cambered rearend

Shocks, Springs, Brakes, Frame, Body Work, etc

Moderator: Team

User avatar
MadBill
Guru
Guru
Posts: 12632
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: cambered rearend

Post by MadBill » Mon Dec 24, 2012 11:50 am

Back in my Formula Ford days, we had a scrutineer that was totally *n*l about battery retention. If we had anything questionable on the car, we'd just tie the battery down with a ratty bungee cord, wait for him to vent his spleen, then hang our heads and fix the mounting. He'd never even look for anything else once we'd made his day.. =D>

But I digress...
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

ZIGGY
Guru
Guru
Posts: 1229
Joined: Mon Mar 05, 2007 3:15 am
Location: Dallas, Texas

Re: cambered rearend

Post by ZIGGY » Mon Dec 24, 2012 12:03 pm

:shock: :lol: :lol:

23Root
New Member
New Member
Posts: 41
Joined: Thu Dec 06, 2012 12:39 pm

Re: cambered rearend

Post by 23Root » Mon Jan 07, 2013 11:36 am

i run a metric chassis my self. your not looking for camber in the rear. its all about rear steer. when your going around the corner you want your driver rear to push towards your passenger front. If you can adjust your springs you can tighten or loosen the car a lot just by raising the right rear over the left. I cant give out to many tricks but that a should help a lot

Bubstr
Member
Member
Posts: 192
Joined: Wed Jul 05, 2006 5:55 pm

Re: cambered rearend

Post by Bubstr » Mon Jan 07, 2013 11:18 pm

This is something we have done since the early 60s. You want 1 degree of positive (top in) on the right rear and 1 degree negative on the left rear. It's all about slip angle. That would be the angle the tire is to the surface your running on to get the best traction. Most all tire manufactures I know recommend 1 degree. In the front also with camber gain figured in to body roll.

As far as getting rear steer from a chassis, that you can not relocate your mounting points might be a tad hard. You need to have different anti squat values to help the car roll over and shorten the left wheelbase. This is used in conjunction with a soft right front spring and a soft rebound shock on the left rear. Play with the soft spring and see what you get. Changing ride height may help this with out breaking the rules. You may want to talk to some spring manufacturer about a stacked spring if legal. It would actually be easier to get rear steer from a leaf spring set up. Look up Fast Boys set up. They work good on the slick tracks. This is basically a leaf Late Model from the 70s -80s, that they use on some limited mods. Don't laugh, CJ Rayburn says don't forget what you know about leaf springs, they may come back. He may just be getting old and senile like me.

There is one other thing you can do. Measure out tires to find your biggest roll out. Mount that tire and Put a hundred lbs of air in it and put it on tin in the hot summer sun. It will grow. There is some stagger to be had there. Rim width can make a difference in roll out too.

I take it this is a bomber or SS. You gave weight percentages but forward and back is only half the story. Center of gravity height could be your biggest advantage. Did you know, most LM chassis have two different engine mounting holes? One for aluminum block and one for steel. don't confuse them, they won't get out of their own way.
Older I get the less I know for sure

23Root
New Member
New Member
Posts: 41
Joined: Thu Dec 06, 2012 12:39 pm

Re: cambered rearend

Post by 23Root » Tue Jan 08, 2013 5:55 pm

i agree 100 percent with your staggering. i always measure new tires to see which is the biggest figure out where i will use each one then if i need more stagger put air in it and sit it in the sun. an inch or so can be made that way.

Bubstr
Member
Member
Posts: 192
Joined: Wed Jul 05, 2006 5:55 pm

Re: cambered rearend

Post by Bubstr » Thu Jan 10, 2013 2:45 pm

Going along with stagger, how you groove and sipe and grind a tire, if you do, can make it feel like more or less roll out. Just a little.

If you can use a wheel 1/2 inch or 1 inch narrower can increase roll out. Wheel spacers or lack of them can increase or decrease the effect of the roll out. If you use a different size wheel, the air pressure requirement will be some what different. A pyrometer can help with this.
Older I get the less I know for sure

turtle
New Member
New Member
Posts: 40
Joined: Sat Dec 08, 2012 7:52 am

Re: cambered rearend

Post by turtle » Sat Jan 19, 2013 11:14 am

Bubstr wrote:As far as getting rear steer from a chassis, that you can not relocate your mounting points might be a tad hard. You need to have different anti squat values to help the car roll over and shorten the left wheelbase. This is used in conjunction with a soft right front spring and a soft rebound shock on the left rear. Play with the soft spring and see what you get. Changing ride height may help this with out breaking the rules.
23Root wrote:i run a metric chassis my self. your not looking for camber in the rear. its all about rear steer. when your going around the corner you want your driver rear to push towards your passenger front. If you can adjust your springs you can tighten or loosen the car a lot just by raising the right rear over the left. I cant give out to many tricks but that a should help a lot

I have put alot of thought into the rear roll steer, CG height and rear roll center for the stock rear suspension. According to Mark Bush (from Afco), when you raise the rear ride hight, it lowers the rear roll center. Now with that being said, we also know that it will raise the weight (the CG). It will also change the angle of the lower trailing arms. The three combined will create more roll AND more roll steer. There is also the added drive angle of the LR trailing arm during acceleration.....
Bubstr wrote:I take it this is a bomber or SS. You gave weight percentages but forward and back is only half the story. Center of gravity height could be your biggest advantage.
You are right, it is a Street Stock. I am familiar with GG location importance, LtoR, FtoR and height when tuning the chassis for different tracks and conditions.
I was inquiring about rear camber because it looked like it could be an advantage but I don't know anybody running it or with expierience that I could get good reliable information from. This sight is the best group of minds that I have come across with good valid information, and I am glad that i can be a part of it.
Thanks for any information,
Turtle.
Our Creed: "Where two or more are gathered, there shall be a RACE!"

65hardtop
New Member
New Member
Posts: 22
Joined: Sun Aug 02, 2009 8:55 pm
Location: Michigan

Re: cambered rearend

Post by 65hardtop » Sat Nov 23, 2013 3:35 pm

I know this is an old post but I thought I needed to post on it. As far as getting more camber in the rear end, I'm pretty sure you could do what your trying to do by just buying a set of rear tires with more stagger. I'm pretty sure at least a degree or more. The more stagger makes the rear end set at more of an angle from left to right. However if you just change the camber that's only changing the camber. If you change the stagger your changing lots of different things. Ride hight. Different tires have different spring rates. Car will need to be rescaled because you just changed the wedge with the added stagger. Just changing the camber .5-1.0 degrees would probably never be noticed on a dirt car. There are so many other variables. I'm guessing .01- .02 a lap. And when lap times can vary .2-.5 a lap that's not much.

turtle
New Member
New Member
Posts: 40
Joined: Sat Dec 08, 2012 7:52 am

Re: cambered rearend

Post by turtle » Sun Nov 24, 2013 11:12 am

65hardtop wrote:I know this is an old post but I thought I needed to post on it. As far as getting more camber in the rear end, I'm pretty sure you could do what your trying to do by just buying a set of rear tires with more stagger. I'm pretty sure at least a degree or more. The more stagger makes the rear end set at more of an angle from left to right. However if you just change the camber that's only changing the camber. If you change the stagger your changing lots of different things. Ride hight. Different tires have different spring rates. Car will need to be rescaled because you just changed the wedge with the added stagger. Just changing the camber .5-1.0 degrees would probably never be noticed on a dirt car. There are so many other variables. I'm guessing .01- .02 a lap. And when lap times can vary .2-.5 a lap that's not much.
My thought was to try and lower my tire pressure, to get more contact patch on our dusty slick track conditions. A side effect from lower tire pressures is the tire sidewall rolls under more, during cornering. I was hoping that I could overcome this by adding camber to the rearend housing. This should allow me to take full advantage of the now larger contact patch when lateral forces are applied.
Adding stagger is an option but it does have other effects on the chassis performance that will need to be addressed.
Our Creed: "Where two or more are gathered, there shall be a RACE!"

Post Reply