280z Suspension Upgrade

[rossiz]

so i only had a couple of hours tonite, but managed to swap the eibach fronts. now i have the correct eibachs in the front and the cut stockers in the rear. will swap out the rear springs later when i have time. the front is now a bit lower, looks quite nice actually, and a quick test drive shows even better front end tracking, sticks really well. the rear is a little higher than the front - not funnycar high, just about 1".

interesting experiment though - kind of an iterative test of different setups.

what i started off with was a really crappy baseline: blown struts, tired, saggy sway bars and too-high stock springs. the ride was really boat-like for a sports car, lots of body roll and not much damping to speak of.

the next test was with all eibachs, but front/rear reversed - very low rear, too high front, and the ride sucked. the front pushed and washed out in corners and the back was harsh.

the third test was with eibach rears in the front and cut-coil stocks in the rear - ride height was level, and it actually felt pretty good (better than the first two setups)

now i've got the correct eibach fronts and cut-coil stocks in the rear - ride is lower in front, it tracks quite well, but i'm actually feeling the road surface more from the back it seems...

i hope to finish the swap either tomorrow or thursday nite and i'll report back.

the good news is i'm getting pretty good at pulling her apart and swapping suspension bits - it's actually kinda fun :}

[240260280z]

Nice to see your observations matching theory.

You are now F183 to R151 so only 17% weaker in rear compared to 30% for the last setup so the gap is closing.

[rossiz]

got a bit of free time this afternoon to pull out the cut oem rear springs and install the eibachs.

the nice things about having done this job 3 times now are:

• i know exactly what tools to use
  
• none of the fasteners are difficult
  
• i can do it in an hour
  

the not-so-nice part is that fact that i've done it 3 times now...

anyway, i did learn a few tricks that might help others:

1. remove spring clips at flexible brake line and disconnect e-brake, un-bolt half-shafts at wheel connection, disconnect sway bar
   
2. a good floor jack is a huge help - use it to prop up the control arm when you remove the strut tower bolts and slowly lower the assembly until it can swing out.
   
3. remove rear bracket (2 bolts) that holds up the rear control arm, loosen the 2 bolts for the front bracket (the one closest to the diff) - this lets the control arm lower/hang at an angle so the strut assembly can be swung out and you can fully service it w/out removing from the car. this way you don't need a vice to get the top shock nut or gland nut off.
   
4. loosen the top shock nut before removing the 3 top strut tower bolts (easier, better leverage) and if you back it off until the strut shaft dips below the nylock ring, it reduces the amount of futzing around w/the spring compressors, then as soon as the spring pressure is released from the perch, you can spin the nut off w/your fingers.
   
5. with the floor jack under the control arm, you can lift the finished assembly up into the strut tower (use your foot to work the handle) while guiding the bolts into the chassis holes - use a socket on the top shock nut to rotate the cap to line up the 3 bolts w/the holes.
   

piece of cake.

the results:

here is a picture of the car w/the eibach fronts and the cut-coil oem's at the rear - back end is slightly high

the ride was pretty good, even w/the wonky, mismatched spring rates, but the rear felt a little bouncy.

here is a picture of the car w/the eibachs both front and rear - interestingly, the rear is actually just a little higher than before. i've heard the springs need to "settle in" a bit, so i'll reserve judgement for a while - anyone know how long it should take for them to "settle"?

the ride is much better - feels more "matched" front/rear. before, when i hit a bump, the front and rear reacted differently, now they react similarly. overall, the springs feel much firmer, but not harsh. the car feels much more crisp over the road, vs. the vague, mushiness w/the oem's. the new springs behave a lot like the suspension on my bikes - tuned for more aggressive riding, they actually feel better the harder they are run. the eibach's feel a little "bumpier" pootling around below 20 mph, but the faster i go, the better the suspension seems to perform. whereas the oem's sort of got overwhelmed at higher speeds, this setup feels quite a bit more confident.

to be clear - i am no racer, but i can definitely feel that the car is a whole lot more fun now!

main takeaway:

• the biggest bang for the buck in stability/handling was the sway bar upgrade - HUGE difference.
  

[LeonV]

Did you make sure to torque any fasteners at pivot points with the car loaded and on the ground?

[240260280z]

I concur, the sway bar was #1 for me too for best bang for the buck for street driving. The t-c ball and sockets were next but you need to a/b without/with to see this. I think your full upgrade masked it.

The weak link(pun) with sway bars are the end links. If they are not tight then some of the effectiveness of the bar is lost. Poly's work better as the insulator pucks in the links.

Of course the mount points for sway bar to the frame is a common rust point on the Z. The sway bar mount often pulls free. Bad Dog parts make plates to reinforce this area.

[rossiz]

the msa kit came with poly bushings and i torqued the links enough to compress them a little with no load on the suspension - about 1/8" proud of the nylock nut.

i'm fortunate in that the bushing connection points are all solid - no rust at all and the fasteners weren't even stuck. lots of grease was applied all over the pivot and bushing points, so i'm feeling good about it.

[Captain Obvious]

For things like sway bars and T/C rods, it never matters. Tighten them hanging or on the ground. No difference.

The only ones that matter are the rubber style control arm bushings. One each side in the front inner, and eight in the back (fore and aft, inner and outer, each side). So, since you loosened the rear control arms to lean the struts out, you should tighten the four big inner bolts (like 26mm or something like that?) while the suspension is loaded. And if you loosened the spindle pin nuts (outboard) you should tighten those under load as well.

And in the front, I couldn't tell if you had to loosen the front lower control arm pivot bolt to get the strut beyond the fender, but if so, then that one needs to be tightened under load.

You might consider just giving it a few days of driving and "settling" and then loosening all ten pivot points while under load, letting the bushings relax, and then retightening them while still under load? Then get an alignment.

If some time in the future you switch to poly control arm bushings, it won't matter anymore. The poly bushings are designed to pivot the inner sleeve inside the bushing instead of torqueing the rubber as the original design bushings do. And because of that, you can tighten the poly stuff while hanging or loaded. No difference.

That rotating sleeve pivoting action of the poly bushings are what causes them to squeak if not greased properly. It's the inner sleeve turning inside the bushing material.

[rossiz]

i didn't mess with the spindle pins - just the clamps that hold the rear control arms to the chassis. there are two: one next to the diff and one towards the rear of the car, each has two bolts. i greased up the rubber bushings plenty before re-installing. not sure how that joint would make a difference loaded or un-loaded, but i'll see if i can shimmy underneath and loosen/re-tighten them. might need some ramps, now that it's a bit lower...

[Captain Obvious]

Grease on the outside of those rear bushings isn't necessary, and might even be an issue. You see... There isn't supposed to be any movement of the outer rubber portion within those clamps. All the movement is supposed to be twisting the inner sleeve inside the outer rubber portion. You really don't want the rubber portion squirming around.

Works like this... You clamp the rubber portion tightly in the strap clamps and do not allow it to move. Then you pinch down on the ends of the bushing with the big flat washer and bolt until you have compressed the rubber completely. You're not tight until you have actually tightened it so much that the inner sleeve (with the toothed serrations) is held tightly against the control arm. So tightly, in fact, that the inner toothed sleeve will always rotate with the arm as the arm moves up and down.

There should be no movement of the inner sleeve with respect to the control arm. They should be locked together.

There should be no movement of the outer rubber with respect to the undercarriage. They should be locked together.

The bushing works by torqueing the rubber between the inner sleeve and the band clamps. And that's what sets the rubber bushings apart from the poly replacements. They operate differently.

The right way to do it would be to clamp down hard with the strap clamps on the outside of the bushings, and then (with the suspension loaded) loosen and retighten the big (26mm?) bolts that go through the centers of the bushings. Problem is, if there's corrosion or anything on the inside of the bushings they still might not spin to their new "happy place".

I'm not a suspension guy and I'm having troubles explaining this... Is any of this making any sense at all?

Edited June 1, 2014 by Captain Obvious
My cat was helping me type and she can't spell good

[Captain Obvious]

There's also some discussion about how the rubber bushings work in this thread. It started about spindle pins and washers, but got to bushings in general at the end of the thread:

http://www.classiczcars.com/forums/suspension-steering-s30/51681-spindle-pin-rubber-washers.html

[rossiz]

ohhhhhh.... that makes perfect sense to me now. i did it all wrong, and am thinking that's probably one of the reasons the rear is still sitting a little high.

i was actually surprised to see that when i lowered the car off the stands, the rear was WAY high (wheels cambered) and i figured the springs needed to settle in. duh...

i will pull them apart, wipe off grease, re-do and report back.

[Captain Obvious]

ohhhhhh.... that makes perfect sense to me now. i did it all wrong, and am thinking that's probably one of the reasons the rear is still sitting a little high.

i was actually surprised to see that when i lowered the car off the stands, the rear was WAY high (wheels cambered) and i figured the springs needed to settle in. duh...

i will pull them apart, wipe off grease, re-do and report back.

If you're going to loosen the rear all back up again, I'd do this:

Loosen (a couple turns) but don't remove the four big bolts that hold the inboard bushings to the control arms. Left side of this pic is a good view of the bolt I'm talking about. You can see it threaded a few turns into the control arm:

Drop the hanger "U" clamps completely and let the inboard side of the control arm hang down a little.

Grab the rubber portion of the bushing and make sure it isn't rusted tight to the control arm. It should spin about the cylinder that goes through the middle. If they're free, cool, if not, take the big bolts out completely, pull the bushings off the control arms and clean out the ID so they DO spin free.

After you have verified that the bushings are free to rotate, position them so the rubber "wings" are horizontal and fitted into the non-round cavity formed by the "U" clamp and the undercarriage and once the "wings" are in the right position, reinstall the "u' clamps to hold the control arm back up against the underside. Not completely tight yet, but couple turns off fully bottomed out?

Snug, but not completely tighten the four big bolts. This will make sure the bushings are properly located all the way home on the cylinder.

Tighten the "U" band clamps locking the outside rubber to the undercarriage.

Loosen the four big bolts a turn or so.

Drop the car to load the suspension and while it's loaded, tighten those four big bolts till your eyeballs bug out.

Since I don't have a pit or an alignment rack... When I lowered my car, I lowered it onto moving dollies with a couple pieces of wood stacked on top for some extra work height. The dollies allowed the suspension to squirm around to wherever it wanted to naturally go and didn't have to worry about friction of the tires stuck to the garage floor. The boards stacked on top gave me the extra inch or two I needed to reach under and tighten those bolts while the car was on the dollies.

Don't drop the car on yourself or anyone else. I had my front end on jack stands at the time so the body was level. Rear on dollies, front on stands.

In the end, the outer position of the bushings should have the wings locked into the corners where the clamps meet the underside, and the inner cylinder should have been able to find it's "natural happy spot" under load and then locked in place.

Summarize the whole thing up like this... When the car is sitting neutral, you want the bushings to be neutral and not under any torque. Then when the suspensions moves up and down, you torque the bushings one direction or the other. But at rest, no torque.