E34 M5 track toy progress

[Benji]

Myself and my mate were looking at building a track toy for fun and to do something different. So the obvious choice is the E34 M5 platform with which we are quite familiar.
First off we sourced a suitable M5. Cheap as chips and in all-round terrible condition, but a good base from which to start building a track toy. While sourcing parts, we heard of a well respected individual who actually had a E34 track toy. We made contact with him so we could bounce ideas off him and get some advice regarding a roll cage, suspension setups, brakes etc. After chatting for a good few hours, he offered to sell us the car at a price we could not refuse.

So the plan for the first car changed: Restore to a respectable condition, sell it, buy the track toy and skip a few steps in the build. Did not take many pics of the original cars progress, was not an inspiring build:
We got that car sold pretty quick and made a little profit from it as well

 

[Benji]

So with that chapter of the story closed, we come to the new track toy, Im sure many of you will recognize the car:

And safely home, almost 2 years later (thank you Graeme for being an absolute legend and keeping the car for us so long)

Came with a few spare tyres



Car is in overall good condition with evidence of good maintenance being carried out. However, as Murphy would have it, the car developed a serious misfire on the way home 😖

 

[Benji]

The wild goose hunt for the misfire start here we started by replacing the distributor, rotor and spark plugs and I also tested all the spark leads and found them to be in spec. We also did an oil change and replaced the fuel filter since the car had been standing for a few years. That solved the misfire issue for all off 2 short drives where it was back with a bang! Or rather a distinct lack of bangs Opened up the ignition cover and found that wriggling the spark leads would have an affect on the misfiring, eventually finding that there was a loose connection to injector 1 which when held down, solved the misfire issue. A fastidious application of a cable tie later, and the car made it home with no further hiccups. Further investigation will be done in due time...



This car is so much fun to drive, very tail happy but as docile as your grandmothers old Labrador. As a certain Mr Hammond would say, "It makes you feel like a driving god!"

 

[Benji]

The plan for the car is to do all the basic maintenance items, gearbox and diff fluid change, replace leaky timing chain tensioner, oil seals etc and enjoy it on the odd track day. Then we will slowly upgrade the car, with focus on removing weight, improving weight distribution and handling and maybe trying to get a little more power....

To that effect, we rerouted the air intake pipe which originally took a convoluted route from the fog light housing to the air filter, now it runs from the headlight to the airbox. We are still not happy with this solution, will be doing an intake trumpet with a larger and smoother pipe. We also have ambitious plans for a custom intake manifold...

And to the light weighting effect: fiberglass bonnet which we lucked out on. Its not the lightest bonnet on earth, but definitely much lighter than the stock one and will also do away with all the hinges etc.

Thanks for reading, this thread will slowly be updated as and when things happen

 

[Fordkoppie]

The plan for the car is to do all the basic maintenance items, gearbox and diff fluid change, replace leaky timing chain tensioner,

While at it, replace the timing chain tensioner with an S50B32 item. I have performed this retrofit many times, and it eliminates the possibility of skipping teeth on startup. Also way fewer seals to leak from.

And BTW - an S38 is not supposed to run on 10W60

 

[Fordkoppie]

I have a trumpet from an old hacked e46 M3 airbox that you can have if you want it

 

[Benji]

While at it, replace the timing chain tensioner with an S50B32 item. I have performed this retrofit many times, and it eliminates the possibility of skipping teeth on startup. Also way fewer seals to leak from.

And BTW - an S38 is not supposed to run on 10W60

Thank you, yes we will be upgrading to the M3 tensioner Ahh the S38 oil debate haha, what do you think is the correct oil to use? Is there a difference between the S54 intake trumpet compared to the S38? We had planned on using the stock S38 trumpets

 

[GoCart]

Damn, another cool thread, what's going on !

Really cool project Benji

 

[evnmopwr]

Love these cars.

My uncle races professionally With an S54 swopped E34.

 

[Fordkoppie]

Thank you, yes we will be upgrading to the M3 tensioner Ahh the S38 oil debate haha, what do you think is the correct oil to use? Is there a difference between the S54 intake trumpet compared to the S38? We had planned on using the stock S38 trumpets

Back when these engines were produced, the go to oil was 15w40. However that is very difficult to get these days in a good synthetic.
So 5w40 is where you want to be IMO.

I think the trumpet might be very similar in size. As said, I have it left over from a hacked filter box lid, so you dont have to hack yours too.

Honestly, if you want the most power from the S38, just re-fit the original airbox. The engineer who designed the entire intake system on the s38 (plenum and airbox) won multiple awards for its groundbreaking design at the time, and you simply cant improve on it.

 

[Fordkoppie]

Just make sure the resonance flap works as it should.

Always open except under these conditions:

WOT < 4250rpm
WOT > 6750rpm

 

[Benji]

Long overdue update. Have not had any time lately to work on the car, but we did take it to its first track day at Swartkops. What an pleasure to have your first track experience with this machine! Car sounds amazing and is really docile on the track. Car performed faultlessly except for an exhaust hanger failure (nothing a repurposed coat hanger cant fix) and a puncture. Weirdly, on public roads with cold tyres, the car is very tail happy, on the track it is very understeer-ey with the tail diligently behaving even under provocation. Many other niggles also crept up during this shake down experience:

Car has no interior ventilation at all, rear brakes have a terrible vibration, understeer, front brakes started cooking as the confidence grew - need brake cooling ducts, Im convinced there is a fuel leak - one of the tank overflow pipes has a hole in it, we recorded an average fuel consumption of 50L/100km which is a bit ridiculous and Im pretty sure the front shocks are toast. Going forwards, a full suspension refresh is on the cards, looking at going for BC racing coilovers, E31 lower control arms and E32 uppers with spherical bearings instead of rubber bushes and all required bump steer spacers etc. Also looking at the option of E32 rear swing arms and hubs. Should push the wheels out some and improve steering feel. Also hopefully get the rear ride height into less of a 4x4 mode

 

[modocrat]

"A bit" ridiculous 🤣 🤣

 

[Benji]

Mini update time, again not much time available to work on this car nor enjoy it...

Found a cheap fiberglass spoiler (I think modelled after the ACS one) and hacked it up to maybe make a bit of downforce but definitely add at least one hundred of your finest verified ricer horse power 😇 We've also fixed our leaking fuel issue, rehung the exhaust, added some front end bracing (For science. If it doesn't make a difference to the cars handling, we will remove it as it is extra weight) and drilled some holes in the front crash structure for weight reduction. Need to change the brake pads, add brake cooling ducts and sort out a intermittent misfire, then we are ready for the next track day Also have some nice goodies on their way from the USA...

Excuse the messy garage, there are are a wholly unnecessary amount of projects in various stages of disrepair and neglect

 

[Benji]

Finally pulled finger far enough to take the car out to Red star raceway (RSR) last weekend, what a blast that was

We fit our fiberglass bonnet and did some fettling to the wing and did some general race prep in the dark - because Eksdom. We saved 15kg from the front of the car drove the car the 100km to Delmas on a freezing cold morning. A noisy and cold drive indeed, but the car performed faultlessly, took the abuse and drove home again without a hiccup.

My initial thoughts on RSR were that it was a crap track, too technical to have fun on. But once we played around a bit with tyre pressures and I got the hang of things, I started really enjoying the track! Definitely more fun than Zwartkops and works out cheaper when sharing a car. The in-field is super technical and requires a strong front end, but the satisfaction from stringing the corners together is immense

I started the day with a best session time of 2.36 and ended the day with a best time of 2.20.621 on the track addict phone app. Mark struggled a bit more with the in-field and could unfortunately not complete his 3rd session due to time constraints.




As always, car requires for more before the next track day. I think the clutch slave is on its way out and I think the thermostat is stuck open as the temp gauge is always on the cold side, even at the end of a session. Next upgrade is to fettle the intake with some 3D printed goodies and install a thicker rear anti-roll bar to hopefully help the understeer tendencies

 

[R!Yo]

Nicely done Benji!

I recall we spoke in Oct at the Dyno about this being a track weapon and fitting that it took the 6NA class. Great to see it coming along and getting seat time!

 

[Benji]

Nicely done Benji!

I recall we spoke in Oct at the Dyno about this being a track weapon and fitting that it took the 6NA class. Great to see it coming along and getting seat time!

Yeah might bring the car to the upcoming dyno event to see how much power it makes when it runs on all its cylinders

 

[Benji]

Small update, Mark got this done at his work, super happy how this turned out, I think its super cool and adds at least 5hp in cool points...

Solidworks:


3D print


And in with the the chrome ring from the original headlight. This should have some "ram" effect and allows us to run 10mm larger hoses all the way to the manifold. And should also sound proper

 

[StrollingCoal]

Small update, Mark got this done at his work, super happy how this turned out, I think its super cool and adds at least 5hp in cool points...

Solidworks:
View attachment 12681

3D print
View attachment 12682

I'd be cautious about the printed part de-laminating, that's an inherent flaw in the FDM printing process. Although the FDM machines are quite stable these days. I could talk to my boss and see if we can possibly have one printed for you in Nylon using a laser sintering process which is leagues ahead of FDM. Let me know if you would be keen.

 

[Benji]

I'd be cautious about the printed part de-laminating, that's an inherent flaw in the FDM printing process. Although the FDM machines are quite stable these days. I could talk to my boss and see if we can possibly have one printed for you in Nylon using a laser sintering process which is leagues ahead of FDM. Let me know if you would be keen.

Thanks bud, sounds good, will keep that in mind if it does fail. This was printed solid and there is an airfilter downstream, so there should not be any catastrophic consequences if it does fail