When I bought my 77 L48, it was pretty well stock, and looks like little had been done to it ...so I immediately chalked up a list and tried to get it more "refined" -- you know, drive like a sports car drives (stock suspension, 9-leaf, no rear-sway didn't meet my criteria).

I installed the street and slalom package -- and whoa, what a difference that made! Thanks VB&P for the suggestion of going to the 550#s -- I'm glad I did now

One of the problems I was hoping to resolve was I have what I think is a suspension issue that is noticed as I progressively turn the steering wheel. On light turns, the car is great and solid. There reaches a point as I increase the amount of turn where it feels like the rear end "flops over". It's really hard to describe, but at higher speeds, I would call it like the rear end just jumped out from under me (loose), but after this "flop" its solid from then on.

I have a 360# mono and a 3/4 or 7/8 rear sway (didn't have one at all before) which really reduced the body roll. However, this issue doesn't feel like the body is "rolling" over -- it drives like it's on rails most of the time.

So, are there any suggestions of where I should look next. I do like a car to be loose rather than pushing (long story, but trust me on this), and this throws me as it feels like its going loose, but only for a instant. Bushings on the sway bars are poly, and the shocks are Billstein. Apart from the suspension, the rest is pretty stock. I just had the car aligned ...and the rear toe is off a bit, but .5 degrees on the left and 1 degree on the right (it would have been $600 to fix that minor issue, and I was going to have the TAs rebuilt at some point).

I know many have tweaked their cars considerably, so I'm hoping you have an idea of what to look for.

Thanks in advance!

Brian.

 

"Flops over" isn't something I can really visualize. Do you mean the rear is stepping out on you a little bit?

How are all of your bushings in the rear? It could be something as simple as a worn bushing.

Does it happen consistently regardless of the road you're on? Does it do it only on certain roads? are bumps worse? etc...

 

It sounds like you are experiencing mild over-steer. Your rear alignment is out of spec, probably not helping things. You may need to check the front sway bar, it needs to be at least 1-1/8 inch diameter to work with the rear bar you have. I think 3/4 inch rear bar is the max (for your symptoms). G/L

 

I guess I'm struggling to describe how it feels ...it does feel like the rear end looses traction for a second but grabs it right up. I guess flopping over was the best I could do as it feels like the body is level, and then it suddenly drops (leans) on the side all at once, but then no more regardless of how much more agressively I turn the car. This usually happens when I turn just a little more than "light" cornering. It only does it once during the turn ...loose is a good description, as I'm often "reactively" turning back to counter it.

Maybe another analogy is if you're in a left turn, and the right wheel suddenly drops into uneven pavement about 1" below the other wheels ...regardless of how much more I turn, it doesn't feel like it drops again.

This happens in BOTH directions.

Front and rear sway bar are new ...I think 3/4" rear and 1 1/8th front (it was part of the kit). Here's the link to the kit:
Street & Slalom 63-77

So, the majority of the system is new. Surprisingly, it didn't seem to "decrease" even after the full system above was installed. That surprised me.

Brian.

 

In my last post, I provided the link to the kit ...it's sold all over the place, so it wasn't something I just dreamed up.

The issue was there before and after the upgrade.

I accept that oversteer may be part of the issue (and I prefer that to tight) ...but it's a shock when it's flipped on, almost like a switch at a certain threshold ...in both directions, and even at different amounts of accelleration.

I'm sorry I'm having a hard time articulating this. Just so you we're clear ...this isn't an issue during "heavy" steering, but as I crank the wheel, it happens at a certain point not too far off center ...I won't feel it changing lanes, but I'll feel it as I reach the amount of steering I need in a clover-leaf off-ramp.

Does any of that help?

Brian.

 

Then look for worn rear trailing arm bushings. I made the recommendation on the rear bar before you posted link, sorry. I have the same kit, but found the 3/4 in. bar too stiff (I auto-cross). I went with a 5/8 bar, and handling is neutral, will only under-steer with addition of power. G/L

 

Yeah, that helps a bit.
So it'll happen as you gradually increase the steering wheel angle while cornering, right? So it's more of a steady-state issue than a transient issue. Hmmm...

What's the trim height on your car like? Is the rear sitting high or low?

I'm wondering if there's not a bushing loose or if you're car is suddenly changing rear toe during cornering. If you're loading a bushing and it suddenly slips, you could run into this sort of issue. A sudden toe change could do that.

Hmmm.....

 

Ditto Big G on the 5/8 rear bar. If you want to run a 3/4" rear bar, go to wide, sticky 17" tires to overcome breakaway.

 

What you are describing is called "jacking". The rear of the car actually raises up. When this happens the rear suspension will toe steer (steer like a fork lift). Its also called trailing over steer and can be very annoying under hard breaking going into a corner. This is an inherent problem of the trailing arm rear suspension. Professional drivers know how to handle this situation but it takes guts.

This is the biggest problem that Chevrolet wanted to solve with the rear suspension in the C4's.

BigBlockk

Later.....

 

Well, the bushings are probably crap ...so if they can affect the toe that much, then I can accept that the issue will remain until I get around to rebuilding the TAs.

All 4 wheels sit about the same height +/- 1/4" (28 1/2 is the approximate height at the rear fender flares). I Figured that was pretty close to the stock 29" and it was even all around ...

Now, I'm guessing that I'll get "accustomed" to it, when I fix it, it'll throw me off again

Brian.

 

Well, that is certainly going to make it harder to resolve, isn't it. Did Chevy figure out a fix for that in the C4 suspension?

I can handle the condition just fine ...but I just have to overcome the tendency to steer back against the turn like I'm trying to gather up the rear end. I can understand what you mean about the needing guts though ...but I'll take a loose car over tight (of course, neither to an extreme).

Granted, I'm not doing any track time with this car -- coz if I was ...that would just kill my lap times.

Brian.