997 4 wheel alignment / Geo etc

[fastgerman]

Hi Guys,

I have noticed that my 997 isn't handling quite as well as it used to, especially on bad roads.

It isn't pulling to either side incl. under braking.

Tyres are the OPC Michelin spec and pressures are all good.

4 wheel alignment carried out and returned to factory.

Porsche Guildford are offering a reduced price geometry and then I've also heard of Centre of Gravity.

What does a geometry check provide over a 4 wheel alignment? Using Farnham tyres by the way.

Thanks

[EGTE]

I'd say they're going to check for misalignment, perhaps caused by pot-holes or worn parts?

It only takes one (fairly big) bump to knock them out of whack.

Maybe just phone them and ask?

[EGTE]

Check this out: could be handy info on Page 2.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[mollytherocker]

In what way is not handling like it used to?

[88racing]

If you're happy with the factory settings, there's no point in going to Centre Gravity (there's no "of").

[mr pg]

It's Center, not Centre too, and there're well worth a trip if you want something other than factory.

[fastgerman]

mollytherocker said:

In what way is not handling like it used to?

I'm not sure how to explain it, seems a bit harsh on bad roads. Just had a major service at Porsche in May so don't think there is anything wrong with shocks, top mounts etc.

I don't want a track setup geo so factory settings are fine for me - assume the 4 wheel alignment at Farnham tyres would have done this? or do Porsche have a different way of calibrating than a standard tyre centre?

Tyres seem to have plenty of tread but are 3 years old now - perhaps not as flexible as they were?

Farnham tyres = £40, Porsche = around £200...

Edited by fastgerman on Thursday 4th June 13:37

[Trev450]

fastgerman said:

Tyres seem to have plenty of tread but are 3 years old now - perhaps not as flexible as they were?

What make are they?

[fastgerman]

Michelin Pilot Sports - purchased approved used via Porsche Guildford so kept the same make

Correction - 4 years old, clearly not driving the car enough

[Mario149]

fastgerman said:

Farnham tyres = £40, Porsche = around £200...

Edited by fastgerman on Thursday 4th June 13:37

For £40 you're unlikely to have got a pucker Hunter-type 4 wheel alignment down south I would wager. I took our BMW family wagon to a place in the lake district while on holiday up there a couple of months ago and watched them do it. Even up north it cost me £100 or so.

[Mario149]

Just to add, I also recently had my 993 alignment done at a very well known indy. I drove home thinking it was a dog all of a sudden, but initially put it down to me getting used to new shocks/springs etc that had also been put on. A couple of weeks later it went in for a major and clutch at the place I normally take it, and I asked them to check the geo to make sure I wasn't going nuts. Turns out whatever the previous outfit had done it wasn't align the wheels even if they did give me a before and after print out. My regular place showed me the before settings they found and they were all over the shop. They then re-did it and car now drives fine. Needless to say the previous outfit won't be getting my car again.

[Magic919]

It's probably fair to say that in decending order it's geometry, four wheel alignment and then tracking.

I've used Wheels in Motion a few times and Guildford OPC did my last one as I was running out of time before a trip. Guildford have a nice Hunter machine, but I thought they were a bit dear.

[fastgerman]

Thanks Magic

What is the difference between 4 wheel alignment and tracking?

Is this not the same?

Geo is only needed if I want to move away from standard setup?

Just to note, my steering wheel does not wobble at any speed, it does not pull to either side, no vibrations under braking etc. Just a bit 'harsh' on dodgy roads, more than I remember - or the road has got worse ;-)

[Magic919]

Tracking is just front axle toe adjustment. I only ever go for geometry as it goes way beyond the basic wheel alignment. That's with standard cars and suspension. You can read a lot of information on this site http://www.wheels-inmotion.co.uk/wheels-alignment....

[GT3andy]

Only advice I could personally give is take it to someone who actual understands, and more than likely tracks Porsches. They're rarer than first imagined as there is a lot of BS out there. I have had mine geo'd on many occasions and around 30% know how to do it properly. last had mine done by JZM, and must say was perfect if you wanted a recommendation. At the same time, if they know what they are looking at you'll find out what is OK and what isn't about the general condition of your suspension. just all very interesting if you're like me. Well worth it if you want confidence in your car.

[Mario149]

GT3andy said:

Only advice I could personally give is take it to someone who actual understands, and more than likely tracks Porsches.

Unfortunately, that's not even certain. The outfit that cocked up my geo go racing....

[PorscheGT4]

And people ask for race geo's on road cars which I see a lot !

[edc]

If your tyres were new and 7-8mm 4 years ago but are now worn and not much above the marker at 2-3mm then that may help explain some of the extra harshness.

[Mario149]

PorscheGT4 said:

And people ask for race geo's on road cars which I see a lot !

I imagine that must make driving on the road a bit special

[Ian_UK1]

fastgerman said:

I'm not sure how to explain it, seems a bit harsh on bad roads. Just had a major service at Porsche in May so don't think there is anything wrong with shocks, top mounts etc.

I don't want a track setup geo so factory settings are fine for me - assume the 4 wheel alignment at Farnham tyres would have done this? or do Porsche have a different way of calibrating than a standard tyre centre?

Tyres seem to have plenty of tread but are 3 years old now - perhaps not as flexible as they were?

Farnham tyres = £40, Porsche = around £200...

Edited by fastgerman on Thursday 4th June 13:37

My personal experience is that an OPC wouldn't know what a knackered damper or a split top mount felt like if they fell over them. It's also a big mistake to make the assumption that any suspension part on a 997 'must' or 'should' be OK. The quality of the suspension parts fitted to the 997 is nowhere near as good as the older cars. Most of the 997s suspension components are made (very shoddily, IMHO) by TRW, unlike the Lemforder and ZF parts on the older cars that lasted (relatively-speaking) forever.

The 997 has several weaknesses in the front suspension. In no particular order: track rod ends fail for fun. top mounts split (or more accurately, the rubber inserts separate from the metal) the rotational bearings under the strut tops fill with water and start to break up, bump stops perish and crumble, rack ends wear and introduce play in the steering arms, steering rack sleeve bearings wear leading to up/down play in the rack, pinion bearings wear introducing play into the steering input side, control arm centre bushes soften introducing fore/aft play in the suspension and inner control arm bushes delaminate. The dampers also have a much shorter life than you'd expect if the car's used even moderately hard. There will be plenty more items I've missed!

To put this in perspective, my own car (a 2010 997S.2 with 50,000 miles) recently had a lengthy stay at CG to sort-out a wayward handling issue. Almost ALL the items I mentioned above had to be replaced. The steering rack had play everywhere and needed to be exchanged (the car is now on its THIRD rack). All 4 dampers where completely shot: whilst they physically looked OK, didn't leak and had recently passed an MoT with flying colours, having all 4 tested on Bilstein UK's damper-testing rig showed there was almost no low frequency damping effect left (which, unsurprisingly, was the primary cause of the wayward handling). In addition, all 4 bump stops were perished, the front top mounts and bearings were split/rusty respectively, and both track rod ends were partially seized. The rear springs had also sagged slightly leaving the car without enough 'rake' (cured by lowering the front a little to match). And all this on a 5-year old car after just 50,000 miles !

So assume nothing, and go to CG where Chris will strip your suspension down and find-out exactly what the real issues are. It will then be put back together in tip-top condition and the car set-up to drive the way you want it to. I guarantee the transformation will be amazing and you'll have a silly grin on your face all the way home!

Edited by Ian_UK1 on Friday 5th June 12:39