348 handling

I don't understand either (not that I have the mind for such things), but it certainly did with mine. Maybe worth telephoning Roger Collingwood at KHPC (aka The Ferrari Centre) on 07000 360 355 and getting the info direct from him. By all means mention my name (Jonathan Tremlett) if you do.

Jonathan

 

Ian for an really really in depth explanation on tyres and handling problems have a search on www.rennlist.com the Porsche guys had a big discussion about it last year

 

This is true. I had original fronts on mine and 2 year old rears when I got it. Although it wasn't what I'd call nervous at high speed it certainly improved when I replaced all four tyres. I noticed some degree of bump steer.

I went with the PZero assimetrico/directionale combination (Pirelli System). Originals were all assimetrico's. Mine is a GTC so it has a wider track anyway. The directionales on the front are said to improve wet front end grip.

 

I'll second the soft hands... I almost looped my 348 in the first ten minutes of ownership. Holding the wheel to tight going around a fast on ramp.. when the wheel jerked my tight grip cause an over correction and scared the piss out of me. A light touch on the wheel and she's straight as an arrow

 

I had a lot of posts here last year about the handling of my 93 348. I was so farking depressed after 5 Porsches..
I tried it all, all tire pressures, all the spacers, 15mm rear / 25mm rear / 15 Front and 25 Rear, etc..

The very best for me is just the 25mm at the rear and NONE at the front.
Tirepressures as my sticker in the door says: 2,4bar front and 2,6rear.
Don't ask me about the psi data.

I have seen speeds up to 285/290 on my speedo.
Remember I live in Holland and close to the german border.

The car hates just one thing: tracks in the tarmac as from big trucks.
Never do high speeds on the slow side of the highway (depends country).
When you intend to change lanes on top speed... don't phone me to sit next to you

Well, I truly love the car. I miss just one thing, a 6 gear transmission. It would have made the car so much faster everywhere. But they didn't exist yet huh..

 

Well Andy has one in his.

 

I know, Andyhls has a great car Ernie.
But I mean "from the factory".

Imagine our car always close to the right revs... yammie !

 

My 348 shoots straight as an arrow at any speed, along any surface. But alas, the engine sits in a T Coupe.

 

with all the talk bout spacers, 348 challenge wheels, 355 challenge wheels , different year oem 348 wheels has anyone calculated the different wheel centerline distances from the hub face? I think we can all agree that the model years hub face position did not change. What you say NO Doubt? If we had this info we could get a consensis of what works to get the best compromise road handling. When you read posts like this we get answers and comments all over the map from spacers, soft hands to wheels, and tires. I also propose to you guys that some of you are running unknown chassis rake and old shocks on 15 year old cars and that makes a huge difference too.

 

Well, rear wishbones were different on a GTC street model so I'm sure the hub position changed, but AFAIK that didn't extend to the GTB/GTS or any other late model 348's.

Yep, bushes, shocks, alignment, tyres etc etc etc. Tyres, Alignment then shocks in that order I reckon.

 

Your local specialist is correct, and the best theory put forward so far is that the chemical compound used for the new tires has a different grip than the rubber itself.

Per that theory, your car is fine with 4 new tires and likewise fine with 4 tires that all have the same wear/age/mileage on them, but decidely **not** fine with 1, 2, 3, or 4 tires of different age/mileage/wear because they will have different (or no) amounts of the new-tire chemical protection compound on them.

This wear effect is more pronounced for the 348 because the 348 suspension is setup and cocked so well, but as the old addage goes "the finer the tuning the more mistakes are multiplied" (or something like that).

The new tire chemical protection compound is supposed to wear off after about 200 miles, but it may be that it never really wears off all of the way...and you don't want tires of different levels of traction on each side (or on each corner!), as that would obviously make the car twitchy.

So the cheapskate warehouse dealers who just buy 2 new tires aren't doing much for your safety or driving ability, they're just making the car "look" presentable-enough to sell.

Bottom line: replace all 4 tires simultaneously on 348's. No exceptions.

 

Ha, ha. You are **Soooooooo** funny. Like a Spider driver would know the first thing about centerline calculations and hub faces.

Heck, I've got Veggie Tales on my CD player and a car seat for my 4 year old in my 348 (well, I did before today...but I had to yank the car seat in order to take my wife to the Alabama football game in Tuscaloosa today - Roll Tide!).

But, if you racers do the leg work, I'll put the answers up on the 348 Primer so that everyone can benefit.

Long live the 348 Brotherhood!

 

I am sorry but I don't buy this. Yes in theory you may be correct but I'll tell you a secret. I'm a cheapskate with a tire changer. I have run new pirelli slicks and sometimes commit sins by running goodyear slicks in the rear and hoosier slicks on fronts...SCRUBS on top of that. I just tune out with tire pressure and rear ride height. I basically go as low as convenient on my front end use some math to get the OEM relative rear height to maintain chassis rake. Then when I screw with tires and tire choices I tune from the rear. I find it easy to keep one end of the car static when tuning. It is rare that I can't get all the tune I need from one end. Tuning this way accounts for basically differences in grip which is what counts regardless of offset, spacers etc... I also balance just on a static bubble balance and run full solid suspension so if I was going to have bad handling and vibration from my tire choice and suspension set-up I would have seen it transmitted via my unforgiving suspension.

 

Correct me if I'm wrong but aren't you heating up your tires prior to racing by doing controlled burnouts?

If so, wouldn't that negate the new-tire chemical compound protectant (which wears away in 200 miles of street driving, anyway)?

I'd think that the 4-new-tires for 348's rule would apply more to street driving.

You're in a different league on the track. Different rules. Different effects.

 

No burnouts and I don't know...you may be right. But from my personal perspective having driven everything from Mud all-terrain tires to road race slicks the only felt difference to me is grip. It is this grip that determines "handling". I'm just not that smart to know why. I just tune for best grip per road conditions at that time (since I'm on a track) by the ass-o-meter regardless of tire/wheel choice.

 

Is it possible that goodyear slicks and hoosier slicks have no street "new tire chemical protection" compound?

Could that explain the difference?

 

If I fit 360 wheels, I don't need any spacers to improve the handling and fill the arches nicely, right?

Thanks