Moparts

Unstable at speeds

Posted By: moparmikethree

Unstable at speeds - 12/05/11 08:05 PM

My 70 Challenger which has all new suspension parts is very unstable at high speeds.I want to drag race this car. Will a front sway bar help this? What about Caster/Camber settings. What settings should it have?

Like I said everything is new, but you have to "saw" the wheel to keep it going straight.
Posted By: bboogieart

Re: Unstable at speeds - 12/05/11 08:09 PM

Who installed all those new parts? Did it do this befor?
Seems to me, you might just need a good front end alignment.
Posted By: moparmikethree

Re: Unstable at speeds - 12/05/11 08:12 PM

The car was converted from a /6 to a 360
with aprox 450 hp. I did all of the work.
Chrysler mechanic 31 years now.

When doing alignment could not get camber where it belongs. May buy the upper control arms ( tubular with adjustment) to get it right
Posted By: bboogieart

Re: Unstable at speeds - 12/05/11 08:15 PM

Sounds like you know what you are doing. I have only played with these so no expert. Sounds like your right about the tubular a arms.
Good Luck.
Posted By: HemiRick

Re: Unstable at speeds - 12/05/11 08:55 PM

You know about the offset controll arm bushings that Moog makes? May give the camber you need much cheaper than new arms.
Posted By: Kam*Kuda

Re: Unstable at speeds - 12/05/11 08:58 PM

How is the steering box?

Lift the car and see if you feel any play when you pull on the wheels? See if there is any excessive movement.
Posted By: Cuda340

Re: Unstable at speeds - 12/05/11 09:07 PM

Quote:

You know about the offset controll arm bushings that Moog makes? May give the camber you need much cheaper than new arms.




This is a good fix...
Posted By: Montclaire

Re: Unstable at speeds - 12/05/11 09:24 PM

You need to:

1) Upgrade to properly rated torsion bars, if you have not done so already. (1970 you could get the 340 performance package which used 383 bars, I would copy that)

2) Buy the moog offset uppers. (You have to install them opposite the instructions though)

3) Check for bumpsteer and shim/slot/gusset the steering mount. Also I think Firm Feel is making an add-on brace for the bottom of the sector shaft on the box.

4) Is the box rebuilt? If not get a rebuilt box from Steer N Gear or Firm Feel.

5) Replace your strut rods. You do not need high dollar adjustables, just the the 30% oversized ones.

6) Pot coupler. The steering pot coupler can wear if left open and dry for extended periods. This will cause slop between the steering wheel and the actual imput on the box. Check for play and replace/repair if needed.

7) Alignment. For handling, you want +3.0 caster and -.5 camber but this is not always possible. Get as much + caster as possible while keeping negative camber.

There is also an adjustment that can be made for dead neurtal, where the box should basically be unassisted if going straight ahead, check the FSM for specs.
Posted By: Challenger 1

Re: Unstable at speeds - 12/05/11 09:29 PM

Quote:

The car was converted from a /6 to a 360
with aprox 450 hp. I did all of the work.
Chrysler mechanic 31 years now.

When doing alignment could not get camber where it belongs. May buy the upper control arms ( tubular with adjustment) to get it right





You mean you can't get enough positive caster, right. Not camber.
Exactly right, invest in some Firm Feel upper control arms, they made a world of difference on my 71.
My black 74 has the offset bushings, the FF upper arms made way more difference ,gave me like 5 degrees of positive caster.
Posted By: Montclaire

Re: Unstable at speeds - 12/05/11 09:30 PM

Quote:

Quote:

The car was converted from a /6 to a 360
with aprox 450 hp. I did all of the work.
Chrysler mechanic 31 years now.

When doing alignment could not get camber where it belongs. May buy the upper control arms ( tubular with adjustment) to get it right




Exactly right, invest in some Firm Feel upper control arms, they made a world of difference on my 71.
My black 74 has the offset bushings, the FF upper arms made way more difference ,gave me like 5 degrees of positive caster.




Did you install them right?
Posted By: Challenger 1

Re: Unstable at speeds - 12/05/11 09:31 PM

Quote:

Quote:

Quote:

The car was converted from a /6 to a 360
with aprox 450 hp. I did all of the work.
Chrysler mechanic 31 years now.

When doing alignment could not get camber where it belongs. May buy the upper control arms ( tubular with adjustment) to get it right




Exactly right, invest in some Firm Feel upper control arms, they made a world of difference on my 71.
My black 74 has the offset bushings, the FF upper arms made way more difference ,gave me like 5 degrees of positive caster.




Did you install them right?




Yes I did...
Posted By: RapidRobert

Re: Unstable at speeds - 12/05/11 09:40 PM

Was it acting like this before the rebuilding?. I'm assuming no & you rebuilt it cause bushings were worn out.
Posted By: BFASTER

Re: Unstable at speeds - 12/05/11 11:09 PM

You should just junk that thing and get a real Mopar!!! Just kidding Mike. Sorry to hear you are having problems with the Challenger. Call me sometime, buddyyyyy!!!!!
Posted By: moparmikethree

Re: Unstable at speeds - 12/06/11 10:27 PM

bought the car as a slant six, never drove it , started to restore it right away so I don't know if there was a problem. I doubt there was a problem before.

where the upper control arm mounts to the body, that was rotted out. Got one from a B-body and welded it in. This is why i think it is off
and why I want to get adjustable upper control arms
Posted By: RapidRobert

Re: Unstable at speeds - 12/07/11 05:13 AM

Quote:

Got one from a B-body and welded it in. This is why i think it is off


What alignment settings did you end up w?
Posted By: MR_P_BODY

Re: Unstable at speeds - 12/07/11 06:06 AM

You might want to check the toe cure in its travel..
if it goes toe out they can get real weird... specially
if it wants to rock side to side...then it starts
to dart back and forth and just gets worse
Posted By: topside

Re: Unstable at speeds - 12/07/11 06:41 AM

Sounds like a caster or toe problem, what was the readout? I'm assuming new leaf spring bushings & strut rod bushings and the sleeves are back in them.
Drag car should have 1/32" - 1/16" toe in, 0 camber, and as much positive caster as you can get. Put your weight in the driver's seat and raise the nose to the height it is in 3rd gear at the track, at race weight & fuel level. My Duster runs +7.0 LF and +7.2 RF caster, but it has the Jack Arnew reworked upper arms from its SS/IA days. It goes straight as a string @ 130, though you don't want to stick your wrist between the steering wheel spokes when you let the car straighten itself from full lock.
Posted By: MR_P_BODY

Re: Unstable at speeds - 12/07/11 06:57 AM

I set up my race car with 10* caster but for my
Rampage(street/strip) I set that up with 5* caster
because of the effort on the street and I have wider
tires on the front of it... both cars are strut
front ends
Posted By: Montclaire

Re: Unstable at speeds - 12/07/11 03:12 PM

Quote:

bought the car as a slant six, never drove it , started to restore it right away so I don't know if there was a problem. I doubt there was a problem before.

where the upper control arm mounts to the body, that was rotted out. Got one from a B-body and welded it in. This is why i think it is off
and why I want to get adjustable upper control arms




Well that would be an important fact to include. Get the adjustable arms and take it to a chassis shop, a good one, and have them blueprint the car. Who knows what may be up with it at this point.
Posted By: 383man

Re: Unstable at speeds - 12/07/11 05:15 PM

Quote:

Sounds like a caster or toe problem, what was the readout? I'm assuming new leaf spring bushings & strut rod bushings and the sleeves are back in them.
Drag car should have 1/32" - 1/16" toe in, 0 camber, and as much positive caster as you can get. Put your weight in the driver's seat and raise the nose to the height it is in 3rd gear at the track, at race weight & fuel level. My Duster runs +7.0 LF and +7.2 RF caster, but it has the Jack Arnew reworked upper arms from its SS/IA days. It goes straight as a string @ 130, though you don't want to stick your wrist between the steering wheel spokes when you let the car straighten itself from full lock.





I agree with this. My 63 is all stock suspension and I have about 0 camber and gave it as much positive caster as I could which was around 2 I believe but I would have to find my printout to know the right spec. I also have my toe very close to zero with it toed in a tad. It handles very good at 125 and I know most race cars handle better with the more caster.

But can you give us the specs that it is set at now ?? Ron
Posted By: Cab_Burge

Re: Unstable at speeds - 12/07/11 06:55 PM

I had issues with one set of wheels and tires, I have three different sets , when I mixed bias plys and radials, turn out the wheel lugs( can't think of the proper name for the retainers, lug nuts, on thick center aluminum wheels )where bottoming out on the brake backing plates not keeping the wheels tight against the axles Little stuff can bite the crap out of you My car would go staright as a arrow(128+MPH in the 1/4) with the right set of wheels, not so when I used the wrong rear wheels on it, shortening the wheels retainer shanks up fix it
Posted By: Silverbullet2

Re: Unstable at speeds - 12/07/11 10:30 PM

Sorry to hijack but I'm having the same problems with my 68 GTX. My front end guy said that to keep the camber right left less than a degree of positive caster on each side. Sure doesn't sound like enough.
Posted By: moparmikethree

Re: Unstable at speeds - 12/15/11 03:22 PM

I put the car one the alignment machine. Its no wonder I have issues

Left Right

Camber -0.9 0.1

Caster 0.9 0.2

Toe 0.28 0.19

What are the idea settings for higher speed stability
Posted By: Cab_Burge

Re: Unstable at speeds - 12/15/11 08:22 PM

Quote:

I put the car one the alignment machine. Its no wonder I have issues

Left Right

Camber -0.9 0.1

Caster 0.9 0.2

Toe 0.28 0.19

What are the idea settings for higher speed stability


I like to see around .15 to .25 camber,(not sure if it is negative or postive camber ) or use the stock specs. for that car As much positive caster as I can get and around 1/16 toe in with the front end raisded up one inch with the drivers weight in the drivers seat and a full tank of gas
Posted By: ahy

Re: Unstable at speeds - 12/16/11 12:06 AM

Agree as much positive caster as possible and some toe in, about 1/8"-3/16" which should be around stock specs on the high side for stability. For cornering you want a little negative camber. More helps the tires bite in turns. At least -.25 degrees. -.75 camber would help the tires bite even more but you get into a tradeoff with caster.

With stock suspension it can be hard to get enough positive caster. 5 or even 7 degrees of caster would be great. One approach while on the alignment rack is to set both sides for max caster. Even it up between the sides and then set the minimally acceptable negative camber.

Offset UCA bushings or tubular control arms with additional caster built in will help increase both caster and negative camber. See Firm Feel's web site.
Posted By: GO_Fish

Re: Unstable at speeds - 12/16/11 02:27 AM

Can a torsion bar expert help educate me? Can/does too low of a ride height contribute to poor stability? I had a front end alignment done at a shop on my GTS (all new front end components/bushings/joints), and I'm certain the ride height is too low and the car likes to wander.
Posted By: MR_P_BODY

Re: Unstable at speeds - 12/16/11 02:49 AM

Quote:

Can a torsion bar expert help educate me? Can/does too low of a ride height contribute to poor stability? I had a front end alignment done at a shop on my GTS (all new front end components/bushings/joints), and I'm certain the ride height is too low and the car likes to wander.




The bars themself wont do it BUT if it has enough
travel it most likely is going toe out during the
travel... being you have softer/smaller bars you
might be hitting the lower control arm snuber and
that could be up-setting it... does your problem
seem to happen on jounce(going down) or rebound(going up)

Posted By: ahy

Re: Unstable at speeds - 12/16/11 04:03 AM

Ride height can affect alignment. If this started happening after alignment, maybe you need a better shop.
Posted By: MR_P_BODY

Re: Unstable at speeds - 12/16/11 04:09 AM

Quote:

Ride height can affect alignment. If this started happening after alignment, maybe you need a better shop.




Yes it can but I'm assuming the height was set prior
to the alignment
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