The ongoing quest for MORE caster, 71 Road Runner
#1950876
11/14/15 01:33 AM
11/14/15 01:33 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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I've had good luck getting my Charger to steer and handle the way that I like, so I took what I'd learned and tried to help out a friend with his 71 Road Runner. He is the original owner and has made small changes over the years, but nothing too drastic. He wanted a firmer ride and more responsive steering so we added the following:
1.0 torsion bars replaced the stock .90 bars. MP XHD Hemi leaf springs replaced the stock 5 leaf pack. Welded in 3x3 frame connectors. upper Control Arms with offset bushings installed to increase caster. Fast ratio Idler and Pitman arms.
The car sits at what may be considered stock height. I didn't measure it but it looks about where I've seen others sit. 15x7 wheels, 235-60-15 tires. He had the car aligned today. I went along to tell the man that he didn't want the stock 1971 alignment specs, I had the following: 0 to 1/2 degree NEG camber 2-4 degrees POS caster 1/8" toe in.
The alignment guy couldn't even get close to anything except the toe #. Why? the car has never been wrecked. The parts are all stock except the bushings in the upper control arms. The car came with 14" rally wheels but that shouldn't make much difference. I didn't get a copy of the sheet but the numbers I recall were almost zero caster on the left, something like 0.2 and about 0.8 on the right with slight positive camber on both sides. What the heck??? wouldn't adding some NEG camber automatically get you more caster? There is more adjustment left in the alignment cams, I could see that. The owner said the car feels twitchy. I know that Fast Ratio arms with overboosted steering will make a car feel a bit funny but the car felt okay to me. The steering wheel returns to center after a turn. My Charger has the same basic setup as this Road Runner but mine feels rock solid. I had mine aligned at a different place and was able to get 4+ degrees of caster on both sides along with .75 NEG camber. The obvious suggestion might be to take the car to a different shop. My first suggestion months ago was to go to the guy that I use. I'm just curious to learn if I did something wrong or if I missed something. The bushings in the Upper control arms were pressed in so that the front side bushings had the thin spot toward the engine. The rear bushings have the thin spots toward the fenders. It seems that this should have easily resulted in getting the numbers we asked for. It was aligned 9 months ago at the same shop after he replaced tie rod ends. At that time it still had the stock UCA bushings. The numbers were not much better than what we got today. The owner is not interested in buying tubular A-Arms. If he was dying of thirst he wouldn't spend $10 on a bottle of water. I'd appreciate any suggestions on what else to try. I'd like to not only help this guy, but others in the future. Thanks, Greg
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: Kern Dog]
#1950907
11/14/15 02:50 AM
11/14/15 02:50 AM
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Joined: Apr 2012
Posts: 18,880 -
RSNOMO
Moparts Torchbearer
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Moparts Torchbearer
Joined: Apr 2012
Posts: 18,880
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a firmer ride and more responsive steering '71 Ply B-body, U-Code... I did the following when I went through the car... Urethane front-end 'components'... OEM 'hard parts'... Gas shocks... One leaf added per side to OEM spring pack(urethane bushings)... OEM rear sway-bar... Alignment specs are OEM... HAD 255-60's on stock 15x7's(w/radials)for many moons... A handful with manual steering... 235-60's up front now... I can two-finger it comfortably with no problem... Haven't touched the alignment specs in 20 years, and 20,000+ miles of driving...
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: ntstlgl1970]
#1950941
11/14/15 05:09 AM
11/14/15 05:09 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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I thought I wrote that this is the RIGHT side arm. This is actually from your car!
" You can always shim the lower balljoint to add negative camber if needed."
I forgot about that! Rick Ehrenberg used to sell those but I bet a pair of 1/8" thick washers would be just as effective.
Last edited by Frankenduster; 11/14/15 05:12 AM.
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: Kern Dog]
#1950945
11/14/15 06:31 AM
11/14/15 06:31 AM
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Joined: Nov 2004
Posts: 420
PasiR
mopar
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mopar
Joined: Nov 2004
Posts: 420
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: Kern Dog]
#1950960
11/14/15 09:33 AM
11/14/15 09:33 AM
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Joined: Dec 2014
Posts: 5,956 ohio
ruderunner
master
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master
Joined: Dec 2014
Posts: 5,956
ohio
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Not all cars will be able to achieve the ideal numbers, just production line tolerances from 40 years ago.
To whit: I've done alignments on 3 69 Roadrunners 2 stone stock and my own with offset bushings. The one stocker could only reach 2 degrees caster with camber approaching 1 deg positive. The other could barely get 1 degree caster. Mine I could get to 2.5 caster with 0 camber. All 3 had fresh front ends and nothing wonky about the cam placements to indicate accident damage.
Mopar was basically plus or minus a quater inch when assemnling the chassis.
Angry white pureblood male
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: ruderunner]
#1951008
11/14/15 12:09 PM
11/14/15 12:09 PM
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Joined: Jun 2005
Posts: 5,112 Western Md.
skicker
"The Champ"
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"The Champ"
Joined: Jun 2005
Posts: 5,112
Western Md.
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Thinking outside the box here but why couldn't an adjustable or slightly shorter strut rod be utilized? I noticed with mine when I rolled it around the shop without the strut rods on it that the lower control arm moves a small amount front to back. Its set up on a rubber pivot at the bushing so if it was forward a small amount it would help and not hurt anything else. This was used years ago on the RF of a dirt car to achieve large amounts of positive caster in the RF only without noticeable suspension modification. There's no reason why smaller increments on both sides wouldn't achieve what your trying to do.
...FAFO...
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: Kern Dog]
#1951117
11/14/15 04:05 PM
11/14/15 04:05 PM
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Joined: Mar 2007
Posts: 3,287 West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,287
West Coast, USA
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My convertible had the same alignment results, and I had the Firmfeel tubular uppers, which tilts the upper control arm towards the rear of the car.
It wasn't until I installed the Hotchkis adjustable strut rods that I was able to finally obtain increased positive caster. I was careful to adjust them shorter than stock strut rods, so that there was no binding of the lower control arm movement throughout the entire arc of travel(torsion bar removed).
This essentially pulls the lower control arm slightly forward of the stock position. The effect is that the suspension is set-up more like a chopper and less like the front wheel of a shopping cart that twitches back and forth while traveling forward. I'm thinking that by cutting the shoulder on the stock strut rods a very small amount on a lathe, one could achieve the same result.
Now, my car no longer feels twitchy. It feels stable and planted. I can let go of the wheel on the highway and it wants to track straight down the road. It does make the car much more enjoyable to drive, especially on longer road trips.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: Kern Dog]
#1951131
11/14/15 04:45 PM
11/14/15 04:45 PM
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Joined: Jan 2003
Posts: 31,078 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,078
Oregon
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I thought I wrote that this is the RIGHT side arm. This is actually from your car!
" You can always shim the lower balljoint to add negative camber if needed."
I forgot about that! Rick Ehrenberg used to sell those but I bet a pair of 1/8" thick washers would be just as effective.
The camber shims are still available. Mancini has them and so does Firm Feel.
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: AndyF]
#1951134
11/14/15 04:56 PM
11/14/15 04:56 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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"The camber shims are still available. Mancini has them and so does Firm Feel." http://www.manciniracing.com/caspki.htmlThey show that these will add 2 degrees of NEG camber. Since the rear cams are currently all the way to the inside, there is the ability to move them out to reduce the NEG camber. If the front cams are at the other end of their range, these shims may only address half of the problem since any outward adjustment of the rear cam results in less caster. Maybe the tubular A arms are the only fix.
Last edited by Frankenduster; 11/14/15 05:14 PM.
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Re: The ongoing quest for MORE caster, 71 Road Runner
[Re: Kern Dog]
#1951163
11/14/15 06:09 PM
11/14/15 06:09 PM
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Joined: May 2005
Posts: 4,759 Florida
BDW
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master
Joined: May 2005
Posts: 4,759
Florida
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