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XLR-V on Z06 suspension w/ big brakes and 19x10 wheels

HarvesterUT

Seasoned Member
Joined
Aug 22, 2017
Messages
72
Location
San Antonio, Texas
My XLR/V(s)
2008 XLR-V
Finally got my car back from the shop! GM goofed and never actually shipped my Z06 springs and sway bars, and it took me 2 weeks to finally speak to a human to get it sorted out. So here's the set-up:

- C6 Z06 leaf spring F/R (part# 25909895 & 15233392)
- C6 Z06 sway bars F/R (part# 20777536 & 25919502)
- C6 Z06 brakes F/R
- Prothane poly sway bar bushings F/R
- GM Superalloy forged 1pc wheels 19x10 +79 offset (stock base C6 rear size) with 25mm spacers (so net +54 offset)
- General G-MAX RS tires 275/35/19 (F) & 285/35/19 (R) (got a screaming good deal on Tire Rack last month)
- Hawk HPS single pc pads
- C6 Z06 ss braided brake lines
- Motul 600 fluid

My main concern was fitment and clearance of the rear wheels and tires. I can confirm that my set-up works with ZERO rubbing in the rear (Edit: After driving the car on a road trip for the holiday weekend, I noticed a slight bit of rubbing on the rear tires on the black plastic fender liner. This only happened when I was driving 40mph+ on some rather bumpy rough roads. I checked the tires and fender, and there doesn't appear to be any damage or serious issue. When it comes time to do an alignment, I might ask my mechanic to raise the rear 1/8" to give me a little more clearance.) The Z06 rear springs are much more firm that stock, so it's possible it would rub on the inboard side under high load scenarios on a stock spring. However, as the car sits, there is about 1 finger of clearance inboard, and the outer tire shoulder just clears the outer fender. See the photo. I have also included the alignment specs for those interested.

The brakes feel great, and ride is much more firm but not overly harsh (relative to my other cars). Body roll and dive is significantly reduced. The car feels much more planted around high speed sweeping turns.

I am extremely happy with this set-up.

Edit: I wanted to share a bit more of what went into making this all work. Maybe I can save someone else a small headache. When picking wheel spacers, I noticed that Corvette owners have a choice between spacer centerbore diameter of 70.3mm and 70.5mm. I cannot for the life of me understand why they exist in 2 almost identical specs. Originally, I ordered the 70.5mm bore, but I found that the GM wheels I was using wouldn't fit around the spacer hub lip. I returned those and got ones with a 70.3mm centerbore and they were tight, but they let the wheel fit. All wheels might be slightly different, so check your centerbore with whatever wheels you want to use to ensure the spacer (if you use them) will fit.

Also worth of mention, The GM Superalloy wheels were actually a dealer option wheel in 2008 for the base C6 only. They are a double staggered set-up like most all Vette wheels. I wanted 19x10 all around, so I bought 4 rears naturally. The fitment issue I rant into - besides the aforementioned centerbore fiasco - was that the back of the wheel mounting face would come into contact with the wheel studs on the car. These are slip on spacers, and the OE studs were about 1/8" too long, and you couldn't torque the wheel flush. My mechanic used a special drill bit that basically grinds down the tip of the OE studs 1/8" and puts a nice bevel on it so it appears stock-ish. The tips of the OE studs are not threaded on the last 1/4" so this does not change how much thread contact the nuts have on the studs. I forgot to mention this, and I think it's important enough to point out. If you don't use a spacer, or if you use aftermarket wheels that have "cut outs" for the studs, you'll probably be fine.
 

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Last edited:

GizmoQ

Seasoned Member
Joined
Jun 3, 2010
Messages
1,079
Location
Traveling the Country
My XLR/V(s)
2006 Black Raven XLR-V; 1996 Eldorado ESC-V
Looks good!
 

MrSunshine

Seasoned Member
Joined
Jun 16, 2018
Messages
65
Location
AZ
My XLR/V(s)
2006 Xenon Blue XLR with Chamere / Slate interior
GREAT info! Thank you for sharing! I was looking into doing the very same thing. Now you've taken out the guess work for me! :)
 

HarvesterUT

Seasoned Member
Joined
Aug 22, 2017
Messages
72
Location
San Antonio, Texas
My XLR/V(s)
2008 XLR-V
Thank you all for the compliments. I put about 350 miles on the car over Memorial Day weekend for her first true shakedown since swapping the wheels and suspension and brakes. The brakes are freaking PHENOMENAL compared to the stock ones. Night and day difference. I know the C6 guys talk trash about the Z06 brakes for being too soft on track days, but for my driving, they might as well be carbon ceramics.

Also, I updated my original post with a few new comments that I wanted to share.
 

mkapoustin

Member
Joined
Jun 11, 2019
Messages
19
Location
FL
My XLR/V(s)
2007 Black Tan XLR
Beautiful work, is it fair to ask what the parts and work cost? Very nice.
 

HarvesterUT

Seasoned Member
Joined
Aug 22, 2017
Messages
72
Location
San Antonio, Texas
My XLR/V(s)
2008 XLR-V
Beautiful work, is it fair to ask what the parts and work cost? Very nice.

I have no issue sharing what things cost. The Z06 leaf springs and sway bars were $852 from GMpartsdirect.com. I paid $2,046 for all 4 wheels, tires, and wheel spacers. I bought the wheels from various wheel reconditioning companies. All wheels arrived looking factory fresh. All 4 calipers and guide pins from Rock Auto for $1,152. Stoptech slotted rotors, Hawk HPS 1 pc pads, braided brake lines, and Motul 600 fluid was $794. I also purchased polyurethane sway bar bushing kit for $32.

Parts total - $4,876
Labor - $1,690 (includes alignment)
Total - $6,566
 
Joined
Apr 6, 2019
Messages
2
Location
OR
Finally got my car back from the shop! GM goofed and never actually shipped my Z06 springs and sway bars, and it took me 2 weeks to finally speak to a human to get it sorted out. So here's the set-up:

- C6 Z06 leaf spring F/R (part# 25909895 & 15233392)
- C6 Z06 sway bars F/R (part# 20777536 & 25919502)
- C6 Z06 brakes F/R
- Prothane poly sway bar bushings F/R
- GM Superalloy forged 1pc wheels 19x10 +79 offset (stock base C6 rear size) with 25mm spacers (so net +54 offset)
- General G-MAX RS tires 275/35/19 (F) & 285/35/19 (R) (got a screaming good deal on Tire Rack last month)
- Hawk HPS single pc pads
- C6 Z06 ss braided brake lines
- Motul 600 fluid

My main concern was fitment and clearance of the rear wheels and tires. I can confirm that my set-up works with ZERO rubbing in the rear (Edit: After driving the car on a road trip for the holiday weekend, I noticed a slight bit of rubbing on the rear tires on the black plastic fender liner. This only happened when I was driving 40mph+ on some rather bumpy rough roads. I checked the tires and fender, and there doesn't appear to be any damage or serious issue. When it comes time to do an alignment, I might ask my mechanic to raise the rear 1/8" to give me a little more clearance.) The Z06 rear springs are much more firm that stock, so it's possible it would rub on the inboard side under high load scenarios on a stock spring. However, as the car sits, there is about 1 finger of clearance inboard, and the outer tire shoulder just clears the outer fender. See the photo. I have also included the alignment specs for those interested.

The brakes feel great, and ride is much more firm but not overly harsh (relative to my other cars). Body roll and dive is significantly reduced. The car feels much more planted around high speed sweeping turns.

I am extremely happy with this set-up.

Edit: I wanted to share a bit more of what went into making this all work. Maybe I can save someone else a small headache. When picking wheel spacers, I noticed that Corvette owners have a choice between spacer centerbore diameter of 70.3mm and 70.5mm. I cannot for the life of me understand why they exist in 2 almost identical specs. Originally, I ordered the 70.5mm bore, but I found that the GM wheels I was using wouldn't fit around the spacer hub lip. I returned those and got ones with a 70.3mm centerbore and they were tight, but they let the wheel fit. All wheels might be slightly different, so check your centerbore with whatever wheels you want to use to ensure the spacer (if you use them) will fit.

Also worth of mention, The GM Superalloy wheels were actually a dealer option wheel in 2008 for the base C6 only. They are a double staggered set-up like most all Vette wheels. I wanted 19x10 all around, so I bought 4 rears naturally. The fitment issue I rant into - besides the aforementioned centerbore fiasco - was that the back of the wheel mounting face would come into contact with the wheel studs on the car. These are slip on spacers, and the OE studs were about 1/8" too long, and you couldn't torque the wheel flush. My mechanic used a special drill bit that basically grinds down the tip of the OE studs 1/8" and puts a nice bevel on it so it appears stock-ish. The tips of the OE studs are not threaded on the last 1/4" so this does not change how much thread contact the nuts have on the studs. I forgot to mention this, and I think it's important enough to point out. If you don't use a spacer, or if you use aftermarket wheels that have "cut outs" for the studs, you'll probably be fine.
Hi; this is good info; I was about to inquire about cost and you already answered it. I have a turbocharged '04 that exceeds the stock set-up.
 

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