Planning some suspension mods for the 911 - any suspension experts resident?

Gibbo

Gibbo

Gibbo

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Hi there

On the road the 911 handles great and has mild understeer. On track however the understeer is more pronounced, I've messed with pressures but that's just moving grip around, not improving anything. Yep there is trail braking of course which helps but I'd rather improve the car too.

Spoke to a few people and many recommend widening the front track not only helps with understeer but settles the front end down more too as it's lowering centre of gravity too. So some recommend that just adding 5mm front spacers helps a bit. Or adding spacers all round improves the whole cars ability marginally or even better fit them all round but say 7mm on front and 5mm on rear to get overall improvements while dialling out some of the understeer.

Thoughts?


Of course what works best to get rid of understeer and improve car further is GT3 sway bars front and rear which are adjustable so can set the car up and even better GT3 lower control arms as the stock Carrera suspension can only max upto -1 degree camber whereas GT3 arms give upto -3 degrees negative front camber which greats helps dialling out understeer. However these mods could be warranty issues whereas spacers are not as they were a factory option. :)
 
I think with a car like yours, any improvement in lap times are more likely to come from increases in your driving talent than messing about with the setup of your car.

That's not a slight on you.
 
PardonTheWait said:
I think with a car like yours, any improvement in lap times are more likely to come from increases in your driving talent than messing about with the setup of your car.

That's not a slight on you.
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Done a lot of track time and feel I'm close to what my limits are and the fact the car is pushing wide is not my driving but due to the cars suspension setup, therefor to go faster I need to dial that out. :)
 
Stiffer/uprated Anti roll bars.
Set up the fronts (obviously full geometry setup rather than just tweaking fronts is ideal) to have negative camber as from the factory most cars are hovering around neutral/positive by a few tenths of a degree or more at the front, and negative at the rear.
This can be seen in your sig picture too.

A few hundred quid(?) and the car will feel like it's cornering in the dry when it's actually wet. :cool:
 
ps, why not look at the geometry to start with

£1 bet says the car has toe out at the rear as standard? loose a bit of that to start with imo
 
LEUVEN said:
Stiffer/uprated Anti roll bars.
Set up the fronts (obviously full geometry setup rather than just tweaking fronts is ideal) to have negative camber as from the factory most cars are hovering around neutral/positive by a few tenths of a degree or more at the front, and negative at the rear.
This can be seen in your sig picture too.

A few hundred quid(?) and the car will feel like it's cornering in the dry when it's actually wet. :cool:
Click to expand...

Already done a GEO and maxed out at just short of -1 degrees, which is max on Carrera, hence GT3 arms required. Car handles great, I just want to improve it further. :)
 
PardonTheWait said:
I wish I was a good enough driver that I needed to sort out the handling of my Porsche :D
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You don't need to be Michael Schumacher to see that you can't open the throttle all the way out of Coppice because the front end slides out wide really.

I don't consider myself an expert, and I don't know anything about the kind of setups that RR layout cars need, but front camber is a good thing.

I've run my car with -1.5, -2, -2.5 and -3 in the front. It makes a massive amount of difference to the cornering grip.
Went from 1.5 to 3 and was blown away by how ridiculously awesome the front end felt. Backed it down to -2 on concerns about the tyre wear. I thought -2 should be ok but the amount of grip and confidence that disappeared was disappointing, so I compromised at 2.5 and it is very good. The point I'm trying to make is that even half a degree makes for a very appreciable difference in the feel and grip level.

Spacers will likely make a nice improvement too, has on both cars I've done it too, if they are a factory option then I'd go for it, nothing to lose. Wider track is one of the GT3 selling points isn't it?
 
Clarkey said:
You don't need to be Michael Schumacher to see that you can't open the throttle all the way out of Coppice because the front end slides out wide really.

I don't consider myself an expert, and I don't know anything about the kind of setups that RR layout cars need, but front camber is a good thing.

I've run my car with -1.5, -2, -2.5 and -3 in the front. It makes a massive amount of difference to the cornering grip.
Went from 1.5 to 3 and was blown away by how ridiculously awesome the front end felt. Backed it down to -2 on concerns about the tyre wear. I thought -2 should be ok but the amount of grip and confidence that disappeared was disappointing, so I compromised at 2.5 and it is very good. The point I'm trying to make is that even half a degree makes for a very appreciable difference in the feel and grip level.

Spacers will likely make a nice improvement too, has on both cars I've done it too, if they are a factory option then I'd go for it, nothing to lose. Wider track is one of the GT3 selling points isn't it?
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Yes GT3 has 5mm spacers fitted as standard I believe. I will probably do the front arms at some point, but spacers are £100 whereas front arms are a grand.
 
centre gravity would be able to help ? Widening the track is simply adjusting the front motion ratio effectively softening the front. Also affects the scrub radius
 
Can't you use adjustable top mounts on the 997? I see they use McPherson struts. That would be cheaper and is a simple DIY to swap them out and keep them away from Porsches prying eyes?
 
LiE said:
You can tell the camber from his sig?
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No, his sig was just an example.
Manufacturers have to have cars set up to slightly understeer as it's safer/easier for average joe to control.
Next time you're out on the road, look at the front wheels compared to the rear and you'll see it too, especially on larger F:R cars like BMWs etc.
 
Simon said:
centre gravity would be able to help ? Widening the track is simply adjusting the front motion ratio effectively softening the front. Also affects the scrub radius
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COG recommended 5mm front spacers to another guy, not had chance to speak to himself myself.

Porsche say upto 7mm is fine, 8-12mm is not fine and 15mm-21mm is ok as long as hub centric. If I get time and Chris is available shall give him a call. Looking around Porsche forums and a lot of running spacers but mainly for the looks though those who comment all say the same, it improves the front-end especially over bumps making it feel less nervous.
 
Surprised to hear of spacers used on the gt3, you'd think given they use different wheels from most 911s that they would use a different offset wheel to deal with track issues if you're talking ~10-15mm per side? Spacers seem a bit aftermarket to be used on a factory spec car...not inherently wrong, but a solution that surprises me on a car of this calibre.
 
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