Slowly fixing things on my C5 Base that I bought a year ago and the one thing in the handling department that I would like to fix is a certain feeling inside the car on acceleration around corners and sometimes just on hard acceleration. The car feels like the rear end of the car is sliding sideways on the chassis/suspension, not body roll such as sway bars limit but more horizontal shift. I am wondering if it is due to mono leaf springs? My built 47 Chevy has the same issue and it is a leaf spring car. My Porsche 944 Turbo does not have the issue, but it has a trailing arm with torsion bar set up and it feels like you are on rails with no issues at all in the cornering department.

A bit of information, my 97 C5 has C6 Z06 shocks and sway bars, the car was high, so I lowered it as far as I could on stock bolts while keeping it even on all four corners and I still have the issue. Just about everything in the chasis and body were replaced/upgraded before I bought it so it seemed like a good base to start from. Upgraded the tunnel plate (Elite Engineering 3/8”) and the engine / transmission mounts are solid mounts. I have taken care of most of the quirky items and put in a rebuilt BCM, etc. just a couple quirks left.

Not certain if getting Z06 mono springs would cure this or if there is a brace or something to improve it, maybe I am extremely picky and it isn't hurting anything, but it actually makes me feel like letting off the gas because it doesn't feel like it is tracking straight. In any event, I tried searching for the topic, but probably didn't know the correct phrases to use and thought maybe someone here would have information and even a solution. I am not certain if a transaxle brace of some sort is the solution.

Having a blast with the car, just trying to fix all the small things with it, top on my agenda is a leaky top where targa corners intercept windshield, eliminated leaks at back corners already, once these little items are done I will be doing a cam, heads and intake upgrade, have the parts, just not dumping the money in if I can't get all the quirks taken care of.

Any information or solutions on this would be appreciated, as I typed this it did come to mind that I may have never paid attention to this item with traction control turned off in case it is the tranction control causing it, I doubt it but maybe. Anyway I was wondering if there is a brace or if spring upgrade is the answer, or what the issue could be.

Thanks in advance for your time.

Russell

 

Might be upper control arm bracket beginning to break off the frame.

 

I'd check all the suspension mounting points, attachments, and moving parts IE., bushings, ball joints, hubs, torque, & etc..

Bushings or ball joints would be at the top of my list...

 

That's not the answer I wanted to hear! LOL Thanks I will check into it.

Thanks I will look into it, at least it backs up onto ramps real easy and lots of room to look around.

Thank you both of you for taking the time to give your thoughts.

Regards,
Russell

 

If it has OE Goodyear runcrap tires, they have a reputation of following grooves in the road. search this forum for “tramlining” and see if the description fits what you feel.

Also a bad alignment can make the car dart.

 

Running BF Goodrich G-Force Sport Comp-2, but the car does Tramline, but my Porsche does that as well, I believe that is just the downside of running wide tires and probably staggered setup and wider tires in the back may contribute. But what I am talking about isn't tramming.

However, having alignment checked is something I have pondered, but have been putting it off as I have been thinking of bumping up to 18" and 19" wheels and after lowering the car (just lowered it two weekends ago), so that may be a good place to start and ask them to check it all out to see if there are any worn out connections etc.. Obviously I can look, but a second set of eyes doesn't hurt.

Thanks for the input, the "Darting" caught my attention.

The good news is that it seems like I tracked down my parasitic drain when I rebuilt my seats, there were some bare wires in the drivers side that I repaired and it looks like the draw falls in range of what it should. Will be nice to not worry about keeping it charged as I typically only drive it on the weekends and sometimes a bit during the week.

 

so if you lowered it, that will change both camber and toe. Also, lowering will give you a rough ride and a car that likes to dart. A car 18-20 years old is not a virgin anymore, and you don’t know who else lowered it and how much.

You can safely lower about 1 inch from optimum ride height. Any more lowering and the spring load will be too low, you might run out of shock travel, and the lower control arm will be too far from where it should be when at proper ride height. You will feel every bump in the road and the car will be jittery to drive; just won’t feel planted in turns at all.

Ride height is what is called a reference measurement. So it is not a hard drawing measurement, but one you can “refer to” after the suspension is set. The FSM has a procedure and special tools to set suspension height. Basically, there is a special tool no dealership has that measures the lower control arm for level. After setting the LCA’s to that level measure, you can now measure, say the top of the wheel well to ground and you now have a reference measure of ride height. You can now lower.

 

Thank you for the informative and knowledgeable response, learn something every day. The car was up pretty high from I am assuming the previous owner installed the C6 Z06 shocks, sway bars, etc. and when I had posted images before there were comments about needing to lower it. if you look at the third outside picture you can see how high it sat. If you look at the current interior pictures, I think I brought it to about what it was supposed to be, I didn't dump it too low, but I will definitely look into that as well.

The issue I am having was there when the car was at the higher height and is there now, only difference I can tell so far is that it scrapes a lot more now! LOL When I get it out on a mountain road I will be able to see what kind of difference there is.

Thanks again for your response and for the sharing of knowledge, just been doing baby steps on the car and not too much all at once so I can quantifiy fixes and differences.

 

I lowered mine as far as I dare go (a year ago) and I don't notice any difference in the ride and it doesn't dart. Z-51 package. Not trying to start an argument. Just my observation.

 

Observations and case studies are always good data to have. I know you can mess things up by lowering and going with bigger wheels and tires.... I am sure alignment plays a role.

I need to get under there and look for something loose, worn out or broken between rear end and frame/body as that is what I am sensing/feeling a shift and not alignment. However, I don't assume I am right, one time I thought an automatic transmission had issues in a car and it turned out that the coil for one cylinder was going out! LOL So what it feels like isn't always what it is, so everyone's input and observations are very welcome. I try not to be that guy who only hears what he wants to hear.

 

Actually, you don't want the car "level". The car was designed to have a slight "aero rake", with the rear about 1/4" higher than the front. This keeps positive pressure pushing DOWN on the hood, as well as deflecting air around the car, rather than under it.

 

Thanks, I didn't know that, thought along the lines of corner balancing.... Good news is that the rear is around 3/16-1/4" higher, it was 3/4" and 1" higher before I lowered it. I was just trying to get it to look more stock and not so high, people were making wise cracks. Downside is it scrapes more now! LOL

 

Trim Height Specifications:
Base, FE1, FE3, FE4----------J Height (Curb)-------------K Height (Curb)
Service Preferred--------------153 mm (6.02 in)---------158 mm (6.22 in)
Service Allowable-------------153 mm (6.02 in)---------158 mm (6.22 in)

 

Thanks for the great information, now I can adjust to spec. Greatly appreciated, thanks again!

 

Interesting, I am around 4 3/4" and 5 1/4" from bottom of body to grade, and my wheels are centered pretty nicely in the wheel wells, Yet I think something is amis! LOL Maybe I need to raise it at least a 1/4".....

 

I'm al very interested in this ride height diagram. Is the measurement at the lowest body part or the Floor Boards ??

W have a '98 IPC Convert and a '04 FRC ZO6 LE Mans Commemorative Edition, they appear to be different heights, although We've never measurement either one, which I'll do so soon.

Michael.