Fixing the driveability issues, Part 4: The Endgame

Note: if you have not read my previous posts, I suggest you to start with the Part 1.

When I bought the E30, it felt almost undrivable and plain dangerous in higher speeds. Thus, it was quite obvious I had to spent the first driving season to improve its handling. The list below is summing up the modifications I made for the E30 during summer 2015:

  • Correcting the suspension geometry and roll center by installing custom made raiser plates,
  • Raising the car approx. three times,
  • Decreasing negative camber on the front by installing eccentric upper strut mounts,
  • Increasing offset on the front by machining rims,
  • Zeroing toe on the front,
  • Increasing traction by changing tires to Toyo R888R Semi Slicks.

At times I was wondering if the V8 engine is too heavy, and despite of all the changes, non of the above tricks will work. But the engine was not the case. And M60 engine is all aluminum, and with small tricks here and there you can save tens of kilograms. But that’s the other story. So what was the end result? I use my daily commuter as the reference point. It is 2009 BMW 335d LCI with factory M-sports aerodynamic kit, M-sport suspension and OEM 18″ alloy wheels. So the reference car is representing a pretty darn good car design from 21st century.

So how does the E30 compare to the 335? Well, I can honestly say – because I own both cars – that the E30 will beat mighty 335 in EVERY aspect of driving. The E30 is more agile, has better feel for road and – what’s most important – is more fun to drive. I cannot say that the 335 is a bad car to drive. No way. I was driving through Norway with the 335 in summer 2018, and it was a great pleasure to drive with a ton of torque in twisty serpentine roads. Of course, there is some features the 335 is missing like limited slip differential, which actually makes a huge favor for the E30. I know, it is a bit unfair comparison, due to the E30 has a custom built race differential in it.

The reference car was 335d with OEM 18″ rims and ContiSportContact 5 tyres, 225/255 in size.

So the E30 is more fun to drive on twisty roads. OK, we can accept that, because it is around 400 kilograms lighter than the 335. But how about high speed stability after the mods? I got an opportunity to test both cars on a airstrip, and oh boy, that was a great fun! It was a windy day, and I was a bit frightened to try the E30, because I had no idea if it will either start flying off from the airstrip, or keep going like it should be. The result was, that in 250km/h speed I did not notice any wind or unbalance when I was driving the E30. Actually I was watching the speedometer and using only one hand on a steering wheel. While on the 335 I noticed the wind, and had to put both hands on a steering wheel. Do you believe it? A 30 years old Bayerische Motoren Werke is beating 20 years and three generations newer 335 in high speed stability too. The handling in my E30 seems to be working. Amen.

This picture is a good example of well designed front spoiler, preventing the air to go underside of the car. The end result is increased downforce and high speed stability.

Fixing the driveability issues, Part 3: Tires and Rim Offset

Note: if you have not read my previous posts, I suggest you to start with the Part 1.

On the first and the second part of “Fixing the driveability issues” I was concentrating my efforts to correct erroneous suspension geometry. Now, when the suspension geometry was set up correctly, I shifted my focus to both tires and rim offset.

Part one and two were just the basic stuff. Most of us do understand the importance of fixing camber and toe. But for some reason, most of use are neglecting the importance of tires and rim offset.

If you think about what single component is responsible in between your car and road, it should be quite obvious that optimizing the tire quality will give you the best bang for the buck. I mean seriously. The best possible performance upgrade for your car is not 20 000 euros suspension kit. It is tires. Period. The quality of rubber compound makes the most difference. It does not matter how wide your rear tires are either, if their compound is not up to the task. Good semi slicks in 225 size will beat any budget tires in 275 size. Anytime. The difference of tire compound quality is huge. You just don’t believe it – until you will try it out.

Toyo R888R Semi slick tires in 225/45/16 size.

In order to improve handling characteristics even more, I decided to change the rim offset a bit. The rims are very rare and good looking RIAL mesh style in 8×16″ size for front and 9×16″ for rear. The front ET was 13, and it made the steering a bit nervous, thus I ended up machining 2 millimeters from the rim center. So the front ET was increased to approx. 15. Believe me or not, it made the difference. The rear ET was also increased to 15, due to a clearance issue with Toyo Semis. This issues was present with rolled fenders. Rears in 225/45/16 size with 9″ rims and ET15 are pretty tight fit for stock E30.

Toyo R888R 195/50/16 tires on 8″ Rial Mesh rims, ET15, made in West Germany.

Fixing the driveability issues, Part 2: Camber and Toe

Note: if you have not read my previous post, I suggest you start with the Part 1.

Because This was my third E30, I already knew how challenging this small boxy bimmer can be with both suspension and tire setups. On part one, I was able to correct some of the suspension geometry challenges by installing custom made raiser plates.

There was still too much negative camber on front tires, though raising fixed the issue on rear axle. The solution for front tires was to move upper strut outwards. Typically you have two options: either install an adjustable uniball strut mounts or select a fixed one. The advantage of uniball mounts is adjustability, but on the downside it will transfer more load and road irregularities to chassis. Uniball is great for a track use, but not so great idea for bumpy countryside roads. So I wanted rubber strut mounts that were able to adjust camber. The Solution was OEM BMW upper strut mounts with +/- 0,5 degrees of Camber Correction. These are more sturdy than OEM mounts, and raises your car a bit too. That was only welcomed feature for my E30, described on previous blog post. OEM part number for the rubber mounts is 31 33 1 139 484. Note: These OEM rubber mounts are actually more expensive than Uniball strut mounts.

Eccentric upper strut mounts for E30, OEM number: 31 33 1 139 484

Actually, I never took my car into any car service for toe adjustment. Instead, I adjusted the toe manually. I set up a string in between pair of Jacks, and aligned them as close as possible to both rear and front wheels. Then measuring the toe was easy task by using a vernier caliper. I put toe to zero. It is a good compromise in between cornering and high speed stability. Using a string is quite simple method, and surprisingly accurate. Don’t laugh. They use this same trick for WRC cars too.

Take home points:

  • Looking cool is not equal to going faster.
  • Do not add too much negative camber for street use, it will only make your car unpredictable and dangerous.
  • Adjusting toe is surprisingly easy at home garage with pair of jacks, a string and a vernier caliper.
  • Choose upper strut mounts based on the usage. Rubber mounts can be better for street use, uniballs for track. Choose wisely.

Fixing the driveability issues, Part 1: Suspension Geometry

When I bought the car, I really loved the sound and responsiveness of the V8 engine. But the handling was plain awful. I spent the first driving season by fixing and optimizing the driveability. The main reason for bad handling was obvious: the suspension was set too low, causing multiple issues in suspension geometry. At times, I was blaming the V8 engine to be too heavy for E30 chassis. This was to be proven wrong hypothesis.

Effects of lowering E30 too much can result into following:


Increased (static) negative camber,

Control arms in wrong position 1: roll center gets worse,

Control arms in wrong position 2: decreased (dynamic) negative camber while cornering,


Fixed semi-trailing arms in the rear axle will increase both negative camber and toe in.

The suspension appeared to be designed for a stance car, although it was high quality components from KW, full Variante 1 kit. All bushings had been changed to Powerflex, thus those were not the problem either. Even on its highest setting the car was too low, resulting into wrong suspension arm geometry. The strut threading allowed you to set the car from low to below the ground. That was ridiculous.

The fix: I had to add custom made raiser plates made of nylon in order to extend the springs.

Custom made raiser plates made of nylon.
KW Variante 1 coilovers with a raiser plate attached to an eccentric upper strut mount. Note the markings in the coil stands for linear race spring (70N/mm), 140 is the height in mm. Helper spring is placed above the main spring. Its only function is to keep the main spring attached, while car is lifted. Helper is 20-60-80, meaning 20N/mm, 60mm inner diameter and 80mm of height.