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

[Gibbo]

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.

 

[Gibbo]

Spacers a factory option? Never heard of that before!

Yep and sold by Porsche parts department too.
Most fit them for stance/looks.

 

[Gibbo]

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.

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.

 

[Gibbo]

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.

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.

 

[Gibbo]

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?

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.

 

[Gibbo]

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

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.

 

[Gibbo]

Gibbo, forgive me if you're a professional driver or something, but wouldn't you benefit more from spending some money on some proper training?

Years ago when I had the RS4 I was convinced it had so many problems with this, that and the other (well, to be fair, it did in some ways ) that I spent a small fortune fixing. I then ended up spending a few days with John from DriveTrain (lol Advert etc.) and I realised a lot of my perceived issues with the car were actually with my driving. A tough fact for me to accept, driving god that I am.

These days I'm loathe to mess with my cars before I mess with my driving style. Spending a lot of time in AWD drive Audis meant I was utterly terrified of powerful RWD for example, and it took some education/training for me to understand why and adjust my driving style accordingly.

Something worth thinking about.

Yes this is true, but not meaning to sound big headed and as Housey says I am going quite well as it is, yes still room for improvement but I feel now that looking to dial out the understeer which 911's have is not a bad thing.

I am not looking to do something which is new or Porsche have not done themselves and the wheel spacers is a cheap and easy option, if they dont work they come off easily, if they do work then great.

 

[Gibbo]

I'm no expert but a stiffer rear anti-roll bar and an extra -1 or -2 degrees of front camber will help reduce understeer. How the car behaves on corner entry and mid corner once you have done this is a bit less predictable.

Nope your spot on!

Some just fit a rear GT3 bar, this dials it out quite a bit, but is not really the ideal solution as essentially all your doing is giving the rear less grip to give the car a better balance.

If I go with GT3 bars, lower arms then the GEO has to be re-done and the car setup to my driving style, aka a date with Chris Franklin. Even fitting wheel spacers will effect the GEO, but nothing drastic.

 

[Gibbo]

My advice is get someone like Sean Edwards in your car for a day before you go messing with it as you can chase the wrong things very easily with Porche's and that will get very expensive very quickly. You need someone who really knows Porsche's to set a marker in your car and tell you what he would adivse. A few hundred quid spent doing this might save you several grand doing something you neither benefit from or really need. All 911's understeer and I think you could improve your technique to improve that. You are going well no question now but I still think there is more time in your car as it is, though I am not the right person to tell you where and how to find it!

Yes agreed m8 and yep improving myself will help but I think you will agree a Carrera has a lot of understeer dialled into the suspension as standard and this is pronounced heavily on track, instead of trying to perfect my trail braking skills, I'd rather it just had a lot more direct front-end with more grip just like a GT3 and as the parts which give the GT3 the better front-end are available then I'd like to play, of course I am not gonna fit anything like that myself simply because afterwards the car would drive terrible as a GEO is a certain requirement.

But fact is my car has just under -1 degree front camber which is absolutely shocking and is why it pushes wide so much on track, the front arms will give me 2.5-3 degrees negative front really allowing for much more front-end bite and I'd aim to run around 2.0-2.2 on a daily driven car to not have bad tyre wear or experiment, but hence a GEO as the whole car needs to be setup so it handles better as a whole, but I will tell you now I hate understeer and on track mine has plenty evident and being able to remove some/most of this will make the car more enjoyable for me.

 

[Gibbo]

Sell Carrera, buy GT3?

Additional cost of GT3, 20-30k. Cost of spacers, £100, cost of swaybars approx £400 and lower arms approx £500 plus a GEO.

So no selling the Carrera which I know is a good example for an unknown GT3 at 20-30k more is not an option.

I cant make my car handle like a GT3 or go like a GT3, if that was possible for a few grand most would do it, but I can improve the Carrera with some basic subtle little mods and then another GEO.

 

[Gibbo]

Hi Gibbo,

You should take a look at: centergravity.co.uk

Give them a call & see what they recommend for your car,

~ Thomas.

I know Chris, spoken to him already, he also made the Mustang handle out of this world, he is a genius.

 

[Gibbo]

Hi there

Spoke to Mr Franklin directly myself at lunch time.

He says front spacers on a 911, particular Carrera works well, hence why Porsche sell them and offer as a factory option.

He basically said yes you induce more scrub, but with 5mm-7mm spacers the advantages outweight the dis-advantages and swapping spacers in and out does not need a re-visit for a GEO.

He said if it was him, he'd have 3mm, 5mm, 7mm and even maybe a 10-12mm too and would experiment with fitting them on the front, back, all at once etc. until got the best driving result.

He says going with 5mm back and 7mm front is a good idea and should be a marginal positive improvement, he gave thumbs up.

Also had a great chat about GT3 Anti-Roll bars, lower arms, again these will give very good improvements for someone who is not a master of trail braking and will certainly be able to set the car up with such parts to make it an understeer king or an oversteer king or simply neutral with a good increase in all round grip levels, resulting in quicker corner speeds.

He said on the MPSS Michelin are saying they work best between -2 too -2.5 negative camber, but any more is not recommended, as such he reckons -1.75 for road and he will do it if I want so I can just undo top mounts, slide right over to give -2.50 for when on track, finish track, undo and push back over. He said this works well and saves having to re-setup the GEO for road or track work. Though fact is 1.75 negative camber would be a huge improvement over the current useless 0.8 negative camber I have.

Still gonna play with spacers myself, find the optimal setup, then save the pennies and visit Chris for some new bits and a full fast road/track GEO setup.

 

[Gibbo]

Hi there

Well went to put the 7mm spacers on the front last night and discovered the car has 5mm spacers fitted all round.

I guess this explains even more so now that why when I test drove a few 911's mine just seem to drive quite a bit better, no doubt due to the 5mm factory spacers and ceramic brakes.

Anyway I still fitted the 7mm fronts as my aim was to go 5mm on rear and 7mm on front as this was my target, just saved pennies by the car already having the 5mm already fitted on the rear.

As such I did not expect to notice much difference, as afterall I've only increased the front track by 4mm overall.

But too my surprise it is noticable and in a positive way, zero negatives. Car still goes to understeer, but definetely more later than it did before, meaning its more closer to a neutral handling setup instead of just understeer and more understeer. Now its more front-end bite, grip, minor understeer which is easily provoked into quite a neutral feeling car. Overall the car just feels more controllable with a better front-end, turn in and response to bumps all seems a little better giving an overall better feel and more fun drive. Car is certainly not oversteer happy though or even close, still tons of grip in the rear, I feel getting more front negative camber would really perfect the car.

Can only imagine the difference it must make going from a 911 with no spacers to this must give a great improvement, so very happy these initial results from such a simple mod and Chris Franklin was certainly spot on, widening the front track would help reduce understeer.

Also picked up new ceramics for the front at the weekend, OUCH!

Question is now I can fit 996 GT3 front arms and get about a further additional 1 degree negative front camber, so would fitting GT3 anti-roll bars give the car more overall grip or would they just be a waste if I did not want them for the ajustability?

 

[Gibbo]

Oh and that's an expensive 4mm!

We did say earlier on that widening track softens it thus dialling US out

The spacers were like £60, so £15 per mm not too bad and well worth it for the results.