Ally wishbones??

[etouring]

Hi all, has anyone heard of ally wishbones braking with the heavier engines? I'm changing to 300lbs+ was wondering if firtting some ally wishbones could help balance the car.

[Brianmoooore]

Alloy wishbones are standard fitment on the E30 325 touring, and I've never heard of one breaking.

[ross_jsy]

They won't break, but don't expect massive weight savings.

300lbs is about 140kg, that's not a massively heavy engine either

[BMG]

So madly priced by BMW, these are only worth buying if you are doing a concours rebuild or have a stack of spare cash. The money can be better spent elsewhere, imho.

[Brianmoooore]

Don't know what the current prices are, but the last time I checked, they were only about double the price of the genuine steel item.
Unfortunately, no one that I know of makes an aftermarket alloy version, while there are many aftermarket suppliers of the steel item, selling for much less than a BMW steel one.

[HairyScreech]

The important thing with Aluminium suspension components is that they do have a life, aluminium fatigues even when only taking a light cyclic load and thus will weaken with age/mileage.

The genuine Aluminium wishbones will last for more than the life of the ball joints pressed into them but is likely why the joints cannot be replaced. Worn joints = new arm.

The steel arms will go on for nearly forever.

Personally I see little point in the aluminium wishbones, the steel ones are fine for 99% of applications and wheels/tyres and brakes have a larger effect on the unsprung mass.

If racing and unsprung weight is vital then fully adjustable triangulated tubular wishbones is the way to go.

Maybe for a concourse M3 the aluminium wishbones might be the way to go, but not even all the M3s had them.

[etouring]

Thanks for the advice. Iv found some 2nd hand ones for £150, didn't know the ball joints couldn't be changed. I'm running alloy brakes already got a carbon bonnet so thought it would be the logical next step. I noticed they don't sell fast when posted on here I'll steer clear for now.

[BMG]

You'd be mad to buy second hand ally wishbones unless you knew the owner and the car personally to check ball joint play while on the car and how old/miles they've done. People trying to flog used one and gullible peeps buying is mad.
At 360 Euro each ! You'd be better off spending the money on some decent brand steel items and having a stack of money left over to improve your car elsewhere.

[etouring]

You'd be mad to buy second hand ally wishbones unless you knew the owner and the car personally to check ball joint play while on the car and how old/miles they've done. People trying to flog used one and gullible peeps buying is mad.
At 360 Euro each ! You'd be better off spending the money on some decent brand steel items and having a stack of money left over to improve your car elsewhere.

Yea I'm not going to bother getting them. Thanks everyone for good advice as usual

[etouring]

Cool I'll give you £2.50 for the lot

[Demlotcrew]

If you can get them, you would be mad not to fit them!

I disagree with every reason why not to get them in this thread.

[HairyScreech]

If you can get them, you would be mad not to fit them!

I disagree with every reason why not to get them in this thread.

Genuinely interested why?

For the sake of stimulating debate I look at the alu wishbones thus:


So unsprung saving from the alu wishbone is only 1lb.
Not really enough to be worth the cost but will have to check the proportions of the mass as I am at work, but it can't be too far off.

Wishbone weights are correct.

So why did bmw change to alu?
I'm pretty sure a lot of the racing regs state that the control arms must remain the same material as the road car, late DTM cars used alu adjustable arms and steel hubs with the magnesium uprights suspiciously absent.

[Demlotcrew]

Not really enough to be worth the cost but will have to check the proportions of the mass as I am at work, but it can't be too far off.

I hate to be the one to tell you this, but any amount of unsprung weight has a massive impact on handling - even on an E30. Going by your calculations (which don't explain everything thats going on, but lets go with them anyway) an unsprung saving of ~450g is substantial for something which is essentially a bolt on part.

[pacerpete]

750 sovs ! now that is pretty f000king substantial !

[HairyScreech]

Of course unsprung mass is significant, but is 450g worth £700?

Considering that money could be spent on better dampers and coilovers which are a 2 fold upgrade, lighter and improved suspension control.
Wheels which would be a lot more that 450g lighter per wheel.
Light weight callipers and rotors? A brake upgrade and reduced unsprung.

For that 450g the last place I would go hunting for it is the lower wishbone and if that mass was so significant then going to a tubular would be the first choice as it would allow adjustment and an improvement in fore/aft stiffness as well.

Given that every other option brings something greater to the table than the alu wishbone I see them an answer looking for a question.
Perhaps that question is a series where you are only allowed to use the "standard" lower wishbone?

Regarding the fag packet calculation:
mass that is in pure rotation adds its inertia (can't be arsed to work out that while at work), beams in osculation - half the mass can be considered static and half moving (that might be 1/3rd and 2/3rd respectively but need to check).
This is essentially the same as the calculation of the rotary and reciprocating mass on a conrod.

[Demlotcrew]

Of course unsprung mass is significant, but is 450g worth £700?

Considering that money could be spent on better dampers and coilovers which are a 2 fold upgrade, lighter and improved suspension control.
Wheels which would be a lot more that 450g lighter per wheel.
Light weight callipers and rotors? A brake upgrade and reduced unsprung.

A lot of assumptions there. I don't know of any good suspension kits for £700 or brakes or wheels for that matter.

Throwing around statements such as alloy arms are 'not worth it' without actually understanding the full effect is simply wrong, but you know this.

Anyhoo, I appreciate that you feel they are not worth the expense, but what is fascinating about your recommendations/conclusions is that they are based on financials only.

With adjustable control arms coming in at roughly £2000, one soon realises how valuable the alloy arms are.

One thing you are correct on, the race multi part arms are absolutely a first choice, just a shame you didnt recommend them

[HairyScreech]

If you live in a world of infinite money then the standard non adjustable alloy wishbones make even less sense as we agree "race" style tubular arms win every time.

Regarding suggesting them, I did in the first post I made.

Personally I see little point in the aluminium wishbones, the steel ones are fine for 99% of applications and wheels/tyres and brakes have a larger effect on the unsprung mass.

If racing and unsprung weight is vital then fully adjustable triangulated tubular wishbones is the way to go.

However the cost is enormous and if money is no object the E30 is completely the wrong car to start with.

I am happy to admit finance in not unlimited and I am sure that is the case with 99% of people on here. So it is only fair to weigh up the bang for buck of an unnecessary upgrade.
That is not to base things purely on financials but to look at the cost/benefit of the part.
The reality of that is all of the suggestions I have made will give greater benefits and should really be looked at before even thinking of the alu wishbones.

"Throwing around statements such as alloy arms are 'not worth it' without actually understanding the full effect is simply wrong, but you know this." - So you feel there is something more to this?
Can you elaborate?
If there is a greater effect than simply sprung/unsprung weight then information like this is gold to communities.

[Demlotcrew]

Tubular arms are not the same as multi part control arms

In any case, not everyone can run these on the road (due to wear/safety) so the alloy units are an ideal compromise. If at a later date you want something adjustable for €400 you can have the alloy arms modified accordingly.

Most are not interested and everyone else already knows, so Ive stopped posting such information.

[HairyScreech]

Tubular arms are not the same as multi part control arms

In any case, not everyone can run these on the road (due to wear/safety) so the alloy units are an ideal compromise. If at a later date you want something adjustable for €400 you can have the alloy arms modified accordingly.

Most are not interested and everyone else already knows, so Ive stopped posting such information.

If an adjustable tubular wishbone is not the same as a multi part arm how do you explain the wishbones on practically every pre1990 and club class race car?

These look pretty tubular, pretty adjustable and very much multi part to me.


Taking a look at the E30 DTM set ups and they all seem to use at least one tube in their construction.

Or you know, practically any of the ones here:
http://tinyurl.com/n5s52lq
But I guess everyone of those is wrong as well.

Either way it's semantics and a long way from the discussion.

Agreed not everyone can run these on the road but on the road 450g of unsprung mass means absolutely fuck all. Anything that is practical on the road is so compromised in other areas.
Christs sake, you can't even be sure tyres of the same size and profile are within 450g of each other.

Regarding this mystical benefit you hint at, you will find more than you think are interested, indulge us.

[Demlotcrew]

Generally speaking, in the E30 circuit, tubular arms are referred to cheap steel incarnations of the Gr.A/DTM multi part alloy versions so its not exactly semantics.

Don't get too hung up on the 450g, its more than you think.

More importantly I would like to see these suspension/brake/wheel kits which are lighter for £700?

[HairyScreech]

Did not say they had to cost £700, just that the money would be better applied there.

£300 on some Bilsteins or £1000 on some mid level coil overs? That's the argument.

You have yet to offer any facts, nothing you have said is of any substance, you have failed to raise one solid argument.

As you state it is more than it appears to be please prove this argument.

Am I to assume you have none?

If you can get them, you would be mad not to fit them!

I disagree with every reason why not to get them in this thread.

I will state my challenge again, justify your statement.

[Demlotcrew]

Justify my statement, for what? You just proved my point with £1000 dampers (assuming you meant inverted?) offering even less of an unsprung reduction than the alloy arms as ok and I am the one who has to spend time to justifying my statements

[HairyScreech]

Last set of mid range coil overs I had in my hands weighed less than the H&R springs and Bilstein shocks that came off.
Whats your point?

I gave a reference point, springs and dampers of normal E30 style and dimensions and stated the coil overs that went on were lighter by about 1kg.
Granted the weight loss came from the fact the body was shorter but the reduction of the massive spring platform helped and the lighter spring counts as well.

You came wading in, implied everyone was wrong and have yet to make a case.

What is the weight reduction of the alloy wishbones worth and why are they something to fit in preference to saving that money and spending it on practically any other part of the car?

[daimlerman]

Wonder just how many M3's still have the mystical ali wishbones?

[reggid]

How much % saving in unsprung mass is it, assuming standard E30?

[etouring]

Just want to add I was only going to pay £150 no were near £700! All I really needed to know was if its possible to change the ball joints as chances are they will be knackered. They probs long gone by now a˜­

[HairyScreech]

How much % saving in unsprung mass is it, assuming standard E30?

very good point, I make a stock 325 front set up at about 36.137kg or 79.668Lb. (by real oem, not going to weigh a corner at this time.)

So 1.245% of the total unsprung give or take about .25%