Looking for STOCK 308 Alignment Specs

Robert- When a 308 is aligned, the procedure calls for 75 kg bags to be placed in both seats and that is your load (2 people, full fuel, 44 lbs luggage). Note there were different alignment specs for the GTB and GTS, at least on Euro 308s.

1 mm of toe is ~0.15-0.16 degrees and 3 mm is ~ 0.45-0.48 degrees toe. (arc sine of 1/355.6- 1/381 mm to 3/355.6-3/381).

 

Terry Steve and All,

So on a 16" wheel the toe in for 2° would be .28°???

Thanks

 

Two things you need to be careful about here (and I'll assume that you meant to type "...2mm would be .28°?..."):

1. You need to be clear about whether you are talking about the "total toe-in" or the "toe-in for a single wheel". The distance method is almost always total toe-in; whereas, the angle method can be either.

2. The distance method (in 1975) usually measures from the maximum bulge of the tire sidewalls (not at the wheel diameter, nor at the outer tire diameter, but somewhere in between those values).

Consequently, I'd estimate that a factory total toe-in spec of 1 to 3mm from 1975 corresponds to a total toe-in of .11° to .32°, and 2mm would be .215°. (So your reported total toe-in of .09° in the other thread is a little lowish, but I'd shoot for the middle to low end of that spec with wide 16" tires -- as I posted 9 years before in this thread -- narrow 14" tires, with a tall sidewall, can live with more front toe-in better and not show as much uneven wear).

 

Dont forget that Ferraris are set up to adjust the wheelbase too.......which also needs to be done.

There are fewer and fewer mechanics who can align a car, and when someone starts relying on specs from 40 years ago, that is a sign they are in over their head.

Here is a link that will help:

Ground Control - "Toe-Out" Calculator

 

So the smartest guy in the room never realized that how you stack the front shims, affects the wheelbase at the same castor settings? And was designed that way in Maranello?

i agree, as long as they care.

The tires, roads and carcasses have all changed INCREDIBLY in 40 years.

You are welcome to use old alignment specs on new spec tires. After all, it is much simpler that way. You don't have to think.....

 

Dear Friends,

Thanks to all who responded. My car is 40 years old and I was just trying to get my head around the conversion from mm to °'s. My goal is to get to the Ferrari guy and have it done correctly. But who knows I need to redo my front end and then maybe my rear suspension, and maybe my springs have settled.......

 

Talk to people racing on radial tires. There is enough difference between modern high performance radial tires that different brands call for alignment changes!

 

Then thank you for teaching us that alignment doesn't really matter. So why did this thread exist seeking out the correct specs again?
Now I can go teach that to the engineers I work with who obsess over setting alignment specifications for production cars tomorrow. I'm expecting to get a promotion for straightening them out and improving their work throughput!

I'll continue to believe that those old XWX tires were of an entirely different concept of construction (why did they keep emphasizing how good their ride quality was?) than any modern tire until someone can convince me that they're really the same internal construction as a modern unit.

 

Friends,

I did not mean to start an argument, and appreciate everyones advice. My toe is on the bottom side of the specs and feels the same as before and even though all my rear toe and camber are all over the place the car tracks straight at high speed and turns and handles like on rails that said Im sure when even closer to spec it will handle better. Im afraid after driving it for 20 years like this I may be uncomfortable with the correct set-up!

Some of the figures were off a bit from from last time and the tech said you could drive the car around the block and get slightly different numbers.

 

I'm looking forward to reading your procedural write-up that instructs all of us less skilled owners, who have no frame of reference beyond the 30+ year old factory specs, on how to re-evaluate and determine what alignment specs we should be targeting for our 308s on modern tires.

So far, your contribution has been to advise that the factory specs 30 years ago are no longer applicable, but you haven't offered anything better.

 

Actually, I'd suggested using the 16" (or even TRX depending on model) specs in the other active 308 alignment thread. (Truthfully, I hadn't realized there were two different threads!)

Of course, if you wanted a procedure, they're written up all over the internet (including, as I recall, something pretty good written up here by Mitch Alsup) about how to go measure tire temps on your favorite curvy road, but that's a lot of time & work.

Did they change spring rates for the 16" (or TRX) cars vs. the XWX? Or maybe bars? Static ride height? It doesn't look like it. If not, then we ask, "Why did they change the alignment spec?" Of course, there can be myriad reasons which we'll never be privy to, but since it IS Ferrari, it seems reasonable to expect handling to be high on their priority list. A 14" tall sidewall tire can be expected to flop over a lot while cornering, and would presumably need static negative camber to help it keep from wearing out the sidewalls, whereas a 16" (or TRX), of similar construction, would need less help from static camber due to having a low profile sidewall, yet the alignment specs between the two are opposite: the 14" calls for positive camber, and the 16" calls for negative. That tells us that something has changed, and the sidewall height change should drive us in the opposite direction!

It's for this reason that I think the 16"/TRX alignment specs should be used by everyone not running XWXs.