dprantl

From what I have observed when watching 928's race, they take *completely* different lines into and out of corners than 911's. It's so obvious even TV commentators joke that the 928 driver made a mistake the first time, then realize that he's still with the other cars. My point is that if you try to drive the 928 around corners like you drive the 911's, you will no doubt go slower in the 928. I'm sure Mark A. can elaborate on the line differences between a 911 and 928 since he races both

Dan
'91 928GT S/C 475hp/460lb.ft

cobalt

Understood, however this is why I chose the stretch of road I did. It limited the line for both cars. The long nose of the 928 requires an earlier turn in than the 911 considering your feet are much closer to the front wheels in the 911 that was quite obvious when comparing the videos and the first thing my wife commented on. Under these tight conditions it seemed apparent to us that the 911 can handle tighter conditions more quickly than the 928. I also feel the lack of input required by the driver in the 928 over harsh straight roads is a product of the amount of power steering present. The power steering in the 964 is designed to assist at slower speeds and then diminish once moving giving more feedback and manual rack feel at speeds above 20 mph therefroe the constant corrections and movement over rougher surfaces. The 928 appears to be under power at all speeds this is why i feel it is slower at responding in comparison requiring earlier input and more of it.

Am I wrong in assuming so?

Vilhuer

All 928 manual gearboxes are G28/xx. G = getriebe, German word for gearbox. All 928 engines are M28/xx. M = motor, German word for engine. In 5sp GTS correct codes are G28/57 and M28/49.

cobalt

OK. I guess the factory documents I have have typos. They clearly list the trannys as M28/57 and A28/xx. MY C of A also has it as M28/57. I will try to scan this info when I get a chance. The same literature for my turbo has it as G50/52 along with my C of A.

Daniel Dudley

In a really open corner, a 928 is quite balanced. In a tight hairpin, i have experienced understeer that does not go away when you lift, and needs to be provoked into oversteer with the throttle. A 911 would have to be set up with the brakes to turn in, but will really hook up earlier and with more conviction.

I think the 911 is much more sensitive to ride height and having a limited slip. You also need for the bushings, particularly the ones on the rear spring plates to be up to snuff, and then you need a little more tire than most run. You are much more likely to see a 928 with larger wheels and tires than to see a 911 with a 245/225 combo.

I would in general agree that the 928 platform is a better set up that will take a classic line in a corner. However, a well set up 911 track car will drive and handle much like a formula ford or similar rear mid engine race car. they will always like an attitude of oversteer, however slight, and they will be dead stable in a corner right up to the limit. You will have much more leeway and forgiveness in a 928. Ultimately, I have experienced that they will plow on a very large sweeper at the limit, unless you do something to the tires or sways. I find this to be more true with the 32 valve cars than the 16 valvers, but then I am just a fair driver with reasonable experience.

However, if you watch some classic Mark Anderson footage, you will see that in many corners of a racetrack the 911 is slower in and faster out than Mark. In others the 928 is faster in and equal going out. Of course the reason he can lap a field besides handling and talent would also partly come from what lies under the hood.

YMMV. I only know what I experience and see. The oft heard comparison is that you drive the 928 on it's handling, and you exploit the 911's handling quirks. Both have their strengths and weaknesses. As you say, it would be hard to do without either.

Daniel Dudley

Wow, thank you for saying that. I have never articulated that feeling.


To the OP. Get your wife a supercharged Miata. It will be cheaper than a cheap 911, and it will drive like a miniature 928 on steroids. Add to that that it is a convertible, and that you can have the pleasure of owning one while being able to say it's the wife's car.

worf928

Anthony, I wish I had roads like you describe near me.

See the following post of mine on the subject of worn 928 racks:

https://rennlist.com/forums/3683389-post84.html

Last month I pulled a supposedly Porsche-rebuilt rack with only a few thousand miles on it out of a car. The rack exhibited the "non-axial shaft translation" described in the above-linked post. Basically, the steering shafts move front and back rather than side-to-side during initial rotation of the steering wheel.

I suggest that you (and your wife) check the rack and the inner tie-rod ball-joints yourself. The best way to isolate the rack is with the suspension loaded. Most shop personnel I've observed just wiggle around an unloaded wheel or use a pry bar on a control arm. And that doesn't make sense to me from the standpoint of isolating a single component in the middle of a system with many, many degrees of freedom.

Thus, you need a set of ramps so that you can slide under the car while your wife is in the driver's seat. Pull back the rack boots so that you can see the inner joints and the rack's steering arms.

Then have your wife load up the steering wheel. Turn left until resistance builds. Then release and turn right until resistance builds. You want to cycle the load left to right. A low frequency ~ 0.5 Hz is about right. Load the rack and the inner ball joints just enough that they move a tiny tiny amount. As the load cycles you will be able to see if the ***** if the inner joints are moving in their sockets and if the steering arms are moving left-right or just up/down or front/back.

As for the comparison: you describe, what must simply be, that the 911 has a quicker steering ratio than the 928. This makes perfect sense as the 928's steering ratio was designed for super-high speed where you don't want a little twitch of the wheel to send you flying off the autobahn.

As to the rear... skipping a tire width in a hard turn isn't right. Just isn't. That might be alignment. Maybe not. What size tires and what pressures are you running?

cobalt

Well I am sure you have superior roads overall by you. This is a little area I have discovered that is not policed or heavily traveled which is a rarity in North Jersey. Most of the time I have to travel 20-30 mins or more from my house to find some decent roads.

I pretty much follow your method for inspecting the rack and ball joints. I have a set of race ramps http://www.raceramps.com/56raceramps.html the 2 piece 56" version which work perfectly for things like this. I agree a pry bar is not the best approach but it does show obvious failure easily. I was able to determine that my C2 rack was shot this way. I didn't see anything out of place on the 928 but will look at the link and check again..

I am leaning towards it just being the steering ratios. IMO I find the quicker turning rack of the 911 to be much more precise and maybe that is an incorrect term. For me the 911 just goes exactly where I want it and the 928 takes more input from me as a driver which I feel is less conducive to high speed track driving. Or maybe I should say I feel less connected to the car, this is a similar but greater feeling I get when I drive my neighbors Z06. Throttle steering/control just comes more naturally to me when behind the wheel of the 911's. Sawing the wheel to gain more speed in the turns is something I don't think I could comfortably/safely attempt in the 928.

I think it is just easier to take the car to the specialist who is factory trained on these cars and have him check out everything and give me a report. He is a good friend so it won't be a major expense to have done. He has driven the car just a few thousand miles ago and never made any other comment other than he loves the car and especially the color combo. I know the car did the same thing but more so before I had the shocks replaced. The factory sport shocks were as i have found with the boges in my 964's they have a tendency to become stiff before complete failure. This would usually cause the back end to bounce around which my turbo did also until I switched to bilsteins. It might be that these are over dampened for the car but i doubt it if the same springs and shocks were used as the GT's sports suspension at least what I was told I was purchasing. Other than under heavy loads and tight cornering the car feels fabulous.

I guess my comments are not as well expressed as Daniel's although I have to agree with everything he says here.

I have not done anything with tires other than go with MPS2's stock sizes and maybe that is needed. The shocks and sways I felt were a must and have helped if anything. I also run stock pressures since i don't want the RDK giving me a warning light all the time. I would love to track the GTS just for ****s and giggles but I know my driving style is more suited for the 911 and it is the exploiting of the 911's handling quirks that for me is where the fun really is. I know 2: 20 seconds is not all that great at the glen but for my C2 it is moving. I honestly don't feel i could comfortably come within 5 seconds of that in the GTS but I could be wrong.