Modifying an OEM Steering Wheel

[BritishRacinGrin]

I've never heard this discussed anywhere before so I wonder if it's possible...

I've always liked the look of the standard steering wheel in my old BMW. This is lucky because it has a fairly unusual spline fitment so isn't easily swapped for a different wheel, especially when you consider the airbag and the horn.

However the big problem with this wheel is it's boat-like size. The rim needs to be 30-40mm smaller in diameter. I think this would improve the steering no end and give me more knee room.

Is it possible that with a bit of butchery I could strip the leather upholstry off, grind the wheel rim off and fit a smaller rim on, before sending the resulting mess off to a steering wheel upholsterer for re-covering? is the 'frame' of the wheel, and the rim, likely to be made from mild steel like they used to be?

[Fastdruid]

No.

Last two wheels I looked were made from magnesium alloy and just in case you think that's because they were "performance cars", one of them was a Corsa B....

(To cover any potential embarrassment I was just using the column in a kit car)

You could probably turn the base down to make a mounting for an aftermarket wheel, although you might be best starting with a s/h wheel.

[kambites]

It might be easier to cut the spline out of the existing wheel and weld it onto an after-market one if you can find one that you like. I believe aftermarket airbag wheels are starting to appear on the market in reasonable numbers now?

[BritishRacinGrin]

Blast.

I'm sure I could get a boss which fits for an aftermarket wheel but I don't want an aftermarket looking wheel, nor do I really want to lose my airbag and horn.

I'm surprised magnesium was used- even for the rim, or just for the center? I had that down as a casting material and I can't imagine anybody casting a wheel rim, I assumed it'd be steel bar or possibly some kind of fibre re-enforced plastic in modern cars.

Sounds as though I need to get my hands on a spare wheel to butcher and find out.

ETA: Lightbulb moment, I just remembered why I assumed it'd be mild steel. Burned out cars from when I was a kid.

Burned out E34 interior;



hmm... The rim looks to be a different material to the center but that doesn't really help.

Edited by BritishRacinGrin on Thursday 24th July 09:42

[kambites]

I think most OEM airbag wheels would look thoroughly odd with a significantly smaller rim, anyway - all the proportions would be wrong. Do BMW not make any smaller wheels that you like?

[Fastdruid]

The entire thing was magnesium alloy on the Corsa, I know as I couldn't get the damn thing off so sacrificed it. It cut like butter.

Now the BMW one might not be but this (from 10 years ago) http://www.igcar.gov.in/transiim/2004/vol57-4overv... suggests it is .....

Article said:

VW’s 3l Lupo has a magnesium steering wheel core similar to many other cars (e.g. models from Toyota, BMW etc.). Actually the highest part penetration in Europe is in steering wheels, nearly 85% of which are made of magnesium alloys.

[Lowtimer]

Is your 1996 5-series an E34 or an E39? There are certainly a different sizes of factory E39 steering wheel that are freely interchangeable. I am less well up on the finer points of the E34 interior.

[BritishRacinGrin]

kambites said:

I think most OEM airbag wheels would look thoroughly odd with a significantly smaller rim, anyway - all the proportions would be wrong. Do BMW not make any smaller wheels that you like?

That did cross my mind but it's quite a spindly looking wheel so I think with careful upholstering it could be made to look pretty good.

BMW make some other wheels I like but not for E34 spline fitment. Modify the column you say? then the airbag and horn contacts wouldn't work.

[BritishRacinGrin]

Lowtimer said:

Is your 1996 5-series an E34 or an E39? There are certainly a different sizes of factory E39 steering wheel that are freely interchangeable.

E34

[Fastdruid]

BritishRacinGrin said:

BMW make some other wheels I like but not for E34 spline fitment. Modify the column you say? then the airbag and horn contacts wouldn't work.

Airbag and horn are via a "clockspring", you could modify the column top and still keep them. Although of course actually fitting them into the 'new' wheel might be problematic.

[Bennet]

Perhaps a z3 or z4 steering wheel would work.

I would have thought the airbags would be designed to inflate to a certain size and position though, that might not be interchangeable between the two cars. Also who's to say for sure the trigger signal to fire the airbag is the same voltage.

Research necessary it seems if you wanted to follow that one up, unless you're already confident about both of the above.

Edited by Bennet on Thursday 24th July 09:56

[BritishRacinGrin]

The current wheel looks right in this period of car... the later wheels wouldn't suit it and earlier wheels won't have airbags.

I may just have to live with it because I love the standard wheel design and I haven't seen a small wheel in an early to mid 90s BMW which I liked the look of.

This all leads me back to the core problem which is the box steering, if I could get quicker steering I wouldn't need more knee clearance but that's a whole nother kettle of fish (I may have just said 'a whole nother'. Can't wait for the grammar pedants to see)

[kutaface]

BritishRacinGrin said:

E34

I really like that

[kambites]

One of the Z3 wheels looks very similar but is presumably smaller, is it a different fitment?

[BritishRacinGrin]

kutaface said:

BritishRacinGrin said:

E34

I really like that

Yeah I love my E34 and I've never wanted for a replacement but the box steering really compromises the driving experience. I've spent most of the morning Googling steering rack conversions but as far as I can tell nobody has made one work satisfactorily and to get a rack in the car at all would involve a significant amount of fabrication work (which, of course, is why BMW fitted the box in the first place). The E39 had a rack but it also has a lot of other stuff I don't want, I've always liked the E34 more as an overall package (see 'over engineered cars' thread!)

[Fastdruid]

What is the issue with the steering box? Is it the ratio, are there not other E34 steering boxes with better ratios (The M5 springs to mind for starters)?

[BritishRacinGrin]

kambites said:

One of the Z3 wheels looks very similar but is presumably smaller, is it a different fitment?

Very interesting, initial googling inconclusive but I'll stick at it.

Fastdruid said:

What is the issue with the steering box? Is it the ratio, are there not other E34 steering boxes with better ratios (The M5 springs to mind for starters)?

The ratio is one problem. I'm aware an M5 one will bolt in and has a quicker ratio but the problem is that have all done at least as many miles as mine has and are all at least as sloppy as mine around the center. Sure, they can be adjusted, but box steering always has a disconcerting and uncommunicative vagueness about it and there is only so far you can adjust them before you start to lose the self-centering effect.

I thought a smaller wheel would kill two birds, i.e. 'faster' feeling steering and more knee room.

[BritishRacinGrin]

Believe it or not the Z3 wheel is only 15mm smaller! I don't think that'd be a big enough improvement to justify the effort in making the electrical bit work.

[kambites]

BritishRacinGrin said:

Believe it or not the Z3 wheel is only 15mm smaller! I don't think that'd be a big enough improvement to justify the effort in making the electrical bit work.

Hmm, I certainly wouldn't want anything smaller than a Z3 wheel in a 5-series.

[BritishRacinGrin]

Why is that, out of interest? In an E34 the steering is lighter and slower than in a Z3 so it makes sense to me.