M140i Improve Handling

[inline6bmwfan]

Hi all,

Changing to a 'proper' M car now is not financially practical and i need the practicality of my 5 door m140i too.

Anyway, im happyish so far with my m140i handling but im wanting to make it even better. The 'problem' i have currently is, the balance of the car is bang on under/oversteer wise, its very neutral, however the front end feels 'sloppy', doesent turn in amazingly or feel sharp during turning.

I knos additional negative camber will help BUT due to my aftermarket alloys i cant do the usually m4 lca upgrade etc, nor do i want camber plates, and tbh i dont feel it needs more camber at the front as it grips well just feels floppy/not confidence inspiring.

The rear feels great i just want the front to match, i have upgraded springs/dampers, LSD and wider tyres at the front, aswell as bush upgrades in the subframe.

Would stiffer control arm bushings help, i.e. polyurethane?

[inline6bmwfan]

Ben_79 said:

Powerflex sell camber adjustable inner bushings for the lower control arm.
That's possibly the cheapest way of adding a bit more camber and the stiffer bushes would help.

I fitted the Superpro control and radius arm set to my 335. There maybe something similar available for the 140i.
They come with adjustable caster on the radius arm and non-adjustable control arms with a degree of extra camber.

I think they were about £600 plus the cost of fitting and alignment.
I wouldn't recommend them as the ball joints have shat themselves after only 3k miles.

Front anti roll bar is another option. Bare in mind you'll also need adjustable drop links.
I've got the H&R ones on my 335i, I'm pretty sure it's the same part. I could only find them as a set of front and rear.
I did some research before buying them and lots of people were saying they were too stiff but they suit me.

I have done a bit of research and someone who has fitted anti roll bars to their m140i said that even on the softest setting at the front it still makes the car understeer more than stock! The rear is non adjustable.

Superpro discontinued camber adjustable control arm bushes as they were failing not long after fitting and they said its due to where they are they just wont last, powerflex still sell their version though strangely enough.

Would changing control arm bushes alone (non camber adjustible) improve anything?

Camber plates are an option (street polyurethane type) but again i dont see how that will help any 'slopiness'.

[inline6bmwfan]

t955daytona said:

If you really want it to handle take it to Birds (Birdsauto.com) or get there B1 suspension kit fitted by somebody closer to you. I cannot recommend their kits enough. It transformed my 3 series (F31) and I would not hesitate to do it again if I had a car they make a kit for (I have actually considered a 140i and that kit and the diff would be the first thing I would do) The compliance on our A/B roads was transformational, so much control, loads more traction (without the diff) and considerably more composed and quicker A to B.

I have bilstein dampers and motech springs im happy with the suspension side of things.

[inline6bmwfan]

liner33 said:

Change the allots then if they are stopping you making the required changes why do you think there is some way around it ?

What a narrow minded view, the only thing the alloys stop me doing is fitting different control arms, plenty of other things i can do just looking for the best option.

The alloys werent cheap so im not just giving them up.

[inline6bmwfan]

RicoOS said:

inline6bmwfan said:

t955daytona said:

If you really want it to handle take it to Birds (Birdsauto.com) or get there B1 suspension kit fitted by somebody closer to you. I cannot recommend their kits enough. It transformed my 3 series (F31) and I would not hesitate to do it again if I had a car they make a kit for (I have actually considered a 140i and that kit and the diff would be the first thing I would do) The compliance on our A/B roads was transformational, so much control, loads more traction (without the diff) and considerably more composed and quicker A to B.

I have bilstein dampers and motech springs im happy with the suspension side of things.

Whilst I appreciate what you've said, if you read the reviews of what Birds do and the problems they sort out, then you'll realise that the problem is wrong springs rates, damper rates, anti roll bar rates, bushing and geometry, so whilst you may think that your springs and shocks are good, if their rates are related to the standard rates, then they are a major part of the problem.

Were I buying an M140i, then I already know that the birds kit, including the quaife LSD would be the very first mod I would make, yes, it's not cheap, but given that it utterly transforms the ride/handling of the car and has multiple indendant back to back with stock reviews, I honestly think you might want to read up on it.

But clearly it's your choice.

Birds is well well overpriced, its good yes but it doesent have any effect on what i am wanting to improve (turn in/steering feel etc), i already have bilstein dampers which have replaced the useless stock dampers, the suspension set up is fantastic im happy with it, the cost to go to birds is not worth it at all.

[inline6bmwfan]

Krikkit said:

liner33 said:

inline6bmwfan said:

What a narrow minded view, the only thing the alloys stop me doing is fitting different control arms, plenty of other things i can do just looking for the best option.

The alloys werent cheap so im not just giving them up.

The alloys are stopping you correcting the issue, yet you think someone there is a get around . You are hamstringing yourself

Indeed. It sounds like both tyre and geometry changes are needed, so you'd kill 2 birds with one stone sorting the wheel widths and trying the M4 LCA's.

What about camber plates? They would provide the negative camber (although control arms would still have stock bushes)

[inline6bmwfan]

What are peoples thoughts on solid bushes for the rear subframe? Thats how most m cars are and from reading about, solid bushing the subframe doesent tend to introduce much NVH, polybushing the diff however does, will solid bushing the subframe but not the diff cause any issues or additional pressure on the diff?


Regarding the front end 'feel/turn in' the M4 LCA's basically provide extra track width and firmer bushings than the m140i control arms. I already have some extra track width with my offset alloys and wider tyres and i have plenty of grip up front just not much feel/directness. Will replacing the control arm bushes with polybushes help for 'feel/turn in' as they will be firmer than stock and not be flopping about when making turns? Is there any other bushes worth replacing like caster or is control arm the main one for what i want?

Anti roll bars will be going on aswell.

Street camber plates are also a potential consideration but depends what the balance is like after installing anti roll bars, if its neutral i wont bother.

[inline6bmwfan]

take-good-care-of-the-forest-dewey said:

Seriously, go visit someone like centre gravity.

You're likely going to end up spending a lot of money randomly experimentingvwith parts, which may or may not help. With the greatest respect, you don't appear to understand what effects the parts you're considering will actually have.

You do have a good idea how you want the car to feel - speak to someone who can translate that into meaningful changes to the car.

What im looking for in the car wont be fixed by an alignment......

An alignment wont reduce body roll, an alignment wont help turn in if camber is non adjustable, stiffer bushes in the control arm will surely provide more steering feedback? Caster isent adjustable either.

I dont think there is much adjustment available as standard on the m140i thats the issue.

Powerflex do sell camber adjustable control arm bushes but i hear these are prone to fail due to their highly stressed location?

Edited by inline6bmwfan on Tuesday 5th July 08:19

[inline6bmwfan]

take-good-care-of-the-forest-dewey said:

inline6bmwfan said:

What im looking for in the car wont be fixed by an alignment......

An alignment wont reduce body roll, an alignment wont help turn in if camber is non adjustable, stiffer bushes in the control arm will surely provide more steering feedback than some caster.

I dont think there is much adjustment available as standard on the m140i thats the issue.

Powerflex do sell camber adjustable control arm bushes but i hear these are prone to fail due to their highly stressed location?

Companies like CG don't just do alignment though. They're chassis tuning specialists. Call them. They can only say not interested.

How do you 'tune a chassis' without doing any alignment? What exactly can they do for me (serious question)

[inline6bmwfan]

take-good-care-of-the-forest-dewey said:

Alignment is just part of the process... But also, for e.g.

Ride height
Roll centre
Corner weighting
Damper settings C+R if adjustable.
Spring rates
Camber / castor changes
ARB adjustment.
Track alterations

+ associated advice on how to achieve if outwith OEM adjustability. Even things like an ill judge polyp Bush can ruin handling if it's in the same system as OEM bushing as you change loadings.

Badically depends on how much you want to spend.

As I said, call one of the respected companies, explain issue, see if they can sort within your budget.

The thing is im not looking for my car to be perfectly track ready and it sounds like them places you are saying to contact are for really fine tuning the car, im just looking for slightly improved handling on the road.

Also, ride height, corner weighting, damper settings, spring rates, camber/castor are all none adjustable on my car.

Im purely looking for some more feedback from the car and less body roll, hence the suggestion of solid mounting the rear subframe (like m cars are, but not the diff to keep NVH down), and possibly polybushing the front control arm and fitting some anti roll bars?

[inline6bmwfan]

take-good-care-of-the-forest-dewey said:

inline6bmwfan said:

The thing is im not looking for my car to be perfectly track ready and it sounds like them places you are saying to contact are for really fine tuning the car, im just looking for slightly improved handling on the road.

Also, ride height, corner weighting, damper settings, spring rates, camber/castor are all none adjustable on my car.

Im purely looking for some more feedback from the car and less body roll, hence the suggestion of solid mounting the rear subframe (like m cars are, but not the diff to keep NVH down), and possibly polybushing the front control arm and fitting some anti roll bars?

I give up. You said just a geo change won't help... I then explained the things specialists CAN advise on to give you an idea. And their advice will be based on whether you want a b road ca... A road... Or track toy.

The bit may be non adjustable, but their advice might be to fit something that offers some additional adjustability.

Your clearly looking for an echo chamber as the last post suggests. I'm out... go and buy a load of different shore value bushes and random suspension bits, bolt them on, and see how you get on.

Which specialist is going to provide me with free advice?

Im not asking for the car to be the best handling track weapon ever, im asking how will certain mods affect the car, i.e. ARB's, polybushes, i dont understand why its being made to be way more complex that it needs to be.