Last night I had a few friendly runs with a Z06 and noticed that my car felt like it was rocking back and forth above 120. I've never noticed it before and was just wondering if there was anything you guys would suggest I check out.

The car has stock suspension with h&r springs, I'm probably getting some swaybars and droplinks for my next mods as well so feel free to name any personal preferences.

Thanks,
Matt

 

Matt,
You've spent lots of time and money on good power and brake upgrades but just springs are insufficient to control the extra HP you've added. Springs without matching shocks will cause this porpoising effect. Sway bars and drop links are good idea but will not fix this problem. To get it fixed it you'll have to get shocks matched for the springs or a complete height adjustable coil over set up. Bilstein makes a cost effect PSS10 system for street (not track) use. Be advised if you lower the car too much (GT2 or GT3), you will end up with too much rear camber and toe that the stock eccentrics cannot adjust out. You'll have to go with adjustable rear upper control arms and adjustable toe steer arm to correct this. Budget 4-5K with installation, corner balancing and alignment. Also consider stiffer motor mounts given the extra HP. IMHO anything less than this is underkill and any more than this is overkill for a street car.

 

Thanks for the response Duane and yeah coilovers(thinking Kw3) are definitely in the future mods list but the car has felt stable above 150 until that night, so I'm wondering what could've caused this all of a sudden.

Also if anyone knows of any good shops along the Ms, Fl, La, AL gulf coast area to do a proper corner balance and alignment let me know.

 

just curious.... was the z06 stock?? and how did the runs go??

 

yeah send details if you can....

 

Im in Mobile right now how far are you from where im working?

my car does the same thing as yours 120-130 it rocks back but is stable up top im looking into stiffer motor mounts n tranny mounts. as my suspension is 100% stock as far as i know heh.

also looking into KW v3's so the adjust ability

William

 

I'm in Biloxi which is about 60 miles west of Mobile. I'll post the video from the run with the Vette along with the mods.

 

http://www.youtube.com/watch?v=c7_Mu5ZGO0U

C5Z06
LG motor sport long tube header with X pipe
Callies rods
12:1 diamond piston 2 degree valve relief
450 precision injector
New crank
New fly wheel
Fast 90 intake/throttle body
Trick flow 215, 58cc heads ported
crower retainer
crower spring
ferrea valve
Comp. cam roller lifter
Comp. cam cr-mo push rod
Comp. cam cam shaft custom ground 242/244 624/622 111
3 degree advance
Harland and sharp roller rocker arms
RPM stage 5 tranny (new just install 2 week ago) w/spec stage three clutch
Coursa indy cat back
Stock z06 rear end with 342 gears
Nitrous express progressive system with bottle warmer/purge system
B & M ripper shifter
06 z06 rims

 

Now that you mention it the car only seems to do it when I was racing and late that night I just rolled into in 5th and it didn't do it. It might be the motor/tranny mounts when I'm shifting. I'm thinking about the Wevo black/blue not sure which one would be best for mainly street use with a few track days here and there.

 

One thing about the video. The driver of the Z06 (camera car) does not know how/when to shift (or drive). He leaves the car in gear too long and allows you to gain car lengths. Even with the stated “B & M ripper shifter” they shift lousily.