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MG MGF Technical - Unsprung weight

Unsprung mass and the weight distribution within the wheel is a topic that hasn't really been covered here before.

I would have guessed in the past that it made no/little difference... until I had the chance to drive a Cooper S with different tyre/wheel weight combinations.

The consensus on the Mini BBS is that the unsprung weight (tyre/wheel choice) makes a massive difference to the handling of the car. In fact, the same car with the same rubber was tested with differing wheels... and a noticible difference in handling was found.

Do we know weights for the various tyre/wheel combinations we all have ?

So should we all be running out to buy the ultra-lightweight wheels and tyres ? :-)

P.
Paul Nothard

>>
Do we know weights for the various tyre/wheel combinations we all have ? <<

One of my little 'pet hobby horses' there Paul! (As if you'd not have guessed!) Some details (but incomplete) @ http://www.mgf.ultimatemg.com/wheel_options_for_the_mgf.htm

The wheels on my car weigh in at around 6.2 kg (they're the MGF Cup wheels, 16" diameter). They weigh, in fact, about the same as the 5-spoke VVC alloy - 6.4kg. Not sure about all the others.

The 11-spoke alloys fitted to the Trophy 160 and TF160 are significantly heavier - over 11kg each!!!

I don't know how much the ULW MG wheels weigh, but if I were going for AP front brakes, then these wheels would be the ones I'd go for.

Regarding tyres, no I don't have this information - except that I did weigh a 215/40 ZR16 Goodyear F1 GS-D2 tyre - came in at around 7kg... :o( No idea how much 205/50 R15s weigh - but Z-rating does add mass, no question.

>> So should we all be running out to buy the ultra-lightweight wheels and tyres ? :-) <<

IMO, yes! ;o)
Rob Bell

Interesting.

I'm sure my TSW Blades weigh an absolute ton, they are quite chunky and with the cover cap and large nut they probably do nothing for the unsprung weight.

Any chance of getting together for a weigh in? Make an interesting article.

SF
Scarlet Fever

Yup, we could definitely do that Andy :o) Great idea.

Regarding aftermarket wheels - it is often frightening how heavy they are. And weight is frequently the last thing that is advertised - afterall, most people interested in alloy wheels are buying primarily on price and looks.

No idea how the Blades fit into the equation - but I doubt that they are the worst.
Rob Bell

Nothing that me going on a diet wouldn't fix anyhow!

LOL :-)

SF
Scarlet Fever

If anybodies got scales why not have a weight in (albeit with tyres) on the fun day on the 30th. There should be lots of Fs there so we could make a good start.
Steve

Cracking idea there Steve! Who's game?

1. Rob Bell - MGF Cup wheels
2. Steve - ???

Add your name and wheels to the list
Rob Bell

1. Rob Bell - MGF Cup wheels
2. Steve - 15" Rover 8-spoke (Front: Goodyear Eagle F1 GS-D2 195/50 R15, Rear: Michelin 205/50 R 15 86V Pilot Exalto)
3. Next ???
Steve

1. Rob Bell - MGF Cup wheels
2. Steve - 15" Rover 8-spoke (Front: Goodyear Eagle F1 GS-D2 195/50 R15, Rear: Michelin 205/50 R 15 86V Pilot Exalto)
3. SteveR - 15" MGR 5-spoke(VVC) Bridgestone RE720s
4. Next ???
Steve

OK, if someone's got a decent torque wrench then

1. Rob Bell - MGF Cup wheels
2. Steve - 15" Rover 8-spoke (Front: Goodyear Eagle F1 GS-D2 195/50 R15, Rear: Michelin 205/50 R 15 86V Pilot Exalto)
3. SteveR - 15" MGR 5-spoke(VVC) Bridgestone RE720s
4. Dave Livingstone - 16" Trophy 11 spokes with Bridgestone SO2 PPs
5. Next ???
Dave Livingstone

Interesting subject Paul.

From years of motorcycling I know that unsprung weight does affect suspension performance. The wheel also has a giroscopic effect on a bike which can adversly affect the steering. All of these before taking account of tyre wall flex etc.

There will be a similar effect on a 4 wheeler but, I would assume, of lesser concern.

Does any body have a contact at the Competition Department of MGR who might comment or point us at a suitable learned treatise?
JohnP

Steve, we *want* the weight with the tyres on. :-)

Rob, didn't realise it was a hobby horse of yours. I should have realised tho.... ;-)

Another thing we could/should look at (in theory) is where the weight is. If the weight is all on the outside then you get more centrifugal effects 'slowing' the steering down.
Anyone know how to measure this? <grin>
I think that tracking settings for example will swamp this effect... but it'd be interesting to work out.

The weight in a great idea. Shame I can't be there. :-(

To add to the thread... who's going to use Nitrogen in their tyres then?

P.

ps. My Mini's wheels at 11.4kg and the tyres are 10.0kg -> 21.4kg PER WHEEL!

pps. http://europeanspeed.com/wheelweights.htm and http://www.wheelweights.net may help some of us.
Paul Nothard

1. Rob Bell - MGF Cup wheels
2. Steve - 15" Rover 8-spoke (Front: Goodyear Eagle F1 GS-D2 195/50 R15, Rear: Michelin 205/50 R 15 86V Pilot Exalto)
3. SteveR - 15" MGR 5-spoke(VVC) Bridgestone RE720s
4. Dave Livingstone - 16" Trophy 11 spokes with Bridgestone SO2 PPs
5. Norman Law - 16" TF 11 spoke with F1s (well worn)
6. Next ???
Norman

If these are going to be compiled onto a web page then it would also probably worth adding the weights of various brake disks and callipers to the list, since these are also on the unsprung side of the equation. Obviously you can't take these off the car, like the wheels, to weigh them. However, it ought to be possible to get the figures from the manufacturers or resellers.

Ralph
Ralph

I use a minilite with Goodyear Eagle F1 GS-D2 195/60 R15 weigh in at 28lb appox 13kg

One site that provide weights
http://www.superlite-wheels.com/technical.html

Paul
Paul Wiley

Interesting Paul

My Cooper S, or MCS between you and me, runs on R84 X-lites which I understand are only 8.0kg and the tyres are about 10.7kg.

On the 30th I'll have the old VVC wheels fitted but I can bring one of the Abingdon 75th multispoke or whatever they're called if that is any help.

Neil
Neil Stothert

Hi Neil,

Bit off topic here.... but it's my thread to hijack! ;-)

I've pulled my Mini's wheel weight figures from the Mini2 BBS.
http://www.mini2.com/forum/faq.php?faq=faq_wheels_tyres#faq_faq_factory_wheels

I'm running R85 S-spokes and Euphoria run flats.
Alas, I'm selling the Mini, but if I were to keep it I'd bin the run flats asap!! In fact... I may even move from the 17" rims to the 16" rims like yours which handle "better". I've got used to 17" rims (esp. after Goodwood! <hehe>) and so found 16" rims "different"... but enough people rave about the 16s for handling that I'd be tempted...!!

Have you noticed that all photo shoot cars are shod with 17" rubber... but all test reports are with 16" rubber... Telling methinks. :-)

Right... back to MGs now. :-)

P.

ps. Anyone want to buy a loaded Silver Cooper S for ~£15k ?
Paul Nothard

I might be talking rubbish here but you know the stub axel at the front wheels, which is basically a crude adaptation of a cv joint. Well I think some weight could certainly be saved here by a little machining.
S Laithwaite

<<ps. Anyone want to buy a loaded Silver Cooper S for ~£15k ?>>

One careful owner:-)
Neil Stothert

<<<<ps. Anyone want to buy a loaded Silver Cooper S for ~£15k ?>>>>
<< One careful owner:-) >>

No.
"One female careful owner."
Registered in Jo's name. ;-)

(Actually has been cared for. Just driven hard at times - as the car was intended. <grin>)

P.
Paul Nothard

>> Another thing we could/should look at (in theory) is where the weight is. If the weight is all on the outside then you get more centrifugal effects 'slowing' the steering down. <<

I 'looked' at this crudely when I had a VVC alloy and 16" 'Cup' wheels sans tyres. Holding both rims it was possible to judge approximately where the centre of gravity was for each wheel. The VVC alloy, for example, clearly had its centre gravity well to its outside edge. My 'Cup' wheels (which, incidently, are GENUINELY off a Cup car LOL!) had it's centre of gravity much closer to the centre line (in fact, much closer to the centre line than I found a 'Cup' wheel when comparing rims at the MGF Centre last year.

>>To add to the thread... who's going to use Nitrogen in their tyres then? <<

Nitrogen? Nah mate, too heavy. Helium me. ;o)

>> If these are going to be compiled onto a web page then it would also probably worth adding the weights of various brake disks and callipers to the list, since these are also on the unsprung side of the equation. <<

That's a very good suggestion Ralph as yes, I am interested to know this too. I'll be compilling the results - so expect an "Unsprung Mass" web page near you soon!!! LOL

>> On the 30th I'll have the old VVC wheels fitted but I can bring one of the Abingdon 75th multispoke or whatever they're called if that is any help. <<

Yes please Neil :o)

I'll bring along a torque wrench. Anyone got some reliable scales?
Rob Bell

1. Rob Bell - MGF Cup wheels
2. Steve - 15" Rover 8-spoke (Front: Goodyear Eagle F1 GS-D2 195/50 R15, Rear: Michelin 205/50 R 15 86V Pilot Exalto)
3. SteveR - 15" MGR 5-spoke(VVC) Bridgestone RE720s
4. Dave Livingstone - 16" Trophy 11 spokes with Bridgestone SO2 PPs
5. Norman Law - 16" TF 11 spoke with F1s (well worn)
6. Andrew (SF) - 16" TSW Blades with Marangoni Zeta Linea tyres
7. Next ???
Scarlet Fever

1. Rob Bell - MGF Cup wheels
2. Steve - 15" Rover 8-spoke (Front: Goodyear Eagle F1 GS-D2 195/50 R15, Rear: Michelin 205/50 R 15 86V Pilot Exalto)
3. SteveR - 15" MGR 5-spoke(VVC) Bridgestone RE720s
4. Dave Livingstone - 16" Trophy 11 spokes with Bridgestone SO2 PPs
5. Norman Law - 16" TF 11 spoke with F1s (well worn)
6. Andrew (SF) - 16" TSW Blades with Marangoni Zeta Linea tyres
7. Neil - Abingdon 75th 16''multispoke (F1)
8. Next ???
Neil Stothert

Very nice thread !!!
Was thinking about the unspring weight during the weekend. Please take into account that the Trophy with its heavy alloys is also equiped with nice big callipers and 304mm disks. Definatly a massive difference with a standard setup found on a MPi/VVC.

Although I thought about it, I didn't weight the ULW wheels I had on the TF demonstrator. I'll try to find them anyway.

Cheers,
Erik

That'd be very useful to know Erik, thanks! :o)
Rob Bell

Is there much difference in the weight of different calipers? The Trophy calipers feel very heavy as did MS's.

Do MG or SS dust caps make a difference?

Sorry:-)

Neil
Neil Stothert

Change of discs (and pads) to EBC Turbo Grooved (& GS) has changed the feel of a steering on my 1995 1.8i (standard 6-rounded spoke wheel with Avon ZV1 front/GSD2 rear). A little more effort required on initial turn, particularly noticeable at certain speeds, and then no difference. I thought I might have been anticipating this and therefore feeling it, but from this thread, it seems that the effect is real.

Chaz
Chaz

Wilwood calipers (but not discs) weights are available prob about half OE.

Paul
Paul Wiley

Hi all,
this will be an interesting list when done in order of weight.... Don´t forget to add a normal steel wheel to the list! It is not always alu-wheels are the lightest OR strongest,especially not if the original steel-rim is re-inforced welded.
BR, Carl.
Carl Blom

You're not wrong there Carl - but since the steel 'space saver' supplied with the car is a good deal narrower than the standard 15" alloys, this wouldn't be a fair comparison. Is there another steel wheel to compare with that you can think of?
Rob Bell

Hi Rob,
I was not thinking about the spare but an ordinary steel wheel as used with winter tyres etc. There is a weight diff of course if there is a true winter tyre (possibly also with studs !) on the rim BUT maybee there is a similare steel wheel dimension with a "normal" tyre on any other Rover product that can be a genuine substitute?
BR, Carl.
Carl Blom

It would need to be a Maestro or Montego wheel Carl - but I think that all the steel wheels fitted to these cars were 14" 4.5J or thereabouts. Perhaps one of our resident Maestro/Montego experts could shed light on this?
Rob Bell

Just weighed the standard front disk 9lbs. Rear brake caliper complete with pads 7lbs.
Ken Waring

Okay, that's 4.1kg for the vented front disc and 3.2kg for the rear caliper (sorry - I have to work in metric Ken! LOL)
Rob Bell

This thread was discussed between 12/01/2004 and 15/01/2004

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