944 heavy steering/power steering fault ?

944 heavy steering/power steering fault ?

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Discussion

J.J.McClure

Original Poster:

22 posts

195 months

Saturday 29th March 2008
quotequote all
My friend has just got a 1990 944,it has very heavy steering,the belt has just been replaced so we know thats ok,does anyone know of any common faults ?
He's just come from a boxster and thought it was just he wasn't use to it,but having driven it,I believe its a fault,as it doesn't centralize when driving straight.
Could the wheels,which are from 17" Boxster be effecting it ?
Cheers J J

diver944

1,843 posts

275 months

Saturday 29th March 2008
quotequote all
The PAS in a 944 is much, much heavier than any modern car if that is what you are used to so it is not neccesarily broken. If it doesn't self centre then the alignment is probably well out. These cars are fully adjustable for camber, caster and toe angle and should be checked at least every two years because they will wander out of true.

17" wheels are not a problem if the alignment is okay, but Porsche do recommend that the caster bush at the rear of the wishbone is changed to the later 968 version when using larger than 16" wheels

Nurburgsingh

5,104 posts

237 months

Saturday 29th March 2008
quotequote all
How old are the tyres?
Worth checking the Castor angle as well

I had a similar problem on a MKI MR2, I changed the tyres fro a fresh set and it was like driving a new car.

NJH

3,021 posts

208 months

Saturday 29th March 2008
quotequote all
Lets put is this way, the PAS belt came off mine awhile back when the tensioner broke. A PAS 944 like an S2/turbo without functioning PAS can have incredibly heavy steering. I struggled at slow speed and even at 40mph I found it very scary because I had to use my shoulders to help steer. One of our 944 community good friends, Fen, drove his car ISTR with the PAS removed but that guy was BIG in the shoulders and arm department. Older cars that are a bit lighter might not be so bad. The early cars that never had PAS had a different rack with more turns in it, to make the steering lighter.

Is the steering really that heavy? Compared to my swedish inbreed daily driver then yes, compare to a mk5 golf the weight feels similar but these modern cars have this really odd thing where the steering feels heavy at first but is easy to twirl.

I wish ANY modern car had steering as nice as my 944 S2, if it did I might not hate modern cars so much.

BTW anything wrong such as geometry error or looseness in any of the bushes / joints will cause the car to catch every rut, bump, odd camber in the road and make the steering feel like heavy hard work. You should be able to drive at stupid speeds on the bumpiest roads without having to make steering corrections.

I hope some of that helps.

hartech

1,929 posts

216 months

Monday 31st March 2008
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Steering should self centralise even though the power steering is not as poweful as more modern saloon cars. I presume you have checked that there is power steering fluid in the container - and if so check the key inside the pump has not sheared. There are 2 ratings for the pumps depending on the model and rack.

A seized steering UJ can also result in the heaviness you have felt.

The oil cooler pipe often corrodes letting the fluid leak out - check that and finally make sure the rack is not bent.

After all this get the geometry checked as any attempt to lower it will put too much camber on and will make it feel very heavy.

Baz

willdew

2,138 posts

263 months

Monday 31st March 2008
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hartech said:
After all this get the geometry checked as any attempt to lower it will put too much camber on and will make it feel very heavy.
Isn't it castor that has the main effect in the weight of the steering?

Whatever other problems the steering may have - sounds like the geometry needs doing.

Edited by willdew on Monday 31st March 10:38

zcacogp

11,239 posts

243 months

Monday 31st March 2008
quotequote all
willdew said:
Isn't it castor that has the main effect in the weight of the steering?
Yes.
willdew said:
Whatever other problems the steering may have - sounds like the geometry needs doing.
Definitely worth doing the geo to see what's going on. Particularly if it is over 2 years since it was last done.

You can test the PAS - turn the engine on, and (while stationary) turn the steering wheel. Then turn the engine off and try the same. You'll easily tell whether it is working or not ...

As Paul (Diver944) says tho', 944's simply have weightier steering than modern cars. I recall swapping from a 944S2 to a 987 Box and back again, and the difference was greater than I had imagined. The 944 was heavier and felt more ponderous on the road, but gave a MUCH more satisfying feel when you really wanted it.


Oli.

hartech

1,929 posts

216 months

Monday 31st March 2008
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The castor theoretically has a major effect on heaviness - if it has lots of adjustment - but it hasn't and therefore doesn't (only the rear eccentric adjustment possible which over the height of the strut to wheel centre is minimal).

If a wheel is vertical then Camber is zero and as you turn the wheel a little there is hardly any weight on it except from the weight of the car (yes I know that the strut angle gradually lifts the steering and turns the wheel onto its inner edge but in normal small steering while driving the amount of movement is very small)- but if you increase camber you will find that the wheel rises and falls much more with the weight increasing on the inner edge of the tyre as the contact patch changes. This makes the steering lift the weight of the car on smaller turn angles and it wants to drop back to its starting point hence the heaviness. But all adjustments affect the feel of weight - even tow as towed out results in wandering about under no weight feel at all while too much toe in also increases heaviness but also straight line stability.

Steering is only ever a compromise anyway since it is not adjusted for the actual speed nor cornering power distribution etc.

Baz


willdew

2,138 posts

263 months

Monday 31st March 2008
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On the off chance it turns out he needs one:

http://www.pistonheads.com/sales/439159.htm