0DSC Sport

Mad Dog thought I would chime in great observation of the toe curve. yes going positive from straight up or 90 degree the factory setting does increase the toe gain in compression buttttt that's only part of the story the real story lies in the rebound stroke. I found the optimum sweet spot to be .8 positive based on the toe curve from ride ht in both comp and reb we check in a 25mm range we then create what I like to call the toe circle. I visualize this as an egg type curve. the most critical component is the relationship reb to comp. I have found in 25mm of comp there is a + 1.5mm gain yet in reb in a 25mm stroke -.6mm ahh that's the magic for calming the chassis. so static I choose -.5mm each rear wheel. with the torque of both atmo and the blown vette slight compression yields positive toe great for straight line grip and grip off the corner . now go to a turn one rear wheel loads yielding a positive toe extending the wheel base the unloaded wheel toe out very little helping to maintain the extended wheel base. the stock setting actually shortens the wheel base not sure what the engineers were thinking on paper at first it looked like my race car in a 25mm stroke comp +.5mm reb -.6 . when my car was new I knew right away it had a problem putting down power my car lit off the mich super sport in 3rd I was scared to death to turn of traction control. now with also being able to tune the dampers in real time as the c7 has ride ht sensors I now tune the chassis with velocity. my c7 with the traction off pulls so hard in first just hazing the tire lightly and flat out hardly can squeak the tire in 2nd I always turn off the traction control and just have fun.
Any questions just ask I don't get online enough but would like to hear the questions im sure I can help and the more you understand the chassis the more you will need to tune the damper next

BEZ06

Okay - that's what we've heard from several sources is the sweet spot for the rear caster.

However, maybe I missed it in your post, but what toe settings do you recommend???

Are you running toe-OUT for the rear like rikhek recommends???
.

rikhek

Damn dude, read the post!!! I'm running Mike's settings verbatim!

For the third time, yes, toe out 0.5mm (i.e., -0.5mm) on each side in the rear. I even posted the universal definition of toe from an outside source for you.

Mike's post above states, and I quote:

"so static I choose -.5mm each rear wheel"

Frustrating.

Newton06

Ditto for me.

I'm not a good enough driver to justify eating the front tires like that.

Mine corded very quickly after going to the track alignment.

Going back to the stock setup.

tracer3030

Thanks great info!!! Are you guys taking the bumper cover off to align? After I set camber 2.0 and slide the heads down to read toe it changes almost .05 in the front. I am running rear caster .07-09 pos felt the best so far. I did have a hard time setting rear caster side to side because when set the angle finder to zero on the rack each side ramp was different so now I only set to zero on one side the rack and then set left and right rear caster off that. I have toe in front and rear. I haven't felt loose turning in yet thats where toe out would help I would think not driving in that hard yet to feel it. Im braking to hard before the turn still. It would be nice to hear how everyone is do their alignment set up as far as head set up. Thanks

0DSC Sport

the preferred setting when running the rear caster at .8 positive is -.5mm so toe out I run my car and most street cars at -1.7 camber in the rear and -2.0 in front all four corners are toe out -.5mm
cars with hoosiers I run -2.0 rear and -2.3 front same caster toe but note in the front I run stock caster seems to be the best setting ill explain that later . once you set the rear caster to the proper angle the car will be better in the softer settings the shocks are all low speed and the track setting is way to stiff the factory used the track setting to limit the suspension travel as the toe curve was not optimal

0DSC Sport

Tracer I do not pull off the bumper cover off. I suggest you find another type alignment machines to use or better yet use strings and a good angle finder. Note and this is important that all that read these posts should understand you must first have a perfectly level surface to work on this is critical can be no deviation. We have a four post that every lock position is perfectly level we check it all the time with a level . next equipment must be accurate. if you can meet these criteria you will have a great car.

BEZ06

Sorry - I thought DSC Sport was a new poster in the thread with new and different info, and I was asking him if he recommended the same settings that your buddy "mike" gave you.

I guess he is the "mike" you talked about in your OP. I'm still not sure, but I guess he is the guy who gave you the specs - and I did not know that.

Thanks for your input with these specs.

.

BEZ06

Do you mean that the best mode setting for the track would be a mode with softer shocks, such as "Tour" or "Sport" rather than the "Race" settings?

Or in the "Race" mode that "Dry" or "Sport 1" might be better on the track if they have softer shock settings?

.

Mad Dog 24

Mike thanks and to your friend RIKHEK for this info as it is just what I was looking for. Question, we lowered our Z07 about and 1.0 to 1.5 inches all the way around when new. With this the car is always in a compression mode in relation to the suspension geometry. Would this effect the rear caster or toe settings for the track? You got me thinking maybe I should go a bit less toe out to get the curve right ??

WGI has more rights than left turns therefor the left side will carry more load and a longer state of compression. With this would you set up the suspension equal in all 4 corners. I know this is getting technical for a "weekend warrior" but these cars are so dam good this is almost fun and I will confess I don't like being passed!

We have trouble getting FRONT caster close from left to right sometimes which I think has to do with the big camber numbers. Is this critical to worry about? Our last numbers were 8.6 degrees left and 6.5 right. Seem to drive fine.

BTW, I have never experienced a snap to over steer or sever loose condition. I'm wondering if its because we have always dialed in a lot of positive rear caster and after checking our alignment sheets the rear got very little to no toe in as I thought was best until now.

rikhek

Mad Dog,

It'll be interesting to hear Mike's comments on the Glen. It's one of his favorite tracks which he can drive with his eyes closed. I believe he has at least one if not several track records at the Glen.

He taught me how to drive it my first race there last summer and coached me down to a 1:59.188. PCA GT1 class record which I run was set by a pro is 1:55.861. Mike's coaching and suspension tweaking after watching my video and analyzing my data throughout the weekend got me within 97.2% of the class record and I had never seen the track before.

I would have done better but we had the power/boost turned done as we had just put a new engine in the car before going to the track to break it in. If you watch the video below you can see my "street" car is getting through the corners as quickly as Cup cars but I couldn't pull them on the straights as I typically would if we had full power. FWIW, I qualified poorly as I was still learning the track. I know, excuses, excuses....

Mike's goal for me was to be under 2:00 as a first timer and he got me there. I guarantee the car setup, not driver skill is what allowed me to do decently. If interested here's video of my first race of the weekend. A number will probably question the line I'm driving at times. Mike has some unconventional lines he drives which he taught me. Also, if you watch my rearview mirror you'll see I have some guys who want to get around me so I'm driving a defensive line a lot.

Video starts just before the green is thrown. Note how I got "pinched" a bit going into T2. Guy didn't even know I was there...

Make sure you set the resolution to 720p.

Mad Dog 24

Very cool "no brake turn 10". It takes some stones but is the fast way thru there! Those Porsches carry some major speed on exit that carries them thru the straights well. We get the same speeds on the back stretch but a good 5 to 7mph off on the front straight. As I watched I think my issue is coming out of turn 11 to easy as I rarely use the whole track up.

A good friend and senior instructor races Vintage GT1 in a Corvette with 800 hp. As a champion driver I think he only gets 1:57 there for a home track. I didn't think those Porsches could come close but they obviously can. The goal with my grocery getter heavy weight is get into the sub 2:10.

rikhek

LOL. Yeah, Mike threatened to remove my brake pedal if I didn't stop using it at T10. He also said to grow a set and stop feathering the throttle as I do after tracking out of T2 and heading up the hill. He said put the damn pedal to the floor and keep it there. Easier said than done. I wish I had video of Mike going through the bus stop. I didn't see anybody able to carry the speed through there that he does. It's one of the main places where he really kills it.

Poor-sha

I know both Mike's car and my car are FE6 suspension cars. Rikhek, which is yours?

I had my rear suspension move after Mike set it up and ended up taking it to Curry's to get it readjusted. I didn't realize we had tow out in the rear before but when Curry's adjusted it we put a little bit of toe in. I was back at the track last weekend and at my mediocre driving ability the car still felt great with toe in.

I've not had any issues with wear on the street with -2.0 camber and I've got probably 8000 street miles on the car on top of the 8000 track miles.

P.S. Mike made some more tuning changes to the DSC config last weekend and it was simply magic at putting the power down.

Mad Dog 24

What's your rear caster set at?

Did one of the eccentrics come loose as it did to mine once?

NTMD8R

Wow, what great information.
I do not have a Z06, but I have a 2014 Z51 M7 with magride.
I do not do track days, but we (my wife and I) autocross a LOT.... 29 events this year.
Ever since last August, I have had major problems with our car....
it will just "step out" when trying to get on it exiting a turn/corner.
I have had several "expert" drivers (Glenn Hernandez is one), tell me there is something wrong with the car.

I have thrown wheels, tires, sway bars, alignments all at this thing... but it still does it.
Stock wheels with R888 tires, Wider wheels with wider R888 tires.
Now I have 18/19 wheels with RE71 tires (I just put them on yesterday).
Alignment:
Front -2.9 camber, 1/4" toe out, 7.x caster both wheels
Rear - 1.9 camber, 1/4" toe in, zero caster both wheels
I have removed ALL the A-arm washers (32 of them) to get this camber.
I am now back to the OEM (magride) sway bars.
But I have tried:
LG C7 swaybars front and rear
LG C7 front sway bar and OEM (Magride) rear
OEM (magride) front, and Z51 rear
OEM (magride) front and No rear bar
All this didn't seem to make much difference.

I have had the rear end checked... fluid is fine,
it has thrown no codes or error messages.

We will be trying out the new wheels/tires on Sunday.
But after that I plan to re-visit alignment.
I'll set it up as
Front -2.0 camber, 1/16" toe out, 7.x caster on both
Rear - 1.5 camber, 1/16" toe in, .8-1.0 caster on both

If I could ask Mike what his opinion is with my planned setup....
and I do have a question about rear toe out versus toe in......
My experience says that toe in will provide more grip on accelerating out of a corner.
But you say to put toe out.
I'm very willing to defer to anyone's superior experience and judgement.
For autocross (with a lot of tight turns/corners), what do you think my alignment should be?

Thanks so very much for the help.

rikhek

Mine is FE6 as well.

Poor-sha

0.8 laid back as described.

Yes, one of them came loose and moved. I had marked everything after Mike set it up so now I check it before the next track day.

rikhek

Several have mentioned they've never experienced the snap oversteer exhibited by the car with the factory alignment. I haven't shared this video as I know it will bring out the folks telling me I got what I deserved. I'm hoping the naysayers who don't really drive their cars hard won't see this as their not interested in a thread addressing track alignment. For the life of me I don't understand why so many forum members take pleasure in posting questionable comments when one of us experience an event/misfortune.... Makes guys like me unwilling to share important information.

However, it is real and it is dangerous and sharing might help prevent others from a similar event.

Watch the video and what I did prior to it snapping on me. Watch my throttle position, speed, g forces, RPM, steering angle, etc. Hell, I was barely on maintenance throttle. I didn't do anything stupid and wasn't going anywhere near the speed the car should have safely went through the corner. Road was dry with no gravel. A bit off camber but nothing drastic. I was only going 64 mph in 3rd gear. It was all car.

Sorry guys but I pulled the video. A forum member saw the video, copied it and posted it in a general thread. Non track drivers immediately pounced as I stated above would happen. The games/hate began and it got ugly quickly.... Most guys participating in this thread will appreciate the humor of comments posted. So predictable....

https://www.corvetteforum.com/forums...pin-video.html

Mike watched the video numerous times and agrees I didn't do anything to provoke it. Two weeks or so later SAME EXACT thing happened to him which scared the hell out of him and initiated his quest to correct the issue. Only difference is Mike was able to catch his...

Randy Pobst had the same happen to him driving the car and said it was scary to drive.

The alignment Mike has developed cured this issue. I know as I went back and drove this corner many times after changing alignment and car went through corner much faster with no drama.

schaibaa

Wow, that is worse than I have seen -- although the corner does look like it is significantly off camber. It looks like you bounced the brakes - on hard, off, back on semi-hard, and then off as the car entered the off-camber section. It looks like it started to rotate when the brakes were applied the second time. Does this sound right, and/or do you think that contributed?