Lack of front end grip

[edc]

Most of the Porsche Indies who do geo and the likes of Centre Gravity dont publish there fast road set ups. There are plenty on here though who have been tweaking and modifying their Boxsters for some time. I've been to Centre Gravity 3 or 4 times with my 2 986. The last time I had my Koni FSDs fitted I didn't go as I knew what I wanted by then. 

The range of adjustment especially on the rear is fairly limited to some extent. I would always go for the drilling/lengthening of the front top mount slot as it gets you up to 1 degree extra negative camber and if you are vaguely lowered or on old saggy suspension I would definitely get some adjustable rear toe links. It just allows you to keep the best balance between camber and toe which will otherwise be compromised. 

[Mr96er]

On 4/24/2019 at 10:21 PM, John K said:

 

...A new set of matching boots transformed the cars handling and the confidence I now have [ON FAMILIAR ROADS] is awesome

Corrected For Accuracy🤓

 

[PaulQ]

11 hours ago, ½cwt said:

As geometry keeps coming up in this thread, is there a place where one can find ideal geometry settings for normal road use, be they factory settings or ones discovered by users over time. 

Have a look over on the 986 forum as people seem to be a bit more willing to share what settings they are running and why. 

I would post mine, but not had a proper geo done since changing the ride height. 

Basically though as much camber as you can get on the front (will be around - 1 degree max unless you elongate the front shock mounts) with neutral toe, same on the rear but with a touch of toe in, and you won't go far wrong. 

[PaulQ]

12 hours ago, edc said:

if you are vaguely lowered or on old saggy suspension I would definitely get some adjustable rear toe links. It just allows you to keep the best balance between camber and toe which will otherwise be compromised. 

What's the compromise.? 

[Daveslp]

Tyre difference front to back really effects under/ oversteer. 

If you have 205 front and 255 rears, 50mm difference(approx) the rear will muscle the front noticeably. It will force the front to understeer, even without tyre squeal, mainly it will cause a lot of sidewall flex up front.

Keeping the balance to 20/30mm difference can be quite noticeable.

 

Of course all this speal is assuming your basic balljoints/arbs/ bushing/shocks/alignment are in perfect order

[½cwt]

OK, I did my own research properly (rather than being lazy and asking everyone else) and seem to have found a definitive factory document covering the 986 posted on another forum.  Answers my own question and hopefully will help others.

https://www.renntech.org/topic/9652-wheel-alignment-specs/

 

Included ride height data in the first part of the table.  I haven't posted the table because I don't know the copyright status however it looks like it could be a Porsche original document.

[PaulQ]

9 hours ago, Daveslp said:

Tyre difference front to back really effects under/ oversteer

It's interesting that the 50mm difference only applies to 17" wheels running summer tyres in stock sizes.

With winters and on 16" rims this drops down 20mm and on the 987 it was 30mm.

[PaulQ]

32 minutes ago, ½cwt said:

OK, I did my own searching and seem to have found a definitive factory document covering the 986 posted on another forum.  Answers my own question and hopefully will help others.

https://www.renntech.org/topic/9652-wheel-alignment-specs/

 

Included ride height data in the first part of the table.  I haven't posted the table because I don't know the copyright status however it looks like it could be a Porsche original document.

 

 

 

Got that one bookmarked for the ride heights.

If you go to any four wheel alignment place, then all the factory settings should be preloaded into the machine anyway and it will show green when inside each parameter, and red if not. 

Bear in mind that if you widen the front strut mounts for extra camber for example, then it will be running outside of the above parameters. 

 

[the baron]

1 hour ago, ½cwt said:

OK, I did my own research properly (rather than being lazy and asking everyone else) and seem to have found a definitive factory document covering the 986 posted on another forum.  Answers my own question and hopefully will help others.

https://www.renntech.org/topic/9652-wheel-alignment-specs/

 

Included ride height data in the first part of the table.  I haven't posted the table because I don't know the copyright status however it looks like it could be a Porsche original document.

Thanks for posting this, as a guide for some alignment centres however the ones using computer alignment such as Hunter kit should have this pre dialled in, but useful for confirming with centre as a back up.

[edc]

As above. I think this is even in the handbook. I've got a PDF copy stored from a few years ago. I'm not sure though that "best" or "best for you" is necessarily factory spec. You can make the car feel much nice just by making sure it's symmetrical and the settings are close to the same side to side. 

[edc]

15 hours ago, PaulQ said:

What's the compromise.? 

If the car is low and you want a more personal geo spec it's very hard to achieve. On the rear once you have dialled in the correct toe you are basically stuck with whatever camber that also happens to give. Typically this would probably be something like -2 rear and -1 front. Nothing wrong with that per se but it's otherwise a pretty standard set up. 

With the adjustable rear links you can still get the best toe but also even out the balance of camber front to rear and even have more negative camber on the front than the rear. 

I think I've had the geo done 2 maybe 3 times since I had the adjustable rear toe links. On either the first or second attempt I had it a very close match maybe even more negative camber on front that rear. The last one I did I backed it off a bit and it's now just a shade less on the front than rear. 

In my opinion it's the front vs rear geo that has the most significant change to the handling and balance assuming you have an accurate as tight standard ish geo to start with. 

 

[½cwt]

Factory may not be 'the best' and you have to respect those that have found improvements by having the ownership time and experience, however it makes a starting/datum point from which to work particularly if there isn't a definitive alternative out there which I what I was seeking to establish.  As I referred to earlier in the post with Impreza's, the Prodrive recommended setup varied from the factory but at least you knew it had been developed from the factory baseline.  If you know the Porsche factory baseline it is a point to develop from.  If you put on something you don't know as a starting point it can be quite easy to lose direction and you pay with uneven tyre wear etc.

[PaulQ]

5 minutes ago, edc said:

If the car is low and you want a more personal geo spec it's very hard to achieve. On the rear once you have dialled in the correct toe you are basically stuck with whatever camber that also happens to give. Typically this would probably be something like -2 rear and -1 front. Nothing wrong with that per se but it's otherwise a pretty standard set up. 

With the adjustable rear links you can still get the best toe but also even out the balance of camber front to rear and even have more negative camber on the front than the rear. 

I think I've had the geo done 2 maybe 3 times since I had the adjustable rear toe links. On either the first or second attempt I had it a very close match maybe even more negative camber on front that rear. The last one I did I backed it off a bit and it's now just a shade less on the front than rear. 

In my opinion it's the front vs rear geo that has the most significant change to the handling and balance assuming you have an accurate as tight standard ish geo to start with. 

 

Yes, when I was lowered on the H&R - 30 springs I ended up with around - 2.3 degrees of rear camber to maintain some toe in. 

With the elongated front strut holes I got around - 1.5 in the front with 0 toe. 

I was very happy with this, but I'm now back on standard springs, and not had a proper geo done yet, so was just wondering what benefits running the same camber all round, or even a touch more on the front then the rear would bring.?

[edc]

Its all just handling preference to be fair. The way the standard car is it is always set up for safety and a tendency to understeer. Squaring up the camber just makes the car more neutral or more oversteer if you keep going with it. In day to day driving you will barely notice the difference as you just don't lean on the tyres enough. 

I haven't tried different tyre sizes or a square tyre set up but imagine it to be of a similar effect perhaps. I've just ended up with a set up I like purely by experimentation. That's why I'm hesitant to say mines the best or to post up the exact geo settings as I just don't know how others drive or what balance they like. For me the suspension and handling is the fundamental core of the car and the single biggest thing you feel when pushing on. The rest of the car be it gearshift or a few extra ponies just don't make as big an impact to the confidence you have in the car or the way you enjoy it. 

[PaulQ]

8 minutes ago, edc said:

I haven't tried different tyre sizes or a square tyre set up but imagine it to be of a similar effect perhaps.

I'm running near square with 225f/ 235r though eyeing up some 245's for the rear. 

I'll have a chat with my alignment guru, and see what he recommends. 

[Daveslp]

17 hours ago, PaulQ said:

It's interesting that the 50mm difference only applies to 17" wheels running summer tyres in stock sizes.

With winters and on 16" rims this drops down 20mm and on the 987 it was 30mm.

That's true, interesting. 

It suggests that the need of the width isn't really for torque traction...you'd struggle less in the dry anyway.

So why? All about driving characteristics?

 Do they think drivers push harder in summer and need some understeer for safety...and a more neutral set up for winter incase it goes wrong the car will be easier to bring back??😅😅

[Ad_78]

I recently had this issue on my 986S and found it to be a combination of things:

low tyre pressure doesn’t help, check all tyres, I have the Carreras 4’s and run 30 psi front and 36 psi rear and find this works well for me.

I also replaced my coffin arms and anti-roll bar drop links and then had a 4 wheel alignment carried out and the difference in the car is night and day. 

I had no confidence in the car recently as it felt really light at the front and unstable over 60/70 mph, since the work it handles like it’s on rails. The other bonus is the low speed knock that was driving me mad is now also gone. The tuning forks could probably benefit from being replaced soon and I will then probably look to do the rears. The car is over 20 years old, so the rubber will be starting to go all round.

I m ow this may sound controversial to some, but I had my 4 wheel laser alignment carried out at Kwik fit. £120 for 2 years or 8 alignments on a proper laser alignment ramp, it’s been Roth every penny. I hide it last year and use 3 times already (hit a big pothole on a BoXa meet and took it straight down after and got sorted).

Replaced my suspension pars as above and took it down and got a free alignment, when I replace the tuning forks I shall do the same again, so I do think it’s worth it.

i know they aren’t always the best being a franchise, but the tracking has always been spot on, I will still use my independent for MOT’s and any other work I can’t do myself, but as far as tracking and tyres, they really are rather good.

I hope this is of some use to you in getting your car sorted.

Thanks

Adam

[Delaneycatz]

By way of an update... new spats fitted and went in today for geo and a few other bits (gear box oil change, ac regas and the mot as its due) failed mot. Typical brake lines are rusted and need replacing, just my luck! Haven’t had results yet.  Thanks all for input and advice.