F355 suspension and alignment experts please help

How did the CO get changed? Who changed then? It is unlikely that the wild CO height discrepancy would result in a properly corner balanced car unless a knucklehead corner balancer tried to balance just by adjusting from 1 corner. Seems like either "corner balance guy" was clueless or the "alignment guy" thought he could influence the camber by changing the spring height rather than properly adjust at the shims. Most cars have adjustable cams on bolts like a corvette or Maranello while these cars have removable shims. Someone was clueless. In other words make sure your shop guys know what they are doing.

 

That's one of us....

 

VROOOOM VROOOOOOOOM! 8500 RPM, VROOOOOOOOOOOOM

 

It's a brotherhood man. Love ya...we all do really. All want to see you fix the car and drive in good health & happiness.

What has some of us confused is the unexpected correction without a real solution to the cause. We are all, after all, control freaks....errrr control enthusiasts.

Happy it is working...but I like to know why & how the **** it was fixed!

 

Ryan is a great guy and a true Ferrari enthusiast.
He is trying to learn these cars as we all are.

He may not be a big DIY'er but would like to know enough to keep from getting ripped off by people who think all Ferrari owners are super rich,ignorant, and deserve to be overcharged for everything.

 

I realize this issue has been resolved but I wanted to point out something that I didn't see previously mentioned and while obvious to me I think it's worth noting.

Simply adjusting the coilovers has no impact on camber change as the suspension goes through its range of motion. Adjusting the spring perch merely affects the ride height (and in extreme cases spring preload). If your tire was going to contact the inside lip of your fender going over a bump (for example) lowering the ride height is not going to make it clear. Lowering the coilover would just make it rub sooner (if it was going to rub).

They must have ultimately increased negative camber as well.

Glad it all worked out either way.



Rob

 

I would have to disagree, ride height alters camber. Just look at all the chopped Hondas wearing out the inside of the tires. It is a dance to get them all balanced. When you change ride height, you need to check toe, camber and caster as well. I know this from setting up my factory five cobra using a Fastrax gauge. Change one setting, you better check the others.

 

It doesn't affect camber as seen in the arc of the hub. Yes it almost always induces negative camber as measured statically but my point is it won't magically make the tire clear the fender by simply spinning the collars on the coilover. I'm sure Mitch and Billybob know what I'm trying to say.

Take the entire coilover out of the equation. Jack the car up and lift the tire/wheel through the range of motion. If its gonna rub its gonna rub, coilover bottomed out or jacked up or not installed.




Rob

 

Exactly. Ride height effects everything....even minuet changes.

 

Wow glad to hear. Yes adjusting the perches will effect camber as you go lower. I was ready to ask you to check the coil overs to be sure they were the same part type! I just adjusted my drivers side last night since I want a little more clearance for my poor front spoiler and I could see some spring sag anyway on matched perch turns. I just went up one turn front and back. Front was hard and required a ton of WD-40 to get the bushing to slide under the spring. Rear was stupid easy and I am very close to maxed height! I went down like 7 turns last spring anyway. Riding on 18s now as well so that explains some of it. I hope the alignment is still ok.

 

All 3 are correct. In the perfect world the suspension geometry is designed to move through its operational range with no change in settings like camber and toe. The reality is that as the suspension moves those static settings change. It is all a compromise. That is just one reason to set the suspension near the design parameters and not slam or raise cars outside the envelope because those changes can happen more or less predictably over the unengineered suspension travel.

 

I was going to lay out the geometry (and still may do so) but the WSM does not have all the dimensions to do so. Therefore, I would need to measure some of the parts. But, I did a quick cartoon sketch model and it seems to take a considerable change in height to effect the camber much at all. As discussed in the other thread, consistent ride height will vary with the driver's own weight....

All I know is, my 98 F1 GTS is on 5K miles with a set of tires and they look brand new. My Maserati GT is eating tires and it's being shipped next week for an alignment by someone who knows the car inside and out and knows how to set it up to compromise tire wear and performance.

 

My 94 Spider is on 18 inch OZs now. With only a few turns down the camber looks more obvious but it could be the width and diameter of the wheel are amplifying what was already there.

 

Really? As I recall the 355 has unequal length A arms, as do many if not most cars with double wishbone suspension, which are intended to make camber change as the suspension moves through its range for very specific purposes.

 

Camber is but one thing that changes even a little. When we race we search for 10ths of a second. Watch any pro race and what the pros do sometimes even during a race is chase set-up. That said google akerman steering, bump steer, and shock travel for starters. Each of those things are greatly effected by alignment which included ride height. Everything feels great under the limit. On the street you don't intend to reach limits but just about every crash happens because someone exceeded some limit. Most lay people do not know the unintended consequences of the changes they make. If you are lucky all you did was make your car slower. If you are not lucky you run out of shock travel hitting a pot hole in a turn and end up over a cliff. Factory alignment settings are designed to be safe. By the same token you can set up a car to be unsafe.

 

One thing missing in this discussion is the distinction between static and dynamic.

Static is what gets set on the alignment machine (or chassis ride height adjustment machine.)

Dynamic is the shape of the curve when the suspension moves in response to forces applied to the car or from the car.

Given a car at factory ride height there is a particular dynamic camber with respect to roll forces.

Given that came car at a lower ride height, there is a greater dynamic camber change with the same amount of roll force. {Plus the <new> roll axis inclination puts a lot of understeer in the car.}

Theses cars are sensitive, I can change my F355 from a docile interstate cruiser into a nervous twitchy daemon with 2 turns on the read shock towers. And people lower them a whole inch (15 turns).

 

I was simply questioning your statement "...suspension geometry is designed to move through its operational range with no change in settings like camber and toe."
The geometry, particularly camber, isdesigned to change through its motion, at least relative to the chassis, in response to roll, etc. Relative to the road surface is another issue.

 

My 348 needs alignment, really bad
I will pick your brain or give you the car a for a week to play with

 

It sounds like the fix was merely adjusting the coilover which is misleading. If it was going to rub the inner lip of the fender adjusting the coilover alone will not make it clear the inner lip of the fender (as the suspension goes through it's full range of motion, hitting a bump).

I thought my description of removing the shock/spring from the equation and moving the suspension through the arc with the tire/wheel installed was going to make things clear, I guess not for everyone. Lol.


With unequal length (shorter upper links) control arms measured negative camber will increase as the suspension travels through it's range of motion. If you don't alter the mounting points in any way you are not altering your camber.

Adjusting the ride height has no effect on camber itself, (yes it will have more negative camber as measured at rest) it simply alters the point in the arc of the suspension (range of motion) where the car rests.

Add a load of bricks to the trunk, put two fat people in the car, fill the fuel tank full. Are you changing your camber or changing the angle of the entire suspension system?

If you lower the car, always haul bricks and fat people, gravity's pull increases.... then altering the static camber setting will increase tire life.


Rob

 

Good post Rob

 

Does that car have stock coils or aftermarket and help springs?

 

Maybe. It is quite possible just a spring perch adjustment can do the trick because the coil over shock will limit the possible "full" range of motion.

 

That and if you raise the suspension up and reset the static camber, the compressed camber will be even more allowing the wheel to tuck in (suspension gains camber as it compresses).