Do you ever feel that you don't know what is going to happen next?

[Guest]

Hello, All

When driving in the dry, I find the 3,2 to be a very fast and predicatable car. It gives endless miles of delight from here on the wild roads North Wales down to the hairpins and fast straights of the French Alps. However, in the wet, it as a whole different story, and I wonder whether it is just me (or my car).

When the rain comes down, the steering goes light, and the car *feels* as though it will understeer. That is, Understeer! with a capital 'U' and an exclamation mark. At the same time, the rear end can be cause to break away under power - I have experienced this in fourth gear and 3/4 throttle! Then again, shedding speed - even in a straight line - is not always easy, because locking a front wheel is so easy (that makes UNDERSTEER! - all capitals).

So, just the other day, I was driving on a wet Welsh B-road, and came downhill on a long straight towards a series of sharp downhill bends - a bit of road that I know quite well, and that I could storm in my Lotus Excel. Looking ahead, I just had no idea what the car would do. I hardly dared press the brake pedal in case of a lock-up so I started braking way early. When I did, I got that weight-pushing-from-behind feeling that all 911 drivers know. Anyway, I ended up approaching SO slowly; sort of Morris Marina with worn-out bushes speed! I still did not know what the car was going to do.

So, the oft-repeated mantra is "slow-in-fast-out". But you cannot do "fast out" in a 911 in the wet, because the rear end will slide away (thankfully quite slowly). Compare this with the 944 technique (in the wet) of stick-it-into-second-and-give-it-full-welly even part-way round a roundabout. I tried to do moderately fast out after an Audi TT and got the back end sliding away in fourth gear (while the Audi disappeared off... way, way off).

My car is well looked after and has 4mm+ tread on its Michelin Pilots. So, what is the real story? I can see several possibilities.

1. After 21 years of driving RWD sportscars and 18 months in a 911, I still have a lot to learn about the 911, and that I can eventually learn to predict how it will behave.
2. I have a big problem with my car that no garage (Shirleys, Tony Greatorex, 9M) has dared to tell me about yet.
3. They are all like that - it is not a problem, it is a feature.
4. They just *feel* understeery and nearvy in the wet - I just haveto trust it more.
5. The tyres are crap.

Any thoughts?

Alistair

PS - I started writing this before reading the current edition of 911 and Porsche World, and the article comparing the wet weather behaviour of the 944 Turbo and the rear-engined cars. Amybe it is something that just is part of the 911 experience

 

[Guest]

Alistair,
Sounds like your driving on marbles??????[&:]
My 911 had all but bald rear bridgestones SO2's 255 x 40 x 17, and I have never, never, felt any need to go easy! Apart from circuit work where we would induce massive over/under steer, on a steering pad. Milford proofing ground.
It would seem to me that your suspension geometry is all up the putt!
The only time the 911 should really come unstuck is when the driver makes a sudden transition from power to brakes or visa versa. A steady nerve and smooth actions will take the 911 through all but anything![]
There's been plenty on this forum about this stuff, plus Porsche & 911 mag last year had an excellent article on car handling, all to do with weight transfer, etc.
Whats your tyre pressures?
Peter

 

[Melv]

It would seem to me that your suspension geometry is all up the putt!

My thoughts too!!

Check tyres, pressures (try 36psi cold all four) tread, that they're all going the right way (don't laugh -Bridgestone S02's for instance). Check they all match, i.e. the same make on all four and the same N rating.

Get a full four wheel alignment done.

Check your suspension, wishbone bushes etc........

Melv

 

[Guest]

wishbone bushes

I though they were a Christmas Day treat?
Touche, Melv...

 

[Guest]

Hi Alistair,

Don't beat yourself up, the old 911 dance in the wet can be a little tricky to master, but it sounds like all is not completely well with the car either.

First off, I am going to disagree with Melv. If you have a 3.2 with standard size wheels and tyres, then 36psi cold all round is too high. There are other threads on the 3.2 forum dealing with tyres and pressures and there is some track related pressure advice in the latest Porsche Post that you may be interested in, but the short story is to aim for around 30/33psi front/rear cold and for the track about the same but measured hot (maybe a little higher). Higher pressures just result in a smaller contact patch and are not necessary for a 16 inch 50/55 profile tyres on our cars, especially at the front.

There is nothing wrong with Michelin Pilots but if they are old then they will deteriorate - rubber gets harder and tread blocks wear so they no longer have crisp square edges that cut thru the water. If you have 4mm of tread you are close to needing new boots for the winter. While there is advice in other threads, you can't go wrong with the major name brands like Michelin, Pirelli, Bridgestone, Yokohama, Goodyear, Dunlop. For a good price/performance option you may like to think of the Toyo T1S. You do not need N rated tyres on a 3.2.

Have you had an alignment check? The specialists you mention can all help in this regard. 9M would be a good bet for a slightly more aggresive alignment.

I really think the alignment could be your problem. Mechanical grip in the dry can hide a multitude of sins. Even if the numbers look right, you can get a lot of camber and toe change if the rear spring plate bushings are worn. Your car is at least 14 years old, so the bushings will be worn. The rear toe and camber are set off the spring plate and worn bushings allow these settings to change under load. With sheer mechanical grip, you may not notice this in the dry but in the wet maybe a different story. Certainly something to discuss with the specialists.

Similarly, old (or incorrect) shock absorbers could be a cause (or contributor). On a lightweight early track car, I once ran Turbo spec Konis. They were great in the dry but way too firm in the wet. With a simply "worn out" set of shocks you may find that the shocks are not properly damping the spring motion. In the dry, mechanical grip may be enough to mask this, in the wet it may be much more obvious.

In a well set up 3.2 with fresh suspension and good tyres, you should be able to brake late and deep - even in the wet - provided you are progressive on the brakes. Bumps and very slippery surfaces can be a problem with a light front, but once the weight transfers you should be ok. I have been on very cold, wet, slippery track days (one with fresh oil all over the track) and it is still possible to brake hard and late. I have had passengers comment afterwards that they cannot believe how hard I was able to brake compared to other cars and drivers. You should also be able to accelerate hard. The back of a 911 squats very evenly when you apply power so it is rare to pick up the inside rear wheel. You should have better rear traction under power than a 944. In transitions - like left-right-left thru a roundabout - you have to be careful with all the weight in the back but once the road opens out and you can see the exit it should be game on.

Jamie has recently had a whole lot of suspension work completed and he has posted about the night and day difference. Maybe he can add something here.

HTH

Richard

 

[Guest]

Dudes,[]
I knew Richard would make a reply, and as usual, "well said".
I must disagree with the tyre pressures though; 32 - 36-psi front and 43 - 44-psi rear are what my car normally runs at. (215 & 255 x 40 x 17) I can tell when they are down as I get less noise from driving over bridge joints, etc. Don't get wear in the centre of the tread, seems to be even wear.[]
Just brought new rubbers for the beast; £94.00 each for new Falkens FK-451, 255 x 40 x 17, plus £10.00 for fitting two. £84.00 each for the two front tyres, same brand, 215 x 40 x 17.
If I can get 20k from these (2 years) = £15.00 per month total cost, or 0.01p per mile.[]
Laughing........
Peter

 

[Guest]

Hi Peter,

I have also used FK-451s - rears lasted about 5,000 miles including maybe 5 track days [].

I found they wore in the centres even with aggressive track driving and a decent amount of negative camber. They are a little softer in construction and less grippy than say Bridgestone SO2s but they are very predictable and a good buy. Wet grip when worn is marginal. Dry when worn is excellent.

I am not sure where your 43-44psi rear pressure comes from. Even with aggressive driving on the open road you could be experiencing hot pressures of 50psi. I hate to think what you would see on track. What is the tyre manufacturers max recommended pressure? I doubt its as high as 50psi (might be wrong). I am not sure if noise over bridge joints is a great criteria for setting pressures.

I am not a tyre pressure nazi. I think in general anything between say 28 and 38psi with a 3-5psi front rear differential is going to suit most people just fine for road use and the individual can tweek for comfort and wear preferences within those parameters. However, the really high pressures that Porsche recommended for rear tyres on 964/993 etc have been proven many times to be unnecessary - try a search on Pelican or Rennlist if you don't believe me.

My personal experience is that with cold rear pressures of even 36psi you can get to well over 40psi hot on even a freezing cold wet day. The drop off in rear grip is dramatic. This was with Bridgestone SO2s in size 225/50x16. YMMV.

RB

 

[Jamie Summers]

Peter, I think that those 17" wheels will make a difference to the required tyre pressures - for those of us running standard 16" (or 15" even) I think Richard's suggestions are right on the money.

As far as my own experiences go I had a horribly understeering car - even in the dry. The solution so far has been to replace the tyres (crappy Avons replaced with Toyo Proxes T1-S) - wider 7" Fuchs rims on the front (now running 7" and 8") and to have the camber set properly. When I took the car in to the garage it was clear from the uneven tyre wear left and right that the camber was out. Annoyingly the full 4 wheel set up wasn't possible as the machine was broken but they set the camber properly using the old fashioned guages. I also took the opportunity to have the Turbo tie rods installed - which go a long way to removing the 'slop' in the steering from 14-odd years of use. It feels much tighter and sharper and the feedback through the wheel is more immediate.

Really with very little work done the turn-in has been transformed - you really can feel the tyres bite into the corners. No longer does the car seem to want to go straight for the nearest hedge. What I would add is that I haven't had a good go on a really wet road yet. I'm doing a trackday on Sunday and am hoping for rain - I'll report back if the rain gods do their thing !

Definitely the next step will be to renew the rather tired (and now squeaky !) shocks, lower the car a tiny bit and get the 4 wheel alignment done properly. With all of these things attended to I really don't think that the 3.2 is quite the beast that it is sometimes portrayed as.

 

[Guest]

Well, just to add my twopenneth worth.

My car (87 3.2) has been lowered, has adjustable Koni all round, and runs on 205/55 and 245/45, on 7/8" rims. I set the tyre pressures to 29 front/36 rear, and have done for a number of years, and have got even wear over the years; the alignment is done every year. The car also has about 320 bhp, with torque to match.

Some years ago, the car had P7000 all round (now PZero, as the P7000 are no longer made), and was driving along the A30/A303 through south Devon. It was raining quite hard, but I conducted an experiment. Doing 80 plus (not fast, you may say, but it was a public road), I would brake late into the roundabouts, down to third, power round and out, without any sign of twitch from the car. This was not hard driving, as it was raining, and there were other cars on the road, but after a few roundabouts, I got bored, and went back to normal, wet weather driving (due care).

Also, I have been round Goodwood, with the same settings, and got the car to slide a bit round the first bend after the straight - it slid gently sideways, with no fuss, then picked itself up and carried on round; no backing off/braking, of course (me too slow ? I like to think that I thought it through).

So, I feel that my car is very safe and predictable - I have been driving them for many years now (9 for this one alone), and, if you don't act like a lunatic on the public roads, you will have no problems.

 

[Guest]

Thanks for all the responses. It has given me lots to think about and look into!

Alistair

 

[Melv]

Look for 6-10psi over the base pressures after a track session................

Melv

 

[ClubSport 911]

Alistair.

I had this "what do I do next feeling" only once - namely giving it the big stick out of a BP station nr. the A5 in MK...the back end let go in the biggest possible way, and I learnt the value of "speed steering" that day I can tell you ! However, this indicident was probably due to excessive diesel on the roundabout, and 11yr old (yes you read right) tyres on the car.

I've since had;

New ARB bushes all round
New Drop links at back
Turbo track rod ends
All new Torsion bar bushes
Spring plates (££ ouch)
Spring plate bushes
Bilsteins (front struts / rear shocks).
7" front, 8" rears
New Bridgestone S02's all round
Revised suspension height / settings all round.
Bottom Swivels
Top Swivels

As Richard mentioned, for cars of our age, rubber goes all gooey, so replace what you can afford starting with fundamentals first.

Result ? - day and night is an understatement. It drives well, and inspires confidence - so so quick now, without any drama or effort from my side.

However...I do slow down on roundabouts near garages, and would do so even in a Challenger tank....

Steve

 

[Guest]

However, this indicident was probably due to excessive diesel on the roundabout

I once spun down the A1 (southbond, on the northbound carriageway !) in a previous, non porker of mine, and parked in the ditch. The old bill said it was oil on the road (next to a garage, and that it was not uncommon) What did they do about it ? Guess.

Actually, it was probably excess speed in the rain, but who was I to argue ! At least my porker would probably not notice.

 

[jamescharnley]

[]

 

[Guest]

There is probably a mix of the car setup and your ability. I had trouble in the wet with part worn tyres, I swapped to new rubber, had a full alignement, and the car was greatly different in the wet.

That said, I still cant drive very hard in the wet, worried about understeer, and oversteer and braking distances. Thats because I dont know how to drive it yet!!!! Had it for 4 years still learning, which is why I keep it. I know it is far more capable than me, if I can learn how to use it. It is a challenge. Make sure you are happy the suspension and tyres, then practice I guess.

Whilst you are practicing, dont try to chase scoobies in the wet!!! [] Remember it is all too easy for them.

 

[Guest]

Gents,
Looking at the Porsche Owners handbook, 7/1985, page 82 for the Turbo model, uses rims almost the same as mine (225 x 16). Porsche recommend 29 psi front and 43 psi rear.[8D]
peter

 

[Guest]

I believe that the turbo rear-end is apreciably heavier than a 3.2, with it's wider track etc., so the pressures would be higher.

 

[Guest]

Looking at the Porsche Owners handbook, 7/1985, page 82 for the Turbo model, uses rims almost the same as mine (225 x 16). Porsche recommend 29 psi front and 43 psi rear

I (and many others more knowledgable than I) cannot explain this incredibly high pressure recommendation. Similar numbers appear in the 964 and 993 recommendations but the vast majority of people disregard them. The difference in weight alone is not enough.

One theory I have heard is that the German high speed autobahn driving (or some other peculiar characteristic of Stuttgart driving) explains what in all other circumstances seems to be a ludicrously high pressure.

RB

 

[Melv]

Higher pressure = less rolling resistance = more bhp...............

Melv

 

[Guest]

= less contact with the road!!