Chassis Rigidity

[Shraka]

I've been looking around the net for some numbers on chassis rigidity for Hondas, especially for the DC2 Integra VTiR and Type R but the only Honda I can find with quoted figures for is the S2000.

I've compiled a list of the cars I've found numbers for so far, as well as weight and their nm/deg to weight ratio below. It's obviously not a 100% accurate guide to the chassis rigidity of a car as it depends where the weight is exactly, and where the strength is, but if gives you some idea of how two cars will compare when given the a similar damper / spring combo.

BMW Mini Cooper S - 24,500 Nm/° - 1130 kg - 21.68 Nm/°/kg
BMW Mini Cooper Convertible - 9000 Nm/° - 1175 kg - 7.66 Nm/°/kg
BMW E90 - 22,500 Nm/° - 1425 kg - 15.79 Nm/°/kg
BMW Z4 - 14,500 Nm/° - 1385 kg - 10.47 Nm/°/kg
BMW Z4 M Coupe - 32,000 Nm/° - 1495 kg - 21.40 Nm/°/kg
BMW E36 Touring - 10,900 Nm/° - 1498 kg - 7.28 Nm/°/kg
BMW E36 Z3 - 5,600 Nm/° - 1175 kg - 4.77 Nm/°/kg
BMW E46 Sedan (w/o folding seats) - 18,000 Nm/° - 1430 kg - 12.59 Nm/°/kg
BMW E46 Sedan (w/folding seats) - 13,000 Nm/° - 1430 kg - 9.09 Nm/°/kg
BMW E46 Wagon (w/folding seats) - 14,000 Nm/° - 1430 kg - 9.79 Nm/°/kg
BMW E46 Coupe (w/folding seats) - 12,500 Nm/° - 1430 kg - 8.74 Nm/°/kg
BMW E46 Convertible - 10,500 Nm/° - 1570 kg - 6.69 Nm/°/kg
Volkswagon Passat - 32,400 Nm/° - 1660 kg - 19.52 Nm/°/kg
Volkswagon Touareg - 36,900 Nm/° - 2332 kg - 15.82 Nm/°/kg
Volkswagon Phaeton - 37,000 Nm/° - 2395 kg - 15.45 Nm/°/kg
Volkswagon Fox - 17,941 Nm/° - 1012 kg - 17.73 Nm/°/kg
Volkswagon Golf V GTI - 25,000 Nm/° - 1357 kg - 18.42 Nm/°/kg
Saab 9-3 Sport - 21,000 Nm/° - 1305 kg - 16.09 Nm/°/kg
MG ZT - 24,000 Nm/° - 1625 kg - 14.77 Nm/°/kg
MG MGF - 7,100 Nm/° - 1087 kg - 6.53 Nm/°/kg
MG MGTF - 8,500 Nm/° - 1115 kg - 7.62 Nm/°/kg
Lotus 33 - 3,253 Nm/° - kg - ? Nm/°/kg
Lotus Esprit SE Turbo - 5,850 Nm/° - 1300 kg - 4.50 Nm/°/kg
Lotus Elan - 7,900 Nm/° - 997 kg - 7.92 Nm/°/kg
Lotus Elan GRP body - 8,900 Nm/° - kg - ? Nm/°/kg
Lotus Elise - 10,500 Nm/° - 756 kg - 13.89 Nm/°/kg
Lotus Elise 111s - 11,000 Nm/° - 714 kg - 15.41 Nm/°/kg
Lotus Elise S2 Exige - 10,500 Nm/° - 935 kg - 11.23 Nm/°/kg
Mazda MX5 NA - 6000 Nm/° - 940 kg - 6.38 Nm/°/kg
Mazda MX5 NB - 6000 Nm/° - 1000 kg - 6.00 Nm/°/kg
Mazda MX5 NC - 8800 Nm/° - 1095 kg - 8.04 Nm/°/kg
Mazda RX7 FB - 9150 Nm/° - 995 kg - 9.20 Nm/°/kg
Mazda RX7 FC - 10500 Nm/° - 1223 kg - 8.59 Nm/°/kg
Mazda RX7 FD - 15000 Nm/° - 1280 kg - 11.72 Nm/°/kg
Mazda RX8 - 30000 Nm/° - 1345 kg - 22.30 Nm/°/kg
Honda DC2 Integra VTiR - Nm/° - 1150 kg - ? Nm/°/kg
Honda DC2 Integra Type R - Nm/° - 1050 kg - ? Nm/°/kg
Honda S2000 - 20000 Nm/° - 1250 kg - 16.00 Nm/°/kg
McLaren F1 - 13500 Nm/° - 1100 kg - 12.27 Nm/°/kg
Ferrari 360 Modena - 23000 Nm/° - 1390 kg - 16.55 Nm/°/kg
Ferrari 360 Spider - 13800 Nm/° - 1450 kg - 9.52 Nm/°/kg
Ferrari F430 - 27600 Nm/° - 1450 kg - 19.03 Nm/°/kg

It's interesting to see the RX8 is actually way ahead of the game, with a stiffer chassis than even the Ferrari F430. It'd be interesting to see how that translates to the real world.

If anyone can provide info on any cars to help flesh out the list that'd be great! Like I said, especially for DC2s.

[Mooro]

How do they measure this? ie if it is torsional rigidity wouldn't it matter how far apart the 2 reference points are in terms of degress of deflection. ie a short wheel base car will result in a lower deflection...then again I guess that is an acurate reflection of rigidity in the a short wheel base car is naturally more rigid under torsion

[Shraka]

How do they measure this? ie if it is torsional rigidity wouldn't it matter how far apart the 2 reference points are in terms of degress of deflection. ie a short wheel base car will result in a lower deflection...then again I guess that is an acurate reflection of rigidity in the a shart wheel base car is naturally more rigid under torsion

To be honest, I have no idea how they measure it! LOL. But you're probably right.

[bennjamin]

its just an amount of numbers entered into an equation really - Mind you relevant to new cars only :) Older cars with wear and tear/damage are totally different.

BTW sharka , you do realise your car has 125kw and
173NM ?

[SeverAMV]

if i remember right, DC5R rigidity is about 25000Nm?

[Shraka]

its just an amount of numbers entered into an equation really - Mind you relevant to new cars only :) Older cars with wear and tear/damage are totally different.

BTW sharka , you do realise your car has 125kw and
173NM ?

If you're talking about my signature, that's measured at the wheels.

[Sp00ny]

Interesting Info!

In Reference To your Sig:
That seems like a very low peak Torque Point for a B18C. Usually the Peak Torque is around 6000rpm+. How was it measured?

[Shraka]

Interesting Info!

In Reference To your Sig:
That seems like a very low peak Torque Point for a B18C. Usually the Peak Torque is around 6000rpm+. How was it measured?

Autronic Dyno. It's the peak torque point for the first cam. I had two runs: first run showed peak torque at 6200 on the second cam. Second run showed it on the first cam at 4100rpm and came up with more torque and power so I use that one for bragging rights. LOL.

Check it out if you like:
http://www.artema.com.au/void/stuff/toymods/dyno/results.php?file1=1&file2=35&file3=&update=View+Chart

[bennjamin]

cool that.
anyway lets keep on topic - interesting facts n figures regards to your NM ratings , can you please quote your links ?

[Shraka]

Sure, I found them all over the place (usually forums), but then most of them are compiled together here:
http://forum.rscnet.org/archive/index.php?t-210895.html

But I've seen a few other places where some of these numbers are confirmed. The RX8 figures for example are around quite a few places and I've seen it measured in lb-ft/degree too and converted it and it comes out at about 30,000nm/deg.

[PaZzMaN-R]

would anyone care to translate this for us lamens?

[Shraka]

It's just a measurement of how stiff the chassis is from the factory. nm/deg shows how much torque (measured in NM) it takes to bend the chassis 1 degree. The less the chassis flexes, the better. Means the suspension can work better on the road. It's the reason why so many people put a strut brace on their car, as that adds rigidity to the body.

Of course, you also have to factor in the total weight of the car. The more weight, the more weight there is acting against the chassis trying to bend it. so that's why I have the nm/deg/kg. It's just a rough guide to how stiff the chassis will be in the real world. There are are other factors like where the weight is, and which points in the car twist more than others, which my nm/deg/kg doesn't take into account.

[PaZzMaN-R]

its very confusing in that layout. interesting information none the less.

[Shraka]

its very confusing in that layout. interesting information none the less.

Yeah, sorry about that. If I could get some bloody info on some Honda's I'd re-do it and put it up on my own website. But it seems the S2000 is about the only car that Honda has posted this information for.

[JohnL]

Maybe they have something to hide? My CB7 responded so well to fitting strut tower braces (yes I know there are no struts per se, but you know what I mean) that I can only assume the standard chassis is quite floppy, at least in the front and rear sections.

Theory says that such braces should work best on McPherson strut suspensions but be less efficacious with wishbone and other suspension designs. However, with the double wishbone style suspensions fitted to Hondas (and some others) the results should be about the same (as with Mac struts) because the upper wishbone mounts right at the top of the suspension, meaning the loads are fed into the chassis in a somewhat similar manner as they are with Mac struts (if you were so inclined it would be relatively easy to fit Mac struts into a double wishbone Honda because the 'strut' towers more or less already exist, so the chassis itself is quite similar to a Mac suspended car).

Made and fitted front brace first, which made the steering significantly more responsive and gave a feeling of more... umm, well, stiffness. It felt almost like the front damper rates had been stiffened up a bit. You could feel the car more closely following bumps / depressions in the road, the car feeling 'tighter' and just... umm... well... nicer! I expected less from the rear brace, but the result was at least as good as fitting the front one.

One thing maybe worthy of note, most sedans these days allow for the rear seat to be folded down in order to allow long loads to be passed from the boot into the passenger compartment. This is good in theory, but only from a veiwpoint of marketing theory.

To achieve this means that there is commonly now no stressed panel behind the rear seat, maybe just a pathetic pressed metal 'brace' on each side of the seat (more useful for attaching trim to than stiffening the chassis). This is unfortunate because this panel is an important part of the chassis structure, triangulating the rear end of the 'box'. Imagine the chassis is a cardboard box enclosed on all six sides, now lets take out the rear panel of the box and see what happens to it's structural integrity? I can just imagine the backroom arguments between the chassis engineers and the marketing department, but then I'd guess the marketing people won this battle years ago!

Another point about this, it's less safe. In a major accident, where are the contents of the boot likely to end up? What if you had say a 15kg tool box in the boot and were involved in a head on collision? The latch holding the seat back in position is going to present little resistance to that mass obeying Newtonian laws of motion!

In addition to the rear strut brace, on my Accord I've made and fitted a bolt in tubular steel 'X' brace behind the rear seat (where sedans used to have a stressed panel before the various marketing departments deemed cargo capacity more important than handling or safety). This works somewhat like the 'X' braces that some people fit into the boot space, triangulating the towers to the rear of the chassis, but it doesn't take up all my boot room!

This made some noticeable difference to handling etc, but not as much as the rear strut brace did. Having said this, the X brace isn't directly connected to the strut brace yet, but will be soon. I hope to never test it's efficacy from a safety aspect!!

[Shraka]

Yeah I've got a DC2, so my back seats fold down too. And because I have a hatch I have even less structural support between the rear wheels.

You can see the difference having a back folding seat makes for performance on the BMW E46 sedan chassis. With folding seats the chassis stiffness is 13,000 Nm/°, and without them it's 18,000 Nm/°!! Folding rear seats make a massive difference.

If you look on that list though, you'll see the S2000 listed. I'm just not sure why they'd list the S2000 and not any of their other cars? Unless you're right, and most of Hondas other cars aren't very stiff.