3.2 Carrera and SC handling

[cwitt]

Hi all,

I'm considering purchasing an '85 3.2 Carrera. While test driving it, I was really surprised at how heavy the steering was. I'm not talking about difficult to turn, like a bad rack/column/joint might cause, but rather the amount of muscle required to hold a line through the corners.

My buddy's '78 3.0 SC, on the other hand, has more of a 'go kart' feel to it. The steering is very light, even through the corners.

I know the 3.2 Carrera is a heavier car, but only by 70 pounds or so from the specs I have seen, which wouldn't cause such a drastic difference in feel. I also know that a multitude of other things can affect steering weight: caster angle, wheels, tires, air pressure, etc.

All those possibilities considered, the question in my mind is:

Can you get the 'go kart' handling feel in a 3.2 Carrera?

Thanks!

Curtis

[Oh Haha]

Yes you can.

The alignment and corner balance was most likely not quite right on the Carrera, which would make it seem hard to handle.

Is there a large difference in the weight bewtween you and the current owner? If so, that could also cause some funky handling.

Without knowing the specs it is impossible to give you much more than that.

[CharlesJones]

Yeah, I would expect its something to do with the set-up of that particular car. My Carrera's steering is very light at speed, and could never be described as heavy at anything above parking speed - in fact most of the time I just steer it with my finger-tips. If you test drive some more Carreras I expect you will find most have handling much the same as friend's SC.

[Wil Ferch]

One more thing..... a great deal of dialed-in caster promotes straight-line self-centering and stability. Porsche's later cars in the air-cooled run up to 89 used big numbers here... 6 degrees or 6.5 degrees. The very early cars were spec'd with something like 5 or 5.5 degrees. I don't know if the SC you drove was set up with 5 and the Carrera at 6.5...but I very much suspect that was the case. Along with a high degree of self-centering effect, high caster angle increases low speed steering effort dramatically. Look also at wheel/tire widths fitted in both cases. Should be the same ( stock) but you don't say, and mods could have been done here, too.

[cwitt]

Does anybody know what the caster adjustability range is for the Carrera?

Thanks,

Curtis

[Wil Ferch]

6 to 6.5 is "max"....unless someone opened up the slot.

[cwitt]

6 to 6.5 is the entire range, or the maximum end of the range? To get it closer to SC spec and lighten things up, I'd want to decrease the caster, right?

Thanks,

Curtis

[Zeke]

A lot of Carreras have 7's in front whereas 6's were the norm for SC's. I'd check tire sizes between the cars you have driven as well.

[stlrj]

Ride height can make a difference too. Quite possible the Carrera was lower than the SC causing more negative camber that also results in heavier steering.

[williecoyote]

My Carrera was hard steering until I had it aligned. Now it is much more nimble.
As others have stated already, I suspect that is your problem.

[slodave]

No problems with either a 6"/7" or 7"/9" combo here. It was aligned and balanced with the former set, but now running the latter and the steering is basically the same. I can tun the wheel with 1 finger while moving. Parallel parking did become a little harder with the larger combo.

[911st]

My 85 with 205/245's Michelin Pilot Sport Cup tires on 7&9's, on a long track sweeper it did take a lot of mussel. I had set my Caster at an my equal max of about 6.5 deg to try to get more neg camber up front.


My guesses:

+1 for caster as potentially the biggest reason.

An undersized steering wheel can increase effort.

Stickier tires that increase the speed potential of a car might have some effect. That is the faster you can go the more you will feel it.

I wonder if front ride height being on the lower side might put the tie rods at an angle to introduce some type of added leverage the the front's geometry. If so this might multiply the caster effect.

With ride height relative to how tall the front wheel is and off set, comes with a lot of other little things like changes up front and in back with things like toe steer, roll center, Ackerman effect ...

[stlrj]

Originally Posted by 911st

My guesses:

+1 for caster as potentially the biggest reason.

Caster is not that adjustable on our 911s. Even if you were to move it up, you would not feel any difference. Camber, on the other hand, makes a world of difference as anyone with lots of camber can attest.

[911st]

Caster is the self centering effect.

Camber is the wheels angle to the road.

I knew Camber it the most important setting for how well the tires hold (stick).

I did not know it effected how heavy steering feel's in a corner.

Can you help me understand how this effects feel?

[KOH]

Tire pressures can make a noticable difference as well.

[Wil Ferch]

The general rule, for those who asked and may reference this thread sometime later....more caster angle = more self centering = harder effort steering. And vice versa.

The early 2 liter / 901 gearbox cars ran 5-5.5 degrees caster, and had notably lighter steering than the later SC's and 3.2 Carrera's with 6-6.5 ( max). The early cars also had skinnier tires which help, but I think caster makes a big difference all by itself. True..maybe camber has an affect too....but I wouldn't think to the extent caster does.

[Superman]

This phenomenon is probably related to the widely known inherent handling superiority of the SC's compared to Carreras.

[GH85Carrera]

Originally Posted by Superman

This phenomenon is probably related to the widely known inherent handling superiority of the SC's compared to Carreras.

It sounds like another plot of the SCWDP. My Carrera has a nice light feel in the corners. I would not want it to feel ANY lighter.

[Eric Hahl]

Silly question but are the steering wheels the same diameter on the cars you drove. When I put the smaller diameter prototypo on my 85 the steering felt much heavier. It's much easier to turn a larger diameter wheel.

[burgermeister]

I recently changed my car's caster from the max adjustment to the min adjustment (maybe a 1.2 degree change) to lower the steering loads - I acquired a case of tennis elbow and didn't want to miss the last track day of the season. That (and rain all day) made for very light steering (and lots of fun driving on a nearly empty track). I actually like the car better with the lower caster setting - seems to have better steering feel to my untrained and totally biased hands.