually.

The easiest way is to use two pieces of triangular metal and weld them on vertically below the existing brackets so that the nut will fit between them. Since I did this the bracket is now very rigid (previously it would flex as you undid or tightened the nut!)

[c_w]

Increasing front (static) negative camber for free

If you want to track your car then some extra negative camber will often help. An old trick with the M3 EVO was to swap the top mounts over since they are handed and swapping left for right will increase negative camber. Since the Z3M is the same as the M3 you can do this modification to the M Coupe too.

As it's free it's worth a try if you feel your car would benefit from more camber. Might be "too much" for a road car though, and there is the risk of increasing tramlining on uneven roads.

[Chris]

Anti Roll bar droplink strengthening

Unfortunately the Z3M isn't as well made underneath as we'd like to hope and all brackets and connections are on the edge of their design envelope IMO. So if you've fitted stiffer H&R roll bars then IMO it's a good idea to strengthen the droplink brackets on the trailing arms as they're very flimsly, bend very easily and it's not unknown for them to break away eventually.

The easiest way is to use two pieces of triangular metal and weld them on vertically below the existing brackets so that the nut will fit between them. Since I did this the bracket is not very rigid (previously it would flex as you undid or tightened the nut!)

Completely agree with this. I have H&R ARB's and KW V3's and had my trailing arm bracket sheer off and a front drop link completely snap!

Get a decent welder to strengthen the RTA mount with either angled (triangular) metal or just double the thickness with a flat plate of metal.

The only stronger droplinks i've come across are Whiteline ones and seem to do the job perfectly.

[ian]

Sorry to spoil the fun folks but unless you're after a track demon, leave it standard.

All road cars are a compromise between handling and comfort. BMW know this and factor this in.

Just make sure your bits (and the cars) are in good condition. Most of us don't get near the edge of the performance envelope anyway on the road.

I have almost done 100K miles in my car, total 115K. Just replace the bits that need it, keep it well serviced and enjoy.

[wfarrell]

My MC was fitted with the ACS 'Race' coilover kit last year.

It is absolutely superb for fast road use, retaining a supple ride and excellent body control.

Absolutely 5-star recommendation - an excellent high-quality product.

[Chris]

Sorry to spoil the fun folks but unless you're after a track demon, leave it standard.

All road cars are a compromise between handling and comfort. BMW know this and factor this in.

Just make sure your bits (and the cars) are in good condition. Most of us don't get near the edge of the performance envelope anyway on the road.

I have almost done 100K miles in my car, total 115K. Just replace the bits that need it, keep it well serviced and enjoy.

That is your opinion for the type of driving that you do, and I respect that opinion, but for a vast majority of people the standard setup is too soft and wooly. I personally don't like scraping my wing mirrors on the ground while cornering hard and I found the front felt very vague before fitting KW's.

[c_w]

Originally Posted by ian
Sorry to spoil the fun folks but unless you're after a track demon, leave it standard.

All road cars are a compromise between handling and comfort. BMW know this and factor this in.

Just make sure your bits (and the cars) are in good condition. Most of us don't get near the edge of the performance envelope anyway on the road.

I have almost done 100K miles in my car, total 115K. Just replace the bits that need it, keep it well serviced and enjoy.
That is your opinion for the type of driving that you do, and I respect that opinion, but for a vast majority of people the standard setup is too soft and wooly. I personally don't like scraping my wing mirrors on the ground while cornering hard and I found the front felt very vague before fitting KW's.

Yep I agree, as standard these cars are extremely soft for an M Car, it's not like a standard E36 or E46 M3 which aren't too bad out of the box. In fact I'd say there's more roll than a standard E46 3-series! They do ride nicely though as standard but obviously that is a result of the soft suspension.

[MGR]

Yep I agree, as standard these cars are extremely soft for an M Car, it's not like a standard E36 or E46 M3 which aren't too bad out of the box. In fact I'd say there's more roll than a standard E46 3-series! They do ride nicely though as standard but obviously that is a result of the soft suspension.

The reason for these things I suspect is to try to reduce the 'twitchyness' of the rear end and make the handling safer. I find the rear is far too soft, and the standard set up of understeer plus the longer ratio steering rack all combine to reduce the possibility of the back end stepping out.

Also 100% with you on the e46 thing.

[c_w]

Quicker ratio steering rack

For reason unknown only to BMW ///M division they fitted a "slower" steering rack to all the Z3 ///M cars compared to the non-M Z3s. The ///M steering is 3.2 turns lock to lock and all the non-M variants are 2.8. What this means is that the steering feels more responsive on the non-M and basically less turn of the steering wheel is required for a give movement of the wheels.

Handily I had a 2.8 Z3 rack in the garage already which I put to good use by swapping it over on to my Coupe. They fit in exactly the same way (all bolts, fixings and hydrraulic connections are identical) so it is a case of removing old one and fitting the quicker rack. Two long bolts and nuts hold the rack on, tow PAS pipes (two different sizes; 2x copper washers per banjo connection). The steering column requires a small nut to be undone and the bolt withdrawn, once the rack is lose it can be tapped off.

Due to the design of the tie rods and tie rod ends they are often siezed and difficult to remove so I would advise buying two new tie rod ends (OE brand from EuroCarparts are around £16 each) and the nut and collar from BMW which are quite cheap. Ensure plenty of grease is put on the thread and around the collar for easy adjustment of tracking at later dates.

[MGR]

Quicker ratio steering rack

For reason unknown only to BMW ///M division they fitted a "slower" steering rack to all the Z3 ///M cars compared to the non-M Z3s. The ///M steering is 3.2 turns lock to lock and all the non-M variants are 2.8. What this means is that the steering feels more responsive on the non-M and basically less turn of the steering wheel is required for a give movement of the wheels.

Handily I had a 2.8 Z3 rack in the garage already which I put to good use by swapping it over on to my Coupe. They fit in exactly the same way (all bolts, fixings and hydrraulic connections are identical) so it is a case of removing old one and fitting the quicker rack. Two long bolts and nuts hold the rack on, tow PAS pipes (two different sizes; 2x copper washers per banjo connection). The steering column requires a small nut to be undone and the bolt withdrawn, once the rack is lose it can be tapped off.

Due to the design of the tie rods and tie rod ends they are often siezed and difficult to remove so I would advise buying two new tie rod ends (OE brand from EuroCarparts are around £16 each) and the nut and collar from BMW which are quite cheap. Ensure plenty of grease is put on the thread and around the collar for easy adjustment of tracking at later dates.

Doesn't the longer ratio make it less easy to turn in too violently upsetting the rear... So trying to compensate for the rear being lively ? I'd assumed thats why they fitted it.

[c_w]

Doesn't the longer ratio make it less easy to turn in too violently upsetting the rear... So trying to compensate for the rear being lively ? I'd assumed thats why they fitted it.

I don't know, I think with the car "set" to understeer it doesn't really matter. Besides, IMO it only changes the steering ratio not the car's handling behaviour and makes it easier to control any oversteer due to less arm movement/flailing.

[h4pry]

Out with the new and in with the old…

Well sort of. My car from the factory had the ACS road kit fitted. When I purchased the car she had clocked up a modest 60,000 miles and at first I never really noticed the idiosyncrasies of my MC’s handling, I just thought it was normal. It would be fair to say however that the springs and dampers would have passed their best at this sort of mileage.

This year (2008) I’ve got really fed up with the car being so low and just catching on most average height speed bumps. Moreover I use my car daily with a 40 mile round trip on HM’s meandering and grossly undulating road surfaces. I just couldn’t take the jerky, hard ride, back problems, wheel arch scraping under extreme cornering, rattles and generally totally shit handling of an ageing ACS (Bilstein) suspension.

As some of you may have noticed within my previous posts on the forum I’m not really an aftermarket modder (certainly used to be). Moreover when I do mod I like to experience something for myself prior to actually buying a product rather than going with the norm of the modding route.

So last friday found me at wfarrell’s abode purchasing his old 40,000 mile stock OEM suspension set-up for a small sum. Then Saturday with the help of a friend (who wishes to remain anonymous because this sort of route is against his religion) we started to fit the new old system to my car. Whilst at the same time replacing the rear top mounts with the obvious improvement over stock rogue engineering items. Unfortunately a drop link was busted during the transplant and thus I couldn’t really test drive the car. However yesterday I replaced the drop links and hey presto…..

The result…

Well laugh at me all you want however I am in love with my car again. She’s awesome in OEM state! By appearance obviously she looks like she’s ready for a bit off-roading but I’m loving the look at present – To me it almost says that the MC can drive past or even over anything. Sweeping through country lanes, ignoring potholes and in absolute comfort, the difference is night and day and I’m so pleased that I decided to go this route, albeit temporarily.

Placebo effect? Most probably – But who cares

Next step will be to actually find a set-up that combines performance and handling. Now that the rear top mounts are done a change over should be executed within a couple of hours!

[Chris]

Nice write up Paul, but I can't help thinking it sounds like you would be best suited to a 4x4! ;)

Completely agree with the ACS comments though, i didn't find them too low, but found them hard and crashy compared to a decent set of coilovers (KW's of course).

I'm not sure what your next step will be, but you have tried ACS and OEM, so only really got ACS race and KW to go now!

Out of interest, do you have H&R ARB's? They will dramatically improve even a standard set up.

[MGR]

Very interesting write up. I've got the same set up on mine and find the car too low, I have also got a set of OEM stuff I was considering fitting.

[h4pry]

Very interesting write up. I've got the same set up on mine and find the car too low, I have also got a set of OEM stuff I was considering fitting.

The car is actually a pleasure to drive around town now. Hitting speed bumps and pots holes are no longer giving me more grey hairs.

I am concerned regarding its performance at the ring next month...We'll see!

[c_w]

With the ACS setup, where was it scraping the arches? (front or rear?). The standard suspension does ride pretty well I thought but there's too much movement IMO. But sometimes a change (whichever way it is) makes it feel better but then a few weeks down the line you wan't to get rid of the body roll and floatyness a bit hehe.

With the ACS springs I only found the rear to be too low (as with most aftermarket springs for all Z3 variants) but have corrected this with thicker spring pads and spacers. I still feel the rear springs could be stiffer to reduce the suspension "folding" when you hit an undulation mid-corner but I think this is mainly down to the semi trailing suspension design (ie it's not felt in other cars I drive/driven however softer they might have been), although stiffer shocks can counteract this.

[wfarrell]

...it's an interesting project switching a car back to OEM chassis.

H4PRY, glad to hear you're happy with the shocks :-)

The OEM setup is (for lack of a better phrase) 'comfy', and gives the MC a true 'GT' character - effortless high speed travel. Like many other owners i wanted to improve the handling, so...

...I changed from OEM to ACS coilovers, and have been absolutely delighted (the car has retained a supple ride but with excellent body control). Like C_W, have had to fit thicker rear spring pads to get the correct ride height and front-rear 'pitch' to improve turn-in.

[-Keith-]

One thing I was hoping to find in this sticky but haven't, is the options available to us for suspension mods.

I've only heard of KW coilys and ACS suspension, but there must be more options?

I'm guessing the big, expensive brands will like BIlstein etc, but are there any mid-level priced options (Eibach, Koni etc)?

And does anybody know about lowering springs? IMO and experience, as long as the OEM shocks are in good condition, springs can be a good choice for improved looks and a stiffer ride with less bodyroll. Has anybody just used springs before? I'm not talking about for track performance here, just an marginally uprated spring option that'll give a good stance too.


Keith

[c_w]

One thing I was hoping to find in this sticky but haven't, is the options available to us for suspension mods.

I've only heard of KW coilys and ACS suspension, but there must be more options?

I'm guessing the big, expensive brands will like BIlstein etc, but are there any mid-level priced options (Eibach, Koni etc)?

And does anybody know about lowering springs? IMO and experience, as long as the OEM shocks are in good condition, springs can be a good choice for improved looks and a stiffer ride with less bodyroll. Has anybody just used springs before? I'm not talking about for track performance here, just an marginally uprated spring option that'll give a good stance too.


Keith

I've tried many springs; H&R, ACS, Ventura, e30 ACS. The Z3M ACS are on of the better springs, giving a level rideheight without having to pack up the back (Ventura springs that normally come with the Bilstein Sprintline kits lower the rear excessively).

Bilstein Sprint line have same similar dampers to the ACS kits (just rebanded), but the ACS springs are superior.

Koni dampers, the rears at least are too soft in bump, so unless you have very stiff rear spring (struggle to find this!) it feels too soft, but the adjustable rebound would work with a stiff spring. The front Koni adjustables are "inserts" which means you have to cut up your OEM damper struts to insert the konis; don't think it's a mega job though.

The dampers are one of the weaker links in the factory setup IMO; I think factory springs with Bilstein Sprint dampers would work well.

[dave p]

the ac schnitzer springs cannot be bought by themselves according too acs uk? they only come with the full road suspension kit (£1100).

[c_w]

the ac schnitzer springs cannot be bought by themselves according too acs uk? they only come with the full road suspension kit (£1100).

Yea I think that's the case, I enquired and he said a silly price just for springs. The ACS kit is too expensive for what it is, the Bilstein dampers are the same just painted black and branded ACS. For springs I think Maahny can get decent ones? forget the name of them (American springs).

[fastdrive]

an good choose for lower price is ground control spring for blistein..
http://www.ground-control-store.com/products/category.php/CA=11