BTCC Inspired E36 BMW 318is

Car is a really impressive build. I can see why its taken as long as it has to get to where it is now. Your giving me hope that I might be able to tackle all my jobs on the Puma in a single garage.

Yeah thats what I'm worried about... luckily my car is a little bit smaller than yours!

I just need to clear the garage out so I can actually get the car in there.

a bit more about suspension..
The e36 was the first of the 3-series to move away from the A-arm trailing arm set-up - this was used right from the 2002 through e21, e30, and even the e36 compact, and z3. For the full-size e36's they changed to a semi-trailing set-up, and this really benefits from some stiffer bushes in the trailing arm mounting portion
For this car I have gone with the powerflex black bushes - these are about 90 Shore and really help with turn-in by reducing "steer" in roll. They're mounted between two brackets which are probably hard to make-out in the photo, but these effectively bolt solidly the middle steel sleeve of the bush and don't contact around the outside. This allows the mounting of the arm to move slightly left/right along the axis of the bush
Several companies in the US make a pillow-ball bush for here, but they're not allowed in some classes of racing, AND they're a bit high maintenance and harsh! As a mid-house some companies sell "limiters" which effectively mimic the chamfer of the mounting bracket on the outside, and the flat of the bush on the inside. This gives full contact across the entire side of the bush preventing movement
Rather than spend money buying some of these and shipping from the US, I set to with the lathe!
Can't see them in this photo unfortunately because I had them hard annodized black

Rear suspension arrangement shown below:
The trailing arm mounting is furthest away (x2) this mounting provides toe adjustment
The trailing arm itself incorporates the "hub" and the wheel bearing
Rear subframe in the middle is mounted directly into the bottom of the shell, and picked-up at the two front (furthest away) mounts by the cage
One upper and lower arm per side, the bottom ones adjust camber, the top one includes the spring perch - the rear springs are considerably inboard from the hub hence usually the rear springs are quite high rated – either close to or the same as the fronts (which are mounted pretty much on the wheel bearing



Rear damper and spring



At the front, it’s a fairly common set-up across most BMW's - a large L-Shaped arm which mounts to the body using "lollypops" at the rear, to the front sub frame with a ball joint, and then 90-degrees (or thereabouts) outwards to the hub with another ball joint
The hub then has a bolt on strut which goes upwards to the strut tower above
The steering tie rods effect toe, strut adjusts camber and castor
Some additional camber and castor can also be achieved with eccentric lollypop bushes - effectively moving the rear mounting point in/out up/down by about 10mm from the centre line within the bush mounting

One issue with this front suspension set-up is loss of camber during cornering. On a standard car the arms point down (static). During roll, the outer arm moves towards horizontal (4-oclock to 3-oclock for the horologists). This increases camber on the outer wheel, assisting cornering grip
On a lowered car, you're moving the static position more towards the horizontal, and so any compression during cornering moves you further around the clock. It’s very easy (even just using lowering springs) to get the arms horizontal (static) and this then causes the arms to move from 3o-clock to 2o-clock during cornering. Because of this camber is actually reduced on the outer wheel during cornering leading to understeer.
This can be quite severe, and you often hear of BMW people who misunderstand the cause making radical modifications to try and fix it with little gain. The actual fix is HUGE front roll stiffness! To give you an idea of HOW stiff - standard springs are around 1.8kg / mm on the sport model, the BTCC e36's were running around 18-20kg/mm in period! They also had massive blade adjustable anti roll bars on top which adjusted from REALLY F’IN STIFF all the way to SOLID!
For me, I went to coil-overs with big springs (12kg front and rear) and a massive "off the shelf" front bar (30mm). I also fitted a ground control roll-centre and bump steer correction kit - don't have the photos downloaded yet, but will get some up soon. This basically moves the steering arm connection point down vs. the hub to eliminate bump-steer, and the wishbone ball joint "up" vs. the arm (ie moves the arm down vs. the hub) to give around 10mm improvement. This helps move the arm back down below horizontal – mine are about 10mm below horizontal now, so some movement prior to loosing camber on the outer wheel

Front strut



Anti roll bar - this is an H&R "Cup" bar, which I got on clearance for just over £100 delivered from Germany - I think these cup bars were for a specific race series in Europe and are 1mm larger than the largest off the shelf bar I've seen from anyone except Ground Control’s race bars (however these are tubular so not as still)
They came with natty purple (and very hard – possibly even harder than Powerflex Black) polyurethane bushes, which are actually about 5mm oversize and have a wound filament type bearing bonded into them. The bar has smooth (but quite stiff as they’re tight) rotation, but hardly any lateral movement at all. It must be one level down from running needle roller bearings on the bars (which then requires excellent alignment so isn’t really practical)





Another advantage for the front ARB - standard cars had the ARB mounted to the front wishbones, about 12" from the front wheel centreline (1/2 way between CL and ball joint). On the M3, much smaller bars were used (about 16mm from memory vs. 19 or 20mm on the non-M-Cars) but these attached directly to the front struts. This gives 1:1 movement (arb drop link vs. wheel movement) rather than about 1:1.5 resulting in a stiffer overall set-up. Moving to this ARB and coil-over set-up has allowed me to mount the ARB to the struts which results in a compounded improvement in front end stiffness – its effectively like running a 45m bar on the standard e36 (non-m) mountings!
At the rear, I'm running the standard (318is I think, or 325i convertible, i forget) anti roll bar, which seems to be the biggest standard bar offered. I may upgrade this at another time, but for the time being this should be enough to get going – I don’t want to load up with tons of rear bar and loose traction as a result or get caught out with a really snatchy set-up

In terms of spring/damper choice, I went with HSD coilovers. These are a "far-east" coil-over for those who aren’t aware, however having driven a bunch of different cars in the time leading up to this I was very impressed. I've driven a couple of e90's with Intrax and Moton set-ups. They were mind blowing, but so was the price! I've driven an e46 on black magic coilovers which seem borderline unobtainable and too expensive for me, an e36 compact on gaz gold (which seems to be the go to choice for a lot of people) an e46 on Nitron dampers (which was pretty awesome, but again a bit expensive for me) and then an e36 on HSD's. This car had the Monopro set-up (monotube dampers, lots of adjustment) and the standard springs - 10kg/mm front and 8kg/mm rear. I then found another guy who had a similar set-up but with the "nurburgring" spring option, which is 10mm/kg front and rear. This was a lot better balanced, especially on a square wheel and tyre set-up. The car was also really nicely aligned, corner weighted, etc - I was impressed!
Cost wise, the HSD's come in around £700 vs. about £1100 for the Gaz set-up. I felt the HSD's were better than the Gaz dampers overall. Nitrons were a bit better than the HSD's however there wasn't a lot in it, and nothing that justified 2-3x the price for the standard set-up and 4x or more for a custom valved option...
I started looking around at buying some, however before I placed an order I found a set available 2nd hand - these had been fitted to a car that was used mostly for shows and then taken off again, and were literally like brand new (had less than 500 miles on them, and looked like it). I spoke with a couple of the guys at driftworks who are a UK importer, and purchased some e46 springs - they're basically the same dampers, and are capable of the higher e46 spring rates, so I'm now running 12kg/mm springs front and rear. Rear springs needed some “adjustment” as they’re not quite right, but everything fits properly now - this is a very stiff set-up
Car is currently set-up roughly but will be aligned with the following settings:

Front camber: -3.5deg
Front toe: 0mm (total)
Front caster: 6deg
Rear camber: -2.5deg
Rear toe: 0mm (total)

This is a pretty tried and tested set-up for e36's – it might be I can dial a little camber out on the front and rear with the stiff set-up, but it’s a good base to start from
An alternative toe set-up is to add a little toe in on the rear and keep the fronts parallel. You can also switch the toe's around so you're running zero on the rear, and about 2mm (total) toe-out on the front
For an aggressive set-up, 2mm out (front) / 2mm in (rear) (total)

I’m sure other people have other preferences on set-up for e36’s but for me the square settings with about 1-deg less camber on the rear vs. the front works nicely as a baseline

Apologies this has been a really wordy post, but hopefully the different suspension arrangement and details are interesting to someone

I do like that colour... reminds of my first car

Loving the Tim Harvey era theme and graphics, who was his team mate in that era?

absolutely love this! Supertoruing era is a bit of an obsession for me at the minute so this ticks so many boxes!

Absolute credit to you for all the hard work and attention to detail in this build - seriously impressive!

Yeah "involved" is right 😂