Z3M Coupe for trackday use

[gatouille]

Hello I'm Gatouille, I'm living in France.
I bought a 1998 M coupe for trackday use. I started with it in July, 2014.

Here are photos when I bought it :








Rims were awful, iddle was not so good.... But I started to work on THE WEAK POINT of M coupe : subframe, trunk floor and differential mount of course !

Everything was in good shape that made easier the work to do.














Camber adjustement with the FACOM U70 tool very easy to use even for an humble DIYer like me !



Also


The car came with BILSTEIN B16, and was to low, I had to fix it and adjusted the BILSTEIN to find the right height


These are out of order and made the car very dangerous even at low speed :


Brand new one harder than OEM parts



OEM back part of the car is not adjustable, this is the same as E30. I bought a kit that made it adjustable parallelism and camber




First testing on track ! You guess that my car was faster than a plane !


A "must have" for all Z3



Thank you for reading !

[gatouille]

Testing showed a very easy to drive car, efficient too.
The car worn out brakes (OEM one) in only 3 laps.

To prevent hot temperature oil I changed these part (thermostat)for a piece of alloy. I was sure that oil had plenty way to go.
These tips makes the engine more reliable as it works at low level oil temperature.







It was time to change these awful rims 17 " by TEAM DYNAMICS one 18" 18X10" ready for my YOKOHAMA 250/66 X18 " race tyres.


Vanos rebuilding, I had only 50 psi of pressure instead of 100.






With this big wheels, my weight was 1235 kilos (2723 lb) without gas and pilot.

This was for the intake of course ! Weight is half OEM parts



Testing brand new wheels on track !







very good parts from HR made my car best in curves. 2 seoonds a lap were win only whit these !




Hillclimbing race


New front brakes calipers from Porsche 996 aspirated (front) disks from M3 E46 CSL 345 mm and PFC 08 very good pads.


From rallyroad


All exhaust from Supersprint (excepted manifolds)


Ready for fun !


It was very hard to drive on wet track .....




Brand new wheels for bad weather.

[Schreier]

Very nice! Solid job on the subframe fix. What kind of kit did you use for that?

[gatouille]

Thank you, it's home made one,


I use this specific tools


Sorry i don't know the name in english. That for spot welding, we did a lot more than genuine.








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These made the car stiffer



Home made part for "oil thermostat" which is a weak point of S50B32 engines, the part is no longer available, for trackday use the best way is this alloy part.
That make sure oil have plenty way to go. Temperature oil is better after this tips.




Genuine


And our tips


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These made the car stiffer



Home made part for "oil thermostat" which is a weak point of S50B32 engines, the part is no longer available, for trackday use the best way is this alloy part.
That make sure oil have plenty way to go. Temperature oil is better after this tips.




Genuine


And our tips

[Tom Liberatore]

Great post! Thanks for sharing, awesome car, fantastic workmanship and interesting approach to solving Z3 weaknesses, always great to see how other folks tackle things. I like the X3-Z3 parade, does the X do a good job of towing the Z?

[gatouille]

Thank you very much indeed for your answer !

The X3 with M54B30 (gasoline) do a very good job, the engine is nice to use even in everyday life.
This is a manual 6 speeds gear box, which is not very common even in Europe.
I find fun to pull the trailor and his "S50B32" with another 6 cylinders from BMW...

I did the same "game" with my ex trackday's car (Alfa Romeo Alfetta GTV 2 liter'83) pulled by my Sedan Alfetta 2000....
[IMG][/IMG]

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Sorry, as I'm not a native english speaker, it may be not perfect at all, thank you for reading !
With my friends of Alfa Clubsport "Scuderia Del Quadrifoglio", most of them are fast, that a good way way for me to improve myself (or trying!)



This one is a "bad guy" Milano 1,8 liter turbo engine homemade very reliable more than 300 hp weight is 920 kilos 2030 lbs



I had to use this "helicoil kit" 7x100 one, very often, people srew to tight and it becom out of order.










4 or 5 srews were out of order, no leak now !



A very nice experience was to borrow my car during a real race (hillclimbing) at one of my friend who is one of the best french drivers (4 years as Formula One test driver, 24 h Le mans....)

He drove my car and I was the passenger during the race, and I also drove the car with him as a "luxurious passenger", the reality met my chilhood'sdreams !!




The race was one the more famous one in Europe "Course de côte du Mont Dore"
I was like a chid meeting the real santa !
A gift from organisation :



I can say I DID IT !

Brand new exhaust from supersprint excepted manifolds stil OEM one.


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an other weak point of my car is the weight, so it's time to loose weight !
I'm trying to save the more, as I plan to change my Roll bar for a Roll cage.

I had a Roll bar from Wiechers, I 've got a very good friend who makes roll cages....

First disassemble the car and save weight as much as possible whithout spending to much money !

One wiper save 0,9 kilo 2 lbs


These from rear windows 0,5 kilo 1 lb


0,830 kilo 30 oz


0,1 kilo 3,3 oz



From doors 2,2 kilos 4,85 lbs



From trunk 0,8 kilo 1,7 lb



For battery this one 1,2 kilo 2,64 lbs


OEM one 2,6 kilos 5,73 lbs



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Stil disassembled, that will make easier the work on the car (roll cage)



You can see roll bar from wiechers (6 points)




Saving weight one this part




Homemade is cheaper !




I want the car meets the FIA rules :




My tip : O ring keep water and dust out


Saving weight everywhere if possible :




After the "war" of weight very long job for few kilos lbs



Before working on wiring and elactrical parts :



Very heavy, this was for music, I don't care !


A little moment of panic, should we able to start the engine after this ???



Pandora's box !


Very long and hard job for an humbe diyer, but I was helped by a friend who knows very well BMW M3 E36 S50B32



It starts to look pretty well


Weight saved 9 kilos 20 lbs !!!

One is in case of fire the other one FIA electrical cut off switch



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Saving weight is my moto ! 2 kilos 4,4 lbs saved !







It'd like to drive the car like this Why not




We started the engine !! Yeeeeeeeeeeeeeeeessssss !



Before 4,75 kilos 10,5 lbs




After 1,7 kilo saved (3,8 lbs)




0,5 kilo saved



The Z3M coupe's french top model




I did my best to try to copy helped by our white rabbit !
1,2 kilo 2,7 lbs
Front





Rear






Odyssey gel Battery 6,5 kilos instead of 15 kilos lead battery 8,5 kilos saved ! (18,8 lbs) In some races, lithium are not allowed by french rules.








time to built the roll cage.



My friend Yannick is an Alfa enthusiast, but stil a not so bad guy !!

Special steel









Yannick's cousin prepare paint.

[bionicbelly]

I love this. Nice job. I had never thought about venting the rear bumper cover that way, but it has to be like a parachute the way it is.

Also, congrats on doing a hillclimb! It is on my list to do some, but I have a pretty good distance to get to one. Soon though

If you have any video of the hill climb, I would love to watch it!

[gatouille]

Thank you very much !!! In case of trouble, you may use rear bumper, as a emergency brake

Here is a vidéo with me driving, sorry it was the very first time I use this camera and it was hard to find the good place for it.

At the end Nathanaël, the famous driver, congratulated me, I was crying like a child......



This part return to his OEM place.




Strong bolts as the weight is 8,1 kilos 18 lbs




Fuse box had to be adapted.




Last week-end, it was time for painting the M coupe's interior !








Next wednesday, I will bring back my car at home !!!

I will have a lot of job to do

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Working on another weak point of our BMW Z3, especially with HR anti roll bar :

[PbFut]

Congrats on a very nice build and meeting your dreams. Good to see.

[gatouille]

Thank you ! I hope this thread will help someone......

The engine M3 europe S50B32 is so excellent, and Z3 coupe are so nice, that really THE car for me !

[Remotion]

Nice stuff. I have been planning on making cuts also into rear bumper and small diffuser. Do you have link to the white coupe's building topic? Or how they ended up doing those cuts. Ofcourse to pressure relief after rear tyres and above diffuser but I would like to read and understand everything about the subject, especially on our cars. What has been tried and tested.

BTW I have made to my knowledge first Lithium batteried coupe and also I have designed a serious battery bracket for that same lithium battery. Connect me when the rules change. You will be happy with 1,92kg battery then.

[gatouille]

Remotion, thank you !
I did those cuts white a tool (woodworker's big compass)

Sorry it's too hard for me to explain with englisg sentences, so I use a draw. I try to figure the rear bumper,

[IMG][/IMG]



You can Cut the bumper with a dremel (disk), I used this one, not easy but possible:


And I finished the work with the Dremel.

For both ends of the "bean" I used this tool, very easy.


You also need to work without anyone buging you around, and bee very patient.

The model was made by GEMO SPORT in FRANCE, they made a car for renting, efficient, reliable and easy to drive, a lot of excellent job, for example the engine is 18 cm further back and mount straight (redress to let the place for big exhaust manifolds) Also Hewland gear box with rear axle nas so on...
Very good car. Intake is also very interesting way...

I will buy the same fiberglass kit for my car but later (lack of money)


http://www.gemo-motorsport.com/227-bmw-z3-m-gemo-motorsport/



If you need more informations about this car I have also a magazine about it, ask for if you need.

A french dealer is selling the same fiberglass kit, cost around 2000 euros without bonnet
If you plan to buy ask me before as their websight is not very good, but I've got an email from them with many details.
I can send you and translate (try to uh!)

http://www.mcracingsa.com/4-pieces-auto-polyester-competition/5-bmw/361-z3/161-coupe/

[gatouille]

Repair the front bumper, it was broken and no more front position lamp.

[gatouille]

I brought back my car at home yesterday, I'm so happy !

[gatouille]

dsc_1817.jpg

Glass blast !

[BimmerBreaker]

Looks great so far, interesting build. But some of these minor weight savings may be inducing drag, no? Like the holes in headlights...

Id also be curious to see how they came up with the design for the rear bumper cutouts too. There would normally just be a pocket of air pressure in there which would act to deflect any incoming air, with it vented it will allow air to flow through and induce drag as it exits and enters. Certainly looks the part though.

[bionicbelly]

Looks great so far, interesting build. But some of these minor weight savings may be inducing drag, no? Like the holes in headlights...

Id also be curious to see how they came up with the design for the rear bumper cutouts too. There would normally just be a pocket of air pressure in there which would act to deflect any incoming air, with it vented it will allow air to flow through and induce drag as it exits and enters. Certainly looks the part though.

One of the big things to do with Miatas is to cut out the rear bumper cover even with the trunk floor. Can get you several mph at the end of a long straight. seeing that our cars have a parachute in the back similar to that of the Miata's, and more HP, I am guessing the effect would be even more pronounced.

[Remotion]

Looks great so far, interesting build. But some of these minor weight savings may be inducing drag, no? Like the holes in headlights...

Id also be curious to see how they came up with the design for the rear bumper cutouts too. There would normally just be a pocket of air pressure in there which would act to deflect any incoming air, with it vented it will allow air to flow through and induce drag as it exits and enters. Certainly looks the part though.

Your thought process is still wrong. Look this:
https://www.youtube.com/watch?v=FTHVg0nID3s

Original bumper works as a parachute behind the car, both pushing air in front of it an as such inducing drag, and also it creates bigger underpressure area behind car which has speed reducing suction effect on car. Show me one LeMans car since start of 1970's with rear bumper.

Also here is super ghetto mod but results speak straight language.
https://youtu.be/pDXKX29MyZo?t=5m
Better fuel economy means less resistive airflow and better top speed.

With diffuser you need to think about pressure gathering over the structure and heat build up so it is vice to went both of those out above diffuser. IF the diffuser is not totally moulded into floor.

How much the idea about air somehow empathizing and bypassing bad bumper desing warms your heart, it is just not true.
We see similar structures mounted on top of the trunk in modern supercars, they only get deployed when braking and they are called air brakes.

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One addition.
Those holes are located behind rear tyres, propably to clear dirty air from tyres from them. They are not on center line where there is much airflow through car.
I dont know what those upper holes do, they might be not so beneficial, but while your theory might work on them they also went behind the car so propably negative effect under bumper is gained with similar positive effect after the air escapes those holes. Anyway there is not much air pocket left because of the cut in bumper

[BimmerBreaker]

On a race car without fender liners I may see more of a point to such a mod, but on a car with fender liners the biggest airflow concern will be air flowing under the car, and once at any sort of speed the air already in the bumper will act as a buffer allowing air under the car to flow over it. Cutting holes forces air to evacuate the cutouts which will create turbulence as air flows out of the cutout and as air flows into the pocket. There is as much information out there saying these types of cutouts do not help as there is saying they do. I was simply asking why they settled on the design they did as maybe that type of slat cutout reduces the drag of the air exiting the bumper compared to holes and may have some information on that. Maybe it just looks cooler than circles. Can't help but notice too that the white racecar with the cutouts has a diffuser with an undertray that seems to extend the length of the car and no fender liners (I imagine OP does not have liners either). Losing the liners completely changes the aerodynamic principles at play...

One of the big things to do with Miatas is to cut out the rear bumper cover even with the trunk floor. Can get you several mph at the end of a long straight. seeing that our cars have a parachute in the back similar to that of the Miata's, and more HP, I am guessing the effect would be even more pronounced.

There are also entire companies devoted to selling mesh tailgates for pickups even though there are tons of tests out there proving such designs hurt efficiency and increase drag. I've never been convinced that something is correct or logical simply because there is a large number of people doing it

[Remotion]

All you say is logical, but then think about mesh in all current M cars, starting from Z4M?
And holes or meshes are one thing but cutted bumper is whole another. If common theory about air nesting under the bumper and flow going below it smoothly is true.
Then cutting littlebit of bumper makes that cavity in slope shape, so in theory that could be designed to work like 7° angle diffuser without any actual diffuser plate, right? If cut is made too high, then we expose unwanded undulations from rear underbody, and that would definately work against flow.

Yes those slats need fenderliners cut to work, I cant see anything useful in them if that's not done. So I wont be doing those cuts because I value my fenderliners.

I contacted just a F1 level aerodynamic engineer, the one whose video I linked in last post. If he could test different solutions on Z3 Coupe 3D model on CFD software.... If it costs an arm and liver I cant do it but if it costs only hundred or max two I can spend that. when I get the price and someone wants to be partial and send few bucks via paypal, that would be cool.


BTW, sorry for OP to robbing your great build blog!

[gatouille]

Sorry if I don't answer as soon as possible, I have friends from.....USA at home and I'm suppose to take care of them during their vacation !!!

Thank you for reading ! See you later.

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I don't know if what I'm doing is really efficient, what I'm sure is that the GEMO's sportcar is; it'a famous car in France well know for its efficient and easy to pilot...

As I'm a very humble DIYer, my target is trying to copy it as well as possible. But not to claim that's the best way to tune a Z3M M coupe....

[Venom13132]

I don't know if what I'm doing is really efficient, what I'm sure is that the GEMO's sportcar is; it'a famous car in France well know for its efficient and easy to pilot...

As I'm a very humble DIYer, my target is trying to copy it as well as possible. But not to claim that's the best way to tune a Z3M M coupe....

The car looks great and you are doing an amazing job making the car exactly what you want. As long as you like it that is all that matters. Thanks for sharing your progress in so much detail!

[Remotion]

That's exactly so! Great job man!

[TurboBimmer]

Félicitation pour ton 'build'. C'est très bien exécuté.
Peut-être un jour je changerai mon E30 de piste pour un Z3 coupé, ils sont tellement beau!

[gatouille]

Thank you for your messages !

My american friends are back to their country, so I plan to work on my car, but the temperature is too low in my garage!

Merci pour ton message ! First I planed to buy a E30 for trackday use, these are very good and very light.