gtpvette

My new car doesn't have Z51 so I'm looking at upgrading the suspension. The adjustable Z51 shocks are pretty cheap as are the springs ($1K for parts). I'm chewing on the two aftermarket spring options but haven't come to any conclusion. In scanning all the threads I can find, these are the spring rates I come up with. Do these look correct??

C8 base & Z51 springrates.

Front Base - 31.5N/mm 177lb
Front Z51 - 39.5 N/mm 222 lb 25% stiffer

Rear Base - 38 N/mm 216lb
Rear Z51 - 46 N/mm 262lb 21% stiffer

Leaked mid-engine C8 Corvette specs hint at big performance gains - Hagerty Media


Paragon/Hyperco springs

Front - 300lbs/in Linear +69% stock, +35% Z51
Rear - 270lbs-350lb/in Progressive +0% +62% stock, +0% +33% Z51

C8 Corvette Lowering Springs by Hyperco | Paragon Performance


Eibach - I haven't been able to verify these

Front 183-275 Lbs. Progressive +55% stock +23% Z51

Rear 275 Lbs Linear +27% stock +4% Z51


Looking at rear sway bars as well. At a minimum I'll do the Z51 bar.

Any thoughts?? If the Eibach numbers are correct not much of a spring rate difference at least in the rear from the Z51 springs. The others is a +35 on both ends which is quite a bit. Too much for Z51 shocks? The drop wouldn't be why I go to these aftermarket springs only crisper handling without destroying my kidneys LOL.


Looking at rear sway bar upgrade as well. At a minimum I'll do the Z51 bar. Bigger better?

itsonlyairandfuel

I went to the Z51 bar on my non Z51 car. Uneven pavement is much more noticeable, ride comfort is diminished. On smooth blacktop it might help cornering, hard to tell.

baf2000_1

I found the Z51 too stiff for my body, crappy NJ roads ( and I am 61 ). So I I down graded to the non-Z51 shocks and springs and the car rides much better. And ride height is the same . The cornering is not affected at all. So I would advise you replace front and rear sway bars first and see if you like it. If you DIY replacing shocks and springs, like I did, be sure to view many Youtube vids. Some are clearly incorrect. The rears are tricky ( tricky means PIA )

CLEAR

I will be replacing my base shocks for OEM Z51 so I will have lowering ability.

CLEAR

I installed z51 shocks on a base suspension car this week. I do not really notice a difference in ride or handling. I was hoping to get 3/4-1" of lowering but got exactly 1/2". I would have gone the cheaper route with Eibach springs for the full 1" had I known. 300 for aftermarket springs vs 500 for new oem shocks. Install would have been the same.

gtpvette

Did you put on the Z51 springs as well?

gtpvette

I'll add,, I picked up my car yesterday and drove it 200 miles to Auto Train. I like the suspension as is but really haven;t pushed it.

CLEAR

No, just the shocks adjusted to 1 thread showing.

CLEAR

gtpvette

I like the white wheels.

CLEAR

I should have check when it was all apart but I bet you can put adjustable z51 perches on the fe1 shocks

allblackeverything

fe1 shocks aren’t threaded so no you can’t

CLEAR

threaded perches slide right off the shocks.

itsonlyairandfuel

Does the FE1 (1LT) strut collar also slide off?

gtpvette

I'm throwing the Z06 springs into the mix. C&D says they're 30% firmer that Z51 so similar to the Paragon numbers but no lowering. I can't seem to get a clear understanding if the base Z06 suspension has helper springs or not. Seems the Z07 option does based on my reading. I've posted a question in the Z06 section.

Any thoughts, pictures, insights?

I have these part numbers, these should be for Zo6, without ground clearance, without performance package (Z07)

Front Z06 85583613
Rear Z06 85583615 maybe,, having a hard time verifying via online parts houses.
Rock Auto says rear is 85583619 although out of stock. GM says this is discontinued and online parts dealer says there is no superseding number.

mikegr

Are the shocks a different part number between the Z51 and Z06? I would just be aware if there are different shock numbers when going up significantly in spring rate, if there are they could have different valving..

gtpvette

Yes the Z06 has MRC shocks standard (as far as I know) so those shocks wouldn't work on my car. Based on my reading, the code the controls the Z06 MRC shocks is different than the C8 MRC as well.

CLEAR

Yes

Thinking if someone sold the perches, it would be a much cheaper option. Looks like through GM they only come as an assembly with the shock.
Does anyone know if the valving between FE1 and FE3 are even different? For all I know its the same shock with a different part number due to the perches.

gtpvette

I've had Speedway Motors dyno shocks in the past. Just checked their website, says $10 a shock for non-adjustable ones. One would think the FE1 and FE3 are different but by how much?? I'd be interested in front to rear numbers as well. They also check spring rates as well.

Shock Rebuild Center (speedwaymotors.com)

CLEAR

Yeah Im thinking instead of spending 500 for shocks that may be the same or not much different if someone just sold the adjustable perches for 100-150 they would sell quite well. Could possibly research more and find out who manufactured them and could probably track down perches. Then again for 300 can buy 1" aftermarket springs which in hindsight I would rather have done. Spend less money and had full 1" drop vs 1/2" but have OEM equipment plus adjustability which I will never use.