front suspension geometry upgrades

[dusterbd13]

ok, ill open a can of worms here.....

I'm looking to get my 70 duster to handle a little better. its currently equipped with
.89 T-bars
rubber LCA bushings, poly upper
poly strut rod bushings
adjustable strut rods
73 steering linkage
1 1/8 sway bar
firm feel stage 3 power steering box
boxed LCA's
KYB shocks
17X8 wheels, tires with a 260 tread wear rating

rear is 340 springs
poly bushings
7/8 rear sway bar
1 inch lowering blocks
kyb shocks

the battery is moved over the axle centerline, front end has been lightened with fiberglass hood, aluminum heads, intake, water pump.

the car handles pretty decent right now.

where I'm trying to go:

my daily is a full on FSP prepped S10. tall ball joints, revised control arms, etc. incredible truck. think spec miata.

i would like to get my duster handling about the same. i think i can get there with a budget approach.

there is currently no noticeable body roll in either direction. i lose traction of the rear tires before body roll starts. so the sway bars are probably stiff enough.
it rides pretty good, and has no aggressive tendencies for squat on acceleration or brake dive. has a little bump steer, but tolerable.

my thoughts are going along the budget route of:
tube UCA's for alignment purposes. and tall upper ball joints.

based on the charts from mopar muscle, i think the tall AFCO ball joints would be a good investment to increase my negative camber gain. they are billed as being .200 taller than stock. the F/M/J spindles are about 1/4 taller than the a-body's, so...
(charts will not copy to the forum, so the link is
http://www.moparmusclemagazine.com/..._and_b_disc_brake_spindles/spindle_specs.html )

it looks like i would get the roll center benefits and negative camber gain, without the bump steer by going to the tall uppers. correct? maybe not quite as much, but with less expense and negative drawbacks.

on the upper control arm side, i have way too many questions and options.
what geometry benefits are there to be gained from one UCA over another? from what i understand of suspension design, the main purpose of the UCA is to control the spindle. the motion ratio controls the camber gain and caster change. that's about it. if I'm wrong, please tell me.

so, the options available are
CAP
RMS
Magnum force
SPC
Speedway
FFI
control freaks
XV
Hotchkis
just suspension

with prices ranging from 150-600. if there is no real benefit other than alignment specs, why spend more? if there is, is there a way to tell what the geometry improvements will be with one arm over another?

I'm really trying to figure this out before i spend money on the front suspension again, so help me out here.

michael

 

[autoxcuda]

.....

on the upper control arm side, i have way too many questions and options.
what geometry benefits are there to be gained from one UCA over another? from what i understand of suspension design, the main purpose of the UCA is to control the spindle. the motion ratio controls the camber gain and caster change. that's about it. if I'm wrong, please tell me.

so, the options available are
CAP
RMS
Magnum force
SPC
Speedway
FFI
control freaks
XV
Hotchkis
just suspension

with prices ranging from 150-600. if there is no real benefit other than alignment specs, why spend more? if there is, is there a way to tell what the geometry improvements will be with one arm over another?

I'm really trying to figure this out before i spend money on the front suspension again, so help me out here.

michael

For an A-body they all have the same geometry. I don't see a big gain having the strength of a tubular A-arm just to run a poly bushing on the end of it. Sort of like making a titanium rod and using a zip tie on the end of it.

Just put on the Moog offset upper bushings and spend the money on some 1.00" T-bars. If you want to run taller ball joints, they will screw into your stock UCA's.

the motion ratio controls the camber gain and caster change. that's about it.

??? That doesn't sound right. But maybe I'm not following your terminology. I'm used to "motion ratio" term being used to for spring and shock location on a control arm.

Or are you talking about the ratio of the UCA length compared to the LCA length. Since the chassis pick up points are not changing, those lengths aren't going to change (or change much).

 

[cjh]

You could try to fit a " Watt's Link " on the rear.....keeps it tracking right on tight corners......since you have lowering blocks.....maybe up the size on the rear sway bar...27mm??

 

[dusterbd13]

i was talking about pick up points.
(sorry for the confusion. im home sick from work, and not exactly hitting on all 8 right now.)

i was thinking about the offsets, but then got to thinking about geometry, etc, and almost got myself talked out of it.

o know that on the s10/gbody stuff, getting a slightly shorter UCA gets a radical negative camber curve. we try to dial them in at 2 degrees negative with the control arms alone for this reason.

so what im hearing you say is that the UCA being tubular or stock really has no impact on the geometry of the front end. just the alignment specs. with that being the case, and with my eccentrics aready maxed, should i be able to get the specs (1.75 negative camber, ~7 postive caster) with the stockers, or pull the trigger on the cheapest of the UCA options?

 

[dusterbd13]

thought about a watts, but the blocks are only temporary unitil i get the hotchkis leaves.

 

[autoxcuda]

i was talking about pick up points.
(sorry for the confusion. im home sick from work, and not exactly hitting on all 8 right now.)

i was thinking about the offsets, but then got to thinking about geometry, etc, and almost got myself talked out of it.

o know that on the s10/gbody stuff, getting a slightly shorter UCA gets a radical negative camber curve. we try to dial them in at 2 degrees negative with the control arms alone for this reason.

How much slightly shorter is that. The UCA pedastal on those GM's make things easier to manipulate. I'm going to guess they run spacers off the frame mount to make up for the short UCA? You can also redrill that pedastal to change roll center and anti dive. They do that with the F-body and GM A-body intermediates. It's called the Guldstand modification/geometry.

so what im hearing you say is that the UCA being tubular or stock really has no impact on the geometry of the front end. just the alignment specs. with that being the case, and with my eccentrics already maxed, should i be able to get the specs (1.75 negative camber, ~7 positive caster) with the stockers, or pull the trigger on the cheapest of the UCA options?

With stock arm and Moog offsets I dialed in 1.5 negative camber and maxed out at 4.5 positive caster. If I went .5 camber I could get close to 5.5 positive caster. Your adjustable strut rod might allow you to cheat that a little, but if you pull it too far foward you will be binding the LCA bushing. And running the tire close to the front fender lip.

I just think $200 torsion bars will give you more performance than that little bit more of camber and going from 4 to 7 deg. caster. And that's IF all those tubular UCA's are really designed to get you that much caster and camber. The once with the spherical rod ends should be able to be manipulated to get those numbers.

 

[autoxcuda]

Wait.... This is the red duster? Your main car.

I was thinking this was the 2nd more "street cruiser" type Mopar you had. I think that is Wracks71? He's building a 2nd "street cruiser" type car. I always get you two confused. I'm sorry.

So I'd say your car has handling objectives that are pretty serious side. Then, I'd go with a tubular UCA with heim joints. That will allow all kinds of adjustments, precision, and smooth action. You play with the length of the arm somewhat and the spacers between the cam adjusters to get about any camber and caster combo you'd like.

 

[dusterbd13]

i think youre thinking of ben bjkadragon with the aero dusters.

the speedway arms look to be my best bet in that arena. any ideas on them?
http://www.speedwaymotors.com/Adjustable-A-Arms-without-Cross-Shafts,2116.html

michael

 

[cudaboy 67]

kinda going thro same myself, was your engine b/b or s/b?

 

[dusterbd13]

aluminum headed small block.

right now im doing this in stages and evaluating the changes.
forst change is k7103 bushings.
second will be tall spindles. less unsprung weight.

heres the same topic on moparts, and very involved discussion by a lot of guys.

http://board.moparts.org/ubbthreads...estionAnswer&Number=6175437&fpart=&PHPSESSID=