ALFAGTV6.COM

[junglejustice]

Get your hand off your cock JJ.

Don't be such a sofcock Ben... Still pissed off about the rugby...?

Any way, local buddy - Brad - came by the shop the other day to have his cut-and-weld rear camber modification to the DeDion verified and to set the rest of his alignment! It was a good photo opp to get under the car and look at where he cut his DeDion, look at the welds and so on. Also, had a look at the new brakes from the back-side and to see his custom brackets welded to the DeDion for the rear outboard conversion etc.

The screen-shot from the alignment rack is a before shot. Basically pretty good - especially when considering that they performed the mods on a welding table with the DeDion out of the car! The cross-camber is within 0.14 of a degree at the rear!

Brad did not go for any toe, but still ended up with about .16 total toe at the rear. I'll be going for about 4mm of total toe-in on mine. Chris set the watts thrust-angle a bit, adjusted the castor and made some other minor changes up front and called it good...

[grant]

Looks sweet! What size tires is he running? I met him at Laguna Seca once, and he did seem more of a body man. But this car is bad ass!

[la_strega_nera]

Ahh, Rugby. The Game where 3 guys try to push two guy's heads up one guys ass.

I'll point out once again that the Alfetta chassis cars roll so badly because of their below ground level front roll centre. They're also a little lacking in camber gain.

One theory of making a car handle is to simply tie the thing down so hard that the suspension doesn't move. While this works on a billiard table, on a real circuit, or even a tarmac rally car it doesn't work so well.

The other issue is that because of the lack of torsional rigidity (relatively) you'll wind up with a car that stops responding to suspension tuning because the 10lb/in change in spring rate is lost in the chassis flex.

Of course the other problem is that as you drive the front roll stiffness up to control the roll, at some point you'll reach a limit where it lifts the inside front tire, and you just overwork the outside tire to death. There are plots floating around (I can't remember if they're in Miliken or the Van Valkenburgh book) that show the effect of vertical load on a tire's coefficient of friction, and show the coefficient degrading with increased load. Ie two lightly loaded tires will provide more grip than one tire with double the load (think about the inside tire off the ground scenario).
Following on from that is trying to minimise excessively loading the outside tires... Its all about using the tires effectively in the end.
Of course, simply screwing with the geometry to get the Roll centre up at the height of the centre of gravity doesn't fix things, because it then causes jacking problems, just like a swing axle. A stock 105 has exactly this problem at the rear.

The obvious thing is, if you get a setup with enough camber gain and the roll centre in a readsonable spot, you don't have to run absurd levels of negative camber, which then gives you a car that is better under brakes... which when it comes to wheel to wheel racing is an important thing.

[ar4me]

...you don't have to run absurd levels of negative camber...

So, what do you consider absurd levels of negative camber...?
Jes

[grant]

And the problem with the front wheel lift is that you would need stiffer rear suspension (which might upset the handling towards too much oversteer) or softer front suspension which would case the roll again?

How necessary is it to lower the watts pivot point? I'm a little lost on the negative effects of jacking.

[grant]

And the problem with the front wheel lift is that you would need stiffer rear suspension (which might upset the handling towards too much oversteer) or softer front suspension which would case the roll again?

How necessary is it to lower the watts pivot point? I'm a little lost on the negative effects of jacking.

[MD]

John,

Thanks for the pics. Clears up a few things.
Not familiar with the specific outboard caliper but unless it has bleeder valves top and bottom, it is mounted the wrong way up.

A simple case of just swapping left to right will fix it.

Cheers, MD

[la_strega_nera]

...you don't have to run absurd levels of negative camber...

So, what do you consider absurd levels of negative camber...?
Jes

Unless you're running radial slicks and generating huuuuuuuuuuuuuuge amounts of grip, I'd consider over 2.5-3 degrees starting to get a bit extreme. Of course, cross ply racing rubber works better at more street oriented alignments, and I remember reading a comment somewhere about someone running crossplies instead of radials because they felt what they gained in braking with the crossplies being stood up more offset the loss of outright grip compared to radial race rubber. The crossplies tend to be less knife edged from what i understand.

MD: Looks like a willwood or similar aftermarket caliper. They generally have 4 bleed screws, allowing you to orient them however you want. Of course, you only have to bleed the upper two (there's one for each side of the caliper)

[junglejustice]

Thanks! Yeah - no - 4 bleed screws top and bottom...

[ar4me]

...you don't have to run absurd levels of negative camber...

So, what do you consider absurd levels of negative camber...?
Jes

Unless you're running radial slicks and generating huuuuuuuuuuuuuuge amounts of grip, I'd consider over 2.5-3 degrees starting to get a bit extreme.

Hmm, that sounds low. In practice it seems successful 75 and GTV6, I suspect (mostly follow the 75 stuff), run more than that. Camber of -4 on the front is not unusual, and I think -2.5 on the rear is not uncommon. Just re-did my front suspension today:
Camber -3.8 degrees
Castor +4 degrees
Toe-in 2 mm
This is a full race car with RSR. Next is the rear. Planning on -2.5 degrees camber and 4 mm toe-in.

Have you raced a Milano/75 or GTV4/6? Which alignment did you use?

Jes

[la_strega_nera]

Hmm, that sounds low. In practice it seems successful 75 and GTV6, I suspect (mostly follow the 75 stuff), run more than that. Camber of -4 on the front is not unusual, and I think -2.5 on the rear is not uncommon. Just re-did my front suspension today:
Camber -3.8 degrees
Castor +4 degrees
Toe-in 2 mm
This is a full race car with RSR. Next is the rear. Planning on -2.5 degrees camber and 4 mm toe-in.

Have you raced a Milano/75 or GTV4/6? Which alignment did you use?

Jes

Are you/they running modified front end geometry? ie increased camber gain/raised RCs (the upside down ball joint/drop spindles provide this as well as the raised roll centre)? The numbers I'm talking about are what works on cars with a geometry that actually works... not the alignments you run to get around compromised geometry. I mean, lets face it, for all the nice stuff in the Alfetta chassis cars, the front geometry outright sucks.
The Australian V8 supercars with scratch built frontends and big slicks don't run that much negative camber... they're set up reasonably soft too, in that you can see (and feel... i've spent a few laps in the passengers seat) them rolling quite a bit... they're much softer than you'd expect.
Having driven a car after "fixing" the camber gain and roll centre heights, it really makes a difference to the way the thing works. Ok, yes, it's a 105, but the problems are much the same. I honestly don't recall the alignments I ran on my old GTV.

[Alfettish]

I was just thinking today how soft the v8 supercars look. Do you have a figure on their front negative camber? I was thinking that's it's quite aggressive.

[grant]

Typically you only hear of macpherson strut guys (E30 for example) running 4-4.5 degrees of front camber, but that's because their camber gain is so bad, they have to compensate for the negative camber lost when the car rolls.

But then again, roll still isn't eliminated with the RS kit and camber gain with the stock suspension is pretty bad, so I think 4 degrees should be appropriate for Jes' car. The only way to really know is to bust out a tire pyrometer and read the temperatures across the tire.

All I know from personal experience is that 2.3 degrees is not enough, even with modified spindles

[grant]

Wait, hold on Zamani, are you ordering Beninca torsion bars and springs?? If you haven't paid yet, let me get in on the band wagon and we'll split costs!!

[junglejustice]

Are you/they running modified front end geometry? ie increased camber gain/raised RCs (the upside down ball joint/drop spindles provide this as well as the raised roll centre)? The numbers I'm talking about are what works on cars with a geometry that actually works... not the alignments you run to get around compromised geometry. I mean, lets face it, for all the nice stuff in the Alfetta chassis cars, the front geometry outright sucks. The Australian V8 supercars with scratch built frontends and big slicks don't run that much negative camber...

Oh boy - here comes another "hand on cock" comment - I can feel it...

I guess that all of the F1 teams must "run alignments to get around compromised geometry"...? Ben - ever have a good look at an F1 car's front end!? Not even close-up - just ANY F1 footage - have a look at the MASSIVE negative camber on those cars! Why? Their cornering appears to be 100% flat and they arguably have PERFECT roll-centers (by design any way...)

Why the extreme -camber then?? Because they run "a geometry that actually doesn't work"...? Wanna tell me that your builders of "Australian V8 supercars with scratch built frontends" know something that the F1 boys don't?

Forget it - it is due to the simple fact that you can NEVER control ALL of the roll and because you are ALWAYS going to have some camber-change - no matter how good your book-theory design...