Thursday 24th August 2017

BMW M135i: PH Fleet

The M135i is getting cheaper, there are tuning options aplenty, we like BMWs... you see where this is going!

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For all that the BMW M135i was hailed as some great game changer for real-world performance cars when it was launched back in 2012, it's actually quite a flawed car. The basics are all there - well-balanced rear-wheel drive chassis, lots of performance, hatchback practicality - and it drives very well up to a point, but when you start working the car really hard it falls apart like an over-stacked Jenga tower.

1 Series rather than 2 for maximum fun-per-pound

It's all to do with the damping, which just isn't good enough. No matter which mode you switch the EDC dampers to they simply don't iron out the road surface or keep the body under control. The standard dampers aren't any better, either. On a bumpy or undulating road, it means the car fidgets around and bounces up and down hopelessly, which just causes you to back off and settle into a steady rhythm.

There are other problems, too. There was no factory-fit limited-slip differential option, for one thing, and the gearshift is a bit vague and rubbery for another. Clearly, then, there's plenty of room for improvement.

The good news is that five years after it was launched the M135i is now a very affordable car. As in, £15,000 affordable. And there are so many of them out there, thanks in part to those suspiciously cheap lease deals, that there's no shortage of cars to choose from. What this really means, of course, is that an M135i is a prime candidate for modifying.

This was already very good, but we'll make it better!

And that's exactly what we're going to do with this 30,000-mile, five-year old example. Working with BMW tuning company Birds we're going to upgrade all the important components to finally realise the car's potential. Over the next few months we're going to change the suspension for a set of Bilstein springs and dampers, which have been tuned specifically for the M135i by people who really know about these things. We'll also be fitting a Quaife LSD and we'll address the rubbery gearshift, too, plus one or two other bits and pieces.

And while we're at it, we'll also give it a power boost, because... why not? We aren't going to get involved in the engine internals, but with a remap and some choice intake and exhaust upgrades we might just see 400hp. That amount of power in a small car with a well-sorted chassis, a proper diff and a manual gearbox could be really rather special.

Typically rubbery BMW manual to be worked on too

In fact, I'm certain it will be a special car because I've already driven Birds' demonstrator. That M235i (the upgrades are interchangeable across the coupe and hatchback) was one of the best affordable performance cars I've driven for a very long time and I can't wait to get this car up to that same level.

We spent £17,500 on the car itself. The full Birds B1 upgrade package, as it's known, costs around £7,000. We'll have a proper little M2 chaser on our hands once the project is complete, which makes £24,500 all in look like very strong value indeed.

You'll be able to follow our progress right here. The car is still completely standard for now, but the first round of upgrades is just around the corner.

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FACT SHEET
Car: BMW M135i
Run by: Dan Prosser
Bought: July 2017
Mileage: 30,000 total, 1,500 this month
Purchase price: £17,500
Last month at a glance: 'You could get an M135i for that' - so we have!

[Photos: Luc Lacey]

[Mike Roberts]

I'm on my second, first was a manual/passive and current is an auto/adaptive with the Drexler LSD.

From what I've learnt, should I buy a third it'll be a manual/passive and I'll keep my Drexler (as it makes a world of difference) and add some Birds dampers.

I'm very interested in hearing what you're going to do with the shift...??

[Mike Roberts]

SturdyHSV said:

Mike Roberts said:

I'm very interested in hearing what you're going to do with the shift...??

In my completely biased opinion, I believe the source of the patented 'BMW rubbery manual' is related to how the stick you wobble about in yours hands is connected to the actual gearbox itself.

In less refined stuff, (talking longitudinal engines here) the stick in your hand is attached to a piece of metal that goes into the gearbox and operates the shift forks and so on. This means you get the vibrations from the gearbox through the stick, and if the shifter has a metal shaft (snigger) that can get warm and such. All terribly uncouth you understand, putting you in contact with those ghastly mechanical components, perish the thought.

To ensure golf / business enthusiasts don't get uncomfortable, BMW fit a damper instead of just a piece of metal between the stick and the box, to absorb this uncouth vibration.

I would imagine you can improve the shift action no end by replacing this piece of engineered slack with something a little less sophisticated.

Someone probably does a short shift kit for it as well as a follow on tweak

It'd be nice if someone could connect the steering to the wheels again too.

[Mike Roberts]

I've got the same 'box in 2 cars - in the other it suits it brilliantly, so much so it made me change from the manual to the auto when swapping the old M135i..... I then found in the replacement it simply sucks the joy out of it.

It's no Porsche riflebolt of a manual, it may well be slower and harder to drive, but it sure makes the car better.

Monkey (when at PHs) ran an M235i with a diff and preferred the manual 'box, Autocar's long termer came to the same conclusion too, I seem to remember.

https://www.pistonheads.com/regulars/ph-chrisharri...

Edited by Mike Roberts on Thursday 24th August 16:25

Edited by Mike Roberts on Thursday 24th August 16:26

Edited by Mike Roberts on Thursday 24th August 16:27

[Mike Roberts]

I had a 135i coupe and it was great. They simply didn't sell in the same numbers, so the few out there have a quiet cult following in the shadow of the 1M.