Push/understeer question • The Dodge Challenger Message Board

by **Jon** » 13 Mar 2009 1:40

Took the Dodge out today and found a really cool road. Highway 229, you gotta try it. :fight:

2nd gear mostly, with bermed corners and good clean pavement. No safe runout though so had to contain myself.

Worked the tires a little and found the steering cut tight early, but eventually into the middle of the corner I could turn the wheel without as much reaction. (turning)

Is that something that can be corrected with tires or tire pressure or maybe just the limit? The fronts are new Indy 500's 15/235's, rears 255 . Sway bar factory 7/8" front with poly, rear no bar at all. T-bars are .92 factory.

I added caster to the front recently (2 degrees pos. ) could that cause the pushing effect?

by **dave-r** » 13 Mar 2009 8:47

Sounds like your front spring rate is too high compared to the rear.

The cure for understeer is actually to add more oversteer to the car.
Try one or more (depending how bad it is) of these things;

Increase front tyre pressure.
Increase front tyre and wheel size.
Increase negative camber.
Stiffen the rear suspension more. (The leafs and or sway bar)

by **fbernard** » 13 Mar 2009 10:47

As Dave said, if you want to have fun on twisty roads, make sure you have between 1.5 and 2 degrees of negative camber.

And a rear bar may actually turn this boat of yours into a car.
:lol:

by **dave-r** » 13 Mar 2009 11:01

Personally, because this is a stock type suspension set-up, I would start by adding a rear sway bar and just making sure you have at least some camber on the front. 1/2 a degree negative is a god start.

These cars understeered as standard. Something Chrysler didn't really care about as long as they didn't oversteer (which was considered more dangerous). Adding wider rear tyres (a typlical muscle car mod) makes this worse.
After a couple of years of production Chrysler started adding a rear sway bar on pretty much every e-body model.

So check you have a little neg camber first. Then fit a rear sway bar.

Then test the car and see if that was enough.

by **Wojpi** » 13 Mar 2009 12:35

Hey for curvy roads you should buy Nissan GTR :biggrin:

Just kidding, changing to lower profile tires will also help a lot, after of course you finish with suspension as Dave said. In my car stiffer suspension + 15 inch high profile tires was also not good for corners.

by **Jon** » 13 Mar 2009 13:45

The front was aligned yesterday and he dialed in 1 degree negative camber. I think I'll let that be for now as he will charge me another fee. That and tire wear??

Wouldn't less air pressure in the front cause a better bite with more contact area?.

It is at 28 PSI. They are new as mentioned so that won't be changer right now.

Buying a Nissan is definitely out of the question. Three vehicles with registration and insurance bills are enough. :rage:

Guess the rear bar is something to look into. Any thoughts on over top or under axle?

Thanks for the input

by **dave-r** » 13 Mar 2009 14:15

Get your tyres up to 35psi and try that.

The over axle (chassis mounted, factory type) rear sway bars are best. 3/4 inch diameter.

by **Moparman1972** » 13 Mar 2009 14:34

Less air pressure means more flex in the sidewall of the tire, and if you have too much flex, you'll roll the tire under the rim.

When I took my porsche to the road course in Limerock, CT, I ran the first session with 32 psi. A friendly gentleman loaned me his air compressor, and I brought the tires up to 38 psi for the rest of the day. What a difference in handling! It's very noticeable.

by **Jon** » 13 Mar 2009 14:53

Good info on tire pressures. Guess it's not the same as dirt bikes.

I looked at the edges and they didn't appear to have rolled under at all.
I'll air them up next time out though.

As a note, the new poly bushings in the LCA and struts did allow much more road noise and vibration to the car. Tolerable though.

by **drewcrane** » 13 Mar 2009 17:59

so uhmm jon thats a nice corner its a sweet and green out there in san miguel

,how fast can you take it? fitty,fitty five? :s016:

by **Moparman1972** » 13 Mar 2009 18:01

The picture messes with my perception. With no center lines, it only looks like a 1-lane wide road.

by **Jon** » 14 Mar 2009 1:56

The picture is from a website and doesn't really show justice. I was alone and had no photographer but next drive I plan to take the camera and a friend. The 20 mph curves are really intense. Stay tuned.

http://www.westcoastroads.com/california/ca-229.html

by **Moparman1972** » 14 Mar 2009 2:21

Aha!! It IS a narrow road! (1 1/2 lanes)

Looks fun! :twisted:

by **drewcrane** » 14 Mar 2009 12:51

hey jon thats a nice site we might be able to put that to good use :thumbsup:

by **dave-r** » 30 Mar 2009 19:36

Just found this on my PC.

by **drewcrane** » 30 Mar 2009 21:45

nice ill keep that :thumbsup:

by **Jon** » 31 Mar 2009 2:30

Thanks Dave. :thumbsup:

A lot to think about.

The rear sway bar seems to be the next logical step. Over the axel is best and I have some old brackets for the end link support at the leaf springs.

Started cleaning them up today.

by **dave-r** » 31 Mar 2009 7:42

Yes I think a little roll control at the back will help a lot. It is the first thing I would do. :thumbsup:

by **Jon** » 01 Apr 2009 2:32

As luck would have it, I scored a rear sway bar today. The Guy lives about 40 minutes away and works on Cudas mostly. He said it is a T/A bar, it looks original Chrysler (even has some undercoating). I got an extra set of leaf mounts also for $125.

Now if the bar works with the exhaust pipes above the axle it should be ready to go. Anyone know where on the frame to locate the body mounts? There is a taper on the bracket maybe that will help.

by **dave-r** » 01 Apr 2009 7:31

The frame brackets should almost fall into place on the frame when you line up the ends of the bar over the springs. :nod:

by **Jon** » 03 May 2009 23:51

As usual Dave you were right. Everything fit fine after attaching the links then moving the U-channel over the frame box.

Had to extend the exhaust 1-1/4" to clear the bar. (don't even say anything about the welds

)

Now fitting the tips in back. Since I added over an inch, thought to ask what you guys think about the distance out from the valence? Should they it be set back a bit closer?

Thanks,

by **dave-r** » 04 May 2009 9:06

I would move the tips back to where they were. :nod:

by **drewcrane** » 04 May 2009 12:08

i like the last pic they look nice and tucked in , some people like them sticking out a bit but i prefer the last pic just my opinion

by **Jon** » 04 May 2009 13:34

My thoughts also. :thumbsup:

I was surprised to see how much these factory tips leak. They are only spot welded and the baffle inside sends vapors in between the two tubes. Thought to use silicone or something in that area.

by **dave-r** » 04 May 2009 18:19

When is the first test run to check the handling then?

by **Jon** » 05 May 2009 1:40

Next weekend fersure.

Do you think the overalxle pipes should be tacked to the muffler?

I had to grind off the ones the shop did to get them out. It was a stout setup though.

The worry is while driving, with just the clamps, they could rotate and the tips hit the valence.

by **dave-r** » 05 May 2009 7:57

I usually hacksaw 4 cuts into the pipe end to allow the clamp to compress the pipe so it grips. I place the clamp half way over the end of the cuts.

by **patrick** » 06 May 2009 5:35

dave-r wrote:I usually hacksaw 4 cuts into the pipe end to allow the clamp to compress the pipe so it grips. I place the clamp half way over the end of the cuts.

Hmmm.

by **johannes** » 06 May 2009 16:11

This was an interesting thread,....believe this has been discussed earlier....

I believe I've read somewhere, that the rearaxle sometimes migth be "banana-shaped", and thus effects the handeling of the car.......
...toe in versus toe out on the rear wheels.......

Comments anyone ?
Can a bent rear axle be straigthened in a jigg ???

by **dave-r** » 06 May 2009 17:37

If the axle shafts are bent you need new shafts.

If the axle housing is bent you can have the tubes replaced. They are just 3-inch tubing.