Entered my 70 in its first autoX.... in the pouring rain.

[JR]

I've wanted to start tweaking the handling on my 70 forever. I haven't been able to because I've been too busy chasing reliability gremlins. It was pouring rain and 60 degrees today, but it was easy on tires so that was a plus.

What I learned;

My suspension is all stock RT stuff, but fresh. That said, it's the worst handling car ive ever owned. By far. Massive understeer. No front end bite at all. Massive amounts of body roll that comes quickly then abruptly stops. Slow steering ratio that requires massive amounts of steering wheel input. The last run was just me furiously stabbing the brakes trying to load the front tires and make them bite.

That said, it was a whole lot of fun. Im going for a rear sway bar, quicker steering box, chassis stiffening, and firmer springs to start with. At least I'm in the tweaking phase now and out of the build phase.

The plus side is the pics turned out great. It looked epic on course. Even if it was slow.

EDIT: Here's a good vid of  a run from a great driver in a c5 Z06. He spun at the end of this vid, I don't know how he didn't spin more. He drove right on the edge of traction, it was awesome.
https://youtu.be/ezeghUZSxyA  -Edit.

Here are some pics. I'll add more as they get posted.

[Ghoste]

Of course you were also using it in a way that was never intended or even imagined.  Glad you had fun though.

[Kern Dog]

I'm just impressed to see someone drive one in the rain!

Many of us have become spoiled because even the cheapest new car today handles pretty good compared to unmodified older cars. However...
Money spent in the right places will transform the old cars into a real competitive machine that can still ride relatively nice.
A friend of mine owns both a mostly original 71 383 Road Runner and a 2013 Challenger R/T. Since he bought the R/T, he hardly drives the Plymouth. He has seen me spend loads of money on my 70 Charger and has often said he wouldn't spend that much on his RR because you can't get an old car to handle like a new one. Funny thing is, I own a 2015 Challenger R/T and can clearly say that my Charger would smoke the Challenger on a road course. YES there are more squeaks and road noise in the old iron, but the platform is sound. Torsion bars and leaf springs will not ride as smooth as the new R/T but it does corner well.
Bigger torsion bars, sway bars, stiffer leaf springs. Better shocks, frame connectors, torque boxes. Reinforced LCAs, K member...Lots of this stuff can be done at home for minimal $$$.

[Kern Dog]

Just a few pictures:

[Kern Dog]

More:

[JB400]

Your last pic with the reflection is cool   Glad to hear you had a great time.

[Kern Dog]

Reinforced K member:

[JR]

I need to do the re-enforcement on the k member too.

Im slightly apprehensive because mine is an original RT k member with the skidplate and I don't know if the collector value is worth putting it to the side and modding another one. Or maybe go the aftermarket route.

Im sure on a dry course I would have noticed the chassis flex more. I was just dying for some front end grip the whole time. I know a basic rules of suspension tuning is "the stiffer end slides first", so I'm going to change the rear springs/shocks/swaybar setup before touching the front springs.

A square wheel/tire combo would help, but I really like the look of the wide rear wheels. I did go down from a 10 inch wide wheel to a 9.5 though. I can't imagine how bad it would have been on the old 15 inch draglite wheels it used to have.

[myk]

Hotchkis,  my friend.  You will not be disappointed.

As for value, most of the mods we're talking here, especially he Hotchkis ones, are easily reversible to stock.  But hey, your car isn't stock and it isn't being used for its stock intention so I say have at it.

Do you really think a squared off wheel setup helps handling?  I've been dying to get a wider rear wheel but your words give me pause.

Wait a minute...don't we have the same wheels?  How did you get a 10 or 9.5 inch wide wheel?  I thought they only came in 8"?!

[JR]

A square tire setup absolutely promotes more neutral handling, 100% fact.

Ive been doing autoX and track days for a few years now (using an E36 M3, my other mistress), and the recommended setup for 99% of cars in a handling setup is a square wheel/tire setup.

The simple reason is, whichever wheels have a wider contact patch, automatically have more grip. So basically:

More rear grip = understeer (the front end wants to push straight in a corner)

More front grip = oversteer prone ( rear end comes loose first, you're drifting, weeeeee)

A popular saying is, "oversteer scares the passengers, understeer scares the driver).

Alot of the reason some U.S. spec performance cars have a wider rear tire setup is to dial in some understeer, which keeps the lawyers happy, as your average driver is better prepared to deal with push than correct the tail swinging around.

The U.S. spec M3 and the refreshed S2000 are good examples of this. When both of them were released, they had square tire setups, and  no toe-in in the rear alignment. After a few years of sales (and crashes) the safety nannys at the companies asked that the handling be made " easier for less experienced drivers to handle" and both were given wider rear tires and a safer alignment for the average consumer. A.k.a.= neutered slightly. The first thing track/autoX guys do is convert their later cars to the earlier tire/alignment setting.

Another example was the C4 corvette. The standard Vette had a much wider rear tire. However, if you ordered it with the Z51 handling package, you got a square setup. (4 matched tires).

Sorry that was a long explanation, but it does make a difference. I'm considering buying a 2nd pair of 8inch wide rear wheels to swap on for autoX days, and using the wider ones for street.

I'm looking into the Hotchkiss stuff, preparing my wallet for the huge shock its about to suffer. I also like the look of the QA1 bolt on rear suspension kit, it eliminates the leaf springs and converts the rear to a panhard bar/coilover setup.

The tinkering never ends.

Edit: oh yeah myk, MB makes a 17 X 9.5. in addition to 17 X 8. That's what I'm running. You have 18s, right? The 18s aren't offered in 9.5. (Or atleast they weren't 2 years ago.)

[myk]

I don't mind the long post at all;  agonizing over my rear tire width is stupid, and your information might finally put that issue to pasture.  I guess the square setup stays!  As for the wheel, again it won't be an issue if the square setup 's better for handling; function over form and all that.

Kudos to you for doing what many of us lack the courage or skill to do on that track with our cars.  I only hope to be as worthy someday.

What are you planning to do about the steering ratio?  Fast ratio setup?  Borgeson box?

[JR]

No problem myk. I wouldn't sweat it.

Function>Form


I wouldn't hesitate to take your 69 out myk. It's a real no pressure environment that's great at teaching car control, and is great to see how mods really hold up.

As for the steering, I'm leaning towards a firm feel stage 3 with the quick ratio pitman arm, kframe bracing, and a smaller steering wheel. That should be enough. I'm used to cars with 12-14 to 1 steering. This current 18 to 1 feel so slooooowww.

Also, this just got posted. Here's a run video from the event. This guy is a fantastic driver in a c5 Z06. He spun only once (at the end of this vid) when he hit the huge puddle at the end. He was driving on the very edge the entire time.
https://youtu.be/ezeghUZSxyA

[Mike DC]

   
The understeering is one reason for the OEMs to use wider rear tires but probably not the primary one.  They could achieve it with swaybars too.


I suspect the reasoning for big rear tires more like:

#1 the macho look. 

#2 producing decent 0-60 times in magazines from cars that have too much power and too low 1st gears. 

#3, keeping the inept owners from getting themselves killed when they do burnouts.  As soon as the owner shits his pants & lets off the gas, there is a lot of rubber ready & waiting on the rear wheels to start gripping again. 

[crj1968]

Looks like fun. Great looking 70 ! 

[myk]

No problem myk. I wouldn't sweat it.

Form>Function.


I wouldn't hesitate to take your 69 out myk. It's a real no pressure environment that's great at teaching car control, and is great to see how mods really hold up.

As for the steering, I'm leaning towards a firm feel stage 3 with the quick ratio pitman arm, kframe bracing, and a smaller steering wheel. That should be enough. I'm used to cars with 12-14 to 1 steering. This current 18 to 1 feel so slooooowww.

Also, this just got posted. Here's a run video from the event. This guy is a fantastic driver in a c5 Z06. He spun only once (at the end of this vid) when he hit the huge puddle at the end. He was driving on the very edge the entire time.
https://youtu.be/ezeghUZSxyA

Yes, the stock steering ratio is ridiculous.  Whenever I try to throw the car around turns and whatnot I find myself fighting the steering wheel above all else.  Since I have headers I will have no choice but to use the Borgeson, if I want fast ratio steering...

[Kern Dog]

A square tire setup absolutely promotes more neutral handling, 100% fact.

Ive been doing autoX and track days for a few years now (using an E36 M3, my other mistress), and the recommended setup for 99% of cars in a handling setup is a square wheel/tire setup.

The simple reason is, whichever wheels have a wider contact patch, automatically have more grip.

Your theory is great for people with cars not powerful enough to break loose their 245 series tires.  I run a staggered setup and still had oversteer despite a pretty decent setup. I went with a smaller rear bar, Bilstein shocks and huge 1.15 torsion bars. The car is very neutral now but will still boil the tires. I'd never reduce my rear tire size for any reason. I'd oversteer more and blow off the tires at anything over half throttle.
In general terms, your theory needs a disclaimer or two.

[Dino]

Good stuff!  I'm glad to see I'm not the only one driving in the rain.   

Myk that's the same rear wheel I have, 17x9.5   

[b5blue]

  How fresh are your T.B.s and rear springs? What shocks are you using? I'm in a similar mode myself with my 70 and bought a set of tire turn plates and an old school clip on alignment tool. (With the bubble gauge.) I want to start trying to tweak front end settings. I've installed Hotckis solid mount front struts and reinforced the LCA's with plates, but everything else is Moog/Mopar parts with Monroe shocks. (Cheap.)  I've 15" stock junkyard rims and 4 tires the same on all four corners.
  Right now I'm messing with the rear end ride height to even the staggered height from springs having different leaf counts. (It's a bit excessive on my car, possibly the chassis is off some.)
  Two things you may consider are ride height, looks as you've a bit of rake going on and that effects front spindle movements orientation to the road and have you checked alignment and settings with you or your weight equivalent at the drivers seat?    (Two things often overlooked.)
 

[JR]

Edit: added a couple of new pics to first post.

Kern Dog, almost any car will break loose the rear end if you apply excess throttle while cornering at the maximum speed the tires can grip at. I agree there are exceptions when staggered would be preferable. (Like a turbo RWD 911 for example), but the general rule is square tires promote neutral handling. Not saying its impossible for a staggered setup to be neutral, I'm just sharing my experience. The z06/shelby drivers I meet at trackdays are usually on a square setup for road courses. But I'm glad to see your setup is dialed in, I wish I were there myself!

You own the red 70 on twisted vista wheels, right? That's a beautiful car man, I've stumbled over your posts a few times looking for tuning info and always pause to drool over it when I see it posted.

B5, my Torsion bars and springs are far from fresh. They're original RT parts, but are fatigued and need to be replaced. My setup now is only fresh poly bushings, adjustable strut rods, moog offset UCA bushings, fresh General AS03 tires in front, Nitto 555s in rear, and that's pretty much it.

 I've been so busy chasing mechanical gremlins I haven't had the chance to get started updating the suspension, but now its priority one. Half the reason I took it autoXing was to get a feel for the baseline and see what I need to change. (Everything, it turns out.)

I aligned it at home using a buddy's tools, it currently has 1/8 toe in in front, and I forget the exact caster/camber numbers, but I tried to Max out camber/caster on each side, reasonably. Its around 1.5 degrees neg camber i think. I didn't sweat it knowing I wanted the adjustable UCAs soon.

I agree the rear needs to come down. The raked rear also reduces caster. It used to be higher in the front, and the rake wasn't as pronounced, but I lowered the front when I aligned it, which bought on the rake. It looks cool on the street, but it sure was crap on the course.

Somewhere on this site, Mr. Angry posted his suspension setup, I was thinking of copying his setup mostly. The man knows how to drive and his 68 sure seems to carry its weight well.

[WHITE AND RED 69]

Sweet pics! Looks like some fun out in the rain.