924Board.org

[Ole Petter]

Hi. My son has bought himself a 924 for his first car! I am a Porsche owner myself, and I very much enjoy sharing the passion with him!
His car is a '84 model with 58.300 km on the "clock". It is in a quite wonderful conditon, but has seen little use the last years.

- But there is a big difference in the way the front and the rear end behaves... In the wet there is very little grip at the rear. The front end is marvellously stable and just about never gives up grip, hardly not even at a recent very wet track-day!

But the rear end is skittish and all over the place in the wet. When testing the dampers (in the classic push-down-way) we noticed that the frond end is firm and gives a great impression. The back-end however, is overly soft and slow to stop going up and down.

So I have ordered new Bilstein GAS dampers at the rear. The old ones are black.
The tires are old and needs replacing, what rubber to choose? Wheels are standard 6x14.
The sway bars are 23,5 mm front and 14 rear. Should we fit bigger bars at the rear? I am familiar with cars having "closer matched" bars than this? And the car has a 50/50 weight distribution...
Is it a good idea to fit spacers at the rear to even out the track f/r?
More grip at the rear wheels is wanted!

I am very thankful for advice. We are at the bottom end of our 924-learning-curve! And I wish my son to have the best possible start of his Porsche-ownership.

[ic932]

The reason why the track is narrower in the rear is to reduce oversteer so spacers will make things worse. I think bilstein rear dampers and premium tyres are the first course of action... then the rear anti-roll-bar diameter.

Sounds to me like you are already following the right path. Good luck

[Mahatma Gadhni]

I run a standard '84 924 on new KYB gas shocks at the rear. In the wet, the rear end gets nervous at braking but never on acceleration.
The exact thing you described happened to me while using old, used-up tyres. It all gets better when you swich to new tyre set. At the moment, I use a set of 185/70x14 Vikings (Norway rubber, I belive) that are dirt cheap, but make a world of difference compared to old tyres.
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1984 924 2.0 NA

[!tom]

A bigger bar in the rear will loosen the car even more.
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78 924 NA
5-lug

[924RACR]

[gohim]

I agree that new rear shocks and tires will help. But the tires need to be the right tires. Here in the US, we have a choice between economy tires for good tire mileage wear (hard and don't grip), comfort/touring tires (soft sidewalls), and performance tires (all season, dry or wet).

If you are looking to improve track and street handling performance, by all means spend the extra money for some performance tires. Try standing up unmounted samples and pushing down on them (in the tire size you're thinking about getting) to see how stiff the sidewalls are. You want to avoid tires with soft sidewalls, they aren't going to handle the way you want, and you have to run a lot of air pressure to keep them from collapsing, or deforming, under high speeds or turning.

[Tiny]

+1 to gohim on this..

speaking from personal experience....when it came time to get new tyres...I got a set of brand new low cost cheapies..and drove out of the forecourt.....thinking i had got a good deal.....until i got to my first bend....and omg.....the sidewalls all collapsed and folded over....and as the back wallowed round....i felt like i was driving clark griswald's station wagon "the metallic pea" from national lampoons vacation. you can imagine my disgust.

However, I guess it was due to the fact that i knew better.....that i soon after got some decnt yokohama's with low profile on the car...and boy.....the difference was amazing.....coupled with a decnet rear ARB.

Anyway....false economy on cheap rubber.....and a lesson learnt.
Tiny
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*****1981 - 924 - Auto - London, UK******

[Rocco R16V]

I agree, Tires are the biggest single change you can make to how a car behaves. That is, if you could only change one thing, get the best tires you can afford. More $ doesn’t always mean better, but good ones are usually above the average price.

A wider track in back will increase understeer. But I think this should be a last resort. Tires and dampers first, and make sure there are no worn out bushings or mounts flopping around. This should be enough to get the car handling good. Then balance the handling by adjusting swaybars or spring rates.

Also, remember that this is a Performance car and should be setup for neutral handling which does not feel like the typical car. Almost every car sold is set up to have massive understeer. If this is what you’re used to, a performance set up will feel loose at the rear, especially in a car with rear wheel drive in the wet.

For a young person you can remove the rear swaybar or use a smaller one to have more understeer, as this is safer for an inexperienced driver, but as he learns to drive better he will want to move toward a neutral balance.

lucky kid!
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"Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves. "
Ronald Reagan

[Ole Petter]

Hello again! Many, many thanks for all the response! Fantastic!

I have ordered new Bilsteins and will get new tires - but which ones? Of course a premium tyre! But as the wheels are somewhat small and narrow it is hard to find a high performance tyre? I have asked my local tyre-fitter, but has got no response from him yet... I was thinking of Michelin Premacy/Continental, but their "sports" performance tyres would not fit the wheels... You mentioned Yokohama? Do they make something good that fits? A friend recomends Nokian? I would prefer a tyre that performs well all-round, the car is not a track-car, but as the Porsche Club over here has track-days, it is very much fun to attend! I feel one learns a lot about the car and oneself!

I know that bigger sway bars at the rear will make for more oversteer, but I guess more controlled oversteer? The 944S had 24/20 mm f/r sway-bars didn't it?
The rear dampers are totally shot, so I would think the car has very little "control" at the rear, and old, cheap, bad tires does not help either... The fronts are Uniroyal the rears are Kleber. The front dampers perform very well, so we will not change them for the time beeing. But eventually there will be Bilsteins...

I don't know if it is possible to get spacers for the 4-bolt wheels, but I have asked a renowned Porsche dealer here for help. Spacers at the rear should bring better grip, but more oversteer as well...

But as the 924 should have a very natural, maybe slightly understeered balance, hopefully the Bilsteins and new tires will do the trick! I would prefer a more playful-rear end in the corners, but ultimately too much rear grip would probably not be a good thing?
Often my mind plays me tricks, and what I see as a good solution is sometimes the opposite... So maybe the car would be better with no sway-bar at the rear at all? Hmmmm

[Ole Petter]

What about the tyre dimensions? We have two set of wheels both 6x14 (one set of original wheels, and one set of telephone dials).

The current dimension is 185/70-14. I was thinking of 195/65-14, or maybe 195/60? A lower dimension would do a lot or good? What do you use for your cars?

Again many thanks for help!

[morghen]

for summer and smooth roads i would use 195/55(or 50)/15 on the 924 NA.
for the winter i would go for...185/65/14
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[Mahatma Gadhni]

[9xx]

[924RACR]

Nokians are also well known and loved in the (very small) rallye-aware community in the States, too! Never got my hands on any, though... then again, don't really need any winter tires... Michigan's too flat, and I drive an AWD minivan... need all-season tires to slow me down to only a bit faster than most people drive (yes, I'm the asshole driving 70mph in the snowstorm ...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Ole Petter]

I have ordered Nokian RSi for winter use in 185/70-14.
The Nokian winter tyre is simply the best winter tyre I have ever tried! Great on snow and ice...

I wonder if Michelin Energy could be a good choice for a summer tyre, it gets excellent results on "Tyre test.com":
http://www.reifendirekt.de/review/129/Michelin_ENERGYSAVER_Reifentestcom.html

Would you stick to the 185/70-14 for the Michelins? Or go wider and lower on the 14" rims?

Again thanks for all the advice! I hope new Bilsteins and tires will make the 924 a fun and safe car!