Unsprung Weights?
Discussion
Does anyone have a comparison of wheel/tyre weights?
I've always been a fan of unsprunge weight after working at a Porsche dealer many years ago and getting to sample cars with lightweight wheels and or Carbon brakes. Feeling the increased tactile pleasure from a car with the EXPENSIVE brake option always remained with me.
I currently run standard fit Imola 15's and 16's wrapped in Rainsport 3's with factory spec/size brakes, and often wonder about folk with their Big Brake conversions and the associated bigger wheels and tyres that go along with them. Is their unsprunge mass significantly higher than mine?
Tubular Wishbines, are they any lighter?
To me, my car should be all about the feel and not necessarily seeking out the ultimate in performance if I'm only to lose the lovely feel and sensations of a nicely balanced chassis.
I've always been a fan of unsprunge weight after working at a Porsche dealer many years ago and getting to sample cars with lightweight wheels and or Carbon brakes. Feeling the increased tactile pleasure from a car with the EXPENSIVE brake option always remained with me.
I currently run standard fit Imola 15's and 16's wrapped in Rainsport 3's with factory spec/size brakes, and often wonder about folk with their Big Brake conversions and the associated bigger wheels and tyres that go along with them. Is their unsprunge mass significantly higher than mine?
Tubular Wishbines, are they any lighter?
To me, my car should be all about the feel and not necessarily seeking out the ultimate in performance if I'm only to lose the lovely feel and sensations of a nicely balanced chassis.
Fan of un spring weight, do you mean a fan of less unsprung weight? .
I have 4 pot Brembo callipers which are way lighter than the originals, id say my bigger wheels are lighter than the Imola’s or about the same, discs are heavier than standard.
I’ve not had any excessive bouncing or rebound over bumps.
The brakes are far more sophisticated and for me using road based pads have a better forward bias so less likely to lock rears up.
The car stops really well.
I’d never go back so this unsprung weight thing is negligible,,, well it is on my motor.
The Brembo callipers are virtually identical to ones used by Porsche around the late nighties and exactly the same as used by Ferrari on the 360 Modena,,,, except the Ferrari branded ones are or were £1500 a calliper (second hand ) on eBay when I looked a few years ago.
I have 4 pot Brembo callipers which are way lighter than the originals, id say my bigger wheels are lighter than the Imola’s or about the same, discs are heavier than standard.
I’ve not had any excessive bouncing or rebound over bumps.
The brakes are far more sophisticated and for me using road based pads have a better forward bias so less likely to lock rears up.
The car stops really well.
I’d never go back so this unsprung weight thing is negligible,,, well it is on my motor.
The Brembo callipers are virtually identical to ones used by Porsche around the late nighties and exactly the same as used by Ferrari on the 360 Modena,,,, except the Ferrari branded ones are or were £1500 a calliper (second hand ) on eBay when I looked a few years ago.
Edited by Classic Chim on Thursday 18th July 08:06
I've developed a lightweight front brake solution consisting of a lug mount Wilwood Forged Superlite caliper that bolts straight to the uprights and Tarox billet steel discs (280 x 24 mm) on custom aluminium bells: complete weight of the disc is 4.60 kg (240 mm std front discs are 4.35 kg, 260 mm are 5.3 kg, 283 x 24 Cosworth discs 6.6 kg). The caliper is about 1.9 kg without pads and there's no adapter bracket.
Cast iron Ford calipers are about 3 kg each excluding carriers for the smallest ones (Escort/non-ABS Sierra on 240 discs), up to 5ish for the four-pot Cossie ones or the 887/888 version.
Of all the OE 15/16" wheels, the OZ lattice pattern split rims are the lightest, the Estorils (7-spoke, std on 500s) the heaviest with the 5-spoke Imolas in between. IIRC I weighed the OZ front wheels with Bridgestone 205/55 tyres at 18.5 kg and the rear ones with Bridgestone 225/55/16 at around 20 kg. The front wheel alone is 8.5 kg; Imolas are in the low nines. Bridgestone tyres are generally about a kg heavier than most.
For the record - 16-inch, five bolt Spiders are 8.9 kg, 18-inch Spiders 12 kg and 18-inch SP12s are fairly light at 9 kg apiece.
There's no appreciable weight difference between a 16-inch tyre and an 18-inch one at the same tread width; the sidewalls of the lower section heights tend to be shorter but thicker/stiffer.
Cast iron Ford calipers are about 3 kg each excluding carriers for the smallest ones (Escort/non-ABS Sierra on 240 discs), up to 5ish for the four-pot Cossie ones or the 887/888 version.
Of all the OE 15/16" wheels, the OZ lattice pattern split rims are the lightest, the Estorils (7-spoke, std on 500s) the heaviest with the 5-spoke Imolas in between. IIRC I weighed the OZ front wheels with Bridgestone 205/55 tyres at 18.5 kg and the rear ones with Bridgestone 225/55/16 at around 20 kg. The front wheel alone is 8.5 kg; Imolas are in the low nines. Bridgestone tyres are generally about a kg heavier than most.
For the record - 16-inch, five bolt Spiders are 8.9 kg, 18-inch Spiders 12 kg and 18-inch SP12s are fairly light at 9 kg apiece.
There's no appreciable weight difference between a 16-inch tyre and an 18-inch one at the same tread width; the sidewalls of the lower section heights tend to be shorter but thicker/stiffer.
Edited by 900T-R on Thursday 18th July 10:16
The lightweight brake option sounds good.
A quick look at wheels throws up the Team Dynamics Pro Forged as being extremely light and available in 16 and 17 inch. I wonder if you could get a set of these to fit?
Something like these and the lighter brake set up would be lovely, as there would definitely be a sizable weight reduction.
Unsprung weight doesn't appear to discussed much, if at all, on here. My bum on seat experiences has proven to me the changes in dynamics can be made with serious attention to it.
At the moment it's just an idea, as I've still not married the body up to the chassis yet, but it is something I'd like to explore and would seriously look at doing when I'm back on the road. A good start is to pick the collective brains on here first though!
Wishbones, have we any comparisons of these?
A quick look at wheels throws up the Team Dynamics Pro Forged as being extremely light and available in 16 and 17 inch. I wonder if you could get a set of these to fit?
Something like these and the lighter brake set up would be lovely, as there would definitely be a sizable weight reduction.
Unsprung weight doesn't appear to discussed much, if at all, on here. My bum on seat experiences has proven to me the changes in dynamics can be made with serious attention to it.
At the moment it's just an idea, as I've still not married the body up to the chassis yet, but it is something I'd like to explore and would seriously look at doing when I'm back on the road. A good start is to pick the collective brains on here first though!
Wishbones, have we any comparisons of these?
motul1974 said:
900T-R...is there much difference in your Willwood superlites in comparison to the normal Brembo upgrades??
Yes, 'cos the Brembos (from an E38 Beemer IIRC) only work with discs from 315 mm upwards, i.e. rather oversized for a car that weighs roughly a tonne and doesn't feature ABS(let alone all the add-on stability control functionality). The 324 mm Ford Focus RS single piece discs weigh 8+ kgs - which is actually quite good for such a large single piece disc as most of similar size are in the 9-10 kg range - but a long way from the 4.6 kg of my 2-piece 280 mm discs....
Dont concern yourself with wishbone weights too much 
the Imola & Estoril alloys are strong and that comes at a price they are also heavy compared to say the popular Team Dynamics etc, the popular Brembo calipers are light ....apart from the rather large heavy discs 
alloy bell style would shave off some lard here, there was a company making alloy front & rear hubs but apparently they wasn't much cop according to a PH'er bearing fit etc 
Dont think UR Rainsport tyres are noted as being heavy like some alternatives though the early cars had solid and smaller discs at the rear and hence lighter which on a road based car come at no cost IMO brake performance wise but I would go alloy bell style discs and ally calipers all round to do things properly if thats what your after coming to a compromise on disc size (brake performance) Vs weight
the Imola & Estoril alloys are strong and that comes at a price they are also heavy compared to say the popular Team Dynamics etc, the popular Brembo calipers are light ....apart from the rather large heavy discs alloy bell style would shave off some lard here, there was a company making alloy front & rear hubs but apparently they wasn't much cop according to a PH'er bearing fit etc Dont think UR Rainsport tyres are noted as being heavy like some alternatives though the early cars had solid and smaller discs at the rear and hence lighter which on a road based car come at no cost IMO brake performance wise but I would go alloy bell style discs and ally calipers all round to do things properly if thats what your after coming to a compromise on disc size (brake performance) Vs weight 900T-R said:
Yes, 'cos the Brembos (from an E38 Beemer IIRC) only work with discs from 315 mm upwards, i.e. rather oversized for a car that weighs roughly a tonne and doesn't feature ABS(let alone all the add-on stability control functionality).
The 324 mm Ford Focus RS single piece discs weigh 8+ kgs - which is actually quite good for such a large single piece disc as most of similar size are in the 9-10 kg range - but a long way from the 4.6 kg of my 2-piece 280 mm discs....
I'm impressed, that does sound good!The 324 mm Ford Focus RS single piece discs weigh 8+ kgs - which is actually quite good for such a large single piece disc as most of similar size are in the 9-10 kg range - but a long way from the 4.6 kg of my 2-piece 280 mm discs....
phazed said:
I have tubular wishbones fitted to the front of the car.
I very much doubt that these are lighter than the standard angle iron ones as those were made of quite thin gauge steel in the first place!
I will weigh my spare set of wheels shortly.
Hi Phazed, do you feel the stiffer wishbones made a real world difference?I very much doubt that these are lighter than the standard angle iron ones as those were made of quite thin gauge steel in the first place!
I will weigh my spare set of wheels shortly.
I guess if you went a lighter brake/wheel combo there'd be less dynamic force of them to start with...maybe reducing such stiffness benefits??
motul1974 said:
I guess if you went a lighter brake/wheel combo there'd be less dynamic force of them to start with...maybe reducing such stiffness benefits??
Actually, this goes for the whole car - the chassis isn't the stiffest, so lessening the dynamic forces on it for a given longitudinal and/or lateral acceleration is rather more desirable than adding performance by adding bigger engines, bigger brakes, heavier drivetrain components, wider, grippier tyres etc (which is a double edged sword as all of that tends to add weight), higher spring and damper rates to keep it all in check... Get rotating, unsprung and overal mass down (in that order of importance) and you can extract more performance from the structure and keep within the same loads that it was engineered for in the first place. Win-win GR_TVR said:
phazed said:
I can weigh a 235/40/17 or 255/40/17 on 17"x 8" RL7 wheels.
Would be interesting to know. I've got the same wheels but run 215/45/17 and 235/45/17 tyres.
I will weigh my SP12s. R1R tyres, 225/45 17 fronts, 225/40 18 rears.
900T-R said:
Yes, 'cos the Brembos (from an E38 Beemer IIRC) only work with discs from 315 mm upwards, i.e. rather oversized for a car that weighs roughly a tonne and doesn't feature ABS(let alone all the add-on stability control functionality).
The 324 mm Ford Focus RS single piece discs weigh 8+ kgs - which is actually quite good for such a large single piece disc as most of similar size are in the 9-10 kg range - but a long way from the 4.6 kg of my 2-piece 280 mm discs....
See I thought bigger discs offer a more progressive feel when combined with the correct pads and simply put offer a much larger braking area to activate. The 324 mm Ford Focus RS single piece discs weigh 8+ kgs - which is actually quite good for such a large single piece disc as most of similar size are in the 9-10 kg range - but a long way from the 4.6 kg of my 2-piece 280 mm discs....
If it’s willy waving your after the big 324mm disc are the nuts when pulling up in a car park
Because I use the Brembo road pads for an E38 Beemer I love nothing more than comparing the wear pattern with modern Audi etc 50k cars, virtually identical groove pattern,,, they work very well on roads I do know that.
My view is all the brake upgrade options available will improve brake capacity and feel for lock up and combined with the correct tyres will be an improvement.
The biggest issue for a normal road car will be brake squeal usually at very slow speeds as in gently coming upto the lights etc so pad choice critical.
I assume my Brembo set up does add some unsprung weight but I never did get round to weighing them, the callipers are much lighter but the connecting brackets are heavy so overall I’d say it’s heavier, but I don’t notice anything other than I love using the brakes.
I rattled some curbs on a track chasing Matt Poxons Griff, didn’t feel any different really.
My view is all the brake upgrade options available will improve brake capacity and feel for lock up and combined with the correct tyres will be an improvement.
The biggest issue for a normal road car will be brake squeal usually at very slow speeds as in gently coming upto the lights etc so pad choice critical.
I assume my Brembo set up does add some unsprung weight but I never did get round to weighing them, the callipers are much lighter but the connecting brackets are heavy so overall I’d say it’s heavier, but I don’t notice anything other than I love using the brakes.
I rattled some curbs on a track chasing Matt Poxons Griff, didn’t feel any different really.
900T-R
“Of all the OE 15/16" wheels, the OZ lattice pattern split rims are the lightest, the Estorils (7-spoke, std on 500s) the heaviest with the 5-spoke Imolas in between. IIRC I weighed the OZ front wheels with Bridgestone 205/55 tyres at 18.5 kg and the rear ones with Bridgestone 225/55/16 at around 20 kg. The front wheel alone is 8.5 kg; Imolas are in the low nines. ”
It’s a shame and good opportunity for improvement at the same time IMO.
A 15x7 alloy - equal to OEM front wheels on the Chimaera should be between 5-6kg. I used 15x6,5 alloys on my mx5, the weight was between 4-5kg.
The lightest rim I used was the Desmond Regamaster at 3,9kg. That’s half of the weight of our Imolas....
Stock wheels are too heavy for lightweight sports car, I can’t help myself thinking of sticking really lightweight wheels on my Chim just to test how it changes ride quality.
“Of all the OE 15/16" wheels, the OZ lattice pattern split rims are the lightest, the Estorils (7-spoke, std on 500s) the heaviest with the 5-spoke Imolas in between. IIRC I weighed the OZ front wheels with Bridgestone 205/55 tyres at 18.5 kg and the rear ones with Bridgestone 225/55/16 at around 20 kg. The front wheel alone is 8.5 kg; Imolas are in the low nines. ”
It’s a shame and good opportunity for improvement at the same time IMO.
A 15x7 alloy - equal to OEM front wheels on the Chimaera should be between 5-6kg. I used 15x6,5 alloys on my mx5, the weight was between 4-5kg.
The lightest rim I used was the Desmond Regamaster at 3,9kg. That’s half of the weight of our Imolas....
Stock wheels are too heavy for lightweight sports car, I can’t help myself thinking of sticking really lightweight wheels on my Chim just to test how it changes ride quality.
QBee said:
GR_TVR said:
phazed said:
I can weigh a 235/40/17 or 255/40/17 on 17"x 8" RL7 wheels.
Would be interesting to know. I've got the same wheels but run 215/45/17 and 235/45/17 tyres.
I will weigh my SP12s. R1R tyres, 225/45 17 fronts, 225/40 18 rears.
Fronts SP12 Wheels, 225/45 17 Toyo R1R tyres, about half worn, 17.6kg
Rears, SP12 wheels, 224/40 18 Toyo R1R tyres, just about on the legal limit, 18.3kg
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