E34 M5 track toy

[Benji]

Before attending the open day at Redstar this past weekend, we lowered the rear of the car by about 5mm as well as adding about 7mm (per side) rear track width. I also hobbled together a "cabin ventilation" system with repurposed drain pipe by harnessing the high pressure air below the windscreen and redirecting it into the cabin. It has been moderately successful, but we at least have some air blowing across our sweaty faces. It was our first outing with the skimmed front brakes and also our first outing since owning this car (4+ years!) without any brake shudder! It really is nice to stand on brakes and get consistent speed retardation. It takes some proper recalibration to learn to trust the brakes.

We are finding we may have a little too much rear brake bias now. The rears underrotate (revs drop under heavy braking) and it will attempt to spin if you have too much brake pressure on corner entry and havent let the rear wheel speed catch up to road speed...I hope this will get better once the front brakes bed in properly, otherwise we will need to look at a more aggressive front brake compound - currently running Ferodo DS2500. We experienced no front brake locking and it is quite easy to modulate the brakes now.

So onto the biggest surprise of the day - the car has suddenly become very playful with the rear end. It is like an excited puppy that wants to be involved in every corner and you need to be careful with the throttle on corner exit. This is probably not the fastest way around a track, but it is fun especially as the car is very communicative about how sideways it wants to go! I suspect that lowering the rear by 5mm has increased the rear camber (was -1.5 before) and increased the toe-in/out due to the "passive" rear steer built into the E34 suspension. If we wanted to fix this, we would likely need to weld in a camber correction bracket with eccentric bolts, but I doubt we will...

Anyway, car was consistently doing low 2.17s at Redstar and I feel it had a high 2.16 to give if I didnt run out of fuel during my last session. That is at least a 2 sec improvement over my previous PB 😎



What a fantastic machine!

 

[gavsadler]

Awesome man, the track machine is out and about early this year.

Any plans for the M Performance Race Series this year?

 

[Benji]

Awesome man, the track machine is out and about early this year.

Any plans for the M Performance Race Series this year?

No, the plan this year is to set the car up nicely and get a lot of seat time at the open days. We will join the race series next year

 

[Benji]

Not too much to report on the race car. Hoping to do a track day in June

Attempt 3 for some interior ventilation:


Many internet points to the one who can guess where this vent comes from. The idea is to force fresh air into the cabin, have not tested it yet.

We also lost 3.5kg by doing a passenger wiper delete, cutting out some sheetmetal and removing the ignition barrel. Next weight saving project is a fiberglass dashboard. I doubt we will save much here as the original dash weights only 5kg, but we went through the effort of removing the dash, we may as well fiberglass it, because, race car! Does anyone know where we can get flocking done on the dash?

 

[NBN]

That looks like a Peugeot bonnet vent

 

[gavsadler]

That looks like a Peugeot bonnet vent

I was going to say the same, 206/207 GTI vent?

 

[sonic6]

Definitely a Peugeot 206 bonnet vent from around 2005 vintage.

 

[Benji]

Correct! The next random parts being added to this car are from a Fiat Panda, more to be revealed soon

 

[Fordkoppie]

Does anyone know where we can get flocking done on the dash?

Good luck on finding someone to do flocking locally.
ATS used to do it, then they started outsourcing it, and now that source also stopped.

Please let me know if you find a new shop that can do it

 

[Bernard///M3]

Good luck on finding someone to do flocking locally.
ATS used to do it, then they started outsourcing it, and now that source also stopped.

Please let me know if you find a new shop that can do it

No that Flocking was done by Danie Human ex BMW SA employee for ATS.

He emigrated about 18 months ago

 

[Benji]

Good luck on finding someone to do flocking locally.
ATS used to do it, then they started outsourcing it, and now that source also stopped.

Please let me know if you find a new shop that can do it

I found a guy on FB who says he can flock, he is based in CapeTown. He said I would need to ship my dashboard down to him which seems expensive and fraught with risk.. I will probably go down the DIY route, I have seen some DIY kits online.

 

[NBN]

I found a guy on FB who says he can flock, he is based in CapeTown. He said I would need to ship my dashboard down to him which seems expensive and fraught with risk.. I will probably go down the DIY route, I have seen some DIY kits online.

Have you considered using Acoustic material to recover the dashboard, its relatively cheap and stretchable

 

[modocrat]

Do an all-round window delete for more weight-saving, plus you will also have enough fresh air in the cabin. Win win

 

[Benji]

The race car gets way too little attention...Finally got the dashboard done, that was way too much work to save a measly 2kg...but the car is now much cooler...

Rip out old dash and make a mold from expanding foam. First layer of gelcoat in the foam


Add some fiberglass


Attempt to wash the itch away with some beer. Swear and shout to get the dash out of the mold, making a mess in the process


Add some "reinforcing sticks"


Turns out expanding foam isnt quite the best material to make a mold from...fill the imperfections with some filler



Hide your sins with some fake Alcantara


Throw in some Fiat Panda vents, the cluster and control panel


To the untrained eye, it looks stock, to the trained eye, it almost looks like we know what we are doing


Do a small bit of plumbing using a carefully selected combination of pool and drain hoses... ie, literally exactly what we had lying around


Never look under a ladies skirt...but we are fairly proud of that. We have air directed to the feet, and both sides of the cluster and they are all adjustable to make those early morning winter drives to the track bearable. Except the amount of air coming through was a bit less than optimal to cool the adrenaline junkie behind the wheel. Bring out the aluminium tape:




That should be sufficient to scoop birds and small children into the cabin!

After doing some maintenance, our next area of focus will be aerodynamics, so we stole some knitting wool from the wife. Again, to the untrained eye, it could really appear like we know what we are doing... To nobody's surprise, our rear spoiler is doing absolutely nothing...It is sitting in turbulent air and while it might look like a wing, it was probably designed by a graphics guy, not an engineer. Anyway, we will experiment with lifting it and possibly removing some "angle of attack" to see how the airflow reacts. The fundamental problem is that we quite like how it looks...




Pack our gear and head out to a very well attended open day at Zwartkops. The race class had well over 30 cars ranging from amateur driven CitiGolfs to fully modified Audi R8 and GTRs.



I had a deep and eventful excursion into the kitty litter thanks to the aforementioned CitiGolf who pushed me off the track in turn 2 while I attempted an overtake on the outside in the braking zone. Apparently, the guy never saw me nor the huge cloud of dust I kicked up while doing a light spot of farming. This was despite my nose being in front of him during my failed overtake attempt. Mirrors? What mirrors?

Other than that, the day was fairly uneventful and a lot of fun with some nice battles in the race class. Mark beat his PB despite the resurfaced track being about 2 sec slower. He would have been deep into the 1.15s on the old surface. My timing equipment failed, so I was just there to have a good time. The car is really enjoyable on the track except for the brake shudder making an unwelcome reappearance and the brake bias shifting too far rearward as the fuel tank empties. Will take all 4 discs in for skimming and possibly change the front pads for something more aggressive. There is also a plan for a brake bias valve, but there is no telling when that might happen...



We were forced to drink many beers while waiting out a mother of a storm at the end of the day, much to our dismay. Did make for a cool picture for a bit more under skirt impressions...

 

[Benji]

Some on board footage:

 

[Benji]

Through a stroke of luck, we got in touch with a previous owner of the M5 who owned the car around 2016 and sent me this epic curb-riding pic at Kylami...His main gripe with the car was the overheating brakes, something we have made significant improvements on, but still some work to be done.



The M5 has been getting some much needed love - all new oil seals and poly mounts for the gear linkage, subframe, stabilizer, diff, engine and gearbox mounts.

We removed more than 3kg of unnecessary brackets and sound deadening. We also removed surely well over 1kg of grease and mud from the underside. What a mess that made, the garage will never be the same...So far, we have removed over 40kg from the car, hoping to eventually get it under 1300kg

 

[Benji]

The E34 has been off the road for close to 8 months with the last track day done in January this year. This is a poor showing on our part, but we did a lot of work on the car and we are generally distracted with other projects and life...

The subframe went back in with new poly bushes for the subframe, diff, gearbox, engine, gear linkage and stabiliser bushes. There is not a single piece of rubber left on this car it sounds suitably race car now, the whines and crunches of mis-shifts have been unmasked.



While the exhaust was off, it would have been rude to leave the inner welds as they were. I was surprised at how thick these welds were, I increased the exhaust diameter by 3mm at the thinnest point - surely an extra 1kW for my efforts? RHS done vs untouched LHS:

Removed these excess heater core hoses - thats about 500g of weight removed once filled with coolant - equivalent to a stout breakfast on race day!


Exhaust hanger could not escape my "lightweighting" treatment... Before:


After:


That saved 100g; Probably not worth it, but I slept very well that night

Anyway, replaced all the leaky seals: rear main, gearbox and diff seals. Replaced all fluids while we were at it. The gearbox is not in a good way...


3rd and 4th gear syncros have left he chat some time back. "New" Getrag 260 gearbox is on the shopping list.

Some chit-chat with AI determined that we could loose about 100W of heat if we put a heat sink on the diff. Got this heat sink cut, bent and installed. It works surprisingly well. Not sure what the diff temps were before we installed this, but measured 68C on the diff, 65 on the fins closest to the diff and 48 at the ends of the fins. Heat is travelling and dissipating. Excellent. Simple yet effective, sure beats the external oil cooler system Alpina fit to the B10...

Yes, my OCD also glitched when I realized the fuel tank is not "square"


Got the front brakes skimmed (again, brake shudder due to pad deposit on the disc) and installed new PFC 11 compound front pads to hopefully bring our brake bias forwards after suffering with rear lockup after upgrading our rear brakes.


Moving onto some aerodynamics, we built a CAD model of a front splitter

Build it out of 12mm marine ply and strength test it. Certified to carry one mildly overweight middle aged man


Built an "airdam" out of some ABS, still some optimising to do, but that looks suitably purposeful. We are actually quite proud of this, it is mounted on springs, so it has about 3cm of upwards travel when making unfortunate encounters with driveways and speedbumps. Splitter has unfortunately added 5.5 kg of weight right at the front. Hopefully it is worth it...

Immidiately ruin it with this beautiful specimen collected on the first drive:


Next up was to improve the efficiency of intake air used for cooling. We sealed off the radiator so that all intake air is forced through the radiator. Break out the trusty ABS sheeting...




Took the car for an alignment, the rear toe is maxed out at 0.13 toe-in per side, would have loved to get it closer to 0. Front toe out at 0.03 per side. Camber is -3 at the front and -2 at the back.

We closed the bottom inlet on the bumper to hopefully increase air pressure on our splitter. Discover we have too much cooling now, the car did not get up to temperature on the way to the track...sealed off the grilles at the track, proper botch job, will refine this to be adjustable to increase cooling when needed.



How cool does that look? We printed a new air intake from black PLA, so naturally sent the wife on a mission to buy the best quality Woolies yogurt that comes in a black tin to match our new black intake.

Gratuitous engine bay pic



Anyways, the car was an absolute peach at the track! This is by far, the best it has ever driven. I swear we are actually making downforce now. The fast back corner at Zwartkops is now a 4th gear affair (5kph faster corner speed) and the first corner is now also almost flat out with the car hitting the limiter in 3rd before braking for the hairpin. We are also doing about 5kph faster top speed, maybe less drag and/or marginally later braking time. I have beat my PB by 0.2sec, which was set before the track was resurfaced last year. This works out to an effective 1 sec faster time which is pretty excellent. The brakes were great, I think we have finally got the bias right. There is also so much more communication from the car, you can hear/feel what the car is doing much better than before.



Car looking a bit dusty after our farming experiments...in esteemed company.


What an absolute unit of a machine, doing back-to-back sessions all day long without any complaints, even tho we both had excursions into the kitty litter.

Next up:
Optimise front splitter - want to do some proper CFD here
Build a functional rear wing
Rehang the exhaust which is holding on with hopes and prayers
Upgrade front brake cooling
More air management
Rear diffuser
More lightweighting - my eye is on the alternator and PS pump

 

[M3boi]

That x-brace is noice.

Would love to see what the splitter mounts look like and where they attach to the chassis?

Create some tunnels for the splitter, ups the efficiency quite a bit. Would recommend joining the Professional Awesome Facebook group and going through it for inspo - https://www.facebook.com/groups/2950472345184860

 

[Benji]

That x-brace is noice.

Would love to see what the splitter mounts look like and where they attach to the chassis?

Create some tunnels for the splitter, ups the efficiency quite a bit. Would recommend joining the Professional Awesome Facebook group and going through it for inspo - https://www.facebook.com/groups/2950472345184860

X-brace is inspired by the unit installed on the E31, it is supposed to make much more of a difference compared to a strut tower brace...but it is difficult to feel the difference it makes since we always seem to do a "batch" of work to the car at a time.

Have a look at that underside pic with the brake cooling ducts...there are 3 x M8 captive nuts directly in the radiator cradle/support and another 2 in the subframe. We debated the mounting over a few beers and thought this was a good idea because they are plenty strong enough to carry the vertical aerodynamic load, but hopefully weak enough to bend/snap without damaging the cradle if the splitter encounters an immovable object.

Diffuser tunnels are next on the list. I am buying a 3D printer and doing actual CFD analyses on the splitter to find an optimal solution for the diffusers. As an engineer, it is against my nature to "spoeg en plak" - even tho the evidence would suggest this is exactly what we have been doing all along Similar process will be followed for the wing and rear diffuser.

Im thinking of offering this as a service for other race cars once I have successfully completed the project

Sneak peak of a diffusor first estimate calculation before optimizing in CFD:



Will be doing a "multi diffuser" setup in this available outlet space in the wheel well:


Note one of the spring loaded splitter supports above which allows the splitter to travel upwards

 

[Alex/M5]

Any idea what the car weighs at its current state?