The "Cayman owners and track days" 2021 thread

[OliR]

Booked in for a Geo setup with Centre Gravity in a couple of months time, and I'm just thinking about how I want my suspension. I know a bit about Suspension Geo but I'm far from an expert, so probably the peak of Mt Stupid on the Dunning-Kruger curve. Those of you with Adjustable Anti Roll bars, what are you running? I'm thinking soft front and medium rear - is it true the car feels quite unsettled in high speed corners with a setting of hard rear?

Thanks.

 

[Twinfan]

I'm running the stock medium/medium on my car, Oli. I've also read that at high speed the rear can be a bit loose on the hard setting.

What's your thinking on soft for the front?

 

[OliR]

I believe softer up front that rear improves the rotation of the car, perhaps at the expense of front tyre wear?

Do you have your Geo settings you'd be willing to share?

 

[Twinfan]

Yeah, sure!

[ul][*]Front: -2 degrees of camber on each side, 1 minute of toe each side (2 minutes total toe)[*]Rear: Just over -1.5 degrees of camber on each side, 10 minutes of toe each side (20 minutes total toe)[*]Standard ride height[*]Standard roll bar settings (medium/medium)[/ul]Note that I needed shims to get -2 degrees camber on the front, but no other parts. This is basically a fast road setup and a good all rounder rather than a track focussed setup.

 

[OliR]

I’m guessing -1.5 was the most you could on the rears too without some additional parts. Was the difference from stock noticeable straight away?

I have noticed some unexpected understeer, but I’d also like to maximise the life of my tyres. Hopefully sort both these out.

 

[Twinfan]

Yep, -1.5 is the maximum you can get on the rear with standard parts and ride height. If you want more, you'll need RSS toe links or similar.

It wasn't a massive difference post-geo to be honest. From the factory my car was maxxed on the camber and the toe front/rear weren't a million miles away from where they are now. So the biggest change for me was going from -1.5 to -2 degrees of camber on the front. It's added stability more than anything else, the car feels like it's on rails on the road.

 

[OliR]

Thanks, have you set the car to "full aero" too? Losing precious 10th's when out on the road . But in all seriousness I intend on doing that the same time as the geo, remove the slats in the wheel arches and tilt the wing slightly.

I see no reason why we can't fiddle with the ARB settings at the track actually, be interesting to compare them back to back.

 

[Twinfan]

Nah, I'm not messing with the aero. Ralph did on his GT4 I believe so you might want to ask him what he thought of it. I don't see the point in adding extra drag as I can only imagine it's needed on very tight and twisty circuits and only then if you're hunting for absolute maximum cornering speeds for lap times.

 

[TDT]

Booked in for a Geo setup with Centre Gravity in a couple of months time, and I'm just thinking about how I want my suspension. I know a bit about Suspension Geo but I'm far from an expert, so probably the peak of Mt Stupid on the Dunning-Kruger curve. Those of you with Adjustable Anti Roll bars, what are you running? I'm thinking soft front and medium rear - is it true the car feels quite unsettled in high speed corners with a setting of hard rear?

Thanks.

Enjoy your trip to CG. Not sure how they are running the operation during the social distancing restrictions however during normal times they are quite willing to treat you to a half day seminar on vehicle chassis dynamics and kinematics.... a real education.

After asking you about how you drive the car and intend use it. You'd usually go out on a test drive on their favourite benchmarking route to get a baseline of the car. Whilst you are in the passenger set - they demonstrate to you the traits your car is exhibiting on the current setup and advise on what they think needs to be done to correct/improve. It's fascinating.... things that you thought were...'oh that just how it drives' - and that you subconsciously modify for - can be dialled out and you then get back to having a completely neutral and balanced platform, when the car reacts only to your input.... not you reacting to what the car wants to do.

Normally you'd be allowed in the workshop and under the car with them whilst its on the ramps - they explain all the changes and the intent of the changes, you can ask all the questions you can think of.

After the set up work, you re-run the test route and they demonstrate the effects of the changes and you get to drive the route and feel it for yourself also.

Ref ARB's - as you mentioned - start out in factory settings M/M for your first day to get a feel for the car if you've not driven it on track before. You'll have lots more to be thinking about that ARB settings.

That said - I run M/H. I have moved back and forth between M and H on the rear and prefer H on the rear for my setup as it puts the car on a little bit more of an edge compared to the front, allowing for better rotation and getting into the corner - its also means that the car telegraphs its intentions more readily compared to M, which feels safe but lazy/or less progressive to me, but both ends will be in balance... and that the point about there ARBs - its about the balance of the roll centre Front-to-Rear and where you want to get messages sent from.

I haven't tried soft on the front yet: this gives less responsiveness to weight transfer across the roll center of the axle (greater roll), and with the weight transfer you'll be leaning even more on the front tyre edges and this leads to more tyre wear - and the spring rates for the car are still relatively soft for track work anyway - but of course this a road car, approved for use on track.

Hard ARB on the rear does not makes as much impact to rear stability as incorrect management rear toe does.

Rear toe deviation is the thing that makes the car the most unsettled and it comes on under various conditions, where weight is loaded and unloaded from the rear.... this can happen under very heavy braking where the rear can get light and start to move around at the end of a 120+mph straight, and also over yumps... like down through Craners @ 100mph+.

The car has a rear toe deviation issue because of the strut based design of the suspension at the rear, the fixed rear toe arm and also the use of rubber for a number of the bushings and joints. The combination of all of these means that rear toe does not stay the same as the wheel/damper travels up and down (known as toe curve) - mean it can range all the way from toe in-toe out dependent on the wheel position.

The way to properly fix the curve is to get adjust rear toe arm to make sure static toe is properly set in alignment with the front of the car in the first place and then to find a way to more tightly control the movement of the rear wheels though up and down motion... this can be via more damper control, better wheel carrier/hump control, adjusting spring rate, removing the rubber bushes/mounts that flex under high loads.

This is the information for reference - but probably won't be something to deal with day1. Maybe something you'll come back to if you get more serious.

Center Gravity will be able to set the car up very very well for you. They are amongst the best in the business.

The first geo i had done on my car was done by them.

 

[TDT]

Something for 718 GT4/Spyder owner to be aware of.. there does seem to be an issue with gearshift linkages becoming unattached on the transmission side... the most common result is that you cannot select odd gear and reverse.

The car is still drivable in the even gears. The linkage needs to be reattached.

I've been passenger in a 718 GT4 and this happened in 2020 and the owner said it wasn't the first time, and there are increasing reports of this happening elsewhere as people are starting to run the cars on track now.

Just to be aware of.

 

[Twinfan]

Yep, saw that on Rennlist earlier T. An easy fix I believe but a pain in the backside if it happens. I must look up where the nearest OPC is to Snetterton...

 

[OliR]

Thanks for the info TDT, really informative post. I had booked into CG based on the good things I'd heard via word of mouth and your comments there echo it which is all reassuring. I'm actually booked in towards the end of May in the hope that some of the restrictions may be lifted and that I can be in the workshop with them. I don't wish to make this thread GT4 specific, and to keep to the spirit of the thread, would you also recommend them for anyone tracking their car? Is there much adjustability on non GT Caymans, for example?

I have heard comments around the rear getting loose under heavy breaking, but it's great to have the explanation of why. Seem to remember an Autocar review said putting PASM into sport helped to dial this out, how much of that I'll notice.. I guess we'll see.

What are you thoughts on putting the car into the full Aero setup? I can't see any reason not to from my reading around.

 

[Twinfan]

All 718s are adjustable, Oli. I had my old 981 GTS aligned and both camber and toe can be done, shims added etc. The non-GT cars generally have lower limits of adjustment as standard but they can (and I'd recommend that they) be aligned properly to get the best out of the them without having to add any parts. Non-GT cars have fixed anti-roll bars though so I think they have less adjustment in other areas than the GT cars.

 

[OliR]

Ah that's good to know, would make sense the limits are lower like you said. Just trying to keep the spirit of inclusivity up as per your OP and not take the thread down a GT4 rabbit hole []

 

[Twinfan]

Of course!

Getting a geo setup done, even just to check it's balanced side to side, is totally worth doing on any Porsche. It costs around £120 at the place I use so you don't have to spend huge amounts to get it done. Just check that the place you go to has good and accurate equipment. OPCs can do it, but I don't think they spend the time to ensure it's absolutely spot on just "within tolerance". For that reason, I'd always go to a specialist.

 

[TDT]

All 718s are adjustable, Oli. I had my old 981 GTS aligned and both camber and toe can be done, shims added etc. The non-GT cars generally have lower limits of adjustment as standard but they can (and I'd recommend that they) be aligned properly to get the best out of the them without having to add any parts. Non-GT cars have fixed anti-roll bars though so I think they have less adjustment in other areas than the GT cars.

Thats not completely correct. Series Cayster (981 & 718) do not come with split control arms that you shim.

Yes you can some some minor adjustment of camber by moving top mounts and setting toe.

But thats about it.

Series cars have fixed ARBs yep.

if you then want more adjustment beyond what the OEM parts allow, you'll need to new bits.

 

[TDT]

Of course!

Getting a geo setup done, even just to check it's balanced side to side, is totally worth doing on any Porsche. OPCs can do it, but I don't think they spend the time to ensure it's absolutely spot on just "within tolerance". For that reason, I'd always go to a specialist.

Yep - I would make sure to get this done as a matter of course... it will even make a difference on the road...let alone track.

OPCs generally will only set geo within OEM limits.

Thats said - a few are now offering a GT car suspension setup service... Bournemouth is one such iirc.

 

[Twinfan]

Cheers T, and thanks for the correction re. split control arms. I knew someone with proper technical knowledge would correct me []

Totally agree re. geo setups for road driving too.

 

[TDT]

Thanks for the info TDT, really informative post. I had booked into CG based on the good things I'd heard via word of mouth and your comments there echo it which is all reassuring. I'm actually booked in towards the end of May in the hope that some of the restrictions may be lifted and that I can be in the workshop with them. I don't wish to make this thread GT4 specific, and to keep to the spirit of the thread, would you also recommend them for anyone tracking their car? Is there much adjustability on non GT Caymans, for example?

I have heard comments around the rear getting loose under heavy breaking, but it's great to have the explanation of why. Seem to remember an Autocar review said putting PASM into sport helped to dial this out, how much of that I'll notice.. I guess we'll see.

What are you thoughts on putting the car into the full Aero setup? I can't see any reason not to from my reading around.

Using PASM setting will help to a point - because this will control the dampers by stiffening. But eventually the loads are such that the behaviour still presents... but nothing to worry about initial i expect. Depends on how hard you going.

Ref aero - no reason not to have a play I'd suggest. I figure there's no point having the features on the car and never playing with them.... may as well have saved the money.

These are still not Aero/DownForce cars and really its about balancing aero performance and negating lift... this will give stability through medium to fast corners. Drag penalty is a couple mph at 125+mph - and by the time yours reaching those speeds in these caysters - you're nearly back into a braking zone anyway. Drag is only small factor on the biggest GP circuits... Silverstone in the UK with Hanger and Wellington and then on the continent like Spa with Kemmel.

The one thing i do have a problem with though is wing risers.... I want to see proper data. I would only do what is done on the CS race car or the RS whenever it arrives.

 

[TDT]

Cheers T, and thanks for the correction re. split control arms. I knew someone with proper technical knowledge would correct me []

Totally agree re. geo setups for road driving too.

All in this to learn together... great thread