Race car suspension Class

[Wylde]

The issue with using two springs or progressive springs is the build in potential energy. When you stack an 800 spring and a 200 spring you will actually get a combined rate of 160lbs. Since you are using two springs in series the equation looks like this:

Rate_equivalent=(800*200)/(800+200)

So, for arguments sake, let's say you have a wheel weight at ride height of 500 lbs. When using a 500lb spring you will have a force of 500lb since the spring will only compress 1 inch (Force=rate*displacement). When you use the 800lb spring and the 200 lb spring in series you develop a force of 500lbs as well but this combination of springs will compress 3.125 inches. The difference in the two setups is the potential energy.

Potential= 0.5*rate*displacement^2

With the 500lb spring you will develop a potential energy of 250 lbs/in^2. With the 800lb and 200lb combination traveling further you develop a potential energy of 781.25 lbs/in^2. This increase in potential energy is where damping is crucial as Ranger Mike suggested. More potential energy means the spring will unload faster. The big factor in this argument is where does the 200lb spring become locked, ie when do the coils begin to touch each other.

P.S. I'm a big fan of this thread and I've been following since May of 2014. I recently graduated with a bachelors in Mechanical Engineering and I believe I now live rather close to you in Indiana RM. I will be following up with another post to get your input. One thing is for certain, You have forgotten more about race cars than I will ever know!

 

[Ranger Mike]

wylde, I appreciate the kind words though i am not the guru you made me out to be..but thanks..sincerely ..
You have some great ideas. This makes race car winners! Please look over this progressive spring stuff..i worked with an old guy at hypeco many years ago on a big bar upside down progressive spring that was one weird deal. Would get to a point during compression then fade big time to lock down the front end..expensive...went back to traditional set up.

http://www.hypercoils.com/mph/tech-tips/linear-vs-progressive-rate-suspension-springs/

from the tech guys at Hyperco Springs
Linear vs Progressive Rate Suspension Springs
This entry was posted on April 15, 2015.

Within the realm of motorsports and high-performance driving there is considerable debate about whether “linear rate” or “progressive rate” suspension springs are better for a specific type of event or vehicle. As with anything that is an engineered product; there are always trade-offs. It is almost impossible to design a product that is all “pro’s” and no “con’s.” Generally we try to accentuate the positive characteristics while minimizing the negative characteristics. Let’s get started by defining the difference between these two types of springs.

“Linear rate springs” have one defined spring rate per inch of deflection throughout most of their range of deflection. For instance, if we have a 300lb/in linear rate spring that is 12 inches long, it will take approximately 300lb to deflect it 1 inch. The next inch of deflection will take another 300lb of load and the next inch of deflection will take an additional 300# of load (and so on until the spring goes solid). At this point there will be 900lb of load on a 12 inch long spring that has now been compressed to a 9” spring height.

The “linearity of rate” makes it quite easy to calculate a given spring length at ride height and this helps in setting up the ride height of a specific vehicle. If we know that we have 750lbs of sprung mass on a corner and we want to run a 250lb/in linear rate spring; we know the spring will compress 3 inches (750lbs ÷250lb/in = 3 inches). That helps us anticipate the total travel of the spring. Also, by measuring the total travel of the damper, we can easily estimate the total load placed on the spring during an event.

“Progressive rate springs” are generally classified into two sub-types: 1) constantly increasing rate springs and 2) a “dual-rate” spring with two linear rates connected with a rate-transition range.

The first type (constantly increasing rate) of springs are most often used as “load-compensating springs” on the rear of a vehicle when the vehicle will often see significant load changes in the cargo area. These are most often stock replacement type suspension springs. They are identified most easily by continually varied spacing between the coils. One area of racing where constantly increasing rate springs are used is dirt modified racing where pull-bar springs, using a constantly increasing spring rate, are used to control rear axle wrap during acceleration. These springs are not suspension main springs, but are supplemental springs.

The second type of progressive rate suspension springs, the dual-rate spring with two linear rates connected with a rate transition range is a much more sophisticated suspension spring. The design is much more focused on the specific use for the spring. These types of springs are used primarily in road racing and high performance street and GT applications where the vehicle trim package will stay in a very predictable range. These springs are easily identified by having a few closely wound coils at one end and then wider, equal spaced coils at the other end. They have rates described as 200/425lb/in. This means that the spring has an initial rate of 225lb/in through some range of deflection and then the rate transitions to 425lb/in through a deflection range of 1”-1.5.” The big advantage of these springs is that they can provide “roll control” in addition to roll control provided by sway bars.

Let’s discuss roll control provided by springs. For “linear rate springs” the discussion is easy. They provide no roll control! Think about taking curve at a very high speed. The side of the car on the outside of the turn rolls over and the side of the car on the inside tends to roll up. For discussion sake, let’s assume we have 300lb/in linear rate springs on the front of our car and the car is rolling too much and cornering speed suffers. If we move up to a set of 400lb/in springs in an attempt to “stiffen” the suspension, we fail because the linear rate springs provide no roll control. Think about it. As you enter the same curve at the same speed your vehicle is rolling onto a higher rate spring; BUT the inside of the vehicle is being pushed up by a higher rate spring, also. So there is not improvement with roll control. With linear rate springs, all roll control must come from the sway bar (anti-roll bar).

With properly designed progressive rate springs, we can have the springs contribute to the roll control of the vehicle. The key here is to have the vehicle sit in the rate transition range at curb ride height with the designed number of passengers in the vehicle. For racing applications, this is usually one person of a known weight. For GT and high-performance driving this is usually two people of approximately 180lb each and a full tank of fuel.

When the vehicle sits in the rate transition point, the closely wound coils will be closed almost to the solid point. This often necessitates the use of rubber or synthetic coil covering on one or more of the closely wound coils to minimize noise when the coils go solid. Let’s assume we are working with a 200/425lb/in spring. At ride height we will be sitting on the low end of the rate transition range, about 210lb/in. As we enter a high speed turn, the outside of the vehicle will roll into the 425lb/in spring rate and the inside of the vehicle will be pushed up with a much lighter 200lb/in rate. This provides a significant improvement in roll control. The use of a sway bar will supplement roll control and can provide a more focused level of suspension tuning.

This all sounds very good and one could easily say, make all road car springs progressive rate springs; but it isn’t that easy. There are several considerations that must be kept in mind when designing progressive rate springs:

1. What is the amount of suspension travel necessary? Progressive rate springs generally have less total deflection compared to a linear rate spring of the same free length. This is because the closely wound coils needed to create the dual rates take up deflection space.
2. Because of the reduced total deflection, progressive rate springs should have a relatively long free length. Short springs and progressive rates do not mix well!
3. What load is needed at the transition point and where in the deflection point should the transition range be placed? Progressive rate springs designed for GT or high-performance driving will work great with 1 or 2 people in the vehicle. However, if you put 4 people in the vehicle, load the trunk, and/or hitch up a trailer; you are guaranteed to have a ride height well beyond the rate transition range and the vehicle will ride very harshly and you will have lost the roll control element of the springs.
4. The range of rates is limited by where the transition range must be. This means that many rate/transition range schemes cannot be packaged in a vehicle just because it is desired.

So what is the best way of proceeding when it comes to selecting spring rates? For oval track racing, linear rate springs are the easiest to set-up and get a chassis competitive. If progressive rates are desired, stacking two linear rate springs with some specialized hardware offers greater tuning possibilities with more convenience and less cost.

In road racing, progressive rate springs offer some potential; but the need for long free lengths, adds weight and packaging considerations that often offsets the advantages of a progressive rate spring.

For grand touring and high-performance driving, progressive rate springs offer great ride quality and superior handling due to the roll control offered by the springs. This is especially true if a reduced ride height is desired. The initial light rate provides a great ride, while the increased secondary rate assures a load carrying capability unavailable if lowering with a linear rate spring is attempted. Most high-performance driving involves a fixed vehicle package with only one or two passengers and very limited extra weight. This is the ideal situation for progressive rate springs.

 

[Wylde]

That is a great read and better helps understand progressive vs linear spring rates.

Here is a question that will make you think. I understand that dampers (shocks) are there to control vertical acceleration. I race dirt modifieds an have recently stumbled across a rather unusual setup. In the attached picture this person did not attach the shock to the standard pre-axle orientation. They mounted the shock on top of the birdcage by the upper link. By my calculations and physics knowledge it looks like they are trying to use the shock to help keep the car "on the bars." Judging by the angle it looks as though the shock is mounted 60 degrees from the horizontal. From a linkages perspective the optimum amount of work achieved is at 90 degrees which is what the shock relative to the upper link looks to be.

From a force perspective this creates two vectors in the x and y direction (looking at the left side of the car x= front to back y=vertical). With the force being broken up into two components with a 60 degree angle you get 86% (sin(60)) damping in the vertical direction and 50% (cosine(60)) damping in the horizontal direction. The damping in the horizontal direction seems like it would aid in getting the car up on the bar and keeping the car on the bar. In a "normal" setup the shock is only damping vertical motion thus there is no dynamic control over the rear steer that is being applied when picking up the throttle. With the big pop up shocks (9-1) that are on these cars currently running do you think this could be beneficial? Am I looking at the problem correctly? What is your input?
http://www.4m.net/attachment.php?attachmentid=56643&d=1478544265

 

[Ranger Mike]

Wylde you are thinking 2-D when you should be thinking 4-D

On dirt cars the bird cage is a “bearing” mounted on the rear end housing with two mounting tabs. The suspension linkage is connected to these. This linkage is meant to use body roll to rear roll steer the car. It does this under or over steer by using the body roll to shorten the wheel base on one side and lengthen the wheel base on the other side. As the car body settles in the turn and the drive starts to accelerate , the rear end returns to the equal wheel base position and ends the rear roll steer event. For a short period of time the rear end is pointed toward the inside or outside of the track and the car will drive that direction until the tires hooking up correct the wheel bases and rear steer goes away.

Now if all cars are running this set up in a race and some genius figures out how to keep the car in roll over/under steer LONGER than the other cars, then this car will be able to drive deeper and longer and have an advantage. Roll over steer on dirt means the car will hold traction and not go into rear tire shear as it would with wheel bases equal ( no rear steer present). We keep the forward traction as the oversteer turns the car.

The shock (damper) used on the bird cage is used to TIME the rear steer event. It can be set up to hold the rear steer for a longer period of time or attain the rear steer at a more adventageous point in the corner. Think " tie down shock". It keeps the rear over steer locked in until the traction overcomes the"tie down shock". Compare this to the other car relying on the body roll and settling to return the chassis to a no rear steer setting. He is through the turn and back to a no rear steer position before you are. Your car has gone through the same body rolls and sets the damper to a " tie down " position and holds the rear over steer so you drive by the other car that is losing traction since its wheel base is now equal.

Remember.. Rear steer does nothing for you going into a corner when you are off the gas. It will help when you get on the throttle. I have seen a lot of these birdcage/damper setups. Some even use a pull bar and damper.
So think 4-D with TIME being the other critical factor.

 

[Ranger Mike]

i am heading to caribeean to drink umbrella drinks and look at beautiful women..be back in week..maybe

 

[Ranger Mike]

Rear Roll Over Steer – say that three times and try to kill a Budweiser. Before we figure this one out we need to understand the spin out and why it happens. Or in a more scientific manner, why does the race car lose traction in a turn? During cornering the momentum overcomes the ability of the tires to maintain proper contact with the track. Let us look at the tire contact patch of a 10 inch race slick it looks to be about 50 square inches of sweet contact footprint in a nice square pattern. It is all adhesive area and no slip area. Now enters the dreaded Slip Angle. All slip angle is can be summed up in the difference between where the tire is pointed and where the tire actually goes in a turn. The greater the slip angle the more the pattern changes from all adhesive contact area to less adhesive and more slip. Its shape and center also changes. So as the slip angle increases our chance to spin out also goes up.There is a formula to figure out your tire foot print or contact patch but if you know there is an 800 pound gorilla in the room you don’t need to know his shoe size... you just need to know how to get rid of um!

 

[Ranger Mike]

Now that we know about slip angle and tire contact patch, how can we use it to our advantage?special thanks to steve smith and Paved Track Stock Car Technology #S239 from steve smith autosports

 

[Wylde]

Hope you enjoyed your vacation! As to your Budweiser comment I am a Colorado boy so I relate better to Coors analogies, anyway I digress.

The correlation I am drawing from your post (namely SA2.jpg) is that slip angle has an inverse relationship with traction. The more slip angle the less traction and vice versa. Its amazing such a simple diagram can explain so much. This brings up an important question, how do you tune the car to maximize slip angle?

I had a car years ago that was a spud until the race was about half way over, all the sudden it would hook up and was a slingshot to the front. My crew chief was convinced I was too conservative at the beginning of the race and I never shot the gaps to go forward quickly. I was conservative at the beginning of the race because everyone always thought they needed to win on the first lap and would rather keep my nose clean than get bound up in a wreck. With that being said we finally realized after I broke early in the race one night it was because of tire temperatures. I would keep the tired almost cold until I finally got mad enough or had to press hard enough to burn the tired off and heat them up enough to go forward.

This segways into my next question: We know traction and friction create heat, how can you utilize roll over steer to create heat in the tired without getting them so hot they glaze over? I realize you want to tune for the last 10 laps but at what point do you give up a little later in the race to get a little bit more early?

 

[Ranger Mike]

Thanks for the kind words and I do drink mucho COORS when the mood hits me..

Your question - how do you tune the car to maximize slip angle? I would say we tune the car to maintain maximum tire contact patch on all four wheels in the turn. We do this by proper camber build on the front. Most times we race a solid rear end housing and once we build in the camber, that’s about all we can do besides getting stagger right.

Your question - how can you utilize roll over steer to create heat in the tired without getting them so hot they glaze over.

Roll over steer is used on 4 link suspension on DIRT tracks. Not recommended for paved track.

It is used to maintain traction on dirt by virtue that the rear end is pointed outward and continuing to drive the car. Compare this to equal wheel base set ups that restrict the rear end “ pointing” and force the tires to transition for traction to shear because the wheel bases are equal during the cornering. See post # 1126 the bottom green cars tire contact patches are perpendicular to the line of travel. The green car above this one is sliding in the turn and has tire contact patch's about 45 degree off set from the line of travel

 

[Wylde]

Ive heard from a lot of racers different options on stagger with dirt 4 link supsensions. From post #36 you explained how to calculate minimum stagger.

D + .5 (TW) x CL \ D - .5 (TW)
where D is the track diameter in feet
TW = rear track width of the car in feet ( divide inch measurement by 12)
CL = the left rear tire circumference

Do you think it is possible to add in a coefficient for the amount of roll over steer that is induced when the car is hiked?

I guess my overall question would be: Is there a correlation between stagger and roll over steer or are they two separate variables? Are they additive or multiplicative?

Coffee is pretty strong this morning!

 

[Ranger Mike]

your question - Do you think it is possible to add in a coefficient for the amount of roll over steer that is induced when the car is hiked?

How much rear roll steer you get depends on your linkage settings. Today the hot set up is to lock in the rear over steer once it happens with tie down dampers.your question - Is there a correlation between stagger and roll over steer or are they two separate variables? Are they additive or multiplicative?Stagger and rear over steer are both efforts to maintain the maximum tire contact on the track. Running a locked differential means you u have to compensate with roll differences in tire diameters so you don't shred the tires when turning. Roll over steer is an effort to maintain as much traction at power on as possible.

are they additive? I don’t know but they both better be right or you aren't going to turn the car with maximum performance.

 

[smever2]

To all that supply informative discusions to the forum, I say thank you! Specifically Ranger Mike as he seems to post the most often and really seems to try to help us novices! I am in my fourth year dirt track racing and try to provide engineering principals to dirt racing...but it seems more difficult than it should. So here comes my question, after reading this article ( http://hyperracing.com/Assets/files/tech_department/chassis_tech/Rethink Dirt.pdf ), and before I ask you have explained peices throughout this forum.

1. From forums, articles, 4m, dirt.net, the more wieght on a tire the less it would want to skid (this is true, we know this... normal force and friction coefficient), but does that really tighten the car or resist spinning? I guess what I struggle to understand, according to the attached article, like steering a tractor with its brakes, the LR would push the car to the wall and the RR would push the car to the infield. So more wieght more traction, it seems contradictory is all.

Thanks
Steven

 

[Ranger Mike]

Thanks for the kind words..
Read post #62 on page 4 Fat kid sitting on a tire
Think downforce as opposed to what you call “ weight”. I wrote a lot on the myth of “weight transfer” in this class.
more down force means more traction to a point. On my Ford NAA tractor when you jam the left brake, the left wheel locks and the tractor pivots. The right rear still drives and swings about the pivot point. By tightening the cart I assume you mean cause the car to go more under steer or cause a push condition. Cars push for two reasons. The right front spring is way too stiff causing the go kart suspension thing where the right front tire has too little grip to counter the force of momentum in the turn. The other cause of a “ push” is the right front spring is too soft and we pancaked the suspension making it act like the go kart suspension thing where the right front tire has too little grip to counter the force of momentum in the turn.

 

[smever2]

I have read about the fat kid, which is a great analogy and only makes sense. What I struggle to wrap my head around is why a few things affect the car the way we know they do. Because there is limited fundamental knowledge base out there, I end up reading forums where people make statements from experience which sound like they have found the next big thing (maybe there right maybe there wrong). I end up drawing more from their findings than what is really there. If I could summarize what I think I understand and you may point me in the right direction, that would help.

1. The longer the moment arm (moment arm COG distance from RC), the more sidebite (tighter, roll over, increased downforce on RS).
   1. Isn't this the reason increased LS weight frees car (reduces moment arm)? To me counter intuitive. Esspecially since increased LR bite tightens
   2. RS ballest wieght, its on RS to increase the effect of redcuing moment arm. Raise it and you do the same by raising COG.
   3. With that was the most optimum moment arm length, seems I saw 3" somewhere, is there really one?
2. Increasing track width allows more what? If I think of a simple anology of a "cheater bar", we add a cheater bar when we can break a bolt loose. If we increase axle length doesn't that reduce the amount of downforce at the tire? Maybe a better example would be a two wheel dolly. It can easily pickup up a washer, but if the forks were 6' long and the washer was on the end of the forks it would be a more dificult.

Let me know if this is too much. Again I have a lot of the pieces put together but I am missing the big picture.

 

[Ranger Mike]

smever - have you read these pages? a lot of your questions are answered in previous posts. or are you just asking for questions you have from some other article?You know I hate the term “weight transfer” but it is easier to understand than the concept of momentum and cornering force. Anyway, imagine your street stocker 3000 pound slab of iron will continue moving in a straight line once accelerated unless out side forces act on it. This outside force is where the tire meets the pavement (dirt). It is called the contact patch.

There is a direct line of the tire contact patch to the Roll center. This line also has an angle. The smaller the angle the less impact the contact patch has on any change to the momentum. Too much angle and we really connect to the track and begin to lift and carry the left front tire.

Working backward, we have tire contact patch to the RC and the lever from the roll center to the center of Gravity. The short this lever the more the camber build rate and the less spring rate we need. The Longer the distance between the COG and RC, the less camber build but the more spring rate required.

the reason we scale the car on garage floor and add left side weight is to equal out the tire load on each wheel when in the turn.

Roll center posts (COG as well)
# 229, #251 pg. 12,
jacking effect #691 pg. 35, #811 pg. 41, #879 pg. 44

Adding weight and location for ballast see # 562 pg. 29, #563 page 29

track width #255 pg. 13, #264 pg. 14, #322 page 17, #505 pg. 26

 

[Vintageracer13]

How do you figure roll center with a straight front axle?

 

[Ranger Mike]

vintage...now come on...how high is the sky?
Is the car configured with coil spring/shock? torsion bar? single leaf spring or two leaf springs or swing axle?
Does it have panhard bar or Watts linkage.
photos help ,,,,

 

[Vintageracer13]

Sorry Mike. I race a vintage modified with a Ford inline six cylinder. It has a straight front axle with a 4 inch drop. I use a single transverse leaf spring that is mounted on top of the axle. I use a panhard bar to locate it.

 

[Ranger Mike]

We figure the roll center by finding the linkages that prevent the side to side movement of the chassis during cornering. Typically on a single leaf spring ( with multi leafs) front beam axle set up, like the old Ford T-bucket hot rods run, we have a multi leaf spring. This spring has spring eyes at each end. A shackle linkage connects the spring eye to the axle. Where the shackle bolts to the axle is the data point we need. Measure the distance between each point and the midpoint is the Roll Center.

The panhard bar you have negates the above as the Roll Center. The Roll Center height and offset when using the panhard bar is the mid point of panhard bar. This roll center may very well be many inch off set from the cars center line. It depends on the panhard bar length.
All the adjustment used on a rear mount panhard bar apply to the front mount panhard bar.

I grew up watching 32 Duce coupes racing flat head V8s and Ford inline 6 cylinder 300 cid monsters. The 6 cyl. block had 7 main caps and was bulletproof. That was racing. This set up can take a huge amount of abuse and once you learn to drive it, you can have a ball racing it.

 

[Vintageracer13]

Thank you. I use the 240 inline that is the little brother to the 300. I have been racing this car for 2 years and this year I want to optimize my suspension. Would the Performance Trends software help me to determine the best front roll center location as related to the rear? From what I understand so far in reading this forum and from other sources the front and rear roll centers need to be designed so that the two ends of the chassis aren't fighting each other when cornering. With these cars we have to make most of the brackets ect.. so it wouldn't be difficult to make changes.

 

[Ranger Mike]

i would call the good people at perf trends and ask about your chassis. you are correct on both RC. Pretty easy to tune with the panhard bars on each end.
thanks for checking out this post..
rm

 

[Vintageracer13]

This my project Ranger Mike

 

[Ranger Mike]

running smokey yunicks colors and # 13 i see

 

[Vintageracer13]

Yes sir. That 1966 Chevelle was a eye opener for me. The things he did with the suspension in 1967 that are still used today!

 

[Vintageracer13]

I want to thank you all that have posted on this site. After reading countless posts and asking a few questions I measured my front roll center and discovered it is on the chassis centerline. I'm going to move the frame side bracket over to the right and this hopefully will move the roll center to about 3 inches to the right.

 

[Ranger Mike]

a pretty good start. ifin you are taking time to do this, i would make the right side bracket slotted horizontally. The cost of the panhard bar tubing is such that you could swap out different length p-bars . The 3 inch RC offset is a ball park figure. The offset depends on the track and the tires and will vary the amount of additional down force on the right front tire. But i like your thinking!

 

[Vintageracer13]

Thank you! When measuring the roll center height would measuring from the ground to the horizontal plane of the panhard bar give the correct number?

 

[Ranger Mike]

, vin...almost there, racer! you want the ground to the center point of the panhard bar height. in other words construct a perdendicular bisector from the roll center POINT on the p-bar to the floor.

 

[Vintageracer13]

I get it now! Thank you so much!

 

[Vintageracer13]

Ranger Mike I have a hypothetical question for you. Say you have 2 groups of cars that want race together. Group A has motors no more than 256 cubes and min weight of 2300. Group B has 360 cube motors and a min weight of 2400. Everyting else about the 2 groups of cars is the same. If group B had to be at 2425 including a mandatory 40 lb on the frame rail of the right side in front of the firewall would this give too much of a advantage to Group A? I don't really think so because the B cars have a 100 cube advantage. Thoughts please

 

[Ranger Mike]

From strictly a bench racer perspective, here you go. Figure one horsepower per cubic inch. This is very easy to attain these days. On some cases we go 2 HP per cube but we can stay with 1 hp per cube.

Next we sue the racers rule of thumb that for every 10 pounds you remove from the car you “ add “ one horsepower. So in theory the car that weighs 125 pounds more would need an additional 12.5 horsepower to be even.
The 360 CID car would have 91.5 more horsepower to race the lighter car.
Early Southern California Timing Assc. veteran Stroker Mcgurk –” if some’s good, and more is better, then too much is just enough" he also said
..there is no substitute for Cubic Inches”

 

[Vintageracer13]

Thanks for the input Ranger Mike! How should the front and rear roll centers compare? My assumption is that the rear would be higher but is there a way of deciding that? Should I also try to match the lateral front and rear?

 

[Ranger Mike]

read
Roll Center heights and offsets and why
page 12 post #229
i would go with ft rc offset starting at 3" and try to center the rear RC. don't worry about the rear ht being taller than the ft.

I like a low front roll center mainly because it has better camber curve..less change and I think it is all about contract patch.
As in life, there are exception and the exception to low RC is street stock class where you must race SPEC tires. You can not change the A-Arms usually and so are limited on changing the RC offset to get any down force on the hard spec tires. So you have to raise the RC to get some side bite in these hard sidewall tires.
Yes, you have a shorter moment arm between the Rc and COG but the angle of RC to the tire contact patch is a lot better than stock. Some stock chassis have RC at an inch above the pavement..
You will just about always have rear RC higher than the front and this is ok too

 

[Vintageracer13]

With a straight front axle camber change shouldn't be a issue for me. I want to thank you again. This forum has opened up a whole new world for me!

 

[Vintageracer13]

Ranger Mike I have been considering running a lift bar instead of a 3rd link. I want to use springs top and bottom in the front to control the bar during braking and acceleration. Thoughts?