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My 2019 718 Cayman GTS PDK

BJ Innes said:
Ralph,

Thank you for posting the above You Tube clip. Always interesting to hear the Vloggers take on the 718 Cayman GTS PDK. All the previous official road tests by UK mainstream mags have been with the 6 speed manual version. The PDK optimises the 718 GTS in no small measure. Also good to hear positive comment rather than the usual chorus of dissenters.

My first track impressions are coming around soon.

Brian

Brian

I'll be interested to hear your impressions as I am taking my 718 BGTS to Blyton Park in May and Castle Coombe in June.

 
718 Cayman GTS Wheel Alignment and more......

Lots to tell following my wheel alignment session at my local Michelin Specialists, GT Tyres, Forres. This was my first geometry check on the car following suspension settling-in after 1170 miles. Tyre pressures were equalised all round at recommended settings, and a full tank of fuel on board.

I had better warn those of a non-technical disposition that the following narrative involves some nerdy techno stuff, so apologies for that.

The first thing to mention is that the Hunter Laser 4 - Wheel Alignment rig at my local Michelin specialists did not have the very latest software update showing the 2019 model year of the 718 Cayman GTS. The nearest model specific programme shown was for the 2017-18 Cayman with -20mm PASM X-73. The 718 Cayman GTS programme showed only the -10mm PASM, not the optional -20mm Sports PASM GTS X-81 version. It was decided to set the programme for the -20mm PASM rather than the -10mm GTS PASM, as this was closest to the ride-height of my car. A Hunter software update is due shortly I was told. Presumably OPC's have this software update already installed on their Hunter rigs. However unlikely, I would be interested to hear from any owners of a 2019 Cayman GTS who have had wheel alignment adjustments done at their OPC if this is indeed the case. Please note the new -20mm Sports PASM on the 718 GTS is now designated X-81, with X-73 being the older version of the -20mm PASM.

Still with me? Good.

The "Before Adjustment" values on my car were as expected slightly skew-whiff on both axles. This has been the case on every Cayman I have owned. Factory geo settings always settle after about 1000 miles as springs and bushings bed-in. Even with the skew-whiff settings shown, my car steered absolutely fine. Most owners would not be thinking of having the geo settings checked after such a short mileage. For my type of driving, along with the undulating, winding rural roads my car is driven on, wheel geometry is very important. It gives "the road feel" to my car through the steering wheel. In my experience with owning 5 Caymans, I have found maximising the negative camber on the front axle with zero toe, or as close as possible, is best for both road and also occasional track driving use. On the rear axle, 2 degrees of negative camber with a total toe-in of between 0-16" and 0-18" absolutely perfect for my driving style. In my experience with these settings, tyre wear patterns on Michelin PS4S N0 tyres have been very evenly balanced across the tread.

My first track day impressions of the 718 CGTS are in approximately 2 week's time at the Oulton Park RS day.

For those interested, I have attached below both before and after print-outs of the relevant geo settings. In my experience, and for my driving requirements, these setting work very well indeed.

Finally, the Michelin tyre rep called in at GT Tyres in the morning prior to my arrival later that afternoon. Apparently there is a new Cup 2 tyre due to be launched soon designated the Cup 2 R. I was told the tyres have already been tested to N-rated specifications for forthcoming Porsche sports cars. My understanding is that the Cup 2 R is a road legal tyre. Perhaps the new 718 GT4 will be equipped with the new Cup 2 R tyres. Who knows?

I will have more information in subsequent posts following close up inspection of the underside of my 718 CGTS while it was up on the ramp. Some very interesting observations resulted. More on this later.

Brian

Below is the Before Adjustment settings ex-factory.









 
Nice results Brian.

I have unusual memories of Forres.

I was about 19 at the time, and as a young design engineer had gone up to survey a Tarmac plant in Elgin.

I went up with one of the site lads, and the follow day (after a skin full of Gillespies the night before [&:]) I was asked to take the long wheelbase Transit pickup back to Nottinghamshire.

I had never driven a van before, never mind a Transit or a pickup.

I stopped in Forres on a side road to consult the map, and the road had quite a camber down towards the pavement.

I tried to get as close to the kerb as possible when I parked, and smacked the H-frame behind the cab on a lamp-post :ROFLMAO:

Oops.

Not the best of starts on a 9 hour drive.

Nothing that a fabricator with a big hammer couldn't put right back home. [;)]

BTT

How does the 718 feel now with the -1.30 camber ?

 
James,

Interesting you know of Forres, in Moray. Small world as they say.

Had an excellent 165 mile drive for lunch with friends in west Aberdeenshire today. I took the Old Military Road via Corgarff on the outward journey. Returning via the Cabrach Speyside distillery route on the homeward leg. Beautiful weather with temperatures more like May than February.

The drive was an excellent shake-down for my revised geo settings. The steering is scalpel sharp, bullet straight, and road feel now comparable with my previous Cayman R. Really! The Power Steering Plus option definitely a contributor to the excellent road feel. The route was empty of traffic, and included fast quick changes of direction with flowing "S" bends, roller-coaster crests and dips, and adverse camber corners. It provided a very good test for both man and machine. I used Sport mode with manual shifting throughout. The car is brilliant at these sort of roads and the revised geo settings are absolutely perfect for me and the sort of roads I drive on. My 718 CGTS is now track ready. 1360 miles up and counting. So far, so good. Photo below taken on the Cabrach distillery route.

Brian



 
Looks great Brian

Nice to hear the geo settings have given the desired characteristics for your road driving - hope they are just as good on track. [:)]

 
718 GTS Top Front Strut Mounts Maxed on slots

The photo below shows the front top strut mounts on my car at their maximum negative camber setting.

With the exception of a few very specialised 911 GT models, all road going Porsches have only rudimentary slots or eccentric bolts for camber and toe adjustments. As a result, the fine tuning accuracy of suspension geo settings is all but impossible. It's very much a hit and miss job, that is why tiny discrepancies from side to side is the normal outcome.

The spherical bearing rose joints as fitted on some 911 GT models provide extremely accurate suspension geometry adjustments over a much wider range than can be offered by eccentric bolts and slots. Spherical bearings also provide solid direct anchoring of suspension components at the expense of NVH.

Brian





 
Looks as though you're maxed-out there Brian.!

I may be wrong but I think the rear camber either isn't adjustable or easily adjustable; only toe-in? From your before and after measurements it looks as though they were pretty close to your target values anyway.

I presume that now you're well into the running-in period (3,000 km?) you're starting to extend the rev range? Keep up the good work reporting your CGTS experiences.

Jeff

 
Motorhead said:
Looks as though you're maxed-out there Brian.!

I may be wrong but I think the rear camber either isn't adjustable or easily adjustable; only toe-in? From your before and after measurements it looks as though they were pretty close to your target values anyway.

I presume that now you're well into the running-in period (3,000 km?) you're starting to extend the rev range? Keep up the good work reporting your CGTS experiences.

Jeff

Jeff,

The rear camber and toe on the 718 are both adjustable by eccentric bolts as on previous Caymans. However, the amount of negative camber adjustment available on the rear is limited by the meagre toe adjustments available. In my experience, you cannot get much more than 2 degrees of negative camber on the rear axle while still maintaining sufficient toe-in.

With 1300 miles up I am now extending the rev range to 5500 occasionally. On my trip across the hills yesterday I did open the taps now and then. It is very difficult to evaluate the comparative road performance between the 718 GTS and my previous 718 CS. Both cars had identical specced steering, chassis, wheels and tyres. On such the roads as I am driving on, there is very little in it, on public roads anyway, between the two cars regarding acceleration through the gears. A true comparison may well have to wait until the Oulton Park track day coming up soon. The GTS is more responsive on the throttle and the suspension in normal mode is definitely firmer than on my 718 CS. The PCCB brakes are in different league as you will imagine.

I put the steering improvements down to a combination of 4 individual elements.

1. Power Steering Plus.

2. Maxed negative camber and zero toe on the front axle.

3. Porsche Composite Ceramic Brakes providing significantly less unsprung weight on the front axle.

4. Michelin PS4S N0 tyres.

Incidentally, following the revised wheel geometry settings, the front wheel crabbing that occasionally occurred previously, has now been completely eliminated.

More coming up. I have some interesting photos of the underside of my GPF spec 718 GTS to follow shortly.

Brian

 
BJ Innes said:
718 GTS Top Front Strut Mounts Maxed on slots

The photo below shows the front top strut mounts on my car at their maximum negative camber setting.

With the exception of a few very specialised 911 GT models, all road going Porsches have only rudimentary slots or eccentric bolts for camber and toe adjustments. As a result, the fine tuning accuracy of suspension geo settings is all but impossible. It's very much a hit and miss job, that is why tiny discrepancies from side to side is the normal outcome.

The spherical bearing rose joints as fitted on some 911 GT models provide extremely accurate suspension geometry adjustments over a much wider range than can be offered by eccentric bolts and slots. Spherical bearings also provide solid direct anchoring of suspension components at the expense of NVH.

Brian

If the 718 is basically the same as the 981, to get better camber you need split wishbones using shims. Pushing camber at the rear by using the more solid GT4 top mounts can risk fouling the diagonal control arms, if wider wheels and tyres are to be fitted. GT3/4 front top mounts don’t seem to offer any extra camber but do tighten up the suspension somewhat. In any event I think it is preferable to achieve extra camber beyond stock via wishbones, rather than top mounts and use after market TCA to keep toe to correct settings.

An issue I have found is the drop link rod end bearings take the brunt of rubbish roads and I’m upgrading my Tarrett parts to specialist bearings after almost 3 years.

 
BJ Innes said:
Motorhead said:
Looks as though you're maxed-out there Brian.!

I may be wrong but I think the rear camber either isn't adjustable or easily adjustable; only toe-in? From your before and after measurements it looks as though they were pretty close to your target values anyway.

I presume that now you're well into the running-in period (3,000 km?) you're starting to extend the rev range? Keep up the good work reporting your CGTS experiences.

Jeff

Jeff,

The rear camber and toe on the 718 are both adjustable by eccentric bolts as on previous Caymans.

Yes, of course Brian...brain fade.! Although they're rather inaccessible, it's a pity that there's no adjustment at the top mount location. Presumably Porsche reckon that a maximum of ~2-degrees negative camber is adequate for general road driving and occasional track driving.

Unfortunately, with your car under warranty none of the undoudtedly worthwhile mods Ralph mentions are available to you. I'm sure that come your next track day some of your GTS updates and upgrades will prove beneficial.

Jeff

 
Ray ... similar to my 981. I went outwith the Porsche spec. for front negative camber (-1.0`) though.

This overall set up appears to be the `max` available from a standard 981.

Brian ... good news and a great test on those roads. My last (year) run over Cabrach saw some very poor road (edge) conditions due to the construction work up there (wind farm).

 
Ray and Andrew,

There is nothing overly critical I can report from looking at your wheel geometry settings. The values shown are absolutely fine for your 981 CS with -10mm PASM. Your zero front toe settings are spot-on. It would do no harm to tweak a bit more negative camber on the front next time you are having a geo reset. On the rear axle it's pretty much the same story. The only comment I would make if being picky, would be to tweak the left side rear toe back to -0.8" and increase the right toe also to -0.8", but I am well aware of just how tricky this is to achieve given the crude eccentric bolt adjustments. Rear axle camber angles look fine to me.

In my experience with Caymans, the irritating front wheel crabbing that occurs when applying large steering lock while parking etc, is mainly due to wheel alignment and camber on the front axle. I've also experienced this phenomenon at some point on all my Caymans. Lowered sports suspension options, the lower the better, together with maxing the negative camber and zeroing the toe on the front axle, can vastly improve or at best eliminate, the wheel crabbing issue. Finally on this topic, it's worth noting that tyre brand, tyre pressures, and road surface, can also exacerbate wheel crabbing.

Brian



 
My Gasoline Particulate Filter 718 Cayman GTS PDK down under.

I had the opportunity at the recent geometry check when my car was on the ramp, to have a closer inspection of the underside of this, the 2019 GPF evolution of the 718 Cayman GTS. Some interesting differences from my previous 2016 718 CS PDK were noted. I should mention that my previous car also had the Porsche Sports Exhaust fitted.

Previously posted photos of the revised exhaust mufflers had already indicated that things "down below" seemed a bit different in both layout and hardware compared to my previous car. The following photos clearly indicate the extensive development work which Porsche has put in to the GPF equipped cars, and the 718 CGTS in particular.

The exhaust mufflers are more compact than on my previous car. Some of the exhaust pipework has increased in diameter and the layout of the exhaust system upstream of the flange joints next to the rear wheel arches has altered significantly. It is already well known that the 718 GTS has a different turbocharger and revised induction and exhaust systems, so many of the changes from my previous 718 CS will be common to the pre-GPF 718 GTS models. On that note, I would be very interested to see if the exhaust muffler layout on pre-GPF 718 GTS cars is the same as on my 2019 model. The exhaust sound seems different on the GPF car, and with the compact mufflers, it would be a relatively easy modification for Porsche to design a different exit point for the twin tail pipes on a future evolution 718.

Moving forward to the undertray, is where the most significant changes apply. There are more cooling louvres and cut-outs in the undertray to facilitate expelling the extra heat generated by the GPF unit. I was surprised to see how small this unit is, which is in clear view being exposed to the airflow by a rectangular cut-out in the undertray. I looked hard for evidence of additional catalysers in the exhaust system but could not find any. I know from reading articles on the 718 GPF installation that a single large diameter 4-way catalyser/GPF unit is deployed on the flat-4 turbo. From what I could see there were no other catalyser units visible in the exhaust system other than this single GPF unit. To clarify this, my plan is to request another look underneath my car at my OPC when I next have my oil and filter change done. The undertray will be removed for this task, so I'll get a better view of the turbo, exhaust, and GPF/cat systems. I shall report back.

Whatever the outcome, Porsche have clearly put a huge amount of development resources into the 2019 GPF flat-4 turbo. Going by the vigorous and emphatic posts elsewhere on this forum, I seem to be one of the very few who see great potential in this excellent engine. I would not be sorry to see a GT4 Cayman or similar with a 450bhp version of the flat-4 turbo. As a motorsport driver now retired, I would not care two hoots how many pistons were involved in producing 450-500bhp with train-pulling torque to match.

Back to the road performance of my 718 CGTS, I would say that as far as road driving is concerned there is not a great deal of difference in acceleration through the gears compared to my previous similarly specced 718 CS PDK. If I were comparing a basic spec 718 CS PDK, that is one without the -20mm PASM, Sports Exhaust, Limited Slip diff, wider wheels etc, the comparison with the GTS would perhaps be more significant. So far, I would say that my GTS has optimised the 718 Cayman experience. This has not resulted in a huge leap in road performance, more like an incremental step forward in power, torque, and throttle response compared my previous car. The track day timings from the on-board Porsche Track Precision app following analysis at home may perhaps tell a different story.

The photos follow below.

Brian



 
2019 718 CGTS GPF Unit.

A very compact installation. I reserve judgement until further investigation as to whether this is the only emissions unit within the 718 GTS exhaust system.

Brian





 
Whatever the outcome, Porsche have clearly put a huge amount of development resources into the 2019 GPF flat-4 turbo. Going by the vigorous and emphatic posts elsewhere on this forum, I seem to be one of the very few who see great potential in this excellent engine. I would not be sorry to see a GT4 Cayman or similar with a 450bhp version of the flat-4 turbo. As a motorsport driver now retired, I would not care two hoots how many pistons were involved in producing 450-500bhp with train-pulling torque to match.

Ah! A man after my own heart. Well said sir, and can I say, as a former GPDA member and past holder for some years of a full unrestricted international racing licence, that makes two of us thinking precisely the same!

Very interesting thread by the way, as was your previous Cayman S one.

 
BJ Innes said:
The exhaust sound seems different on the GPF car, and with the compact mufflers, it would be a relatively easy modification for Porsche to design a different exit point for the twin tail pipes on a future evolution 718.

An interesting observation Brian. Just to play devil's advocate, bearing this in mind maybe the Boxster and Cayman running around with an exhaust arrangement similar to that of the GT4 which have been labelled 718 F-6 are in fact just 718 F-4 mules with a different exhaust..!

Jeff

 
Jed and Jeff,

Good to know that I am not a completely isolated soul who doesn't share the views of those who wish to see the flat-4 turbo engine binned. Jed, your motorsport credentials are very impressive. I was merely a National Speed event licence holder. Good to have a fellow motorsport driver who views the engine only as a mere facilitator working in partnership with a great chassis to achieve track success. For everyday driving, the current flat-4t as installed in the 718 GTS does a great job.

Jeff, Porsche could well be playing the flat-4 naysayers like a Stradivarius violin with the test mules. For my part, I have an open mind. If it transpires the 718 GT4 has the flat-6 4.0, then fine by me. If by some remote, all planets aligning miracle, and Porsche choose a development of the flat-4 turbo for the new GT4, you will hear my cheers from the Highlands all the way to Lands End. Being realistic, it's more like "Fat chance" for a flat-4t, as has already been posted by one emphatic naysayer on this forum.

Brian

 

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