BC racing coilovers, not too low please

[peteslag]

Hello all,

I'm definitely going to buy BC racing coilovers but I don't want to lower the car. Before I pull the trigger on a purchase I was wondering if any body on here has BC coilovers set to their highest setting, if so I was hoping you could measure the ride height for me.

I contacted BC racing but they couldn't say with any certainty what the figure was.

Thanks in advance,

Pete

*EDIT* i have my answer, they are height adjustable to near standard height. Thanks for looking.*EDIT*

 

[Martyn]

I recently switched from B12s to BCs, I have the ride height around the same as it was on the B12s with plenty of adjustment to go either way.

 

[peteslag]

I recently switched from B12s to BCs, I have the ride height around the same as it was on the B12s with plenty of adjustment to go either way.

From memory the B12's have a fairly moderate affect on the ride height. If there is room for adjustment to make the car a bit higher, BC could be perfect for me. Thanks for that

 

[peteslag]

Look out wallet, you are about to get some abuse.

 

[RedUn]

Hello all,

I've been driving my Z4MR for a few days now and I'm really not getting on with it. My old Z4 3.0 used to understeer a bit but that was easily fixed with an adjustable anti roll bar kit. The M seems to have lots of understeer/oversteer/squatting/diving problems, in fact it is really unsettled in most conditions compared to previous sports cars I've owned.

After a fair bit of research there seems to be a lot of good feedback for BC racing coilovers given by the lovely people on this forum. I think a set of these would alleviate most of my moans and groans about this car. My only worry is the ride height. I don't really want to lower it at all if possible. I was wondering if any body on here has BC coilovers set to their highest setting, if so I was hoping you could measure the ride height for me.

I contacted BC racing but they couldn't say with any certainty what the figure was.

Thanks in advance,

Pete

Before you go spending money on upgrades...

What tyres? Presures?
Is it lowered at all? How many miles on springs and dampers? Are the rear springs cracked?
Is the geo OK?
Rtab bushes also wear with mileage giving a loose feeling at the rear.

Lots to go at before I'd change the suspension, not that I'm against that it could just be something simple...

 

[peteslag]

It has

Hello all,

I've been driving my Z4MR for a few days now and I'm really not getting on with it. My old Z4 3.0 used to understeer a bit but that was easily fixed with an adjustable anti roll bar kit. The M seems to have lots of understeer/oversteer/squatting/diving problems, in fact it is really unsettled in most conditions compared to previous sports cars I've owned.

After a fair bit of research there seems to be a lot of good feedback for BC racing coilovers given by the lovely people on this forum. I think a set of these would alleviate most of my moans and groans about this car. My only worry is the ride height. I don't really want to lower it at all if possible. I was wondering if any body on here has BC coilovers set to their highest setting, if so I was hoping you could measure the ride height for me.

I contacted BC racing but they couldn't say with any certainty what the figure was.

Thanks in advance,

Pete

Before you go spending money on upgrades...

What tyres? Presures?
Is it lowered at all? How many miles on springs and dampers? Are the rear springs cracked?
Is the geo OK?
Rtab bushes also wear with mileage giving a loose feeling at the rear.

Lots to go at before I'd change the suspension, not that I'm against that it could just be something simple...

Thanks for the sage advice and you are completely right, better to look at the cheap options first. It has covered 43,000 miles and the suspension system is in extremely good order.

My car history is quite varied, I've had plenty of fruity cars from Audi/Toyota/Ford/Jaguar/Porsche/Renaultsport, a couple of mad VX220's and quite a few beamers. They have been FWD,4wd and rwd with a good mixture of LSD and open diffs. I've driven most of them on track days but that said I'm no racing driver so I suppose my opinion is not worth much more than any one else's.

My opinion of this car is that the engine/gearbox combo is incredible. The styling is timeless. The carbon weave interior and the sports seats are much nicer than my Z4 3.0. The brake calipers are too small for the amount of engine power. The addition of the LSD has been done poorly, the damping or spring rates aren't quite right. I'm not clever enough to know which. I know this will not be a popular view in an "M" forum but in the immortal words of Clint Eastwood "opinions are like arseholes, we all got one".

 

[Vanne]

Not sure extremely good condition would qualify for a 15 year old suspension system, even at low Kms. Which is probably why you say that the rates aren't quite right. Bushes deteriorate, even more so when not used much. The brake calipers are more than fine on this car, just need to pair it up with some proper fluid and pads, and some new braided lines.

Excellent advise from Red.

 

[peteslag]

I think this thread is going a little sideways. Like I say, we all got opinions.

I was asking about the ride height for the BC coilovers and I am very thankful for the answer.

 

[RedUn]

I think this thread is going a little sideways. Like I say, we all got opinions.

I was asking about the ride height for the BC coilovers and I am very thankful for the answer.

Most people in here have modified zeds so we are just giving advice, feedback from the journey we've all been on, it's not that it's not a popular view we just try to help people not waste money

Swapping for some BCs if your bushes are knackered for example will solve nothing.

If you you want to spend some money though, completely different story and I get it, I'd recommend some KWs though, they ride so much better due to their design, it'll give you the damping your after.

I'd also get all the bushes checked, change the rear rtabs to rogue, rogue rear top mounts, front spacers, front oem z3 strengthening plates to protect the top mounts with a CSL geo no matter which coilover you go with these go hand in hand.

Strut brace and arbs is up to you.

Brakes as Vanne said are fine, pads, fluid, hoses if you want. If you want to go bigger lots of kits out there.

LSD sounds like it needs a fluid change, also remove the cdv while your at it, it makes the clutch feel 'normal'.

A properly setup zed is very capable on the road and on the track

I don't have BCs so I can't answer your question, most people on here tend to run KW or Bilstein, I'm sure someone will know though and be along soon to answer.

 

[peteslag]

Thanks everyone for the advice but I know Z3's/Z4's extremely well and I've had a good poke around underneath this one so know what state the suspension components are in. I'm also very aware of all the tuning options/rod bearings problems/vanos etc etc but thanks to every one for the extra info.

I was just after some advice on the ride height and I got my answer almost straight away. Maybe I should have kept my first post a bit more simple.

 

[Simon 3.2M]

I can attest to the KWs, they are great - they really smooth the ride and give the car a much more planted feel. When I changed my suspension, admiringly it was very tired, the car was transformed!

I do need to get the geo setup (M3 CSL) in the near future but the improvement is vast.

Hope that helps
.

 

[peteslag]

I can attest to the KWs, they are great - they really smooth the ride and give the car a much more planted feel. When I changed my suspension, admiringly it was very tired, the car was transformed!

I do need to get the geo setup (M3 CSL) in the near future but the improvement is vast.

Hope that helps
.
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I see you have uprated calipers as well, that is a lovely set up. Loving the wheels as well, my old Z4 had CSL's. I think they looking stunning on a Z4.

I know that KW are very good but I'm only really interested in BC racing coilovers, I always found them to be superb if you like a bit of mixed road and track use.

 

[wspohn]

I use the BC units on another car (I still have the stock units on my Z4MC and they do the job very well). The BCR shocks have a lot of adjustment and can be tailored to your BMW.

 

[perttu]

Hello all,

I'm definitely going to buy BC racing coilovers but I don't want to lower the car. Before I pull the trigger on a purchase I was wondering if any body on here has BC coilovers set to their highest setting, if so I was hoping you could measure the ride height for me.

I contacted BC racing but they couldn't say with any certainty what the figure was.

Thanks in advance,

Pete

*EDIT* i have my answer, they are height adjustable to near standard height. Thanks for looking.*EDIT*

Came across this old thread while looking for an answer to exactly same question. Pete, if you ended up purchasing BCs, can you confirm if you're able to reach stock or close to stock height with the highest setting? Or maybe your EDIT comment was already based on your own experience after installing the coilovers? .

 

[wspohn]

The BCR shocks allow adjusting to the stock ride height.

 

[perttu]

The BCR shocks allow adjusting to the stock ride height.

Thanks for comments! I guess I'm one more step closer to pulling the trigger now

 

[plenty]

I am running close to stock height in BCs. In fact I could run significantly higher than stock if wanted...haven't measured but from memory at least 20mm higher than stock front and rear is available should you want it.

BCs on the default 6F/10R springs, or any decent aftermarket setup for that matter, are a massive improvement over OEM regardless of condition, as OEM spring rates are far too hard at the rear and too soft at the front. I would actually suggest opting for 7 or 8 kgs springs at the front as IMO 6 kgs are still a tad soft.

 

[perttu]

I am running close to stock height in BCs. In fact I coild run significantly higher than stock if wanted...haven't measured but guess at least 20mm higher than stock front and rear is available should you want it.

BCs on the default 6F/10R springs, or any decent aftermarket setup in fact, are a massive improvement over OEM regardless of condition, as OEM spring rates are far too hard at the rear and too soft at the front. I would actually suggest opting for 7 or 8 kgs springs at the front as IMO 6 kgs are still a tad soft.

Thanks, it's good to have first hand comments since there is quite much conflicting information about this. One dealer says this, another says that and the internet says something in between or both at the same time ;-).

I'm currently looking at 7kg/mm / front, 10kg/mm / rear. What has been your experience on different stiffness settings? Mostly what I'm hearing is that softest setting is close to stock and stiff is really hard.

 

[maupineda]

Rears need to be stiffer due to placement within the upper control arm, the effective rate due to where it sits relative to the wheel is about 0.5 (0.45) of the rate and about 0.9 (0.91) for the front

i.e a front spring effective rate would be rate x 0.9, and the rear would be rate x 0.5

You need the rear to be stiffer for the rear tires to even the fronts after a bump at speed

In my case, my spring rates are 225 and 600 which gives me a wheel rate of 202.5 and 270 respectively. Not ideal, if I wanted a 14% delta front to rear for a fast road/ GT setup I would need to have a 500#/in spring at the rear. The reason I have 600 at the rear is that I calculated to a 250 front, but then back down the fronts. Eventually, I will go to 500 at the rear.

So, the thought that the car is off from the factory is incorrect. The issue is the damping. the rates are on the firm side, but not extreme. Also, keep in mind that we seat closer to the rear axle, so the need of a stiffer spring and more aggressive damping are exacerbated by this, and we cannot do much about it, is the car's architecture trait. That is why the Z will never ride very well if you want a sporty suspension.

The reason why the Z has even stiffer rear springs relative to the fronts VS the E46 is due to the shorter wheelbase, this requires the rear wheel to recover quicker from a bump to keep up with the front.

 

[plenty]

Even taking into consideration the positioning of the springs, the OEM wheel rate is too stiff at the rear and too soft at the front.

On a front-engined car you want harder suspension at the front as there is more weight at the front, especially with the heavy iron S54 block on the Z4M. Furthermore, the seating position on the E8x is so close to the rear axle that you want as much compliance at the rear as possible.

The OEM suspension is a strange combination of the front end being too soft, contributing to poor turn-in, a general feeling of vagueness, lift under hard acceleration and dive under braking, but also a jittery ride and a back end that hops and skips over bumps rather than absorbing them, due to the lack of compliance at the rear. The end result is a car that does not reward being pushed hard and has the sensation of the front and rear being disconnected, as if you are driving halves of two different cars that have been spliced together.

Most aftermarket suspension including BC and KW fixes this with wheel rates that are higher at the front than the rear, making for a more planted, confidence-inspiring and cohesive drive.

The Caterham is another example of a car which is front-engined with the seating position close to the rear axle. Most Caterhams run wheel rates at a delta of roughly 2F:1R. The only cars which have stiffer wheel rates at the rear are mid- and rear-engined.