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Car 54,
Something is definitely wrong.
Have you lowered the car ?
On my Z51, I removed ALL the Upper A-Arm washers to be able to get the camber
I wanted... -3 on each wheel up front, -2 on each wheel in rear.
I had lowered mine about 1/2" on the stock bolts, and when I ran
wide wheels and tires, it rubbed on the inner fender lips.
So I raised it back up to stock.... bingo no rubbing.
I would check the ride height.... make sure the spring adjusting bolts are
at least mid-point, or even further down into the springs to get it higher.
Mad Dog...I agree with you it should not happen. in the first pic there is a transmission line that is pushing the liner....however, in the second pic I had changed the line to move it further toward the rear of the car. The tech at the chev dealer was able to get -1.3 camber on the rear without removing washers. Car is at dealer now for track alignment for next track day. I will get him to check ball joint...thanks.
Bill Dearborn....neither Goodyear that did street alignment nor dealer that did track alignment removed any shims. I will take a look however to make sure....thanks.
NTMD8R...car has not been lowered and is running stock tires.
Car54, Something is wrong that should not happen even pushing (negative)-2.5 camber. There may be a line, hose or something not allowing the inner fender to mount properly to the wheel house or body. Even with the big Z06 tires and all washers removed on the rear UCA of our Z06 we had clearance with a lot of camber.
There was a tech bulletin on some C7's having loose ball joints if I remember right. Make sure all suspension components are properly torqued.
Yeah, should not be rubbing.
Mine is even lowered on the stock bolts.
Stock wheels, with slightly larger front tires (MPSS 255/40-19).
No rubbing.
Mike Skeen ran a 2:09 with me in the car last weekend on VIR full. Best I could muster was 2:17.
I wonder if you have a bad shock. I wore all of my wheel well liners on my C7Z on stock shocks. Most of that was on Summit Point Shenandoah though which has a replica of the ring Karousel that you drop in to. However, where my rears liners wore was in the back like that.
Poor-sha.....It may be a bad shock...but if it is there are several of them. After VIR here is the Passengers rear looking toward the front of the car with .25 caster on both sides (again...I am not sure if that was positive or negative) and -1.3 camber. The tech at the dealer opened a ticket with the suspension person at TAC and his answer was to move one side positive caster and the other side negative caster. Based on the discussion here anything other than equal on both sides is dangerous. After street alignment and 4,000 road trip it did not rub on the passenger side:
and then there is the drivers front rubbing at the top of the fender liner which cannot have anything to do with caster but also could be a bad shock:
Newton06...the last time at VIR my best run was 2:09.26.
Just a final update from me about my alignment.
I was able to get a "good" alignment last week, after I replaced all the washers (shims),
correctly (2 for each bolt).
It was necessary to drive the car for a few miles (I did about 25), to "settle" things down,
before doing the alignment.
Bingo.... perfect.....
-2 camber both fronts, 7.3 left, 7.2 right front caster, 1/8" toe in on both
-1 camber both rears, 1.0 caster on both, 1/16" toe in on both
And now on 18/19 wheels with Potenza RE71 tires.
The car handles MUCH better.
2 autocross days this weekend; we did very well (still on a Miata course),
the back end still wants to come out if I am too aggressive on the throttle
coming out of turns/corners, but nowhere NEAR what it used to be.
Just a final update from me about my alignment.
I was able to get a "good" alignment last week, after I replaced all the washers (shims),
correctly (2 for each bolt).
It was necessary to drive the car for a few miles (I did about 25), to "settle" things down,
before doing the alignment.
Bingo.... perfect.....
-2 camber both fronts, 7.3 left, 7.2 right front caster, 1/8" toe in on both
-1 camber both rears, 1.0 caster on both, 1/16" toe in on both
And now on 18/19 wheels with Potenza RE81 tires.
The car handles MUCH better.
2 autocross days this weekend; we did very well (still on a Miata course),
the back end still wants to come out if I am too aggressive on the throttle
coming out of turns/corners, but nowhere NEAR what it used to be.
I am a very happy camper with this setup.
You didn't follow GM's recommendation (see Feb. 2016 TSB) to remove 1 shim from behind the front UCAs??
You didn't follow GM's recommendation (see Feb. 2016 TSB) to remove 1 shim from behind the front UCAs??
Bill
Bill, I've scoured the GM info. They state 'remove a MAXIMUM of 1 washer on each front UCA' in the TSB document. It seems to imply one can choose to remove no washers if they're able to achieve the desired specs.
Last edited by spearfish25; 08-29-2016 at 11:45 AM.
Agree and surprised he could even get -2 out of the front with all shims \ washers in. Those eccentrics are surely maxed out!
But hey if it works so be it!
This just crossed my mind...if he was able to get -2* with the shims in and it maxed out the eccentrics this would effectively act similar to having a "block" installed wouldn't it? If so that would be a good thing.
Just a final update from me about my alignment.
I was able to get a "good" alignment last week, after I replaced all the washers (shims),
correctly (2 for each bolt).
It was necessary to drive the car for a few miles (I did about 25), to "settle" things down,
before doing the alignment.
Bingo.... perfect.....
-2 camber both fronts, 7.3 left, 7.2 right front caster, 1/8" toe in on both
-1 camber both rears, 1.0 caster on both, 1/16" toe in on both
And now on 18/19 wheels with Potenza RE71 tires.
The car handles MUCH better.
2 autocross days this weekend; we did very well (still on a Miata course),
the back end still wants to come out if I am too aggressive on the throttle
coming out of turns/corners, but nowhere NEAR what it used to be.
I am a very happy camper with this setup.
Glad to hear you got it working (with toe IN on the rears)
This just crossed my mind...if he was able to get -2* with the shims in and it maxed out the eccentrics this would effectively act similar to having a "block" installed wouldn't it? If so that would be a good thing.
Not sure, We will know more soon about what the blocks will look like and work like when LG gets there's to market. For now the eccentrics work fine.
Odd.... We re aligned our Z to end the season with a street alignment. We could not get the front castor in on the left drivers side. Tried every combination of eccentric adjustments and could not get less than +11 degrees! We check the ball joint nuts and were fine along with the UCA were all tight. In the end and to get it around +7 we installed two original washers in the rear of the UCA. Now we are at stock washers in that area or two at each bolt. It pushed the upper ball joint forward.
Any ideas out there? I've hit nothing but the track rumbles but suspect a bent UCA.
^ Using string to align a Z06... not me! There is way to much going on with these cars.
Odd.... We re aligned our Z to end the season with a street alignment. We could not get the front castor in on the left drivers side. Tried every combination of eccentric adjustments and could not get less than +11 degrees! We check the ball joint nuts and were fine along with the UCA were all tight. In the end and to get it around +7 we installed two original washers in the rear of the UCA. Now we are at stock washers in that area or two at each bolt. It pushed the upper ball joint forward.
Any ideas out there? I've hit nothing but the track rumbles but suspect a bent UCA.
^ Using string to align a Z06... not me! There is way to much going on with these cars.
Has anyone managed to get the Smart Strings setup to work on the C7 Z06? I am looking to buy a set but want to make sure that they work on the Z06.
If there are any vendors that make something similar specifically for the C7 or Z06 that may also be helpful.
I have a set of smart strings that I used on my C6Z but haven't even attempted to use them on the C7Z. I think the front brackets will work on the C7Z but the rear brackets are difficult to fit over the rear spoiler. It might be possible to hold them in place by setting the hatch on them but they will stick out at a pretty severe angle behind the car which might keep them from dropping low enough for the string to run across the center of the wheel hubs. I suspect the rear spoiler has to be removed to use the Smart Strings.
Mike Levitas is a Daytona 24 hour winner and owns TPC Racing. Mike/TPC also preps the Porsche 997.2 911T I race.
Mike is also a big time Corvette guy and owns a C7 Z06. Mike has mad skills on setting up the suspension on a car. He has an amazing God given talent on suspension setup.
He has done EXTENSIVE suspension testing with his C7Z. Mike, his friend Randy Pobst and I agree the setup from the factory is TERRIBLE, DANGEROUS and SCARY when driven 10/10s. Mike's been close friends with Randy for decades. The car exhibits snap oversteer without any warning. Happened to me resulting in a bad situation and to Mike as well. Mike is a better driver than I and was able to catch his but told me is scared the hell out of him. The car is so bad even with the GM suggested track alignment WHEN DRIVEN HARD he was going to sell his after only 300 miles.
Instead, he invested many hours working on the suspension setup. Just last week he informed me he got it to where it's his favorite car to drive of the may cars he owns. He shared his setup with me and it is remarkable. I was scared to drive the car at 10/10 prior to using his setup. What he provided TOTALLY transformed my car. I can't believe it's the same vehicle. So easy to drive with the setup he told me to go with it's unreal. It's really hard for me to put into words the transformation. It truly is game changing.
The biggest problem he found was in the rear caster. Other changes were also warranted but the rear caster is the biggest factor in making the car dangerous/undriveable at speed.
Here's the hot setup which Mike informed me gave him and 7 others with C7Zs 1-2 seconds per lap WITHOUT the car wanting to snap oversteer:
1. Pull 1 washer from behind the attachment point of both upper control arms, front and rear. Total of 16 washers as there are 16 bolts.
2. FRONT: -2.0 camber and -0.5mm toe each side for total toe out of -1.0mm. Most alignment racks measure in degrees. The -0.5mm equals right at -0.03 to -0.04 degrees depending on tire diameter. Mine is set at -0.03 degrees each corner.
3. REAR: -1.7 camber and -0.5mm toe each side for total toe out of -1.0mm.
4. The rear uprights MUST be laid back 0.8 - 1.0 degree of positive caster. The 0.8 works best on just about every car they tested. DO NOT go less than 0.8. Laid back/positive caster means the top of the shock is laid back closer towards the rear of the car relative to the bottom of the shock.
Hope this helps.
Rick
Never tow out at the rear.
Interesting info. that Mike has, but it is like putting lipstick on a pig. The problem lies in the poorly designed suspension geometry. I was the first to suggest that the C5 thru C7 has poorly designed geometry, a 2' +caster fix and possible ediff actuation problems here.
A few things: No tow out at the rear in any circumstances. Absurd.
At a glance, the negative camber gain from squat to droop is just plain awful. It's been that way since the C5. The inside wheel has increased negative camber in high G turns where the reverse is required. -camber gain in droop is unheard of. I won't even mention the front. The location of the upper control arm is simply wrong. It must be positive in droop at one G roll or at the very least, zero. Tons of grip is being lost on the inside tire and the outside tire reaches saturation prematurely because of it. The inside tires can't even handle the approx. 700 lb load each on a 1G turn because the friction circle evaporates because of no camber thrust and reduced contact patch. This is the major factor in the C7s unpredictable handling. 650 HP doesn't help. The sad thing is, is that is very easy to fix by relocating the upper control arm and steering rod.
This coupled with severe anti-squat geometry, major binding couples are generated, aggravating suspension compliance. It does have a damping effect on a spike LOAD transfer in launch and straight line activities, however, which is good at shift points for stability. LOAD and not weight xfer is determined by mass acceleration.
I want to see bump and dive tow-in to be at one degree minimum. I want to see .5 tow static. You will need at least 2' +caster to achieve that tow (CURVE)
Some questions for Mike: @.75 +caster gives -.5 tow out????
What steer migration (tow curve) do you get for droop and squat?
Tow out at the back is never a good thing in any circumstance.
Also, loose the eccentrics especially if you have slicks or high downforce. Tadge says they have them because they allow 3 minutes for alignment. Also a simple fix.
Another contributing factor in the sudden change in direction could be delays in the ediff actuation. When my normal Salisbury diff begins to open, I get violent directional changes to the right in low gear shifts. C6Z. It is then time to replace clutches.
Notice how the right rear wears faster than the left even when the diff is working right? Think about that one. Watch Steve McQueen in his Mustang with an open diff. Smoke off the left rear tire in reverse and smoke off the right tire in first. Why?
Each time you lift off with the ediff, it opens. Suspension unloads and cambers become more negative. Squat geometry forces cease. Stomp on it, and the instant asymmetric torque split and the instant negative camber change with an unloaded suspension and squat reversal forces, will turn the car. It will get worse with miles. Don't lift when shifting with the ediff.
Mikes solution only masques the real problem.
If you have the dimensions of the of the lower control arm, distance between lower control arms, upright dimensions including steer hard point, ball joint inclination and factory scrub radius, tire diameter and tread width, wheel base, total weight and CG location, my computer will fill in the rest properly. I'll add and subtract squat geometry (which Mike can control with the dampers,) to show binding and hysteresis. I'll estimate hysterein and hysteros values. A arms are obsolete in suspension design anyway but I don't know how to design a multilink system like Corvette's competitors have where you can seriously optimise the tire friction circle..
Note daylight under the inside tires.
Upper control arm is wrong.
Exaggeration but try to trend camber gains in turns to look like this.
Check that camber in droop. What were they thinking?
Loose these things.
You know something Shaka, why don't you just go and **** off and stay away from the C7 Z06. You are the most arrogant ******* on this forum. Do you really think that you know more than the actual GM high performance suspension engineers?
The C7 Z06 has been proven to be one of the fastest vehicles on the market today AS LONG AS THE ALIGNMENT IS SET CORRECTLY. It has been reviewed multiple times by professionals and owners who have all stated that you have to spend at least twice as much to enjoy anything close to the performance envelope that the C7 Z06 offers. The car has issues, but they aren't suspension related as long as a decent track alignment has been performed.
Bish
08-25-2016, 05:24 PM
