Chassis weight
Discussion
Has anyone ever noticed that the Ultima chassis is made of rather low-quality steel (ST 37). Because of that they have to use very "thick" material to provide the necessary protection (4-5mm). If they used Cro-Mo steel, the weight of the chassis could be majorly reduced (at our calculations about 25-35%) and the stability could be improved. Any comments to that?
What exactly makes the Ultima GTR/Canam so heavy excluding the engine/tran? I remembered Ultima Cars said, the Ultima GTR roller weighs in at about 1700 lbs without the engine/tran.
The chassis and body can't weigh over a 1000 lbs? The parts that makes up the car shouldn't add on that much weight at all, like the wheels, brakes, suspension, and etc... If majority of the weight comes from the chassis and the body then there are definitely solutions to lightening the car by 100-200 Kg. Would it be reliable to use aluminum for the chassis?
Aluminum won't be an alternative as it tends to break without a warning. If you used high-grade steel on the chassis, the stability would highly increase, you wouldn't have to powder-coat it AND you would loose some weight. The weight of the chassis could easily reduced by 50 kg or so which is a not so bad figure.
I guess the reason is that it's technically more difficult to fabricate a chassis from high grade CroMo steel. The good ones all tend to be heat treated, which makes stress relieving after welding a bit of a pain.
We looked into CroMo chassis tubes (quite a while ago, when I was a student), and we found a good supplier hard to find. We ended up looking at a stregthening treatment, post fabrication called Nitrotech which we found was very good www.nitrotec.co.uk.
We looked into CroMo chassis tubes (quite a while ago, when I was a student), and we found a good supplier hard to find. We ended up looking at a stregthening treatment, post fabrication called Nitrotech which we found was very good www.nitrotec.co.uk.
If you start using more exotic steels then you start to have issues with welding and localised hardening. When you are building one of these things you have to drill holes practically through every member so if you make it of a harder material your going to have fatigue problems as well.
Then there is the whole issue of proving the design. The current Ultima chassis has evolved slowly over the the past 15 years and is very race and road proven. If you made a new one you'd be starting from scratch. If you were going to the effort of a complete chassis redesign then I would have thought that a ali/honeycomb monocoque would be the way to increase the chassis rigidity for a slightly lower weight....eventually.
No idea exactly how heavy the chassis is undressed. It took about 2 people to lift it (3 comfortably) so I figured that it was in the 80-100kgs range. If you have a set of scales and can be in Edinburgh next month I can tell you how much a complete rolling chassis weighs
Then there is the whole issue of proving the design. The current Ultima chassis has evolved slowly over the the past 15 years and is very race and road proven. If you made a new one you'd be starting from scratch. If you were going to the effort of a complete chassis redesign then I would have thought that a ali/honeycomb monocoque would be the way to increase the chassis rigidity for a slightly lower weight....eventually.
No idea exactly how heavy the chassis is undressed. It took about 2 people to lift it (3 comfortably) so I figured that it was in the 80-100kgs range. If you have a set of scales and can be in Edinburgh next month I can tell you how much a complete rolling chassis weighs
My engine weighed 215kgs fully dresses (less headers).
The whole car fully wet weighs 1000kgs (75litres of fuel + 9litres of oil + coolant?).
I can lift the gearbox easily on my own so I recon it must be below 80kgs.
So I my guess at the weight of my car less engine and gearbox will be around 650kgs.
The chassis was lifted by two of us (me and the wife) so its not that heavy and 50kgs seems a lot to lose but if it was titanium..... maybe
The whole car fully wet weighs 1000kgs (75litres of fuel + 9litres of oil + coolant?).
I can lift the gearbox easily on my own so I recon it must be below 80kgs.
So I my guess at the weight of my car less engine and gearbox will be around 650kgs.
The chassis was lifted by two of us (me and the wife) so its not that heavy and 50kgs seems a lot to lose but if it was titanium..... maybe
If you want to lessen the wieght, then you go ahead but, --- Tornado tryed to lessen the wieght of their GT40 Chassis. Guess what happened, under extreme race conditions, the thing had a tendancy twist and SNAP.
Two cars I know of had serious suspension failure while under hard cornering!! ( The chassis was about 200 pounds lighter than the GTD item. But being pritty much the same. )
Moral of the story Don't fix what an't broke.
Two cars I know of had serious suspension failure while under hard cornering!! ( The chassis was about 200 pounds lighter than the GTD item. But being pritty much the same. )
Moral of the story Don't fix what an't broke.
I think the goal here is to lessen the weight responsibly, thus increasing performance without sacrificing strength or stability. No one here is trying to get themselves hurt or damage the toy, but 'tweaking' is half of the fun. Did you push your car out of the shipping container fully assembled and leave it at that? I say if there is excess weight, pull it out!
GTRCLIVE said: If you want to lessen the wieght, then you go ahead but, --- Tornado tryed to lessen the wieght of their GT40 Chassis. Guess what happened, under extreme race conditions, the thing had a tendancy twist and SNAP.
Two cars I know of had serious suspension failure while under hard cornering!! ( The chassis was about 200 pounds lighter than the GTD item. But being pritty much the same. )
Moral of the story Don't fix what an't broke.
The car does not have a weight problem! Now the corvette, viper, and porsche are a different story. You'll find bigger improvements in lap times if you focus on your own capabilities (and weight) as a driver rather than the chassis weight or tweaking of the Ultima. No matter how good we all think that we are, as a driver, we need to be realistic about this. This car is capable of performing at a much higher level than most of us as drivers!
-Mack
You'll find bigger improvements in lap times if you focus on your own capabilities (and weight) as a driver rather than the chassis weight or tweaking of the Ultima. No matter how good we all think that we are, as a driver, we need to be realistic about this. This car is capable of performing at a much higher level than most of us as drivers! -Mack
Lets put the lardy aspect into prospective.
The new Lambo has 585Bhp ish but weights over 1850kgs.
The Zonda is slightly less powerful but weighs about 1350kgs.
A Can-am with sound deadening, stereo, full screen and weather gear weighs 1000kgs, a GTR about 1100Kgs.
However by only having one tank, removing the stereo, sound deadening, having the airoscreen and alloy block I would expect to be able to get the wet weight of a Can-am down to below 900kgs........
All we would need is 1000bhp and we would be knocking on the door of a F1 car.
The new Lambo has 585Bhp ish but weights over 1850kgs.
The Zonda is slightly less powerful but weighs about 1350kgs.
A Can-am with sound deadening, stereo, full screen and weather gear weighs 1000kgs, a GTR about 1100Kgs.
However by only having one tank, removing the stereo, sound deadening, having the airoscreen and alloy block I would expect to be able to get the wet weight of a Can-am down to below 900kgs........
All we would need is 1000bhp and we would be knocking on the door of a F1 car.
bigmack said: The car does not have a weight problem! Now the corvette, viper, and porsche are a different story.
-Mack
Absolutely right.
I could't have put it better myself.
As the man said. Amen
In view of all the discussion about chassis weight, I have just been out and weighed my GTR chassis which was delivered a couple of days ago. It has the full RAC spec roll cage and weighed in at 290 lbs (133 on the front and 157 on the rear). Admittedly, this is quite a lump but for road cars, the chassis spec. has to be a trade off between weight, stiffness and cost. If cost were not a factor, then titanium would probably be the material to go for but you'll need to win the lottery to buy the tubing and then win it again to pay to have it welded. At the end of the day and other things being equal (which they won't be) you could probably save 60 kilo's. This is a lot in a race car but if it's a road car your building, do what Stig has done and buy a bigger engine.
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