mrjonanni

Hi there, would love some help from other 964 owners about some concerns I have with my handling.

When I'm driving along at say 50 to 100 mph the car sometimes has a tendency to feel like the rear is floating about and sort of weaving on the road. It is most notable if you touch off a road line, cats eye or rougher concrete. It feels horrible, very disconcerting and isnt really what you'd expect from that type of car.

Something else which may be related is that normally when driving through roundabouts and bends the car feels extremely planted and solid on the road, but every now and then the car feels like halfway through a bend it sort of falls (not the best description). Again sort of floaty feeling. I dont slide or anything but again its very disconcerting and doesn't instill confidence.

My car is a '93 964 Anniversary so it's a widebody C4 and it has a Bilstein suspension system so is slightly lowered. When the suspension went in all other components were replaced like the bushings and rubbers. Car is perfectly tracked and aligned and my mechanic- who knows his stuff, insists that everything is perfect. Engine undershield isn't fitted and it has a decat pipe and rear muffler bypass if thats relevant.

Anybody got any ideas or is that just the way it is?

Thanks a lot

J richard

All 911s are very sensitive to tires, wear, pressure and sometimes type and size. How old and or worn are your rears? For high speed is your spoiler deployed?

jimq

some tire brands are not happy when following road grooves more then others causing a squirming feel.

mrjonanni

Sorry I should have said that, tyres are correct size and spec, Michelin PS2s, plenty of rubber left and pressure is good, 36psi. This happens regardless tho, it was the same with the older Potenzas. Yep no issues with spoiler either. Thanks tho

joey bagadonuts

The short answer is: No, your car should feel planted. I've ridden in many 911's at the track (964-on) and I'm always amazed by how incredibly stable they feel at speeds well over 100 mph. None felt as if they were floating or weaving.

Perhaps you should take your mechanic for a spirited drive. Specialists rarely like to admit mistakes but it sounds like you definitely have an issue.

crg53

Is your car fitted with LSD, that can sometimes give you an unstaple feeling if you get off the throttle mid corner.

SAM DACOSTA

Has the car been 'corner balanced' after all the suspension and alignment modifications?

Jimjacqmx5

Um, I'm guessing you need to check your alignment as it will do EXACTLY what you are saying if you have any toe out on the rear suspension.
I have had this previously with a GTR Skyline set up for the track. The guy swore that toe out on the rear was great for turn in for the car and yes, it made the car incredible quick to turn in on the track but I hated it otherwise and it made me feel like it wanted to spit me off the road.
With that said, if alignment checks ok, perhaps a worn bush is causing toe changes under compression of the rear suspension. Lastly if it is lowered too much it could be hitting the bump stops which does very strange things but it doesn't sound like this is your issue.
I am with the other guys here, I have a very lowered car with around 3 degrees negative camber all around and it feels as solid as a rock.
The only weaving you get can be from the front tramlining if you have a road with grooves embeded in it from trucks sitting at intersections etc. But you expect that with large amounts of negative camber.

psiegel

do you know what your alignment specs are? Alignment can make all the difference.

ACSGP

You should also check all your dampers (shocks), esp the rear ones. If one of them has sprung a leak, it could cause this instability as the springs are bouncing away without proper damping.

I've also found that the 911 is very sensitive to tire pressure. I used to pump 37 psi all round. Now I use 39 psi at the back, and 38 in the front. Big difference.

mrjonanni

Thanks for all the suggestions so far,

@Sam Dacosta- I'll look into that as it hasnt been brought up before but I would feel it has.

@joey- my mechanic's car is a 993 turbo so he's happy to give it some, but it never happens when he is in the car with me or on his own and it's hard to explain.

@Jimjacq- I really dont think it can be toe but will look at that again. The idea of a worn bushing makes the most sense to me personally, but as mentioned these were all recently replaced.

I should stress that this isn't a constant thing, most of the time the car is fine and very planted but because this feeling happens it makes you less confident and its always on my mind. With the "falling" through a roundabout, this doesnt really ever happen if I'm having fun but usually if I'm just driving along normally.

I had been told in the past that the floating was a feature of 911's but from what everyone is saying here this isn't the case, or at least not as much..

roblav

1: Tire pressure - increase it like already mentioned. 2: Alignment - again as previously mentioned - you don't want toe out in the rear. 3: Dampers - again as mentioned.

911/964 should NOT float at all. I have not driven my 964 much, but within the first mile, I knew that the recommended tire pressure is too low.

Carrera51

No "floating" with my car. Sounds like a toe issue in the rear to me. Mine feels planted whether on back roads or the interstate.

hamah

Very interesting thread. I myself was about to start one because at speeds over 140 Km/hr I feel like the front end is light and floating....depending on how aggressive I am on the gas (stepping on it seems to "plant" the car). I'm not familiar enough with the 964 (or any Pcar for that matter) to know how it should feel but now I think I'll have the alignment and suspension checked to start with.

Jimjacqmx5

Steve,
If you have stock suspension, it is a charecteristic to have a 'floaty' front end.
Applying power, even though it is transforming the weight rearward will always settle the car as will light braking as it pushes the car onto the road, hence why many drivers brush the brake pedal before a corner to settle the suspension(it is also helpful knowing you sill have brakes too!)
If you have stock suspension, a good set of shocks and springs will make a massive difference, as will bigger swaybars.
I know my car used to feel quite nervous in the front when i first got it, especially at high speed circuits with the stock suspension. It also had quite dramatic power on understeer. Now it is tied down with Koni shocks and HR 965 turbo springs it is much better. Moving from stock 20mm to adjustable 24mm front and 22mm rear bar made another massive difference. The car now feels totally planted, even at 220km/h in a high speed sweeper. Best thing is, road ride is still really nice as springs are variable rate. Best of both worlds.