high speed driving

Nature of the beast unless you want to go with an aftermarket suspension setup...

 

Some of the 348 guys have indicated an improvement with the SS lip (or other similar splitter like the Valence lip) for high speed driving.

 

don't rear spacers helps this problem, or is that just at lower speeds?

 

My understanding is that it helps most with the high-speed stability. I believe spacers solve most problems, but I hear the front add-on valence or splitter really helps too. Also have to make sure tires are proper pressure and suspension aligned properly. Ricardo - try doing a search here in the forum... I'm sure there are lots of threads.

 

He's right about the front splitter, I learned that from previous racing cars. Does anybody know of an aftermarket front splitter (spoiler, whatever you want to call it) for a 355. I have had similiar experiences where I wish I had more down force in the nose on my 355. I think Hamaan used to make one but i'm not sure.

 

+1 I was going to lower my car a little to see how much that would help, but at about 150mph my car doen't feel stable. Not that I feel like I'm going to lose control, just a bit uneasy...

 

The wider rear track helps with cornering quite a bit; I don't know that it really helps much with high speed driving in a straight line. The later 348's (spider, SS, Euro GTB and GTS) had extra material in the rear wheels effectively increasing the track 1" so the OP should already have the advantage of the wider track.

Wouldn't a spider always feel a little less stable at high speed than its' coupe counterpart? Having a soft top or no top would create more air turbulence around the vehicle I would think.

 

my spider came with the SS lip - still not what I'd like to feel at speed, but I do believe it helps. Also looks better with it, imo.

 

I've got hill spacers (25mm) at the rear, some improvement. But if I'm correct the GTB/GTS/Spider wheel are allready 5cm more apart from each other.

Taking my car above 250 km/u is a scary project (so I've heard).

I'm much happier with this behaviour since I experienced a gallardo spider at near top speed in the passenger seat. This car is that stable at these speeds that there is less thrill even at these enormous speeds. The thrill is what we are after I think not absolute speed (unless a friend appears with a faster car).

It's like a CS vs 360, much more fun but scarier.

 

My car is very stable on a racetrack - have taken it up to 130mph. It brakes straight and corners confidently. the key factor is that most race tracks are smooth surfaced.

By contrast, the car is nervous and bump sensitive on the back roads at high speeds. When I brake on an undulating road, the car crabs about a little bit. I found that reducing a little tire pressure in the front helps alleviate the issue a bit. The car is incredibly sensitive to tire pressure adjustment. Lowering the ride height might help reduce the air going underneath the car but will throw off the geometry and could make the car scrape more.

 

I've said it before

355 SUCKS at high speed! It needs a splitter....I pretty much top out ever car I own at least once and above 160 I didn't feel good in the 355......

 

yeah, 150 was all I had the guts for.

 

I would assume with a splitter or chin spoiler you want a rear spoiler as is the case with 911's. Only problem with rear one is lose of top speed but the downforce should help a lot over 100mph. A homemade undertray should help as well.

 

I hit 160 in my 355 and my left rear tire had 10psi tire pressure, pulled a little to the left but was stable and very controllable, with correct tire pressure car is very stable and planted 150+

 

The SS chin spoiler helps for high speed stablity as does the wider rear track. You can get some weird oscillations in cross breeze at speed without it. Scared the crap out of me! Lowering front a bit helps too - try using slightly smaller profile diameter tires up front. This really helped my Spider and it had no chin spoiler (but it should have if I was to do it right). Check your road height front and rear for OEM specs. Should be just under 5 inches (4.7 to be exact). Watch that when you adjust the rear lower, the front might elevate slightly. This is as much as one can do with the stock suspension. It wouldn't hurt to switch to 18" wheels on a 348 too. In fact, the F360 wheels look pretty cool.

Ferrari NA has SS chin spoilers for $900 and there are other sources for aftermarket parts. Plugzit made his from sheet aluminum; so did FBB on his race car, I believe.

 

I'd definitely go with an aftermarket suspension. It's probably going to be expensive, but if you got the money, I'd say do it. It makes a HELL OF A LOT of difference.

Spacers don't do much, except make your tires stick out a few cm's more.

 

Your right about suspension and downforce. Luckily the previous owner of my 355 berlinetta did a few things that have helped me in the excessive speed range.1) LOWERED 2) BILSTEIN 3) WHEEL SPACERS . I hit a little over 170mph last month on a great straight away in east Texas that I have been dragg racing since I was 16. Main issue with going these speeds, is not really the car, but the PAVEMENT, Not a road that I know of doesn't have undulations or some irregularity that effects the level plane of the car. Only thing outside of building my own sandflats , is to add some options, which some of you have mentioned here. 1) front spoiler , splitter 2) rear spoiler 3) extended rear splitter preferably CF. If you really want to get a little more then start stripping junk out of the car (I think 10lbs of weight saved = 1hp? somebody correct me if I'm wrong, old Collin Chapman ideology), tool case, seat, radio, passengers, etc.. lolololololol !!!! I would make sure you got the suspension adjustment switch on also when you get ready to go this fast , just a thought. Take care and everyone be safe out there ,
-jake

 

Ric,

My high speed driving evolved as my car got faster on the racetrack. The 348 chassis is very tuneable. In fact it is too tunable and that makes it twitchy because other people screw it up. Manufacturer's have a different view of what they want to achieve but you can change those driving charactors easily if you know what you want. Drive a 911 Pbug, 348, and a vette and you can feel a trend in how the cars handle bumps on the same road. All three cars handle great on flat roads but when the bumps come in there is an interaction between what the chassis actually feels and what you actually feel and when there is a mismatch you take your foot off the gas. The higher the speed the faster the bumps are felt and the more unsettling that is in perceived lack of grip.

In the 348 I would First get everything (including chassis rake and ride height) set to factory specs and check the alignment guy using strings and a ruler. Alot of these guys do a 4 wheel alignment with mirrors and lasers but never spend any time finding the chassis centerline as a referrence point before aligning. They always seem to jump in and start adjusting things. So when you have a tuneable chassis like the 348 you get car "aligned" but wrong = twitchy. I just use strings and a ruler.

Next I would adjust chassis rake and ride height for how you like to drive. There will be a balance because if you slam a car you can't go over the speed bumps. Lowering the rear helps straightline braking and help dramatically to control over/under steer. I like to set the front ride height (mostly to a point where I could get my car on the trailer) and then tune with the rear ride height. Doing this throws off the alignment so then once you change the rake and height you need to reestablish the alignement settings and test again.

You can also find ideal tire pressures for the conditions of the day and how you drive by using a probe pyrometer to make sure you are using all the tire surface effectively by making sure your heat is even. I am not sure the value of doing this with street tires but so many of us have changed tires and wheels that factory recs on the 17" 20 year old tire may or may not be suitable. A lot of hi perf drivers are using DOT harder compound race rubber like toy RA1's on the street. They wear out fast but the grip well. I think lots of test time needs to be spent right here.

Next you start changing out parts and the first place I would look at is your 20 year old bushings. Bushing deflection is huge at higher speeds. The bushing isolates you from what the A-arm is feeling. This is something you get used to at high speed or with more and more solid bushings. With rubber bushings and the car going 50 you may feel nothing. Solid metal bushings at 50 you think you are going 100. That is a good thing in faster cars because it gives you feedback you can adjust to. It a bad thing in faster cars with inexperienced drivers because it gives you feedback that you might react to but should not. Get what I mean?

Then I would look at shocks. You can revalve your 20 y/o shocks to factory specs or revalve to a custom spec.. Bilstein does this for like 100/shock to factory. Its on their website and bilsteins are what the 348 has. Custom valving is more money and you could buy single or double adjustable shocks which will dramatically allow you to control what the suspension does and feels. You could even play with spring rates but how much time do you want to spend? Personally I like the 348 rock hard sprung with a good valving in the shock and the handling improvement is dramatic. The heavier springs reduce alot of suspension movement allows more chassis lowering and better braking stability and less roll more kart handling.

Finally aero is a funny thing. Most of the stuff just does not work. When you take a car set-up well for mechanical grip and you put a piece of aero on it you need to feel it. If the aero piece does not ruin something about your balanced car it ain't workin and you don't need it. If you can feel it upset something then you got something that works. Now the key will be taking that effect and taming it to get the effect you want. For example a big wing on the rear should make for hi speed understeer when you first put it on and a big splitter should make for hi speed oversteer when you first put it on. IMO those little lip spoilers do nothing. I had a giant 4" carbon fiber splitter on a lowered 348 before I could get some reall changes. That large splitter had to be balanced but the angle of my wider than 348 rear wing to just get a bit of high speed understeer which is the safest place for inexperienced drivers. So I liked the car set up for neutral steer mechanically and slight understeer with the aero. I'm not a great driver and that was safe for me.

There are other things to change but what I posted above is plenty.

 

Great stuff!