Front end neg camber, how much have you got, how'd ya get it Options

[ottox914]

Looking for some inside secrets, black magic, motorhead mojo, on front end camber. I know our cars are a mixed bag in terms of what you can get in front. My '73 with the GPR/tarrott camber plates can get 2.4 neg on one side, only 1.8 on the other. The chassis measures out fine, no tweekage. It'd by nice to be able to equalize them both at around 2.5, or better still, 3.0, but how. I have no interest in taking this car to autocross nationals or get into hard core scca auto x stuff, just want to putter around and make a better local car, so bending the rules a little doesn't scare me, depending on how far the bend is.

So what do you all have, and how'd you get it?

Anyone use an aftermarket bolt on camberplate like all the little ricer guys run? I've never seen one for our cars, but they don't look hard to make. I was wondering if one could be designed to hold the top strut bearing up over the plate, thus allowing: 1) a little more strut travel on lowered cars, and 2) if the bearing is up over the adjustable top plate, the strut could maybe "tip" more to the inside, as the slim diameter of the strut rod would be smaller than the bearing or strut tube, and could be tilted in, closer to the edge of the factory hole.

I'm picturing something like this: http://cgi.ebay.com/ebaymotors/Steeda-Cast...1QQcmdZViewItem

[J P Stein]

By all means, get more negative camber. Brad Roberts says good drivers use lots of negative camber so if you wanna be thought of as good, get -3/-4. You may wear out the iinside edges of your tires quickly, but you'll look cool doing it.(IMG:style_emoticons/default/biggrin.gif)

[Borderline]

By all means, get more negative camber. Brad Roberts says good drivers use lots of negative camber so if you wanna be thought of as good, get -3/-4. You may wear out the iinside edges of your tires quickly, but you'll look cool doing it.(IMG:style_emoticons/default/biggrin.gif)

As long as I look cool doing it that's all that matters! (IMG:style_emoticons/default/smile.gif) Actually I'd like to like good on the results page too. I remember Brad's posts about the euro drivers using so much camber and going so fast. Gotta be the way to go! (IMG:style_emoticons/default/biggrin.gif)

A recent copy of Grassroots Motorsports profiles a 240sx champion that is running 4.5* neg up front. And Nathan did very well when he was running his teener. I had no idea he was running so much neg camber. The way I see it, the more body roll you have the more neg camber you have to put in to get the tire upright in the corner. Of course, all of this seems to go out the window when you start talking about bias ply slicks.

OK JP, what you running and how'd you get there?

[nebreitling]

By all means, get more negative camber. Brad Roberts says good drivers use lots of negative camber so if you wanna be thought of as good, get -3/-4. You may wear out the iinside edges of your tires quickly, but you'll look cool doing it.(IMG:style_emoticons/default/biggrin.gif)

As long as I look cool doing it that's all that matters! (IMG:style_emoticons/default/smile.gif) Actually I'd like to like good on the results page too. I remember Brad's posts about the euro drivers using so much camber and going so fast. Gotta be the way to go! (IMG:style_emoticons/default/biggrin.gif)

A recent copy of Grassroots Motorsports profiles a 240sx champion that is running 4.5* neg up front. And Nathan did very well when he was running his teener. I had no idea he was running so much neg camber. The way I see it, the more body roll you have the more neg camber you have to put in to get the tire upright in the corner. Of course, all of this seems to go out the window when you start talking about bias ply slicks.

OK JP, what you running and how'd you get there?

run whatever you need to go fast, regardless of what JP or Brad or anyone says (actually, that's exactly what Brad is saying). for me (running hoosiers/710's), this was -3.5~ish. was about to go for more, but I sold the car. tire temps, wear, and timeslips will always reveal the truth.

yeah, I think of myself as good. not because of freakin' camber.

[J P Stein]

By all means, get more negative camber. Brad Roberts says good drivers use lots of negative camber so if you wanna be thought of as good, get -3/-4. You may wear out the iinside edges of your tires quickly, but you'll look cool doing it.(IMG:style_emoticons/default/biggrin.gif)

As long as I look cool doing it that's all that matters! (IMG:style_emoticons/default/smile.gif) Actually I'd like to like good on the results page too. I remember Brad's posts about the euro drivers using so much camber and going so fast. Gotta be the way to go! (IMG:style_emoticons/default/biggrin.gif)

A recent copy of Grassroots Motorsports profiles a 240sx champion that is running 4.5* neg up front. And Nathan did very well when he was running his teener. I had no idea he was running so much neg camber. The way I see it, the more body roll you have the more neg camber you have to put in to get the tire upright in the corner. Of course, all of this seems to go out the window when you start talking about bias ply slicks.

OK JP, what you running and how'd you get there?

run whatever you need to go fast, regardless of what JP or Brad or anyone says (actually, that's exactly what Brad is saying). for me (running hoosiers/710's), this was -3.5~ish. was about to go for more, but I sold the car. tire temps, wear, and timeslips will always reveal the truth.

yeah, I think of myself as good. not because of freakin' camber.

I run -.5 at both ends and that's too much up front...meaningless for guys running R spec tiars. When I ran Rspecs I used right around -2 which gave good temps across the face & a good wear pattern.

As to "good", competition reveals the truth. For me, top 5 at PCA = top 20 at SCCA......sometimes better, seldom worse. Britian (my co-driver) does considerably better, so I know my place in the pecking order.

BTW:
I'm off tonight for Packwood WA & a NW Region SCCA AX tomorrow. I've never run with these guys before and looking over the pre-reg. (177 entered thus far) there are some well known names coming....class ass kickers at the Nats. I'd prolly better find some pillows
to stick on my backside cause it's gonna get kicked a lot (IMG:style_emoticons/default/alfred.gif)

Ah well, you can't make an omlet without breaking a few eggs.

[Joe Ricard]

Good luck JP. sounds like Packwood is where the big fish swim in the deep end.

un-like the local stuff where only a few regulars show up and nobody upsets the tea cart.

I like going to other regions and never say nothing to anyone. Just be cool get set up and walk te course. help out if needed. then Let the time slip stand.

Next event I bring all my cajon friends and we put a whoopin out.

Then buy a round of beer at dinner. answer all the question about the car. like is that a 6? (IMG:style_emoticons/default/confused24.gif)

[ottox914]

So, seems for DOT R's, more camber is more better. For the schlick guys, less gets the job done.

For us DOT guys. anyone got pics of what they had to do to get what they got? I'd be interested to see some of the grinding and such needed to take a factory camber plate and modify it to hit 3 degrees or so.

[Joe Ricard]

This picture show would be interesting. Who wants to show thier cards at the poker table? Some people have to run under the rules of thier sanctioning body for the events.
I'm not taking pics. However I am totally legal in X prepared SCCA. You would really not be able to tell anyway unless you had a stock car and a measuring tape.

What I don't like is people doing this shock tower mod and then claiming stock class eligibility (IMG:style_emoticons/default/chair.gif)

[Dave_Darling]

So, seems for DOT R's, more camber is more better.

Up to a point... Check the latest issue of Grassroots Motorsports, they do some testing with a MINI Cooper. Their lap times drop from -1 to -3 camber, then when they go to -3.5, they have real problems putting the power down and braking. (Actually, those problems were cropping up earlier, but the gains in mid-corner speed more than offset the losses from those.)

More static negative camber means less tire on the road when the car is going straight. Therefore, less traction for braking and accelerating. So at a certain point you are trading off traction in the corners for traction braking and accelerating.

Alignment setup is always a series of compromises...

--DD

[Borderline]

Hi Dave!

I saw that article. They were running on a mini road course, Streets of Willow Springs, where I believe braking effort is a more important factor than on an AX course. Though I've never seen the "Streets". I make changes from one event to the next and analyze how the car feels and see how I'm doing in the overall rankings of the competitors. It's just smart to see what others are doing and what works for them. I guess it's just about time to pick a pyrometer.

I've been running a rear sway bar and as of late been having a problem getting the power down on corner exit. I just like the idea of having a rear bar cause that's what race cars have and I put a fair amount of time into mounting it!! Next AX I'm going to run make a couple runs and then disconnect it and see how it feels.

[J P Stein]

I use brakes a lot and hard at AX. Your HP may differ.(IMG:style_emoticons/default/biggrin.gif)

[J P Stein]

Good luck JP. sounds like Packwood is where the big fish swim in the deep end.

un-like the local stuff where only a few regulars show up and nobody upsets the tea cart.

I like going to other regions and never say nothing to anyone. Just be cool get set up and walk te course. help out if needed. then Let the time slip stand.

Next event I bring all my cajon friends and we put a whoopin out.

Then buy a round of beer at dinner. answer all the question about the car. like is that a 6? (IMG:style_emoticons/default/confused24.gif)

There were a fair passel of big dogs there....not like a Tour event, but a good
crosssection Brit got all but 2 I think. I sucked as usual.....but I got the tiars hot.(IMG:style_emoticons/default/biggrin.gif)

Bout 170 drivers.

[Joe Ricard]

That was my job last year. "tire warmer for my own car".

It is time for me to put on a pair of big boy pants and drive the car fast myself.

I am holding auditions for a tire warmer for this winter and ramp up for the Early tours next year.

[jhadler]

Static negative camber is essential for a strut car on radial tires. Critical even. The strut will decamber as the body of the car rolls. But it's a compromise. The more camber you dial in, the more tire you're likely to have on the ground in the turn (to a point), but the less tire you'll have for braking and acceleration.

The stiffer the roll rate of the car is, the less this decambering effect is. In some cases, a monster front sway bar can actually reduce understeer by helping keep the front wheels from decambering. The 914 is not an extreme example of this however. A VW Gti though... MONGO front sway bar will actually help reduce understeer.

SLA suspensions really minimize that, and radial shod cars can get away with less static negative camber.

Then up front, there's caster... Caster is good, more is better. And, up to a point, giving up a little static camber for more caster is a deal worth making. Caster is -dynamic- camber. The more you turn the wheel, the more camber gain you get.

Bias ply (slicks) shod cars, that another story. The relatively soft tread face of the bias ply tire allows the contact patch to move with the shifting loads. And the more rigid sidewall, prevents the tread face from rolling away from the ground. And cars with these tires can take advantage of less camber than their radial shod cousins...

A setup that's good for slicks is definitely NOT good for radials, and vice versa.

-Josh2

[Joe Ricard]

Holy crap Josh you been peeking in my race car books?
I like JP's idea of Cantilevered slicks in front and regular slicks on the rear.

[J P Stein]

Odd, I checked my front camber as I pushed it to the bump stop. It gained negative camber all the way....maybe sumthins' bent. This pic isn't quite all the way, but the angle on the tire is more revealing.

Body roll, we got some.

I think you are overstating the effect on camber of a strut suspension or taking something out of context. Also, caster adds camber to the outside wheel as one turns which is why AXers run as much caster as they can get.
I may be fulla shit, but pics don't lie.(IMG:style_emoticons/default/biggrin.gif)

Then again, I read your post more carefully and find we agree....put it down as a senior moment.....my work here is done.(IMG:style_emoticons/default/confused24.gif)

[jhadler]

Odd, I checked my front camber as I pushed it to the bump stop. It gained negative camber all the way....maybe sumthins' bent. This pic isn't quite all the way, but the angle on the tire is more revealing.

Of course you gained camber. Just follow the geometry. As the a-arm rotates upwards, the hub goes with it, and as it pivots up, gains negative camber.

Body roll, we got some.

I think you are overstating the effect on camber of a strut suspension or taking something out of context.

It's not just the suspension movement to consider. As the body of the car rolls, the strut top moves with it, and because the strut is directly coupled to the a-arm, if there's body roll, the strut will loose some negative camber. In some cars, this is really severe. In other car, not as big a deal.

Also, caster adds camber to the outside wheel as one turns which is why AXers run as much caster as they can get.

You betcha!!! (IMG:style_emoticons/default/biggrin.gif)

I may be fulla shit, but pics don't lie.(IMG:style_emoticons/default/biggrin.gif)

Then again, I read your post more carefully and find we agree....put it down as a senior moment.....my work here is done.(IMG:style_emoticons/default/confused24.gif)

Yes sir... I think it's time for... (IMG:style_emoticons/default/drunk.gif)

-Josh2

[Dave_Darling]

Well, strut suspensions usually gain positive camber when they get up toward the bump stops. Have you done anything unusual with your fronts? Raised spindles, perhaps?

When the A-arm goes upward past level, the horizontal component of its length starts shrinking. That effectively pulls the bottom of the tire inward a bit, which gives you more positive camber than you have when the A-arm is completely parallel to the road. If you start with your A-arms pointing downward, then you gain negative camber up until the arm is parallel to the road.

Unless the A-arm is very short indeed, the effect is generally fairly small. With more sophisticated suspension designs (multi-link, SLA, double wishbone, etc.) you can get the tire to gain quite a lot more negative camber in bump.

--DD

[Dave_Darling]

Chuck Moreland (of Elephant Racing) posted a very good observation on the Bird Racing forum. The key being that it's the angle of the A-arm with the struts that induces the camber change, and that the struts are something like 15 degrees tilted out! So you will keep gaining negative camber until the A-arms are ~.15 degrees up. But the gain is larger when the arms are down further, so it's still not a bad idea to have the arms tilted downward.

If Chuck OK's it, I will post his note on the subject.

--DD

[Dave_Darling]

Chuck assented, so here is his reply on the Bird board:

The front suspension will continue to gain camber until the angle between the control arm and the strut equals 90 degrees. Beyond 90 degrees and you begin losing camber.

The strut is actually angled in the range of 11-14 degrees static and actually angles more as the suspension compresses . Actual value depends on static camber. So your wheel continues gaining camber until the lower control arm is something more than 11-14 degrees above horizontal.

Turns out the stock suspension bottoms out about the same time the angle reaches 90 degrees. So camber loss never really happens in any meaningful way.

However the rate of camber gain is greatest when the angle between strut and control arm is smallest. Rate of gain approaches zero as the angle approaches 90 degrees (gain is the sine of the angle). It is therefor advantageous to get the lower arms angled down at static ride height to keep the camber gain decent through the usable range of suspension travel. This is the primary value of raised spindles.

--DD

[Borderline]

Dave:
I agree that you get camber with suspension travel, but it's not that much. My rough analysis show that 3 degrees of body roll will give the outside tire 2.5 degrees of positive camber if it started with 0*. So if I start with 2.5* neg and the suspension travel gives me .5* then the wheel will be upright when the body rolls 3*. Obviously more body roll will need more camber to start with. Some AX photos have shown that my car some others have about 3* body roll in some of the tighter corners.