I have a Z51 equipped 85; owned it since 2001. The only thing I have not restored/replaced/upgraded are the suspension and most of the interior.
The suspension is still pretty crisp, the Bilstein (originals) shocks still work very good and the car is stiff but not overly stiff; handles extremely well on the twisties. They lowered the spring rates in 85 from 84 so the car is not bad at all when driving in traffic either; I make the analogy that it feels like a go-cart on steroids.
85 Vette with many modifications: ZF6, TPIS/AFR alum. heads, TPIS LT's, TPIS ZZ9 roller cam, TPIS 52 mm throttle body, RT hi-flow cat., miniram, 355 ci. rebuilt engine, 3.73 gears; air pump delete, "1990 ZR1style" rear fascia w/admiral blue GS stripe, custom wheels, chassis dyno tuned by TPIS
There are just minor differences in lap times that i have noticed between Z51 and base suspensions, i am a member of a corvette car club here in Australia and the wide variety of C4's are very similar in lap times. I am sure a driver that doesn't care if he hits a wall may find a slight edge with a Z51, however as said by previous replies modern suspension upgrades are way better.
Z51 bilstein shocks on soft base model springs are the best suspension combo, combined with 32 mm swaybar and the small (24 or 22?) Rear swaybar.
Several months ago, I queried one of the forum's Bilstein employees. I specifically asked if there was a benefit to "upgrading" to Z51 shocks. He recommended against it, though I can't remember why. I don't have that PM in my inbox anymore.
Because I have low-hanging side-pipes and custom front air-dam, I have extra interest in avoiding bottom-out situations. It seemed logical to assume a stiffer shock would help. Thought it might also help if stock spring rates have "relaxed". If I keep the car long enough, I might consider coil-overs....though I don't get THAT wild very often.
This is for a street car where I'm less-than-thrilled with common highways and city-streets. Camber brace and cross-brace are also in the works for this year.
.......Stock FE1 versus Z51, which handles better. Easy question, HUGE difference between FE1 of ANY year and Z51/Z07 package cars. .......
How the car handles bumps, etc...is NOT handling. That is ride. From a pure handling perspective Z51/Z07 is what you want.
Originally Posted by Domobomb
.......I was basically asking if not having the z51 suspension makes a c4 handle like a donkey on roller skates.
I think I'll really just be missing the quick ratio steering........
On my Z51 I really like the quick ratio steering, the flat cornering, and even the stiffer ride. But on non Z51 cars it is not like a donkey on roller skates, it is a Corvette and they all handle pretty well.
Yeah...I saw that after my prior post. Re-f'in-diculous! Guess I'll be driving my C4 much longer than I thought! LOL
On another note, prior threads have pointed out Lingenfelter was a good price for Bilsteins. I found out there website isn't up-to-date and they think HD/Z51 stocks are discontinued. They wouldn't investigate. So, I called Bilstein.
Both are still manufactured and available. I found [even] slightly better pricing at ALLSHOCKS.com. Plus, at least they know what's still made/available.
I also asked a rep about installing Z51 (sport) shocks on my base suspension car. Here is his reply....
"I recommended the HD's is because you have a base suspension car. The Z51 cars have much higher spring rates. The higher rate resists suspension compression more than a lower rate, so the compression damping forces do not need to be quite as high. Conversely, the rebound damping rates need to be higher for a higher spring rate. The HD shocks will give you a better ride than the Z51 parts because they are a better match for the spring rates you have in the car. That is not to say that the Z51 parts won't work well in your car. They will work just fine, but they will offer very little improvement in ultimate handling at the expense of ride."