AAR / T/A Handling

[Nereth]

I read this thread a while back, I just decided to come back and give my 2c. I don't remember what other points have been made yet though.

I haven't had much (read: any) experience with E bodies except whats online, but I have taken an interest in suspension and handling.

Anyway, to the best of my knowledge, if maximum lateral gees is your aim, then one of the most important starting points for the car is where the center of gravity is, since it isn't going to change very easily. For maximum lateral gees, you would want a low one to minimise lateral load transfer, but for straight line acceleration, a high CG will get more load on the rears, so it's a trade off. I don't know where on a barracuda the CG is so I can't make much of a conclusion, but just compare its dimensions to another car and make your judgment. By the way, if anyone has a pair of 1000 ish pound scales and some way of lifting the front end of the car, I can walk you through a procedure to find the height of the CG, and off course where it is front to back. The CG position also defines how much weight is on each wheel when the car is at rest (Ie: weight distribution), which you all know is important.

Another thing is the wheelbase and track. Wheelbase is important because the shorter the wheelbase, the more weight is transferred for a given acceleration. Weight transfer is basically directly proportional to the length of the wheelbase, so the couple inches between a cuda and a challenger won't make a huge difference, but a 10 inch or so difference will be very much noticeable. So a short wheelbase will give you more straight line acceleration. You want a large track, on the other hand, since lateral load transfer isn't very good for traction, and is proportional to track in the same way as longitudinal weight transfer is proportional to wheelbase.

The live rear axle on an E body is definitely bad. If you had a dead smooth track it wouldn't be so nasty, since unsprung weight is such a huge issue with a live rear axle, but god knows there aren't many of those around. Even with a perfectly smooth track, a live rear axle has a nasty habit of causing load to transfer from one wheel to the other. That is bad for traction, as usual, and while it can be remedied for a given torque, if that torque changes, ie you change gear or take the throttle off or drop or add some revs, the remedy will no longer work (to the best of my knowledge).

I would also worry about chassis stiffness, because chances are the front will be very slide out happy as you go around a corner with throttle off, and the simplest solution to that is probably adding some rear roll hardness, but that won't be all that helpful unless the chassis is stiff enough to transfer the hardness through.

Those are probably the main things I would be worried about if I was thinking about racing an E body. I don't know numbers for the E body, but I'm sure a good old guesstimate from you guys with more experience, would suffice.

Oh, and again, if anyone wants to put the rear of their car on a scale and jack up the front, I can walk you through a procedure to find the position of the center of gravity. I'm working on a simulator for vehicular handling, and some good test figures would be nice. I can even give some info back (although it will probably be pretty useless at this stage, except for novelties sake)

[TreeFrog]

One trick the circuit cars used was to dip the car in acid.  It would eat though most of the steel.  leaving a thin shell behind.

neat trick but unsafe, and not much for lasting. 

[RabidScott]

.....mopars are way underspring up front and over sprung on the back in stock form. If you look at the kit car data Direct Connection put together back in the 70s, they only recommended a 120# rear spring rate coupled with 1.06 to 1.16 torsion bar and a 1-1.125 sway bar up front. For a point of reference, the stock XHD spring pack is approximately 140# and the super stock springs are around 160#.

I've seen Chrysler type leaf springs advertised before for circle track applications, would these work in a street car?  Why is the spring rate so much different for circle track cars than what one would assume for a "good" handling car?
http://www.speedwaymotors.com/p/3526,156_Speedway-and-Landrum-Multi-Leaf-Springs-Chrysler.html

Also, what about these mono-leafs?  They are rated at half the above springs.  Are these springs being rated individually, or in pairs?
http://www.speedwaymotors.com/p/7365,156_Speedway-and-Landrum-Mono-Leaf-Springs-Chrysler.html

Where would be a good source for the 120 lb rate rear springs?

Excuse my lack of knowledge, I'm trying to figure out what springs would be best for a hard driven street E body.

Thanks guys!!

[HP2]

Its all about the combination of parts, achieving balance, and application. Application is a big factor when choosing racing parts that may see street use.

For example using Speedway's catalog, they sell springs for cars that range from 1800-3500 pounds  with varying degrees of offset that run on tracks made of dirt, clay, concrete, or asphalt with banking ranging from a few degrees to over of 20 degrees in flat or parbolic angles. Additionally you have chassis' variations for those tracks that may have lots of body roll to virtually none and the same for down force generation. That is a huge range of applications that would require a very diverse set of spring rates. A quarter mile dirt track car with minimal down force requirements on a flat track would have a very light spring rate to allow lots of body roll to increase traction whereas a half mile asphalt car running on high banks creates so much down force that a very high rate spring is needed to avoid bottoming out. In a street handling application we have a much narrower set of variables since we all have very similar suspension set ups, with fairly similar weight distributions. I'd also be willing to bet that the average enthusiasts isn'tconsidering odifying geometry either, which can have an influence on needed rates as well.

Things to keep in mind about springs rates; any spring actually has three rates- the actual spring rate of compressing the spring 1 inch, the applied rate of the spring at the wheel hub after calculating geometric leverage against the spring and including any sway bar rates, and the wheel rate as calculated where the tire touches the pavement, which includes tire sidewall deflection and shock rates. So it is entirely possible that a 1000# spring only creates 250# of force on to the surface of the road.

The reason why the oval track springs appear to have a lighter rate than what you would think for handling is because of the application and balance. This is because of the weight distribution within the car. The springs must support the load, there is more load in the front, so spring rates need to go up substanially in the front compared to the back when compared to a strip car, or a street/strip car that also performs drag launches with high shock loads to the back springs.

Mono-leaf vs multi- leaf again gets back to application and the need for lighter rate, lighter weight springs. However, there are a couple of exceptions to this. One is fiberglass composite springs, which are mono-leafs, but come in higher rates from 150-300#. The other is split mono leafs that are actually two short leafs that are cut and then stacked under the axle at the mounting point. Calvert springs come to mind here where a lighter rate, lighter weight spring is desireable and when combined with the adustable link traction mechanism creates an almost solid front segment for drag applications with a soft, pliable rear segment to allow for suspension motion.

If you read any of the XV literature, you'll find that they have similarly reduced rear springs rates considerably. Looking at their offerings, they have a variation on the old kit car program. They are tight lipped about their actual rates, but looking at their product pictures, they appear to have torsion bars that are likely 1.12 to 1.16, front sway bar that is 1.125, rear sway bar that is .75 and leaf springs that are probably 110-120#. Obviously good shocks are a big part of that combination. Lacking the means to measure and dial in a fixed rate shock, adjustables would be the best choice for us shade tree tuners. XV has combined the pieces together to produce what is the best reasonable compromise of handle prowess and ride comfort that is out there for the average handling enthusiast. Anymore, copying their layout is almost a sure thing.

If your actually competing, then you would be getting into the significantly higher rates like 1.22 torsion bars, 175-200# leaf springs and/or adjustable sway bars up to 1.5 inches in solid or tubular configurations.

[Bullitt-]

Something I've never seen referenced..T/A power steering conversion..look at top of page 3
http://www.steerandgear.com/images/Mopar_Catalog-1.pdf

[B5 T/A]

I love my TA but it can't hold a candle to even a basic car from today. 

[brads70]

 

[challengermaniac]

Hey guys,

A little off topic, but I am getting ready to rebuild the frontend of my 70 Challenger (SB, Auto, ps, disc, with 15" Rallye Wheels) and just wanted to find out whether or not I needed to put new leaf springs on the rear.  Can someone tell me what the stock ride height should be (front & rear) for the above car--- being sure to let me know from where the measurements are being taken? 

Thanks, Charlie
70 Challenger TA (Clone)

ps: In the old days, we adjusted the two bolts on each side of the frontend to get the desired ride heigth, if that's not the correct way to do it, let me know as well.   

[ChallengerHK]

Hey guys,

A little off topic, but I am getting ready to rebuild the frontend of my 70 Challenger (SB, Auto, ps, disc, with 15" Rallye Wheels) and just wanted to find out whether or not I needed to put new leaf springs on the rear.  Can someone tell me what the stock ride height should be (front & rear) for the above car--- being sure to let me know from where the measurements are being taken? 

Hey, Charlie. Re: replacing the rear springs, I think that's more of matter of personal preference. HP2 makes a pretty convincing argument that all or most of our cars sat low in the rear from the factory, and that by adjusting the to sit level we're re-engineering a poor design rather than replacing overly worn parts. I personally like e bodies sitting level front to rear or with a little kick up in the back, so I've replaced my springs.

ps: In the old days, we adjusted the two bolts on each side of the frontend to get the desired ride heigth, if that's not the correct way to do it, let me know as well.   

That is the correct way to do it. If you make a large adjustment you'll need to realign as well. Ride height is measured in inches of differential between two points on the lower control arm, but I think most of us are measuring distance from the highest part of the wheel well arch to the ground.

[HP2]

mopar never specified a ride height for the rear. It simply was what it was. The front however has a spec that most people will not like as it creates a nose up attitude in most E bodies. See the attachment below to see how the service manual calls out this measurement as well as the factory spec.

Mopar's chassis book ha always called for a 1.5 to 2 degree nose down rake for best performance.

[4THECHALLENGE]

Great points .. Thanks for sharing guys

[Mr. 440SixPack]

This topic still lives Great posts with very interesting info

From the day i've first heard that cuda was raced in Europe i am looking over the internet to find what kind of suspension modifications were on racing cudas...
I mean a heavy car with a large hemi engine up front was actually a good competition to europe sports cars of the era like porsche 911 and renault alpine.

If anyone have more info please post it here.

[SBDave]

I read through this whole thread two weeks ago and really liked all the input.  While I'm not looking for AAR or T/A Handling specifically, I am looking to make my 73 Cuda handle the best it can.  I want it to feel like a road racing car and am willing to sacrifice some comfort in the process.  I want to keep the stock suspension design so that means I need new sway bars, shocks and torsion bars/leaf springs.  Does anyone know of any threads following the installation of an XV Motorsports Level 1 suspension?  Or know any sources/reviews that give specific performance figures over stock suspension (lateral g's...)?  I got the DVD from them and am very impressed with what I have seen so far however I want to hear some user feedback.  I remember reading about someone on CC that had the level 1 suspension and didn't like the rear leaf springs because they wanted the rear end up in the air more (if I remember correctly). 
thanks,
Dave

[PlumCrazyChris]

Is this the thread your looking for? 

http://www.cuda-challenger.com/cc/index.php?topic=55883.0

[PlumCrazyChris]

You may want to search through the topics of  Suspension, Wheels/Tires, and Brakes, because there are some Really Great threads in there about making your ebody handle, that should be archived....if they aren't already.