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I posted this in the Wheels and Tires section (link to the thread with pictures is below) and am not getting much to work with, so I figured I would post it here because there are plenty of guys with experience running the C5 Z06 wheels on their track cars. My issue is that I am trying to find the right hub-centric spacer to go with my C5 Z06 wheels and longer ARP studs. Bought a set online and the bottom of the lip is flared out and that doesn't mate up properly to the C5 Z06 wheels despite the advertised 70.3 mm center bore sizing for the spacer. Any suggestions on who sells these with a smooth lip?
I run flat spacers just under 3/4" from Blaine fabrication. I'm not sure if he's on here but he has a website. I run them on the street and track no problem with c5 wagon wheels and c6z06 repos. And with longer ARP studs of course.
Used to run 1" thick spacers or some ridiculous size in the rear that put the wheel face past the hub. Never had a vibration or any other issues, but I also never ran them over 120mph.
Any hubcentric spacers under 20 mm are going to be shaped that way. Not enough material to have the hubcentric portion extend as it needs to, past the existing hub bore on the car. I had hub centric 12mm spacers and they the hub centric portion broke off the material was so thin.
Under 20mm you'll need to non hubcentric. 20mm and up you can use hubcentric without issue
I have been running the Eibach 15mm hub centric spacers for years and have never ran into any problems. I have been running 18x10.5 C6 replicas. They are a little spendy but I ended up just getting another set a while ago for my rear wheels as I had been running them only on the front to clear the 6 piston brake setup. I can get a part number off the box when I get home if needed.
I run flat spacers just under 3/4" from Blaine fabrication. I'm not sure if he's on here but he has a website. I run them on the street and track no problem with c5 wagon wheels and c6z06 repos. And with longer ARP studs of course.
I'm running Blainefab non-hub-centric spacers too, been doing so for years just like everyone else I road race with. Just get some ARP studs and you'll be fine. For reference we run 275/40/17 Toyo RR tires and I've never seen a broken stud. I know it sounds bad in theory but it works just fine. Right now the car has -2.9 degrees of camber, runs a 74" track width, and wears a 1/16" spacer first, then a 3/8" spacer on top of that to achieve the desired track width with the aforementioned C5Z wheels.
Thanks for all the insight. Got a message from a buddy for another shop that will make these custom and I talked to the guy this morning. To have enough material to run a flush lip (no flare at the bottom), they need a spacer size of at least 14mm. I went ahead and ordered a set at 15mm to provide a little extra cushion and I'm thinking this should be the fix.
In searching for a fix here, I did also pick up a set of 12 mm spacers on ebay without the lip and mounted those and it didn't go very well. It was difficult to get the wheels centered perfectly without the assistance of the lip. No noticeable vibrations when driving, however there was clearly some noise coming from the rear wheels that changed with speed, so something in the setup was not properly in line. I'm going to take those off today and run my street tires/wheels while I wait for the new spacers to arrive.
Forgot to mention that the front needs to be about 1/4" wider than the rear to make the car handle decent. The delta can be, and needs to be tweaked to the driver's liking. It has a very profound impact on the way the car drives so one set of spacers to rule them all should not be the approach here. Screwing with the front camber also affects front track width directly so you may falsely attribute an increase in negative camber to a newfound lack of understeer.
Forgot to mention that the front needs to be about 1/4" wider than the rear to make the car handle decent. The delta can be, and needs to be tweaked to the driver's liking. It has a very profound impact on the way the car drives so one set of spacers to rule them all should not be the approach here. Screwing with the front camber also affects front track width directly so you may falsely attribute an increase in negative camber to a newfound lack of understeer.
Thanks for the insight. One glaring hole I have in my track setup is I’ve been running the staggered C5 Z06 Speedlines for years. I’ve never run the car on track on a square setup (my street setup and rain setup is staggered too), so I don’t have a feel for how much of a difference that will make, but I would guess it’s significant based on the advice I’ve received from others.
I will eventually put together a square setup all around, however I wanted to address the rear end first before trying to tackle the front hub issues + longer studs + spacers and the 18” x 10.5”s up front.
With a good set of rear spacers en route, I may soon be one step closer to rolling up the sleeves to get to work on the hub issue.
Thanks for the insight. One glaring hole I have in my track setup is I’ve been running the staggered C5 Z06 Speedlines for years. I’ve never run the car on track on a square setup (my street setup and rain setup is staggered too), so I don’t have a feel for how much of a difference that will make, but I would guess it’s significant based on the advice I’ve received from others.
I will eventually put together a square setup all around, however I wanted to address the rear end first before trying to tackle the front hub issues + longer studs + spacers and the 18” x 10.5”s up front.
With a good set of rear spacers en route, I may soon be one step closer to rolling up the sleeves to get to work on the hub issue.
I went to a square 18x10.5 C5Z setup on my C5Z and it was noticeable. Finally the nose would tuck on throttle lift and the front was just more in command without it being loose. At this point I really have to wonder though if a lot of that difference is due to the increase in front track width that came with it. I run square 17x9.5 C5Z wheels on the Camaro. If the nose feels like it just isn't responding the way it should, try widening the front or narrowing the rear by 1/4". Even if you're not that great of a driver you'll feel it. I didn't expect to feel a damn thing but I did. 1 change at a time is the smart way to mod the car though, just like you're doing now.
The track width of the front relative to the rear was a concept that I never really considered. Just thinking about the Corvettes coming from the factory with a staggered setup I just assumed it made sense. It does make sense, but more so on the street and in the interest of safety (tone down the oversteer for cars that already have traction issues under power).....in thinking specifically for road course use, it makes sense that you would want to balance that out.
Just thinking out loud about the variables this presents for me, if I went with the 18x10.5" Speedlines all around, I'll need to account for the 14 mm spacer in the rear. It looks like I could get away with a smaller one up front, however perhaps that doesn't mean that I should go smaller. Another consideration would be the rear sway bar setup....I'm running the Strano hollow 3-way adjustable on the middle holes. Slightly more prone to oversteer now (by design), however I would guess the additional front track width might be enough to consider the third hole. The alignment would be yet another consideration. Anything else I'm missing that jumps out at you?
Yes, measure your front vs rear track width! This is your new starting point, again influenced directly by camber changes. Clearly the bars give you an easy way to shift the balance, but so does track width.
As far as track width, don't assume they are automatically even, the front alignment can make a big difference depending on how far in or out the control arms are.
I have square setup wheels, tires, spacers and my front is something like an inch wider, can remember exactly. I grinded the slots to get more camber and it moves the wheels out quite a bit.
As far as track width, don't assume they are automatically even, the front alignment can make a big difference depending on how far in or out the control arms are.
I have square setup wheels, tires, spacers and my front is something like an inch wider, can remember exactly. I grinded the slots to get more camber and it moves the wheels out quite a bit.
Any time one of our cars has a front to rear delta that substantial the rear gets very snappy and unforgiving at the limit. It's good to 9/10 then tries to kill you when you go for what's left. My car is very easy to deal with at the limit and beyond. Not so for some of our rookies' cars. I drove them to validate their gripes.
Any time one of our cars has a front to rear delta that substantial the rear gets very snappy and unforgiving at the limit. It's good to 9/10 then tries to kill you when you go for what's left. My car is very easy to deal with at the limit and beyond. Not so for some of our rookies' cars. I drove them to validate their gripes.
So i measured just to see and eyeballing it at the outer tire edge rear is 73 and front is 74.5. I think its fairly balanced and forgiving, but I'm probably not at 9/10s either. since I have 3/4" spacers I can remove the fronts and be even so I might try that at the next event and see how it feels. I'd rather bring the rears out but not sure whats the safest way other than lengthening the axle.
I have ARP studs and just run a slide on spacer. I think my car has a 5/8" spacer out back and 3/8" up front. The car's dark side won't reveal itself until you really lean on it.
I have ARP studs and just run a slide on spacer. I think my car has a 5/8" spacer out back and 3/8" up front. The car's dark side won't reveal itself until you really lean on it.
Yeah I already have the 2.5"(?) ARP studs with 3/4" spacers all around so not sure if 1.5" spacers with longer studs is okay or not
I wonder if the LS1 axle is narrower than the LT1 axle?
Why, what's yours measure? Just for comparison mine is measured with 18x9.5 c6z knockoffs +56mm with 275s and 3/4" spacers. It does seem like the wheels are still tucked more than they should be with spacers, but I guess that's how they made em in the 90s
12-11-2018, 04:01 PM
RR guys running C5 Z06 wheels 
