As part of my ongoing project I'm looking to reduce weight on the car. I've changed the driver's seat for a Sparco FIA approved comp seat which is incredibly light after the original one. I've deleted the rear wiper. Are the rear seats heavy ? How many drivers use a cannister instead of the spare wheel ? What other suggestions ?
Quest for lightness.
- Thread starter ocallen
- Start date
Peter Empson
PCGB Member
Hi Nicholas,
The upper part of the rear seat is heavy, as is the rear carpet (although removing this will make it quite noisy). I don't have a spare in the white car (it doesn't fit over the front calipers anyway) so a can of foam replaces it. A lightweight gel battery is a good idea too. The exhaust can be a good saving too, but naturally it's best to wait until you're doing the engine swap for that. Other than that I can't think of any large weight savings in single items, but naturally the sunroof (assuming it has one), central locking, electric hatch release motor, electric windows and so on all add up.
The upper part of the rear seat is heavy, as is the rear carpet (although removing this will make it quite noisy). I don't have a spare in the white car (it doesn't fit over the front calipers anyway) so a can of foam replaces it. A lightweight gel battery is a good idea too. The exhaust can be a good saving too, but naturally it's best to wait until you're doing the engine swap for that. Other than that I can't think of any large weight savings in single items, but naturally the sunroof (assuming it has one), central locking, electric hatch release motor, electric windows and so on all add up.
Peter Empson
PCGB Member
Oli, whilst you're clearly a convert to the superiority of the S2 you still need to make the next step and realise the path to lightness is the path to righteousness 
When the likes of Colin Chapman and Gordon Murray value the advantages of lightness before power it has to be the right place for me to start my project. To discover Mr Empson is already ahead of me on this path and has not given up says that it is the right way to do this or that there are two people making the same mistakes. The fact that I have a 924 turbo badge panel in the garage waiting to be fitted and have discovered that Peter has fitted one already does make me wonder what I have to do to be a pioneer in the 944 world. Maybe a four wheel drive system ?
Peter,
Absolutely agree with you about lightness. Chapman was quite correct in his term "adding lightness to add performance". Less weight = better acceleration, better braking, tighter cornering and less fuel consumption if everything else is equal. It HAS to be the way forward (and an increase in weight is one of the major problems with modern cars, in my opinion. Multiple CD changers, air-con, electric everything, big comfortable seats, crash protection for all eventualitites = much more weight).
I'm with you all the way, chum!
Oli.
Absolutely agree with you about lightness. Chapman was quite correct in his term "adding lightness to add performance". Less weight = better acceleration, better braking, tighter cornering and less fuel consumption if everything else is equal. It HAS to be the way forward (and an increase in weight is one of the major problems with modern cars, in my opinion. Multiple CD changers, air-con, electric everything, big comfortable seats, crash protection for all eventualitites = much more weight).
I'm with you all the way, chum!
Oli.
944 man
Active member
Beyond whats already been said, I would add that the glass hatch and the bonnet are both heavy and represent an extremely worthwhile weight saving (at the vehicles extremities too, where its most useful). Of the two parts, exchanging the bonnet for a fibreglass part will be the cheapest and Id suggest doing this first to counter the other weight easily lost from within the rear of the cabin. Id look long and hard at my chosen wheels too...
Simon
Simon
Tam Lin
New member
Just to add, I think Peter has a carbon bonnet, I have a glass fibre one. Mine is from Simon, of what used to be ESS, with standard mounting/catch, which is very useful if you don't want half the contents of your engine bay nicked every time you park up.
And good luck with the S2 engine swap, it's definitely a good move [
]. Just not a cheap one.
944 man
Active member
Also, you need to consider where the weight is coming form. Much of the weight in my car has been lost from within the middle of the cabin backwards and this will sompletely mess up your weights. In an extreme case the rear of the car will ride high due to the amount of weight removed!
Peter Empson
PCGB Member
I knew you would, so when should I pop around with the skip and the angle grinder? [
]
Peter Empson
PCGB Member
Most of the weight has gone from the rear of my car too, although I can't say it's ever caused me any concern, but I guess my suspension was quite tired when I started out (it didn't look too high even with the lightweight hatch). Nowadays I like to have my suspension fairly regularly setup/corner weighted and the balance is very good.
Naturally I agree about the bonnet and hatch, but they're both fairly big and expensive things to do and will be more of a compromise than a lot of people will want at first (admittedly this is less of an issue with the bonnet). I'd also suggest doing the bumpers if you're having any paintwork done.
I use struts on the plastic rear hatch but not on the bonnet (don't think there's provision for it on mine, but I didn't like the thought of them exerting a constant upwards force anyway), I carry a piece of wood for that duty [] (soon to be replaced by something a bit more hi-tech). I will be gutting the normal bonnet release and replacing them with lockable aerocatches soon, but I'm not actually sure if there's much saving to be had here as these latches are relatively heavy.
Naturally I agree about the bonnet and hatch, but they're both fairly big and expensive things to do and will be more of a compromise than a lot of people will want at first (admittedly this is less of an issue with the bonnet). I'd also suggest doing the bumpers if you're having any paintwork done.
I use struts on the plastic rear hatch but not on the bonnet (don't think there's provision for it on mine, but I didn't like the thought of them exerting a constant upwards force anyway), I carry a piece of wood for that duty [
] (soon to be replaced by something a bit more hi-tech). I will be gutting the normal bonnet release and replacing them with lockable aerocatches soon, but I'm not actually sure if there's much saving to be had here as these latches are relatively heavy.
Peter Empson
PCGB Member
I wouldn't worry too much, get it on track, do a session and come in and remove the spare tyre, tools, carpet and rear seat back (that's probably 30kg in total I guess). Then do another session. The difference isn't subtle, the extra agility will more than outweigh (pun intended [
]) any loss of balance in my experience. It's worth remembering the weight of the fuel and the location of the tank when thinking about this too, my car feels it's best with less than half a tank and I guess I had in the region of 50kg+ removed from the rear when I last ran the car.
Weight is an issue but so is the dynamic centre of gravity. Any weight at the extremities of the car, and high up, is good to go.
Handling a car is much down to moving the weight. The less weight you have at the extremities the less polar inertia so the less you have to worry about it. A significant shift of weight forward will harm rear end traction but will also reduce the polar inertia of the back end during cornering.
Far better to get rid of the weight first and then workout how to dial out any dynamic changes after. If the worst comes to the worst you can always put weight back.
Handling a car is much down to moving the weight. The less weight you have at the extremities the less polar inertia so the less you have to worry about it. A significant shift of weight forward will harm rear end traction but will also reduce the polar inertia of the back end during cornering.
Far better to get rid of the weight first and then workout how to dial out any dynamic changes after. If the worst comes to the worst you can always put weight back.
John,
I agree about the polar moment of inertia point, but with a high polar moment of inertia comes stability. The layout of the 944 (engine front, gearbox rear) increases this figure and makes the 944 an inherantly stable car.
Compare it with a Boxster or Cayman, with the engine and gearbox in the middle, and you realise the difference. My experience of a Boxster is that it is a very nimble little thing which was hugely prone to snap oversteer. Yes, in experienced hands this will make for a more capable vehicle, but inexperienced hands will find themselves heading for the scene of the accident very quickly.
OK, I am taking two extreme examples (and you will never ever get the weight distribution of a 944 to be the same as that of a Boxster/Cayman) but there is merit in each. And the relatively tame handling of my 944 is a source of much comfort when going briskly in greasy conditions. (I consider my driving abilities to be pretty low.)
Oli.
I agree about the polar moment of inertia point, but with a high polar moment of inertia comes stability. The layout of the 944 (engine front, gearbox rear) increases this figure and makes the 944 an inherantly stable car.
Compare it with a Boxster or Cayman, with the engine and gearbox in the middle, and you realise the difference. My experience of a Boxster is that it is a very nimble little thing which was hugely prone to snap oversteer. Yes, in experienced hands this will make for a more capable vehicle, but inexperienced hands will find themselves heading for the scene of the accident very quickly.
OK, I am taking two extreme examples (and you will never ever get the weight distribution of a 944 to be the same as that of a Boxster/Cayman) but there is merit in each. And the relatively tame handling of my 944 is a source of much comfort when going briskly in greasy conditions. (I consider my driving abilities to be pretty low.)
Oli.
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