BMW BTCC Inspired Track car

[smallspeed]

I've had a few people ask about this car, and I've not posted a build thread anywhere because I don't really post anywhere else, so here goes.. I'll post a bit at a time and hopefully by the time I catch-up to "current day" it will be on the road and running!

This car started as a cheap track toy, I did a few track days in it, then pulled it off the road to rebuild the LSD... ...which is where it all went wrong!



Rear end came out, was disassembled, and the suspension bits sent off for sandblasting..



While this was out, I decided to weld in the rear suspension reinforcement pieces - they have a tendancy to tear the rear boot floor, so BMW kindly made some strengthening plates which can be brought fairly cheaply.
One of the rear-most plates being held in position ready for welding..



Here you can see 3 of the 4 plates where the subframe mounts..



I also did the rear trailing arm mounts while I was in there - these are 4x bosses which pass through the floor and are welded in on the inside. Again they can tear out or crack around the root and are hard to diagnose before its too late, so AKG strengthening plates purchased and welded in.. This basically levels the area where the trailing arm "cup" mounts, and so doesn't alter the geometry however it does need flattening off properly so you're not twisting the brackets and pinching the bush/bolt. Not the best picture, this was prior to dressing it all and had been given a quick blast of paint as I was off with work for 2 weeks to Canada and didn't want it sitting there un protected!



When I got finished with this welding, I decided to stitch all around the rear end where the panels passed near mounting points and things - this was done with roughly 1/2" weld, 1" skip, effectively tying the whole array of rear end suspension mounting points in to the rear of the cills and the transmission tunnel. Don't really have any pics of this sorry..

I also cut the top damper mounts out and fitted some offset mounts from Amspeed - these are only really needed with true coilover rear suspension, however it moves the top mounting point across about 15-20mm and gives some more clearance to the inside in the back end, which seemed like good insurance with the larger adjustable damper bodies I had fitted

After that, everything under the car got cleaned-up - fortunately the shell is in really good shape with no rust to worry about

[smallspeed]

About this time all the bits came back from blasting, and so I set too with some reinforcements. These are fairly standard things to do on the rear end of an e36, however rather than purchasing plates I made most of these myself..

Rear upper arms





Front subframe



Rear lower arms


I also boxed in the rear ARB mounting tabs, and added some reinforcement/closing plates to the rear subframe as these are a known weak point, although I don't seem to have any pics of this for some reason.. Then it all went off to the powdercoaters

On return, I set about begging/borrowing a press from our local friendly Porsche specialist to get on with re-assembly..



..you can see here that a lot of the standard rubber bushes are identical sizes to the rose-joint bushes on the "hub" on the rear trailing arm, and so a "cheat" (read "cheap") way of tightening everything up is to replace these with the rose-joints instead.. That's exactly what I've done here, along with new rear wheel bearings, etc.. So now its a fully rose-jointed rear end, with the exception of the main trailing arm mount which is a powerflex "black" bush, and the subframe mountings which are also hard polyurethane..



..the subframe here is a cronky old one that I had spare, which proved useful as the "proper one" took a while to get powder coated!

Reassembled and put back in the car, shown here with no diff (waiting for parts from Porsche), cheap ebay rear springs, and no dampers!
Also note, most of this was done on a car tilter thing which someone was asking about previously - this coupled with a set of axle stands is a cracking way of moving the car around to work on it..



And back down on its wheels, ready to properly move onto the front!..

[smallspeed]

That's probably enough for one day, will post some more soon..

Couple of notes:

1) yes this jumps about a bit - the eagle eyed amongst you will notice the front engine bay is already welded in one of the pics!
2) yes, this is all happening in a single car garage with no heating and no help except a few bits where my wife got stuck in
3) no I'm not the best welder ever, but they are strong and functional

[MikeB]

Interesting stuff, have considered a Beemer for some sprinting so great to see all this detail, please keep it coming

[dragonfly]

I'll be interested to follow this too, as a good friend has an M3 he uses on track.
I'll be most interested in what you choose to upgrade the brakes, as they seem under-specced for the track, which surprised me on an 'ultimate driving machine' from the Motorsport department

[964RS]

I wonder how this all turns out?

Look forward to following Ben...

[smallspeed]

Hahaha.. No spoilers!

Brakes wise I hear people moan about BMWs a lot.. Biggest problem is they're quite heavy and the standard cooling isn't good. People tend to prefer spending 1000's on fancy cross drilled grooved floating discs and multi piston radial calipers because they look good, yet never spend 100 quid on some hose ans backing plates!
I have 325mm vented discs (no grooves or drilling) and big single piston calipers, bad ass pads and fluid, and bronze caliper guides.. They're rock solid and have great feel with ZERO fade, even 2 up on a demanding track..

More details on brakes in a while

[smallspeed]

Monday instalment:

so the engine came out with the help of the worlds largest engine crane!..



..not much to say about that really - I was talking about it one Friday night with my ex-prodrive mechanic neighbour, and the next morning he knocked on the door about 9am - we went for an early lunch about 11:30 and a trip to screwfix, leaving the car on the drive those rally boys don't f**k about!

As you can see, not much space in my garage at the best of times, let-alone with an engine and a huge crane sitting in there.. So it got wrapped up in a 4x6m tarpaulin (overkill in hindsight) and left on the driveway behind the wheelie-bins, and I spent a lot of time with my fingers crossed that no one nicked it!

With that I set about the engine bay - it was surprisingly clean, and again hardly any rust..
More bird-s**t welding - again, not the prettiest prior to dressing..



..but more penetration than ron jeremy, so I think we're good..



..all sealed up again, which I appreciate isn't the best for weight reduction, but I don't want it rotting out from the seams..



..and then given the quick once-over with some primer..



Basically everything from the front suspension turrets back to the rears had been done by this point - there's no pictures of the transmission tunnel because it was such a pain to get under there and do it on the tilting table thing.. If I ever do this again I will build a rotisserie first and do it all standing on the floor!

[smallspeed]

Onto the inside!
Few little crusty bits around the fuel-pump covers, but nothing major - gave them a quick clean-up above and below..
Before:



..and After:



And then onto what some people have referred to as the worlds worst job! Stripping all the tar and sound-deadening from inside the car..





As you can see BMW don't bunk on the tar!
I did a lot of reading on this and ended up going with the method that sounded cleanest and quietest! Anyone who knows my neighbour will understand the latter (Jason..) and anyone who knows me will appreciate the science vs. brute force approach!

Bring on £20 worth of DRY ICE!!



The method is as follows..
Pour 1/2 into the first part of the car you want to remove it from then go make a coffee..



..hope that the crackling and pinging noises are a good sign, and then after 5-10min, shovel the ice out of the current area and into the next one. Bonk the floor-pan with a rubber mallet, and the tar immediately releases from the car and comes out in about 3 or 4 pieces!
Around 1hr later the ice will be about 1/2 its original size and not really working anymore, so chuck it down the drain and put the other 1/2 in and carry on.
By this time I'd done all the major areas - 4x footwells, rear parcel shelf, rear seat area, spare wheel well and the boot floor - however had the awkward "vertical faces" to tackle! To do this I built pockets from cardboard and shovelled the ice between these and the panels which worked really well! I tried putting the ice in a bin-bag and using that like an ice pack, but amazingly the bin-bag was enough insulation to stop this working

So around 2.5hrs after I started, I was done! All tar removed.. ..well except for a little bit because I ran out of ice, but I was basically done and it was basically painless! AND I got to play with dry ice



For anyone wanting to replicate this method, a couple of notes..

Get prepared up-front with things like card to make the pockets, and duct tape (everything else seems to freeze and fall off)
Get a cheap plastic dustpan for shovelling, but don't get a fancy one with a rubber lip (it will freeze and fall off). Also, don't plan on using it after, it will get really shrivelled up and fall to bits!
Get some decent thick rubber gloves from screwfix, pref LARGE ones and wear some wooly gloves underneath - dry ice is exactly that, DRY, so it won't stick to you like normal ice, but it is really cold, and because it doesn't stick to you its really easy to get burnt off it without realising
Plan up-front and work fast! If possible do it in the winter when its cold anyway

[smallspeed]

For notes at this point, because the tar came out in big lumps, I put the bits in a bin-bag and weighed them - there was about 10kg all told which is quite a bit! The carpets with insulation/backing foam came in at around 20kg, and all the plastic "crap" totalled around 5.. I also removed a bunch of brackets and things I didn't need anymore (drilled out spot welds, welded-up and dressed back) which totalled about another 6kg.. All in about 40kg out, and probably 1/2 back in, in terms of weld, sealer, etc

Now for the next top-tip! While the ice method works really well, it leaves the adhesive residue! Evostick sell a really nice "solvent remover" in B&Q which is under lock and key, in little tins.. Its only about £2 a tin (they will look at you a bit sideways when you buy a tenners worth) and it works brilliantly, although IT WILL GET YOU WASTED! WEAR A DECENT MASK. I have one of the 3M ones with filters specifically for solvents - you only realise how good it is when you take it off

Pour some on, bit of super-fine wirewool, and a wipe-down with a rag, et-voila!







At this point the car was shipped off (with a dodgy eastern European chap) for one of the only bits I didn't actually do myself..



..more on that next time

[keith fellowes]

What an amazing trick! The hours and hours I have spent in the past with a scraper - never again!
Thanks for that

[smallspeed]

You can buy it all sorts of places but if you're near to Leicester (or even if you're not I guess) dioxice on troon ind est will sell to the general public, and will do mail order
More dry ice trickery from them another time

[23e Heure]

Nice project, keep the photos coming...
What will the car be used for? Road use mixed with some track days? Or serious track day tool?
If the latter, here's some bmw based inspiration for a proper cage:

[964RS]

There's going to be some seriously miffed people reading this thread that spent days getting all their interior and glue out by hand...!

[smallspeed]

I've told a couple of people since I did that and they've all wanted to twat me for not mentioning it BEFORE they spent days with a heat-gun and a head-ache removing it all from their cars!

Blue car looks very nice!
Is it an e46 or an e90? Hopefully they picked-up on the diff-mounts either way.. I had the privelige of driving an e90 320si (ex Schnitzer ETC and ex BTCC car) with the full NGTC update around brands hatch a few years back - MIND BLOWING cars!

The car was a road car for occasional track-day use, its been re-built around the kumho bmwrdc group c regs so it can be raced in the future - someone gave me guidance early on that if I was going to go to the trouble of "rebuilding the LSD" (which did get done eventually ) then I should follow a set of regulations rather than build something willy-nilly and finding out it couldn't be raced later on.. My plan is to use it for track / road for the time being, and if I'm lucky enough to have the time / money / wife-sign-off to commit to a season of racing some time in the future then I'm good to go!

Given my storage / space restrictions right now I've kept it MOT'able as I don't have the room for a trailer, so it can be driven on the street to/from tracks and for occasional blasts here and there.. That said, there's not a lot that's on the car for the MOT which could be removed to be honest, and keep it inside the regs/blue book requirements.. It will probably become a non road legal race/track car at some point, although a couple of the BMWRDC guys have said its really handy to keep them MOT'ed as you can then check component and setting changes over on the road without needing to commit the money for a track or test day - that doesn't mean testing out geo settings with flat out cornering, etc, more making sure nothing leaks and things like that
I imagine there's nothing more frustrating than spending £150 on a track day, only to have to head home due to a stupid failure on the second lap