Help needed sorting P-body suspension issues

[Shadow24]

So now that I have some of the running issues sorted out with my car, it is time to get a few things addressed with the suspension/steering. The car as it currently sits definitely has suspension issues. I did put new dampers on about 2 years ago (car sat for the last year and a half). but I'm pretty sure the springs are shot. The car still squats in the back with new rear dampers and the right front is slightly lower than the left front. I also have very bad dive and nose lift when accelerating or braking. Add in that I have what I believe is massive bump-steer on acceleration, means the car is fairly twitchy and quite a handful at anything over 1/2 throttle. (Keep in mind, I do have an OBX LSD in the car that was in good working order when I pulled the drivetrain out of Lucy 1.0 to put into Lucy 2.0. This also included swapping the 5-speed K-frame over).


The torquesteer/funnybusiness in the front is what usually gives me the most grief. When I get on the throttle, you can visibly see the front end rise by at least an inch to 3" (at WOT) or more (caveat: guestimate). This causes the steering wheel to rotate to the left by about 1/16 to 1/8 of a turn. The car then likes to start pulling to one side or the other under heavy acceleration and proceeds to bounce from pulling to one side then the other. Couple that with the random steering wheel movement makes keeping the car in a straight line very hard as when you let off the throttle and the front end comes back down, you are now oversteering to one direction or the other. While I do have an LSD (I will try and check to make sure the LSD hasn't separated on me again causing all sorts of wierdness before), I believe this erratic behavior is triggered by a completely unbalanced suspension setup.


I believe that the first order of business is to deal with the rear springs as I am only an inch or two off the bumpstops at present. This also gives the car a very noticeable rearward rake angle of approximately 1.77 degrees. Couple that with the extensive compression of the springs, I believe I am genning excessive rear squat and front end rise. This (from what little I know about suspension) can cause all sorts of issues with front end alignment, bump steer etc.


wheel arch heights (ground to wheel arch through center axis of wheel)
LF - ~27.5" (Spring compressed to ~8.25")
RF - ~27" (spring compressed to ~8.75")
LR - ~25.25" (spring currently compressed to 6.5")
RR - ~25.25" (spring currently compressed to 6.5")


I have found some 10" tall, 5" round springs I believe will work with no to little modification and can be had in many spring rates from Speedway. I am considering going with a linear rate of 350lb/in. This should get my static height closer to normal and increase my front anti-lift/rear anti-squat. I believe this will help bias the weight distribution back towards the front of the car and may alleviate some of the torquesteer/funnybusiness going on in the front end.


If anyone has input on spring rates for a good balanced setup on a P-body, I am all ears. The same goes for finding what is causing the erratic front steer issues under acceleration.

[Reaper1]

For budget suspension tips, Vigo is your guy! :thumb:

On the front end...what do the bushings look like? Are there spring spacers on the bottom of the springs on the struts? Tie rod condition (inner/outer?), ball joints? Sway bar bushings? Engine/transmission mounts?

I know that all seems basic, but any one of them could cause some serious issues given the right conditions.

Also, what kind of alignment? That will have a HUGE impact on how the car acts under acceleration. If it's got negative camber and some toe out it will tend to wonder on roads with a crown. I found that with my car and the OBX that I had to really hold on to the wheel and concentrate when I was on it on suspect roads. It would certainly yank you in a ditch if you were careless (as what happened to many many SRT-4's).

As for the rear, what do the spring isolators look like? I bet they are smashed flat. Maybe replacing them with new ones from Johnny would get it back to the correct height.

Keep in mind that dampers (shocks/struts) don't hold the car up at all (unless they have nitrogen or air bags in them). That is the spring's responsibility. So replacing the dampers should not change the ride height appreciably.

[Shadow24]

ok, lets go down the list :)

engine bushings are OK (prothane Passenger side, and one-off poly-filled front and trans mounts, rear bobble strut has been replaced with solid unit from FWDperf)

A-arm bushings are (I believe) Moog poly on drivers side and generic rubber replacements on the passenger side

Ball joints are new-ish (less than 6-mo driving, put in about 3 years back). Pass. side is slightly loose in the A-arm. I have a junkyard A-arm to replace that side to eliminate the ball joint slop (and a new ball joint)

Inner/outer tie rods are unknown, same as came with the car from the PO 4 or more years ago...may warrant replacement

sway bar bushings are Moog replacements, no real slop AFAICT

Spring spacers? Never seen any on Lucy 1.0 or 2.0...

Alignment - 85% to 95% factory from Firestone (lifetime FTW, can take it back as many times as I need for no additional cost). I didn't harp on teh alignment as I know I'd have to fix a few things and get it re-done anyway. I do know that I will need to get a rear shim pack as the rear was a little out if i remember correctly. Also was done with the rear end in it's sagged position, which may not have helped the case any.

On the rear, I have no idea what the isolators look like, what I can see is the spring is basically against the body and the axle perch, with nothing in between..

Yeah, dampers don't really help when the springs are !@#$%ed. The struts/shocks are Gabriel units and I can feel that they are at least dampening properly with smaller bumps at speed, but anything other than that and the springs just don't seem to have enough spring left in them to properly work the suspension.

[crusty shadow]

You really need to replace all the worn/mismatched suspension parts- especially things like the ball joints and tie rod ends. if your front end is loose the car will be a handful to drive no matter what shocks and springs you install.
one thing that can be causing some issues with torque steer is the different suspensions bushings from side to side on the A arms. poly has a different stiffness than rubber and the control arms will have a different amount of resistance movement wise from side to side- this can definitely cause problems with torque steer and ride height.

I would replace the rubber bushings on the one side with moog polys so both sides match. also when you do this you need to unbolt both control arms with the car on jackstands so they can be bolted back down with the same amount of preload on each side.

definitely replace the ball joints if they are even remotely suspect. replace the inner and outer tire rod ends as well- they are dirt cheap and loose tie rods can make a big difference with the car wanting to wander all over the road like you describe.

as for springs - like stated above the springs are what set the ride height, shocks control movement. you have 2 options with the rear springs- replace them, or install a set of air shocks. I would recommend installing air shocks as you can adjust the air pressure and ride height to your liking. I have a set on my shadow and they work very well and have a decent ride quality as well. you will be able to adjust your front to rear weight bias as well as being able to "weight jack" the car if you install a ball valve to separate the right and left air shocks so you can get identicle traction on both sides.
the fronts your only real option will be to replace the springs, and make sure the strut mounts are in good shape. ive seen way to many cars running around with strut mounts that are just flat out toast- there are bearings in there that allow the strut to rotate when you turn the wheel. if that bearing is shot or the strut mount is falling apart or badly worn the top of the trut wont be solidly mounted in place and as you drive the geometry will change making the car very unpredictable- same thing as a double wishbone type suspension with a badly worn out upper ball joint.

the isolators wont affect ride height very much at all, they are just a rubber pad to isolate the springs from the suspension and the body so you don't hear any squeaking when the suspension moves.

get the shim pack before you go to get an alignment and don't let the tech pull the car off the rack until alignment is properly set. you cant align the front wheels at all if the rears are not correct as the fronts are measured in relation to the rears. they will usually ----- and cry and moan about having to install shims so do him a favor- break those bolts loose that hold the wheel hub onto the rear axle before hand.

[Shadow24]

So how exactly do the air shocks help ride height when shocks are usually used to dampen spring oscillations? I think with the severe amount of sag I have already, I need to replace the rear springs one way or another (hence the spring rate inquiry).

I am definitely going to go through and re-do the suspension bushings and strut mounts to help eliminate any potential issues.

Once the weather warms up and I can take the car down for a couple days' I'll pull the diff and see if that is still OK.

[crusty shadow]

air shocks have an air bag incorporated into the shock- essentially an "air spring" . the dampening is still controlled by a hydraulic shock absorber but the air bag portion will allow you to adjust your ride height pretty much wherever you want. I run those on my shadow and they work quite well, even with the car being considerably lighter than your average p body the ride is not harsh at all.
how far down is your sagging? any pics?

[Shadow24]

Heres a shot from today, I did have some eight in the back, but it shouldn't be this far off with what is in the car.

http://i76.photobucket.com/albums/j16/shadowplane676/Duster%20engine%20swap/20150220_131506_zps84da0ptl.jpg (http://s76.photobucket.com/user/shadowplane676/media/Duster%20engine%20swap/20150220_131506_zps84da0ptl.jpg.html)

[GLHNSLHT2]

lol, that pic shows it would be a handful right there.

[Shadow24]

I figured as much. She has always sat really low in the rear since I bought the chassis. That is one reason I am led towards replacing the springs in general, not just with a higher spring rate

[Shadow24]

So I finally got around to installing the 10.5" tall 300# springs I picked up from Speedway. While 1/2" shorter than stock, I gained 1" in rear ride height (even with the extra weight of my tools etc in the trunk). Ride in the rear is more sporty than the land-yacht float I had before and doesn't feel like I am overworking the dampers (no multiple oscillation on bumps). Unfortunately the steering issue has persisted. Hopefully I can check on the inner and outer tie rods and to check on the diff this weekend.

[Reaper1]

Check the rack mounting bolts. The nuts that are welded to the inside of the K-frame are known to break loose. With all of the extra vibrations and such this is a possibility.

[Shadow24]

I was wondering if that could be an issue as well. Is there a known fix or does the K frame need to be dropped and modified?

[Reaper1]

I suppose you could fix it in the car, but I'd drop the thing out and do it. Either that or replace it! I have heard of people attacking this different ways...you could drill holes in the bottom to access the nuts with a socket or something to hold them. They are supposed to be "fixed" (not move), so I think most people just weld them back on.

[Shadow24]

Hmm, I'll have to see what I find and go from there. I didn't have this issue on the old chassis, so it may be the steering rack mount bolts. The steering rack is from the new car but the K-frame is from the old car.

[ShadowFromHell]

Got a link to the speedway springs? I've been wanting to do something like that for years but never pulled the trigger.

[Shadow24]

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| valign="middle" align="left" colspan="1" style="width: 179px" | Tru-Coil 5 x 10.5 Oval Track Racing Rear Spring, 300 lb Rate



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These are regular 5" OD springs, I think you can find variants with one "pigtail" end that would be a near identical stock swap. Mine haven't had any seating issues without the pigtail end so far...