[GunMetalGrey]

Originally Posted by Mountain

Think this could partially be mitigated by installing the BMR spherical bearings into the large end of the front lateral/radius link (the front-most link)? That link has a very large, rubber bushing and all of the models Camaros have some version of this large busing - I'd have to think that there is some movement during cornering and braking that causes some toe change (toe-out during braking for both wheels and the pull on the inside wheel during cornering causing toe out at that one wheel).

I guess you’re referring to this...

http://m.bmrsuspension.com/?page=pro...productid=1686

They claim it will reduce the changes in alignment caused by aggressive driving during track days.

Does anyone know if the alignment would have to be redone after installing these? I just got my alignment done.

[GunMetalGrey]

Those Toyo RR’s are super cheap in 295’s in both 18” and 19”!

I started a thread on these last year wondering if anyone had experience with them.
TireRack reviews seems to be that they may not be a good match for heavier cars like ours, a number of users said they only bought them because they had to according to the rules of the series they were running in and called them mediocre.

The guys with lighter cars seemed to love them.

I have no experience with them and I’m only going Off the reviews I’ve read.

[Norm Peterson]

Originally Posted by GunMetalGrey

I guess you’re referring to this...

http://m.bmrsuspension.com/?page=pro...productid=1686

They claim it will reduce the changes in alignment caused by aggressive driving during track days.

Does anyone know if the alignment would have to be redone after installing these? I just got my alignment done.

Alignment should at the very least be checked whenever any suspension link or component is changed out. Parts have tolerances, and variations within tolerance can and will cause alignment settings to shift slightly. It can happen that nothing changes, but there's no guarantee that you'll get that lucky and not see anything shift.

Even if you're willing to let alignment slide when replacing OE with OE, it's more important to do check alignment when replacing OE with aftermarket, and I would make that "demanded" when the replacement component does not behave exactly like the OE piece it's replacing. Here, you'd be replacing a component that relies on 'compliance' to permit rotation with one that permits rotation by geometric means alone (ball in socket).

Those OE parts that work via compliance effects are allowing motions in more directions than just the rotational one that is necessary. There are also some translational movements going on - a 'squishing' of the bushing along the axis of the link in addition to the rotational twisting - that effectively moves the pivot point around slightly. What this also means is that Chevy's alignment settings also account for these 'unwanted but unavoidable' movements, and optimum alignment settings for using the compliant link end would in all probability not be optimum for use with its ball-in-socket replacement.

That is what BMR is getting at when they wrote " This also reduces front alignment changes during aggressive cornering when high loads are applied to the chassis.". GM would be accounting for those alignment changes, and when you eliminate those changes the alignment would not need to be providing any compensation for said compliances.


Norm

[Mountain]

Originally Posted by GunMetalGrey

I guess you’re referring to this...

http://m.bmrsuspension.com/?page=pro...productid=1686

They claim it will reduce the changes in alignment caused by aggressive driving during track days.

Does anyone know if the alignment would have to be redone after installing these? I just got my alignment done.

That would be them.

[Tachitup]

Originally Posted by seanblurr

I believe the reason ZLE's cord the inner edge of the tires is because of a dynamic toe change during braking and or cornering. I do not believe it is related to camber at all.

I've noticed that on tracks with more right turns than lefts, that it's the right front inner shoulder that wears the fastest. The opposite is true for tracks with more left turns than rights. Which is the opposite of what one might think.

This leads me to believe that this inner wear is cased by a combination of two things:

1/ Dynamic negative camber change on the inner tire. Mac struts gain significant camber in droop. This makes the inner tire on a corner have an even small contact patch and puts more cornering load on that smaller contact patch.

2/ Too much Ackerman Angle. During a corner the inner tire is turning tighter than the outer tire and pulling the car into the corner. Now add this to the already high cornering load on the smaller contact patch caused by the increase in negative camber and you're literally tearing the rubber off the inside edge of the front tire.

[Norm Peterson]

^^^ makes sense.


Norm

[seanblurr]

Originally Posted by Tachitup

I've noticed that on tracks with more right turns than lefts, that it's the right front inner shoulder that wears the fastest. The opposite is true for tracks with more left turns than rights. Which is the opposite of what one might think.

This leads me to believe that this inner wear is cased by a combination of two things:

1/ Dynamic negative camber change on the inner tire. Mac struts gain significant camber in droop. This makes the inner tire on a corner have an even small contact patch and puts more cornering load on that smaller contact patch.

2/ Too much Ackerman Angle. During a corner the inner tire is turning tighter than the outer tire and pulling the car into the corner. Now add this to the already high cornering load on the smaller contact patch caused by the increase in negative camber and you're literally tearing the rubber off the inside edge of the front tire.

#2 is exactly what I meant by a "dynamic toe change", I just didn't know there was an actually name for it. Cool.

[seanblurr]

Originally Posted by glamcem

I hear you. Ever considered using 18/19" staggered setup? I know the fact they have those sizes for Corvettes.. 315/30/18 and 345/30/19 might be pretty close to overall size for keeping the same rake.

I'm not 100% sure whether or not you can keep the same proportions as stock but worth checking on Tire rack's website

Also have you ever considered 315 Sq setup since wider wheels will be used in the back and you can adjust the ride height on ZLE that might be another option. Afaik RRs typically run wide (well not as much as R7s probably) so with the added grip and already wider tires it may not be a downsizing.. besides the weight savings are tempting

I've never thought about running different size wheels, interesting. The only combo that would really work would be a 305/35/18 and a 345/30/19 Toyo RR. That would create a 2.7% diameter difference vs 1.9% factory. A 315/30/18 345/30/19 would be too much of a difference at 6.7%. I wonder how the car would like a taller sidewall (35 v. 30)

I actually run 315/30/18 Nankang AR1's currently, the car does not seem entirely happy with a square set up. Tad loose, and ive had the electronics trip out on occasion.

[glamcem]

Originally Posted by GunMetalGrey

Those Toyo RR’s are super cheap in 295’s in both 18” and 19”!

I started a thread on these last year wondering if anyone had experience with them.
TireRack reviews seems to be that they may not be a good match for heavier cars like ours, a number of users said they only bought them because they had to according to the rules of the series they were running in and called them mediocre.

The guys with lighter cars seemed to love them.

I have no experience with them and I’m only going Off the reviews I’ve read.

I would take those TireRack reviews with a grain of salt as there are so many other variables that often times they neglect to take into the consideration.

If you think about it same thing can be said for R7s (more pressure advised by Hoosier due to tire carcass and of course load ratings). I have been using them on different cars and my friends with C7 GS and C7 Z07 puts very competitive lap times in our local tracks with relatively low cold tire pressures (27psi vs Hoosier's recommended 32-34 psi starting pressures.) As you may already know weight difference of the C7 Z06 and say SS 1LE is not too bad around 170lbs. As I am planning to shave about the same weight on my 1LE I am not too concerned. Power affects the tire life more than the weight, faster you go faster the tires get corded. We have a chance to take tons of data and compare them. For a reference my friend who owns a Z06 (with Z07 package) can cord the front R7s in one day. RRs typically last twice as much as the R7s on his car and it's no different on our Miatas. The only difference is on a Miata it's typically HC limited not the shoulder wear

Originally Posted by seanblurr

I've never thought about running different size wheels, interesting. The only combo that would really work would be a 305/35/18 and a 345/30/19 Toyo RR. That would create a 2.7% diameter difference vs 1.9% factory. A 315/30/18 345/30/19 would be too much of a difference at 6.7%. I wonder how the car would like a taller sidewall (35 v. 30)

I actually run 315/30/18 Nankang AR1's currently, the car does not seem entirely happy with a square set up. Tad loose, and ive had the electronics trip out on occasion.

Nankang AR1s are also in my list as they're being hybrid tires (like NT01/R8888Rs) it's also better when it rains and they're only marginally slower than those RRs since they're slightly faster than the R8888Rs.

If I were you I would first try the RRs on 315/30/18 F and 345/35/18 R (there are some crazy discounts on both and I will share some information soon on that) since on a ZLE you would be able to see some benefits from having slightly more profile/meat in the back because of the added load rating and life.
AFAIK, ZLE front suspensions are height adjustable (up to 10mm I believe) so I see no difference between adding a bit rake in fact it may be even beneficial on a Camaro as our cars prone to understeer a bit. These are just the hypothetical guesses of course and YMMV. "There's one way to find out"

[seanblurr]

A 345/35/18 would be too tall IMO, it's significantly more than a factory 325/30/19 and when combined with a 315/30/18 front it makes it a 13% split which is far too much. These cars need to be within a certain factory difference or the car trips out. Even a 305/35/18 with the 345 is about an 8% split. It's not just about "rake" of the suspension/body, its all about wheel diameters. This car can only handle so much out of factory before the electronics flip out.

[glamcem]

Originally Posted by seanblurr

A 345/35/18 would be too tall IMO, it's significantly more than a factory 325/30/19 and when combined with a 315/30/18 front it makes it a 13% split which is far too much. These cars need to be within a certain factory difference or the car trips out. Even a 305/35/18 with the 345 is about an 8% split. It's not just about "rake" of the suspension/body, its all about wheel diameters. This car can only handle so much out of factory before the electronics flip out.

345/35/18 R7s are 26.8" (vs 26.7" OEM) I couldn't find information about the RRs when I looked but I'd assume they would be close. 315/30/18 RRs are 25.5" so the split would be 1.3" vs factory .4" (26.3F and 26.7" R). I also looked at all the tire sizes as I was seriously considering a ZLE and since the front height is adjustable 10mm, I was under the impression it would still be within the range.

I might be wrong of course

[TrackClub]

Originally Posted by glamcem

345/35/18 R7s are 26.8" (vs 26.7" OEM) I couldn't find information about the RRs when I looked but I'd assume they would be close. 315/30/18 RRs are 25.5" so the split would be 1.3" vs factory .4" (26.3F and 26.7" R). I also looked at all the tire sizes as I was seriously considering a ZLE and since the front height is adjustable 10mm, I was under the impression it would still be within the range.

I might be wrong of course

The front would still be considerably higher vs stock even with a full 10mm adjustment. Almost 25mm...
That would surely affect mechanical balance as well as aero balance. Imo.

[glamcem]

Originally Posted by TrackClub

The front would still be considerably higher vs stock even with a full 10mm adjustment. Almost 25mm...
That would surely affect mechanical balance as well as aero balance. Imo.

It's actually the other way around. As I stated, 315/30/18 Toyo RRs have 25.5" of overall diameter (according to TireRacke) and ZLE OEM 305/30/19 Goodyear 3Rs are 26.3" . There's no information on the 345/35/18 RRs but 345/35/18" R7s are 26.8". Since Hoosiers are typically very short in overall diameters when compared to similar sized other brands (so they can run wider without rubbing) , I think we can safely assume the RRs would br at least 27" (if not more)..
So I think that's what worries Sean since OEM F/R ratio is slightly changed. I am not sure if it's big enough to trigger something or whether or not it would make any difference when running at the track when all the nannies off.. and as ZLE suspension is somewhat more traditional as opposed to ours. I think Sean had some issues in the past maybe he can shed some lights on that.

[TrackClub]

Originally Posted by glamcem

It's actually the other way around. As I stated, 315/30/18 Toyo RRs have 25.5" of overall diameter (according to TireRacke) and ZLE OEM 305/30/19 Goodyear 3Rs are 26.3" . There's no information on the 345/35/18 RRs but 345/35/18" R7s are 26.8". Since Hoosiers are typically very short in overall diameters when compared to similar sized other brands (so they can run wider without rubbing) , I think we can safely assume the RRs would br at least 27" (if not more)..
So I think that's what worries Sean since OEM F/R ratio is slightly changed. I am not sure if it's big enough to trigger something or whether or not it would make any difference when running at the track when all the nannies off.. and as ZLE suspension is somewhat more traditional as opposed to ours. I think Sean had some issues in the past maybe he can shed some lights on that.

Yes. Considerably lower vs higher. Same effect but in reverse. ZLE still has the ediff just like our cars, which plays a dominant role in overall balance, different dampers notwithstanding. Personally i am not sure the RRs would be worth friggin around just to find out. It is not like they are something super special as far as DOT slicks go. Imo. Besides, it seems that Sean is pretty much unbeatable on G3Rs anyway...