Not happy with my ///M ride....solutions..??

[exdos]

Is your "butt-strut" in the boot between the shock towers or under the car? I've seen something for the Z4 that goes beneath the vehicle but the description of its benefits wasn't wholly convincing...

It's the Strongstrut Butt-strut as here: http://www.strong-strut.com/Butt-Strut.htm It fits under the car on the subframe pins. I can feel the difference it makes on that car.

I've also enlisted the Butt-strut to form part of an under-car rear diffuser system that I've made in conjunction with a pair of OEM silencers which I gutted for improved performance but I also flattened their undersides which also form part of the rear diffuser as per the photos below. The rear diffuser works a treat and it throws up a great "rooster tail" in the wet. 8)










I've also made some similar undercar strakes for my Z4MC which are attached to the OEM "pull rods" in the diagram below (Part 16 which is essentially a triangulated butt-strut), the idea being to prevent air coming in from the sides in front of the rear wheels and to straighten the airflow at the rear of the car so that the OEM rear diffuser works better and to make the rear OEM silencers flow "Coanda" style to prevent lift at higher speeds.

 

[DONDP]

I too have pulled the plunge and ordered kw v3s after reading all the info supplied by exdos. Thank you for providing so much information on the matter. My car is a DD and I just can't live with the bumpy ride on the bad roads we have In Malta.

Is there anything else I need to update whilst installing the new suspension?
Exdos I tried looking up your alignment settings and from what I gathered you are running 0 toe front and back, -1.3 camber front and -1.0 camber rear. Can you confirm these settings and are they adaptable for daily driving?

Dondp, since the kws have so many settings can you maybe suggest where I should start from.

Thanks

Kerstien

Sure no problem for the road I have settled on the following (all settings are from full hard (+) or full clockwise)

Front 5 clicks rebound 1 turn(6 clicks) compression
Rear 12 clicks rebound. 0.75 turns compression (roughly 5 clicks if you can feel them)

And for track:

Front 5 clicks rebound 0.66 turns (4 clicks) compression
Rear 8 clicks rebound. 0.75 turns compression (roughly 5 clicks if you can feel them)

Depending on the track and conditions I sometimes soften the compression on the rear too 1 full turn if I want to reduce a bit of oversteer.

 

[kerstien]

I too have pulled the plunge and ordered kw v3s after reading all the info supplied by exdos. Thank you for providing so much information on the matter. My car is a DD and I just can't live with the bumpy ride on the bad roads we have In Malta.

Is there anything else I need to update whilst installing the new suspension?
Exdos I tried looking up your alignment settings and from what I gathered you are running 0 toe front and back, -1.3 camber front and -1.0 camber rear. Can you confirm these settings and are they adaptable for daily driving?

Dondp, since the kws have so many settings can you maybe suggest where I should start from.

Thanks

Kerstien

I would recommend that you either fit Rogue rear top mounts or fabricate your own rear top mounts (as I've previously described elsewhere) that are inverted, so that you can remove/install the dampers from the underside in the wheel arch.

You've correctly listed my geometry and that's what I run on both public roads and at The Ring. With my suspension this works great.

With regard to initially setting up your KWV3s (essentially the same as my AC Schnitzer Racing suspension), if your use is primarily for a DD and road use, I would set the front up at quarter of the range from full soft and the rear at full soft and then progressively increase the settings until you feel that the suspension becomes too stiff at either end of the car, and then back-off that end by one adjustment. You will find that the rear suspension settings essentially determines your perception of the ride of the car and softish settings are best on the roads. At the front, you will find you can go stiffer than at the rear, and the front will feel too stiff when too much of the bumpiness of the road is being transmitted to the steering wheel; when you get to that stage, back off the front settings by one adjustment. Once you feel that the car is both comfortable and handles well, drive the car for a while so that you can experience the car on as many different roads surfaces as possible, and then you can decide if it's necessary to fine tune the settings. I have KWV3 on my Z3MC, but this variant has separate rebound and bump/compression adjustment: for road use I have the front at 50% from full soft and the rear at around 20% from full soft, but on track I have both the front and rear at around 90-95% from full soft. You don't want to be a "hero"with stiff suspension settings on public roads, because your car will handle badly and the ride will be dreadful.

Perfect thanks for that. Ca automotive seem to sell them in the uk. just sent them an email to check whether they have them in stock. Is the installation of RTAB limiter kit a must? Can it be installed at a later stage? Is this also from rogue engineering? I'll check how the kw's work before getting into uprated ARBs

Thanks once again for all the info

Kerstien

 

[kerstien]

I too have pulled the plunge and ordered kw v3s after reading all the info supplied by exdos. Thank you for providing so much information on the matter. My car is a DD and I just can't live with the bumpy ride on the bad roads we have In Malta.

Is there anything else I need to update whilst installing the new suspension?
Exdos I tried looking up your alignment settings and from what I gathered you are running 0 toe front and back, -1.3 camber front and -1.0 camber rear. Can you confirm these settings and are they adaptable for daily driving?

Dondp, since the kws have so many settings can you maybe suggest where I should start from.

Thanks

Kerstien

Sure no problem for the road I have settled on the following (all settings are from full hard (+) or full clockwise)

Front 5 clicks rebound 1 turn(6 clicks) compression
Rear 12 clicks rebound. 0.75 turns compression (roughly 5 clicks if you can feel them)

And for track:

Front 5 clicks rebound 0.66 turns (4 clicks) compression
Rear 8 clicks rebound. 0.75 turns compression (roughly 5 clicks if you can feel them)

Depending on the track and conditions I sometimes soften the compression on the rear too 1 full turn if I want to reduce a bit of oversteer.

Thanks for this. Will try the settings and report back once my kit arrives and all is installed
I want the least possible drop due to clearance. Do you lower it when going on a track apart from the above settings?

thanks
kerstien

 

[exdos]

Perfect thanks for that. Ca automotive seem to sell them in the uk. just sent them an email to check whether they have them in stock. Is the installation of RTAB limiter kit a must? Can it be installed at a later stage? Is this also from rogue engineering? I'll check how the kw's work before getting into uprated ARBs

Thanks once again for all the info

Kerstien

I don't think any UK supplier stock KWV3 suspension, they just act as agents for KW, and once they receive your order they then order themselves from KW.

The RTAB limiters are not a "must" but certainly well worthwhile doing whilst you're uprating the suspension. They can be installed at any time, but you'll have to part dismantle the rear suspension to fit. Rogue make some Polyurethane (?) limiters, but mine are from Turner Motorsport. The Rogue RTAB limiter kit should be easier to install (and cheaper) because you don't have to remove the RTAB brackets to drill for fitting, which you do for those from TM: I didn't know the Rogue RTAB kit existed when I bought mine.

 

[kerstien]

Perfect thanks for that. Ca automotive seem to sell them in the uk. just sent them an email to check whether they have them in stock. Is the installation of RTAB limiter kit a must? Can it be installed at a later stage? Is this also from rogue engineering? I'll check how the kw's work before getting into uprated ARBs

Thanks once again for all the info

Kerstien

I don't think any UK supplier stock KWV3 suspension, they just act as agents for KW, and once they receive your order they then order themselves from KW.

The RTAB limiters are not a "must" but certainly well worthwhile doing whilst you're uprating the suspension. They can be installed at any time, but you'll have to part dismantle the rear suspension to fit. Rogue make some Polyurethane (?) limiters, but mine are from Turner Motorsport. The Rogue RTAB limiter kit should be easier to install (and cheaper) because you don't have to remove the RTAB brackets to drill for fitting, which you do for those from TM: I didn't know the Rogue RTAB kit existed when I bought mine.

I don't think i made myself clear. my kws are already ordered and on the way I emailed ca automotive for the top mounts you suggested. they seem to sell them.
When you say RTAB limiter kit is it just these that i need?
http://www.ca-int.co.uk/single_prod-cHJvZF9pZD0yNTk3JmNhcl9tYWtlPWJtdyZjYXJfdHlwZT16NCZjYXRfaWQ9MTExJmNvbXBfaWQ9MTY=.html

thanks kerstien

 

[exdos]

I don't think i made myself clear. my kws are already ordered and on the way

I see!

I emailed ca automotive for the top mounts you suggested. they seem to sell them.
When you say RTAB limiter kit is it just these that i need?
http://www.ca-int.co.uk/single_prod-cHJvZF9pZD0yNTk3JmNhcl9tYWtlPWJtdyZjYXJfdHlwZT16NCZjYXRfaWQ9MTExJmNvbXBfaWQ9MTY=.html

thanks kerstien

No, those are complete RTA bushes. What I'm suggesting is either these: http://www.rogueengineering.com/rogue/S_BUSH/RTAB_SHIM.html or these: http://www.turnermotorsport.com/p-9...ng-arm-bushing-limiter-kit-rtab-shim-kit.aspx They fit at either side of the RTA bushes in the RTA brackets. Once you can see the parts in situ, they're self-explanatory.

 

[kerstien]

I don't think i made myself clear. my kws are already ordered and on the way

I see!

I emailed ca automotive for the top mounts you suggested. they seem to sell them.
When you say RTAB limiter kit is it just these that i need?
http://www.ca-int.co.uk/single_prod-cHJvZF9pZD0yNTk3JmNhcl9tYWtlPWJtdyZjYXJfdHlwZT16NCZjYXRfaWQ9MTExJmNvbXBfaWQ9MTY=.html

thanks kerstien

No, those are complete RTA bushes. What I'm suggesting is either these: http://www.rogueengineering.com/rogue/S_BUSH/RTAB_SHIM.html or these: http://www.turnermotorsport.com/p-9...ng-arm-bushing-limiter-kit-rtab-shim-kit.aspx They fit at either side of the RTA bushes in the RTA brackets. Once you can see the parts in situ, they're self-explanatory.

Perfect if ca automotive have these in stock I'll get them also

Thanks

Kerstien

 

[kerstien]

I don't think i made myself clear. my kws are already ordered and on the way

I see!

I emailed ca automotive for the top mounts you suggested. they seem to sell them.
When you say RTAB limiter kit is it just these that i need?
http://www.ca-int.co.uk/single_prod-cHJvZF9pZD0yNTk3JmNhcl9tYWtlPWJtdyZjYXJfdHlwZT16NCZjYXRfaWQ9MTExJmNvbXBfaWQ9MTY=.html

thanks kerstien

No, those are complete RTA bushes. What I'm suggesting is either these: http://www.rogueengineering.com/rogue/S_BUSH/RTAB_SHIM.html or these: http://www.turnermotorsport.com/p-9...ng-arm-bushing-limiter-kit-rtab-shim-kit.aspx They fit at either side of the RTA bushes in the RTA brackets. Once you can see the parts in situ, they're self-explanatory.

I contacted ca automotive and they have both shims and complete bushes in stock. They mentioned that the complete bushes have more 'feel' to them. Is this true? The way I understood them is that if I got the bushes I wouldn't need the shims. Is this correct?

Thanks for the help.

Kerstien

 

[exdos]

I contacted ca automotive and they have both shims and complete bushes in stock. They mentioned that the complete bushes have more 'feel' to them. Is this true? The way I understood them is that if I got the bushes I wouldn't need the shims. Is this correct?

Thanks for the help.

Kerstien

I would never go near any Polyurethane bushes which have to rotate, like trailing arm bushes must. I say this with the experience of having used these things before. THEY WILL DRIVE YOU MAD! They creak and squeak and there's no way of stopping this over the long term. OTOH, a rubber bush (i.e OEM) twists during its range of movement and makes no noise. You have been warned!!!!!!!!!!!!

 

[BMWZ4MC]

And I would try to find an alternative to CA Automotive! They are unreliable and don't communicate with their customers when there are delays with delivery. If you have need to phone them, once they have your money you'll find them bloody rude too! They also overcharge for delivery.....

 

[kerstien]

I contacted ca automotive and they have both shims and complete bushes in stock. They mentioned that the complete bushes have more 'feel' to them. Is this true? The way I understood them is that if I got the bushes I wouldn't need the shims. Is this correct?

Thanks for the help.

Kerstien

I would never go near any Polyurethane bushes which have to rotate, like trailing arm bushes must. I say this with the experience of having used these things before. THEY WILL DRIVE YOU MAD! They creak and squeak and there's no way of stopping this over the long term. OTOH, a rubber bush (i.e OEM) twists during its range of movement and makes no noise. You have been warned!!!!!!!!!!!!

Ill take your word for it and just get the shims

Thanks

Kerstien

 

[kerstien]

And I would try to find an alternative to CA Automotive! They are unreliable and don't communicate with their customers when there are delays with delivery. If you have need to phone them, once they have your money you'll find them bloody rude too! They also overcharge for delivery.....

Do you know of anyone else that gets rogue engineering products in the uk? Ordering from the US will take too long plus I will have to pay import charges. So far CA have been very prompt in answering my emails. Thanks for sharing your experience however.

Thanks

Kerstien

 

[BMWZ4MC]

Is your "butt-strut" in the boot between the shock towers or under the car? I've seen something for the Z4 that goes beneath the vehicle but the description of its benefits wasn't wholly convincing...

It's the Strongstrut Butt-strut as here: http://www.strong-strut.com/Butt-Strut.htm It fits under the car on the subframe pins. I can feel the difference it makes on that car.

I've also enlisted the Butt-strut to form part of an under-car rear diffuser system that I've made in conjunction with a pair of OEM silencers which I gutted for improved performance but I also flattened their undersides which also form part of the rear diffuser as per the photos below. The rear diffuser works a treat and it throws up a great "rooster tail" in the wet. 8)










I've also made some similar undercar strakes for my Z4MC which are attached to the OEM "pull rods" in the diagram below (Part 16 which is essentially a triangulated butt-strut), the idea being to prevent air coming in from the sides in front of the rear wheels and to straighten the airflow at the rear of the car so that the OEM rear diffuser works better and to make the rear OEM silencers flow "Coanda" style to prevent lift at higher speeds.

Ah, more pictures of your ///M Coupe to make me jealous John

The butt-strut is similar to something I've seen for the Z4M. I can see how it would be useful for the Z3. I was think of trying to fit a strut brace between the rear shock towers rather like that at the front. I appreciate the body shell of the coupe provides a great deal of torsional rigidity already though...

I like what you've done with the rear diffuser - have you any photos of what you've done with aero for the Z4?

 

[BMWZ4MC]

And I would try to find an alternative to CA Automotive! They are unreliable and don't communicate with their customers when there are delays with delivery. If you have need to phone them, once they have your money you'll find them bloody rude too! They also overcharge for delivery.....

Do you know of anyone else that gets rogue engineering products in the uk? Ordering from the US will take too long plus I will have to pay import charges. So far CA have been very prompt in answering my emails. Thanks for sharing your experience however.

Thanks

Kerstien

I don't - I got my RTAB limiter kit direct from Turner in the US, and my Rogue top mounts cheaply as barely used second hand since buying direct from Rogue isn't straightforward.

 

[kerstien]

And I would try to find an alternative to CA Automotive! They are unreliable and don't communicate with their customers when there are delays with delivery. If you have need to phone them, once they have your money you'll find them bloody rude too! They also overcharge for delivery.....

Do you know of anyone else that gets rogue engineering products in the uk? Ordering from the US will take too long plus I will have to pay import charges. So far CA have been very prompt in answering my emails. Thanks for sharing your experience however.

Thanks

Kerstien

I don't - I got my RTAB limiter kit direct from Turner in the US, and my Rogue top mounts cheaply as barely used second hand since buying direct from Rogue isn't straightforward.

Ok thanks. So the RTAB limiter kit are in fact the shims right? Sorry for all the dumb questions.

Thanks

Kerstien

 

[NeilP]

I contacted ca automotive and they have both shims and complete bushes in stock. They mentioned that the complete bushes have more 'feel' to them. Is this true? The way I understood them is that if I got the bushes I wouldn't need the shims. Is this correct?

Thanks for the help.

Kerstien

I would never go near any Polyurethane bushes which have to rotate, like trailing arm bushes must. I say this with the experience of having used these things before. THEY WILL DRIVE YOU MAD! They creak and squeak and there's no way of stopping this over the long term. OTOH, a rubber bush (i.e OEM) twists during its range of movement and makes no noise. You have been warned!!!!!!!!!!!!

+1

the main reason people rave about them is due to them replacing their worn out oem rubber ones. The difference would obviously be different! :lol:

Had a lengthy conversation with another BMW enthusiast (who also knows his fair share about handling geometry) who echoed the same thing and for that reason alone swears by the oem bushings.

Exodos, thank's for the tip regarding the toe...the car needs to have a full alignment done so will be looking into running less toe!

 

[exdos]

Ah, more pictures of your ///M Coupe to make me jealous John

Is it working? There's a nice very low mileage S54 Z3MC in PY for sale at the moment...

The butt-strut is similar to something I've seen for the Z4M. I can see how it would be useful for the Z3. I was think of trying to fit a strut brace between the rear shock towers rather like that at the front. I appreciate the body shell of the coupe provides a great deal of torsional rigidity already though...

I think you'll have to fit a half roll cage to increase the rigidity of the Z4MC some more, which would link the rear shock towers.

I like what you've done with the rear diffuser - have you any photos of what you've done with aero for the Z4?

Thanks! I'll take a few photos for you in the next few days.

 

[BMWZ4MC]

Yep - stop tempting me....I wish I'd bought the sub £7K track prep'd PY S50 we talked about a year or two ago

Maybe one day when it's a track only animal

And thanks

 

[exdos]

And thanks

Richard, I changed the gearbox oil this morning so whilst I was doing that I took a few photos for you of the undercar aero I've done, as below.

Obviously, I've no way of properly assessing this, but the idea is that of instead of letting all the air under the car find its own way out the back end, by putting four small vertical strakes on the underside, the air should flow with more directional control from a line in front of the rear wheels and behind that line.

The strakes situated closest to the wheels should prevent some air from coming under the car from the sides and help the OEM flaps in front of the wheels to work more effectively. The OEM flaps create low pressure in front of the rear tyres which helps water on the road to disperse to improve traction in the wet. The two central strakes are intended to make the air passing between them flow longitudinally, which should make the rear diffuser in the bumper work more effectively as well as cooling the differential. At the same time, the air passing on the outside of them and between the outer strakes should also flow longitudinally, and thus pass under the curved profile of the rear silencers which should create a "Coanda effect" thus pulling the silencers towards the road and reducing any tendency to lift at high speed. I had to remove the OEM pull-rods to drill a pair of 8mm holes in each so that I could bolt the strakes in the appropriate locations.

As I see it, putting vertical strakes under the rear of the car is akin to the longitudinal strakes on speed boats which give directional stability without the need for a deep keel. The car certainly feels very stable at high speed and I did over 150mph at The Ring with these strakes and the car was going arrow straight with good steering input. When I fitted my ACS suspension I deliberately increased the rake angle by dropping the front by 10mm.