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Project C7 Corvette Stingray Z51: Suspension Upgrades

by Mike Kojima

 

In previous articles about our Project C7 Corvette, we got into the high tech chassis construction of the C7 that rivals the stuff found in exotic cars for a fraction of the price. We also did our baseline testing of the car at Buttonwillow Raceway to get an initial impression of the car. We were quite impressed with the results. In stock form, the Corvette is one of those cars that is so good from the factory that heavy-handed, poorly conceived aftermarket suspension mods can ruin.

Knowing this, we turned to Chevrolet for their expertise in tuning the C7 for SCCA competition. The C7 is a popular car in SCCA's T1 class. In the class, the SCCA allows for homologated modifications, such as suspension kits. Chevy designed the kit with racing in the T1 class in mind. This is a well-integrated kit designed by Chevy's engineers with compatibility with the car's electronics in mind. 

Would the race-derived T1 kit prove to be a bitch on the street? Read on and find out!

 

Read more about our Project C7 Corvette here!

The Chevrolet Performance T1 kit includes a set of shocks, new lower control arms with front and rear anti-sway bars.  
 

The T1 shocks are made for Chevrolet Performance by Bilstein and are a high gas pressure monotube design. 

The shocks run Chevrolet's own specific valving developed specifically for track use.

The shocks come with a hard, high durometer rubber upper mount to transfer more of the suspension motion through the shock than flexing the stock soft rubber for better control.
 

New lower control arms are part of the T1 kit and come with special high durometer hard rubber bushings. This helps keep the alignment true under the harder loads generated by sticky race rubber. 
 

We really like the factory large diameter, but hollow aluminum control arms that have the huge cross-sectional area for stiffness while being hollow for light weight. 

 

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Comments
SM_Clay72
SM_Clay72link
Thursday, November 09, 2017 8:23 AM
Nice bits on those cars.

Guessing Howard put that LCA bolt in form the other side when he reassembled. You know, for all those future control arm swaps.
Samuel
Samuellink
Thursday, November 09, 2017 5:19 PM
Yeah, I would have cut the bolt and replace it with a new one.
Jeff Naeyaert
Jeff Naeyaertlink
Thursday, November 09, 2017 7:10 PM
hmm, never thought to cut it off 🤔 And no, we replaced the bolt like it was before--not down with punctured fuel tanks and fiery explosions!
spdracerut
spdracerutlink
Thursday, November 09, 2017 10:55 PM
Man.... nice to have a factory upgrade option fully engineered by OEM guys. Guys that actually do FEA analysis and durability testing. The GM guys certainly know how to make a car handle well around a track too.
warmmilk
warmmilklink
Friday, November 10, 2017 6:23 PM
I'm not seeing the adjuster on the shocks... Just looks like the typical hex to be able to loosen / tighten the top nut... just like the stock shocks... definitely not seeing the "Visually, the Z51 stock shocks and the T1 shocks look exactly the same, other than the adjuster on top of the shock" claim at the top of page 4, well I see the "exactly the same" part, but not the "other than the adjuster on top of the shock" part. the only difference in the pic showing the tops of the shocks is that one is dirty and one is clean, otherwise they look identical.

MotoIQ is the only place on the internet that claims the T1 shocks are adjustable. Everything I can find from GM on the subject just says "track-optimized passive shocks". I can't find anything that says they're adjustable from GM or otherwise. And the pic you guys show on page 4 does not show an adjuster.

My buddy with the C7 Z51 FE3, the shocks that his car came with new match the part number of what you guys posted at the T1 shocks. Well at least the rear, I wasn't able to pick out the part number you guys have for the front shocks in any of the pics. Front is 22873513, which matched the T1 shocks he bought, not realizing they were the same shocks that his car already had till after he bought the T1 stuff.


ginsu
ginsulink
Saturday, November 11, 2017 3:26 PM
@spdr - That would be nice, but since the control arms are exactly the same, that means you don't get anything better. Don't drink the Kool-Aid.

Aftermarket is usually better IMO, especially for the price. Solidworks, and CATIA both have built in FEA, with good enough results.

I mean honestly, it's not like all of the mechanical engineering is really that complicated when you are dealing with such simple parts. Hydraulic dampers, control arms and sway bars have not changed significantly in nearly 70 years. You can find those exact same designs in a 1950's Cadillac.
ginsu
ginsulink
Saturday, November 11, 2017 3:29 PM
@warmmilk - I had the same thought. Good research. Sounds scammy to me. Besides the fact that to get new bushings you have to buy completely new control arms. I think I would rather just replace the bushings.

But, we all know, these articles are written for people with bigger wallets than brains.


What I've noticed in media, is you have to understand your audience, or you will lose them over time. If you don't know exactly the type of personality you are writing for, then they will 'tune out' over time because the material simply won't resonate.
Jeff Naeyaert
Jeff Naeyaertlink
Saturday, November 11, 2017 4:02 PM
@warmmilk you are correct.. Mike wrote the article based on the photos I took--he wasn't there for the install. At first glance they do look adjustable but you and the rest of the internet are correct--they are not. thank you for catching that!

I have also heard this before about the T1 damper part numbers being identical to stock (are you sure about the FE3 part though? those are completely different dampers). Our T1 dampers have different part numbers than what the car came with. The rears you can see in the picture are different, the front stock damper part number on ours was 23313991 while the T1 damper is 22873513. I will ask our contact at Chevy if they can shed any light on that. Maybe it's like the 600W radiator fan upgrade that eventually made it's way into at least the Z51 stingrays and perhaps the base models as well from the factory? We got the radiator too before realizing it was the same part our Z51 came with.

@ginsu Say what you want about the LCA's but the labor and potential damage saved not having to press or burn out the stock bushings make replacing the whole arm a nice option for some--and you can either have a spare or sell the old complete arms 👍
warmmilk
warmmilklink
Saturday, November 11, 2017 8:12 PM
@Jeff Naeyaert
Thats what the owner says (about FE3), he's usually pretty good about this kinda stuff.

yeah, he also got a lot of the OEM upgrades, fans, grills, vents, coolers, even Z06 front fenders. But the T1 dampers only lasted him 1 track session. He went too wide with the tires (325 NT01's) and they rubbed in the rear. So he went out and got some LG coilovers for some more roll stiffness. and never being satisfied, he's just wrapping up his Penske coilover install.
warmmilk
warmmilklink
Saturday, November 11, 2017 8:14 PM
@ginsu
idk, MotoIQ is usually pretty good, but with this C7 Vette project there's been quite a lot of incorrect info posted. not just this article, past articles on this project too
Mike Kojima
Mike Kojimalink
Sunday, November 12, 2017 10:22 AM
Ginsu, what are you talking about? OEM engineering is way more sophisticated than most aftermarket stuff. The amount an analysis and validation is an order of magnitude more involved. Unless I was racing a much higher class I would rather get an OEM engineered performance part. I know this because I was an engineer for two different OEM performance programs for two different manufacturers and have consulted for a couple of different ones as well. Also, you don't understand the scope of SCCA's T1 class which is a maturation of the old Showroom Stock classes. The suspension kits like this one are homologated by the SCCA and that's what you are allowed to race with. Suspension engineering is not "simple" and the technology has changed by orders of magnitude since 1950's Cadillacs in all aspects. Massive changes have been made in suspension technology from the geometry to damper design and valving strategy to the basic understanding of vehicle dynamics. To arrogantly dismiss this and call it all simple shows a lacking of understanding of the history of the engineering behind these things and perhaps lack an understanding of how this stuff works and what can be done. Saying that using these parts means you have more money than brains and don't drink the cool aid is also very dismissive. I hope you continue to learn as your career advances.
RedX
RedXlink
Monday, November 13, 2017 9:52 AM
How do they make hollow cast arms like these?
Mike Kojima
Mike Kojimalink
Monday, November 13, 2017 12:43 PM
Probably using the lost foam technique where they use a foam core that vaporizes as the metal cools.
SM_Clay72
SM_Clay72link
Wednesday, November 15, 2017 8:39 AM
I generally read Ginsu's comments for humor factor. I don't think anyone should/does take them seriously.

Back to my nitpick about the bolt though Jeff; putting the bolt in from the other side would reduce any chance of the bolt backing out and puncturing the fuel tank. In a race environment (which this car is not being built for) where you may need to swap a bent control arm on the quick-fast having the bolt come in from the inside would save a lot of ass pain.

Mike Kojima
Mike Kojimalink
Wednesday, November 15, 2017 10:43 AM
This car is being built as a high-performance street, occasional track day car, not a race car.
SM_Clay72
SM_Clay72link
Friday, November 17, 2017 8:57 AM
I said that^!

I still want that bolt swapped Mike. This should be keeping everyone up at night!
Jeff Naeyaert
Jeff Naeyaertlink
Friday, November 17, 2017 11:47 AM
lol, that bolt isn't going to back itself out and puncture the tank! go to sleep!
engineered
engineeredlink
Tuesday, November 21, 2017 2:19 PM
I thought ginsu deleted his account? Guess not.
Mike Kojima
Mike Kojimalink
Tuesday, November 21, 2017 2:46 PM
This was an earlier article, Ginsu melted down a few days ago.
engineered
engineeredlink
Tuesday, November 21, 2017 2:57 PM
lol, I forgot I was catching up in reverse order :)

Keep up these C7 articles. I'm enjoying them but it's tempting me to get one myself.
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