Suspension aligned, car not as much fun to drive.

[moneymanager]

Car is a 74 911, the tires are BFG g-force R1’s 205/50 x 15’s . It’s lowered quite a bit (see below) and corner balanced. Car handled wonderfully before I recently added a camber plate to allow bit more negative camber at the front, a camber maximizer at the rear, and a Rebel bump steer kit. No other hardware changes were made. After the work I had an alignment done at a shop well known to me where I watched it being done; we got a bit more negative camber at both ends and the bump steer to zero.
Here’s where I am: front caster at 6.3°, which I would think should be a tad “dartier” than stock. Front camber 1.3° negative, rear 2.1°. Front toe 0.03°, rear 0. Ride heights are about 25” at the front fender and 25.5” at the rear. This was not changed.
Compared to the prior alignment, we got a bit more negative camber front and rear, the caster was increased 1°, and the toe-in at the front was slightly reduced. Car is very stable and predictable, but I’m not happy with the result. It feels less responsive somehow, not as much fun to drive fast. To sum it up, it feels more like a Carrera or an SC than an early car. Could 1° more caster be the difference? This seems like the only change made that might be big enough to matter. Any help appreciated.

[john walker's workshop]

more caster = more tendency to want to go straight.

[911st]

I am not an expert but here is my two cents worth.

As John said, increasing the caster increases the self centering effect and also increase the steering wheel effort.

Less toe should help liven up the front. Toe out making it change directions even faster.

Did the rear toe get changed. This can have some effect to.

You are running a full on track tire that is very small in diameter. Your ride height sounds good for a stock height tire of about 25" but to tall for what I guess is a 23" tall tire. Maybe shoot for about 24.25" front fender and 24" rear. Or lower the front till the front A arms are parallel to the ground and set the rear so the chassis is level or up to 1 deg rake. With taller tires I used to run my front A arms sloping up with the CL of the ball joint about .7" higher than the CL of the torsion bar. This let me get a bit more neg camber from my stock suspension when cornering. Better yet, have the front struts modified for more camber and to raise the spindles for a better camber curve.

I would think you could use a lot more neg camber. Maybe up to 3 deg front and rear depending on how stiff your spring rate is. The Smart Racing Camber King with the shock hat removed should let you get close.

A good corner balance done at the same time as the alignment (camber effects corner ballance) being the finishing touch.

[Gunter]

Quote: "front caster at 6.3°, which I would think should be a tad “dartier” than stock. Front camber 1.3° negative, rear 2.1°. Front toe 0.03°, rear 0. Ride heights are about 25” at the front fender and 25.5” at the rear. This was not changed.

Like JW says, more Caster means more stability going straight (Which I like)

IMHO, the Cambers are too negative unless you do a lot of track. With 2.1 deg rear, you're driving on the inside edge of the tire until it wears down (Unevenly, of course)

I think 1/2 to 3/4 deg front and 1 to 1.25 deg rear Camber is plenty for mildly agressive street driving.
Not sure how much 0.03 deg Toe-in front is in inches; 0 rear is good.

Fender height is usually the other way around: 25" front and 24.5" rear to get the 1 deg nose-down attitude.

Do you have a front spoiler and rear wing?

[rfloz]

What I found in trying to dial understeer out of my auto-cross oriented '84 (if you have some time to burn, see 911 Understeer Issues at Auto-Cross (long)), was that these cars respond well to small changes.

My car was plowing big time and I had front brake lockup issues. By changing front toe from zero to 1/8" out (my trig sucks, so someone else will need to convert that to degrees) and lowering tire pressures by 4 psi, all that was gone.

You don't mention what your intended use is, but if it includes track or auto-cross, try a little toe out in front.

If it's street only, try going back to your old caster setting. Most of the people who auto-cross run at least 5 degrees and up to maximum they can get (6 degrees plus in most setups).

If one or the other doesn't do it, try both.

[moneymanager]

Thanks to all. Should have said car is 75% track/25% weekends so I want/need more negative camber, not less.
John, I know more caster = more tendency to go straight. Would a 1° increase be enough to change the feel as much as I seem to sense?
911st, you're right, I'd like more camber. Will probably be making more changes. Ride height is low now, driveways (and tire rubbing on fender at the rear) are a challenge at my current height. But the measurements I gave above are wrong: should read 24" front, 23.5" rear with those tires, so I'm closer to your spec than it appeared above. Shock hat is gone and I have a Tarett camber plate. It yielded less negative camber at the front than I had hoped for.
Gunter, no front spoiler but I do have a ducktail. But I don't think aero is my problem. If anything the car is almost too stable. You can't have too much stability I know, but you get my point.
Bob F, two of you mentioned a bit of toe out might be good. And your point about the impact of small changes must be right, given the change in feel I sense with the tiny changes I've mentioned.

[kodioneill]

Did you give your tires enough time to wear in to the new set up?

[john walker's workshop]

[QUOTE=moneymanager;5332347]Thanks to all. Should have said car is 75% track/25% weekends so I want/need more negative camber, not less.
John, I know more caster = more tendency to go straight. Would a 1° increase be enough to change the feel as much as I seem to sense?
QUOTE]

you may want to ask bill verberg about it. you were probably at the "sweet spot" previously.

[moneymanager]

No, tires got no chance to adjust to new settings. And I'm now mounting a new set of tires, so we'll try again with them. Won't change anything until I have a bit more experience.

[Flieger]

I would try setting the caster back to the previous.

[aradsinc]

Hi Guys
I have a silly question
When adjusting camber and toe do you adjust the height first using the eccentric bolt or everything is done at the same time.
This is of course after you have adjusted your spring and torsion bar to get the height you want say 24"at the rear and 24 1/2" at the front.
I attache photo of my 1974 Carrera 2.7 RS engine
arads

[stlrj]

Arads,

Looks like the Polo Club parking lot...right?


Cheers,

Jose

[914efi]

Keep in mind that you can't look at caster in a vacuum. More caster angle might increase straight line stability (reduce quick responses) but it will also increase camber gain with steering input which might help cornering and reduce the need for excessive static camber which would help braking, etc. Lap times, tire temps might be the best way to evaluate this.

[cgarr]

Where is this caster adjustment?

[moneymanager]

Art. I agree. It's possible that this "less fun to drive" 911 is in fact faster. Need to get some times before making changes. At the moment my plan is to add a tiny bit of toe-out, because I can do that without upsetting anything else. Then if that doesn't get me where I want to go, I'll fool with caster.
Craig, caster and camber are both adjusted by loosening/moving the plate at the top of the strut.

[Dueller]

Originally Posted by cgarr

Where is this caster adjustment?

Caster is adjusted by fore/aft of the strut strut top...the more you move the top of the strut to the rear (i.e., towards the driver) the greater the caster ; camber from side to side. But you knew that

[cgarr]

Originally Posted by Dueller

Caster is adjusted by fore/aft of the strut strut top...the more you move the top of the strut to the rear (i.e., towards the driver) the greater the caster ; camber from side to side. But you knew that

Duh!

[Bill Verburg]

Originally Posted by moneymanager

Car is a 74 911, the tires are BFG g-force R1’s 205/50 x 15’s . It’s lowered quite a bit (see below) and corner balanced. Car handled wonderfully before I recently added a camber plate to allow bit more negative camber at the front, a camber maximizer at the rear, and a Rebel bump steer kit. No other hardware changes were made. After the work I had an alignment done at a shop well known to me where I watched it being done; we got a bit more negative camber at both ends and the bump steer to zero.
Here’s where I am: front caster at 6.3°, which I would think should be a tad “dartier” than stock. Front camber 1.3° negative, rear 2.1°. Front toe 0.03°, rear 0. Ride heights are about 25” at the front fender and 25.5” at the rear. This was not changed.
Compared to the prior alignment, we got a bit more negative camber front and rear, the caster was increased 1°, and the toe-in at the front was slightly reduced. Car is very stable and predictable, but I’m not happy with the result. It feels less responsive somehow, not as much fun to drive fast. To sum it up, it feels more like a Carrera or an SC than an early car. Could 1° more caster be the difference? This seems like the only change made that might be big enough to matter. Any help appreciated.

first there is no such thing as zero bump steer, you can only minimize it by minimizing the difference in the arcs of the A arm and steering arms

why the large rear camber relative to front? depending on tires I'd expect ~ -1.5* at both ends(hard to get it w/o camber plates). the more camber(to a point) the more grip. More grip in back means more understeer

zero front toe w/ a small amount of rear toe in is more usual

zero or positive toe at whichever end promotes turning, at the front it's useful in back not so much unless you like oversteer

your front caster is fine, there are lots of 911s that can't get that much

[moneymanager]

Thanks to all. Had planned to wait for a track day at this setting before making a change but couldn't stand it. A 1/4 revolution turn on both tie rods moved me to very slight toe out. Car is transformed. Dead feeling is gone, car turns nicely. Amazing what a relatively tiny change can do!