aeronautica86

The thread about making a 951 competitive with the gt3 RS made me start to wonder about this topic. In that thread many responses imply that the 951 will always have a disadvantage in the handling department compared to the RS due to the latter's much newer and more advanced suspension components/setup, and I assume that chassis design comes into play here somewhat as well.

I am no suspension whiz, so my curiosity compels me to ask the experts and racers on the forum. What are the differences in the suspension setups of the two cars? I know the 951 uses a torsion bar rear and macpherson strut front suspension. What does the GT3 use, and how does it differ mechanically from what the 951 uses? Also, how do those differences create a car that inherently handles better on the track - or in other words what does the modern GT3 suspension do better than the 951?

hot-J

Well, the better parts from a stock gt3/rs are better dampening shocks, coil overs, adjustable sways, upper and lower control arm links, meaning there are 2 on the top, and 2 on the bottom that create a "V". The upper and lower arms together react to camber changes in the road better than most any other setup there is, creating better traction in all situations.

gt37vgt

Well the later suspension genraly to react better= reacts less.. if you were to put 16" rims on a 911 the 951 would probably be faster ..
suspension design of the 80's the toe and camber changes alot over the wheel travel to try to counter act the tire flex.. with later desighns the wheels have almost the same camber and toe as the spring compresses as the tires flex much less ...

that is the simple version there is also alot of other subtle developments in anti dive virtual pivots to get better low speed / high speed combo ...

also i would imagine there is a little bit of flex in 951 suspension compared to 997 not sure where parahps the rear sub frame ..
to try develop a 951 for later 18" wheels its better to look toward other front engined sports cars for advice than 911's as rear engined set6 up is way differnt ..

DanR

serious question but why does wheel size change things so dramatically especially when you look at track wheels and tire combos and the rolling diameter is very similar 16 to 18 (certainly when shed in R6's)

gt37vgt

as there is simply half the side wall on a larger rim..and ther fore half the tire flex.. also tire flex has reduced heaps with tire tech over time ..

944CS

All you have to do is take a look at newer cars to see where the magic happens. Started with the 993 (LSA multi-link rear), 996 evolved it, 997 evolved it even further

Front of 2010 cars is still McPherson strut. The design and adjustment range, stock to stock, is better on the newer cars, but if you know what you are doing and are not limited by rules, you can change the 944 Turbo geometry in the front to increase the performance.

In the rear of the GT3 RS you have a multi link set up. It really doesn't matter what I say about it, to answer you question as to what does it do better than the 944 Turbo's, it allows for more control of the wheel/tire. Now, you can get into a lot of trouble because the more things you add that are adjustable, the more you can really screw up the car's handling. But if you know what you are doing, more adjustability is a nice thing.

aeronautica86

thanks for the responses guys

this brings me to another question, if you take a 951 and fully upgrade the suspension - I'm talking control arms, bushings, adjustable sways, top of the line coilovers like moton/ohlins/jrz, 18" rims and tires, changing the torsion tube to something like the koklen setup - how much difference would there be between the two cars in terms of handling ability? Obviously the GT3 is still going to have some advantage, but at that point how close would the two be in ability?

944CS

In a non professional racing environment it would come down to the drivers, but this is assuming:

Same tires
Good alignments on both cars
944 upgraded to similar hp/weight

If you go a step further and say same hp/weight, same pro driver, same tires, the GT3 will be faster

333pg333

So to go further with this on a hypothetical level, what would you add or change if given a blank canvas? Excluding the Motorsports division based on price.
As most of us would have seen Steve Rea's car with the Corvette rear end. Can we change the front end without having to tube frame it?

gt37vgt

Although effective i think the vette rear end is just not right I think you should have built a vett based cobra/clubman type thing ..but if you are goin to get a 951 tub for $ 500 i can understand how it happens ..I think my rear end is a reasonable compromise .it took a few days . it has moved the pivots up and the outers back ..so it now has a bit of anti squat heaps less tow change heaps lass camber change..
my chassis guru believs it will happily put down 500hp with 10" tires and be more stable under brakes .
i turn my nose up at the KOKLEN thing..

Chris White

In reality the most amazing thing about the GT3 suspension is that it does so well on the track and can also be used on the street. Sure it’s a bit stiff and low for the street but it is usable!

JohnKoaWood

As seen in another forum.. currently being worked on a 951 chassis purpose built! Yes that is dual front a-arms.... not sure about the off axis rear pivot point.. but hey it is his ride!



from the same thread...



AND


"We has the first doors ready for delivery for a Spanish race team 3.7kg with hinges a door locks."

944CS

There is nothing special about a Vette rear end. Hell, it uses tie rod ends as track rods for cost savings. The 993 and later rear suspensions are more advanced. If you are going to go to the trouble of putting another rear suspension in a 944, why not custom double wishbone, it will be the easy to model and you can design it exactly the way you want it instead of mixing something designed for an entirely different chassis.

Rogue_Ant

John, can you PM a link to that thread?

Van

The (modern) 911 rear end is an evolution of the Weissach suspension that was developed for the 928... The geometry of the "multi-links" keeps the alignment of the rear wheels more consistent and desirable under load.

The front suspension isn't that different in geometry, but flex is reduced in the components and in the chassis. Unlike the 951 which has a large hole in the body in the front for an engine, the 911 has a metal floor pan and sheet metal connecting the shock towers - thus providing a lot less front end flex.

There are also other subtle, but non-suspension related items, that play a role. I'm pretty sure the 911 has a lower center of gravity, since it has less glass and a flatter engine. The 911 may have a lower polar moment of inertia (although not as low as a Boxster or Cayman). The rear end weight bias of the 911 actually gives it an advantage under mid-corner acceleration and even under braking stability.

All of these things add up. As stated in the previous thread, a lot can be done to help the 951, solid bushings, strut tower and camber mount braces, different rear suspension designs, reducing unsprung weight, adjustable sway bars and shock absorbers, and so on. But it all takes money and effort, and will compromise the "streetability".