Hey guys. I did the suspension over the winter and by that I mean hubs, bushings, rack and sway bars. Long and short I drove it a bit and it felt weird but I knew I needed an alignment. So per @MatthewMiller I used his reccomended specs and they got it fairly close so I figured it would be good. Fast forward to yesterday coming home. New tires, 4 matching wheels, all new suspension. The car feels great in a straight line... coming up a twisty road at 60... it felt like it was holding on for dear life still. It actually feels worse than before I did anything.

Now mind you I can do the same speed in my 2007 sierra double cab long bed 2500hd with a utility body weighing roughly 9000lbs and push it even more without even being nervous about it.. so the car feeling that way really bummed me out. So what it feels like is this... the front is totally planted. The rear... well... you come back straight and it walks all around. Going into the turn it feels like it slides against itself then when you come out just as the nose straightens out I get rocked in my seat as the tail sort of snaps back to a true center. Something feels loose to me but they drove it 3 separate times and put it on the rack and the rear held alignment perfectly. And I know damn well it's all torqued to spec so I'm sort of at a loss.

Is this just how these cars feel? I never pushed it that hard before because it was scarier but the sliding around wasn't there because I know it didn't do it at the lower speeds this does... needless to say I'm pretty bummed out right now and any input is appreciated.

 

..... Check the inner axles for a broken snap ring ... see if either inner axle will pull out of the diff any distance at all ... tolerance is in the .0xx range .....

 

I'll give it a check. Don't recall feeling anything doing the joints but I'll double check.

 

Yikes....reading your post....it SOUNDS scary! What 409 said. I'd double (triple?) check toe, too.

 

The two sheets I have from the shop show -.01 left, 0 right in the rear and -.02 and 0 in the rear. Idk if that's even noticeable... its just unsettling more than anything. The 67 firebird does it but given the shackles on the springs that I'd expect it in... I don't know.

 

The 1996 FSM says the end play on the inner stub shafts is .0005 to .0085 decimal.

What kind of bushings did you use ? You probably mentioned it in another post, but it is important.

Have you jacked the back end up and watched the suspension to see if there is any bind as the rear is lifted ?

 

Everything is super pro except for energy on the sway bars.

It drives fine otherwise (better than ever as bumps don't upset jt like they used to.) and lifting the rear of the car it travels smoothly.

 

Here is the 1987 alignment section 3A. I haven't found any earlier FSM's on the web to save. This is the earliest I have.

 

When the control arm bushings were torqued down, was the car at ride height?

 

Does this also apply to the trailing arms in the rear?

 

The front pivots freely on the crush tube. I confirmed this in the car so no they were not. IE they move along their axis of movement freely.
The rear I did torque with the outer knuckles on jack stands simulating ride height.

 

that is a little different than what my FSM specs bspecs about what it is aligned to.

 

With poly bushings (even SuperPro), it shouldn't matter where the suspension sits when you torque the bolts down because the inside sleeve is meant to rotate inside the poly. It's only an issue with stock-type bushings, which have the rubber bonded to the inner and outer shell and allow rotation by twisting the rubber. Also, there shouldn't be a ton of bind with the SuperPro bushings, so I think you're fine there.

The inner axle snap ring is a good thing to check. Also, did you replace the halfshaft U-joints? Those are suspension joints too, because the halfshafts also serve as the upper lateral links. If even one of those joints is bad, it will allow the alignment and geometry to change between on-throttle and off-throttle. You may have changed those and told us - sorry if this is a repeat.

On the toe links, don't just check alignment, but make sure their inner and outer joints have no play. Also make sure that the center mount for those links is securely fastened back to the batwing. Likewise, make sure your batwing bushing bolts are tight.

Finally, what about the rear shocks? Are they in good condition? If one is losing its damping rates and the other is good, it could cause some issues every time the suspension moves.

 

I went through everything while rebuilding and it all checked correct....

I also found out what it was that was causing the issue.... dropped tire pressure from 42 down to 34 and all is well with the world. I probably should've checked that first lol.

 

42!! Yikes!

I run mine ~25. Ish.

 

I bet they meant to check it after popping the beads and they were installed but probably forgot to. All good. 34 felt about right. Iirc the door says 35.

If I ran the car hard on a track I'd probably go lower.