Z3 & Z3M Buyers Guide for Bertini GT25

[Choc]

I am putting together a simple buyers guide for the Z3 and Z3M for my Bertini GT25 website and for an upcoming issue of one of the Kit Car magazines.

I have trawled the forums, Wiki, Parkers and used my personal experience of the 5 x Z3's I have owned to put this together so far.
But i would really appreciate any input to obvious mistakes i have made and and additions to the things to look out for when buying a Z3 and which are the best models to own.

Also any favourite modifications would really help for the guide.
here is what i have so far: - i will edit as suggestions are made
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BMW Z3 and Z3M Buyers Guide

BMW Z3 1996-2002 Assembled in South Carolina USA

1.8 118 bhp 10.1 secs 1295 kg (1999-2002)
1.9 140 bhp 9.2 secs 1275 kg (1996-1999)
2.0 150 bhp 8.6 secs 1345 kg (1999-2002)
2.2 170 bhp 7.6 secs 1345 kg (2000-2002)
2.8 193 bhp 6.7 secs 1360 kg (1997-2000)
3.0 231 bhp 5.8 secs 1360 kg (2000-2002)
3.2 321 bhp 5.1 secs 1450 kg (1998-2002)

(2.3, 2.5 units were used in the USA)
(4 speed autos were available - these are slightly heavier and slower than the 5 speed manuals)


4 pots are a little under powered but are lighter but can be supercharged along with the six cylinder cars
2.2, 2.8 and 3.0 engines offer an exciting drive
3.2M engines are FAST and FUN but can be a handful in the wet and most don't have traction control
2.8s had wider rear wings and axles


Facelift changed:
all models had wider rear wings and axles
remote central locking
headlining in hood
rear light / boot shape
wider rear arches and bumps over the wheels
some had clear lenses to headlights and indicators
chrome headlight rings
redesigned boot and boot brake light
DSC dynamic stability control replaced ASC traction control
a few interior modifications

Z3Ms
they have the s50 engine with 321 bhp (post 2000 cars were given the s54 engine with 325 bhp)
they share the same rear wings as the 2.8 wide-body but have a shorter rear axle and run rear wheels with a crazy low offset.
most Z3m's do not have traction control like many of the other six cylinder Z3's. (post 2000 models do have TCS)
all Z3M's have a LSD - these were an option on the Z3's
they benefit from uprated suspension, bushes and chassis
(this reduces the rear end droop experienced under acceleration on the higher power Z3s)
the Z3m has a colour coded interior dash


Common problems and things to look out for:
rotten sills, mini front wings, rear wings and lock on rear boot
Vanos problems characterised usually by loss of power at low revs and a funny sound for the front of the engine. (Mr Vanos can help repair these)
rear cross member and boot floor spot welds coming loose due to flex from the diff in the Z3M, 3.0 and 2.8 - check the boot floor for broken spot welds
electric hoods which are common on the higher spec. cars can often be temperamental
bonnet release mechanism often stick and need to be kept greased
each electric seat uses 2 motors. these can sometimes fail, also the rail bushes can become worn - check the seats in all directions
the clips on the side of each seat that funnel the seatbelts often brake
The wing mirrors can be affected by corrosion
Water/condensation in the boot - often caused by faulty weather gaskets
Check roof for signs of water penetration - if leaking then it is often just the hooks that need tightening
rear plastic windows on the hood is difficult to replace - but there is usually a crease along the window this is a common unavoidable problem
check for accident damage, resprays and panel gaps
BMW engines are usually sound if well maintained with a good service history
(however viscous coupling and the water pump are well worth looking at changing around 80,000 miles along with the guibo/flex disc)
Bushes tend to wear also especially the top mounts - this can be a good opportunity to install a polybush kit.

Best Modifications:
Bilstein or Eibach shocks and progressive lowering springs
Poly bush kit
Butt Strut system (ok with a lowered Z3 but clearance can be an issue with a lowered Z3M)
Braided clutch hose on z3m
induction kit (simota carbon airbox comes recommended)
reinforcement to the rear crossmember
(this mounts the rear diff - Randy Forbes USA do a kit)
twin ear rear diff

Price guide (UK Summer 2014)
The prices change a lot depending on the time of year and the quality of the car.
1.8 and 1.9 cars can be as cheap as £1500 - but a nice low mileage example can be close to £3000
2.2, 2.8 and 3.0 cars seem to start at £2500 and rise to up to £4500 for very well kept examples with low miles.
The Z3Ms can range between £6000 and £10,000 depending on the condition.

Wheels and Wheel options
BMW Z3's came with 16 or 17 inch wheels. 18 and 19 inch will fit with lower profile tyres.
Avoid the run-flat tyres that come on many second hand sets of BMW wheels
BMW Z3s had 5x120 PCD with 72.5 centre core
Z3 & Z3M have a front ET of 41
widebody and facelift Z3's have a rear ET 37
slimmer body Z3's have a rear ET of 41
while Z3M an ET of 8
However as standard the Z3 wheels did not 'fill the arches' well so 10mm hubcentric wheel spacers enhance to look of the standard wheels

Wheels for the Bertini GT25
The Bertini front and rear width is the same as the Z3M and wide-body 2.8, so all wheels designed for a Z3 will fit the Bertini
Most BMW wheels will fit – but wheel spacers may be required
(Z4 108's on the blue Bertini have 25mm rear spacers and 15mm front spacers)
(BMW style 32 18" deep dish alloys (7 series) on the Z3M Bertini also use 25mm rear spacers)
(BMW style 32 18" deep dish alloys (7 series) on the Z3 Bertini do not need any spacers)
(BMW style 32 18" non deep dish alloys (3 series) require 25mm spacers on the rear and 15mm spacers on the front on the Z3 based Bertini)

Tips for buying a Z3 or Z3M for converting to a Bertini GT25
Ensure you buy the car you want with the engine you want.
(The small premium you pay for a facelift or bigger engine may be worth the longterm investment)
Ensuring the retained features of the car are in good condition can save you lots of money in the long run.
A car with a hood in good condition is advantageous
Doors in good condition with minimal dents etc
A good quality and well maintained interior can save you doing a retrim!
Buying a car in the colour you wish to have your bertini can save a lot in the paint shop! Or at least a similar colour can help cut the cost.
There is a temptation to by a crash damaged or write off car. However the resale value of the unused Z3 parts is high so this rarely makes economic sense.
A nice set of 18 or 17" alloys in good condition of an expensive audio system can save money if you wish to retain them in your Bertini.

[mnbrennan]

Hi Choc.

Congrats on the media coverage you've been receiving.

Looks good. Feedback below

Not all facelift z3 s came with Clear Indicator lenses (mine didn't )

There weren't ANY facelift z3ms as far as I'm aware, although the later models (post 2001) came with the s54 engine which included TC.

The double ear diff can be used, but requires modification to the exhaust system on the z3m

Reinforcement of the cross member can be done with a Randy Forbes kit from the USA.

Sent from my HTC One using Tapatalk

[('_')Z3]

Hi Choc.

Congrats on the media coverage you've been receiving.

Looks good. Feedback below

Not all facelift z3 s came with Clear Indicator lenses (mine didn't )

There weren't ANY facelift z3ms as far as I'm aware, although the later models (post 2001) came with the s54 engine which included TC.

The double ear diff can be used, but requires modification to the exhaust system on the z3m

Reinforcement of the cross member can be done with a Randy Forbes kit from the USA.

Sent from my HTC One using Tapatalk

I'm pretty sure there was a subtle facelift to the z3m including the hood lining as stated as well as a few other small bits.

[deni2s]

About - "2.8 193 bhp 6.7 secs 1360 kg (1997-2000)" : 1997-1998 had m52b28 engine with 189 bhp and 1998-2000 had m52tub28 engine with 193 bhp
6 cyl cars also can be supercharged, not only 4 cyl.
not all facelift cars had clear lenses - http://i.ss.lv/images/2014-05-29/340352 ... -7.800.jpg
all z3m's are prefacelift
LSD was also standard option for some z3 not only z3m (my 1997 2.8 z3 has LSD as standard option)
what do you mean by "the Z3m's do not have traction control like many of the more powerful Z3's"? I do not know more powerful z3's than z3m's. Ok, I got your point, but this doesn't sounds right.
"Poly bushes on Z3 (but can be a harsh ride on Z3M)" - I don't believe that poly bushes will make z3m to ride harsh
Vanos is not an issue on all engines (for example it is not an issue on M52B28, but it is on M52TUB28).
"Facelift changed: wider rear arches and bumps over the wheels" - bumps - yes, agree, but rear arches where not wider than on wide body prefacelift z3.
According to wiki http://en.wikipedia.org/wiki/BMW_Z3 2.0 engine was available from 1999.

[deni2s]

I'm pretty sure there was a subtle facelift to the z3m including the hood lining as stated as well as a few other small bits.

Some options might change, but not body panels.

[Choc]

thanks guys - keep the corrections coming - its really helpful

any additional modification, upgraded components and changes that improve reliability, handling etc. would be great

[mnbrennan]

Braided clutch hose on z3m is a recommended upgrade.

Also the simota carbon airbox

Sent from my HTC One using Tapatalk

[deni2s]

thanks guys - keep the corrections coming - its really helpful

any additional modification, upgraded components and changes that improve reliability, handling etc. would be great

I believe giving the link to this forum and bimmerforums.com would be the best cue everyone needs. There are different opinions regarding changes that improve reliability and other things.

[Mac The Tank]

No mention of the coupe and how it relates to the Bertini?

[Choc]

the coupe will work with the front end of the Bertini.
i am planning a fastback FTC version of the Bertini - but this is based on the roadster - but these will be special order factory cars.
(think porsche cayman, corvette C2, ftype coupe)

im not sure if the curves of the Bertini will work well with the edges of the rear of the standard Z3 or Z3M coupe

[Choc]

I have added a wheel section and updated a few things.

anymore suggestions?

i think i have got the offsets in the wheel section correct.