[yourmomshouse]

Ok so if I'm understanding correctly, I need the vorshlag camber plates to run a 305/30/19 square setup. I don't need the ARP studs and spacers if I get the plates. Is that correct? There won't be any further mods necessary, such as grinding the strut or knuckle. Are there any downsides to running a 305/30/19 square setup other than poke and rock chips? I'm guessing 1 season of 10-12 runs and 2000 miles is all I'd get out of a set of RT660, Rival S 1.5, Making CR1.

[MatthewAMEL]

Originally Posted by yourmomshouse

Good Info here. Thanks.
I think I'll be in CAMC. I'll need to research some more to see how the 305 fit up front. Car is already a money pit. Other than camber plates, what "several other parts" are you referring to? Sway bars? I've already done BMR endlinks, BMR springs, all the BMR arms in the rear, BMR cradle lockout, front ZLE control arms (2 pairs that were replaced: 1 pair was ZLE specific, the other pair were shared among ZLE/ZL1/1LE. I'm thinking I'll do a front Hotchkis and rear BMR bar when I do the wheels and tires.

Your handling is going to be a mess.


Out of the box, the 6th Gen is one of the finest handling cars in the world.


While there are certainly some parts that could use a little help (rear cradle for sure), I always advise against wholesale changes until you learn the car and decide what you need it to do.


With those suspension mods you have no choice but to run CAM or ESP. Any Street class is out.


There is no need for camber plates. You can get -2.5 up front pretty easily. If for some reason (due to your suspension changes) you can't then I would investigate plates.


I run 305 square for AutoX, but the front/rear offsets are different. So I would investigate what wheels you are looking to use. For AutoX, 3-5mm spacer would be fine. Apex sells a 6th Gen set that lets you use the same 11" wheel so you can rotate.



I'd also recommend the 660s. They are a forgiving tire if you tend to overdrive and have tremendous grip.

[yourmomshouse]

Originally Posted by MatthewAMEL

Your handling is going to be a mess.

Why do you say?

All the work in the back definitely got rid of the side to side wag under hard acceleration and quick direction changes.

Reading from Apex's site they say I would need the camber plates OR spacers and studs to run a 305/30/19 up front.

As far as sway bars, I'll probably wait until I get comfortable on the new wheels and tires first.

[MatthewAMEL]

Originally Posted by yourmomshouse

Reading from Apex's site they say I would need the camber plates OR spacers and studs to run a 305/30/19 up front.

I assume you are referring to this part of the Apex Fitment guide?

• Front: 19x11” ET11 - 305/30-19
  Rear: 19x11” ET35/43 - 305/30-19
  • On models equipped with the bulkier MRC suspension, it is important to note that if you dial in camber at the spindle, you may have inner strut clearance issues up front. 3-5mm spacers would be needed at that point. If you dial in camber with adjustable camber plates, no spacers required.
  • This is an aggressive fitment for the SS and SS 1LE since they do not have wider front fenders. Negative camber, via plates, required up front to limit poke.
  • Direct fit with the wider ZL1 front fenders with stock alignment

Do you have MRC? I would assume 'no' since you have made some fairly substantial suspension changes.


I can tell you from experience that I have no problem getting -2.5F with the Apex 19" on 305/30-19's. No spacer. No plates.


I think holding off on any further suspension changes until you pick a tire/wheel setup and get some time with it, is a good move.


And I agree that the rear cradle is one of the areas that benefits from aftermarket (or ZLE bushings). I did BMR lockout and the (front) rear cradle braces to get rid of wheel hop. Also helped my PTM more accurately push me out of corners.

[yourmomshouse]

Originally Posted by MatthewAMEL

I assume you are referring to this part of the Apex Fitment guide?

• Front: 19x11” ET11 - 305/30-19
  Rear: 19x11” ET35/43 - 305/30-19
  • On models equipped with the bulkier MRC suspension, it is important to note that if you dial in camber at the spindle, you may have inner strut clearance issues up front. 3-5mm spacers would be needed at that point. If you dial in camber with adjustable camber plates, no spacers required.
  • This is an aggressive fitment for the SS and SS 1LE since they do not have wider front fenders. Negative camber, via plates, required up front to limit poke.
  • Direct fit with the wider ZL1 front fenders with stock alignment

Do you have MRC? I would assume 'no' since you have made some fairly substantial suspension changes.


I can tell you from experience that I have no problem getting -2.5F with the Apex 19" on 305/30-19's. No spacer. No plates.


I think holding off on any further suspension changes until you pick a tire/wheel setup and get some time with it, is a good move.


And I agree that the rear cradle is one of the areas that benefits from aftermarket (or ZLE bushings). I did BMR lockout and the (front) rear cradle braces to get rid of wheel hop. Also helped my PTM more accurately push me out of corners.

That is the part of Apex's site I was referring to, yes.
Thanks for the input. Cool to hear that the square 305 setup will fit without plates with -2.5 degrees. It looks to be a good place to start.

I do have MRC. The plan is to get the DSC Sport Controller. If I'm not happy with the BMR springs, I'll swap to something else. I think the springs are what you were referring to when you said it will be a mess? I just can't stand the monster truck ride on the stock MRC setup. Not just in looks, but it also feels like it has a high center of gravity.
I don't see the BMR arms/bushings and ZLE bushings having an adverse impact.

[MatthewAMEL]

Originally Posted by yourmomshouse

That is the part of Apex's site I was referring to, yes.
Thanks for the input. Cool to hear that the square 305 setup will fit without plates with -2.5 degrees. It looks to be a good place to start.

I do have MRC. The plan is to get the DSC Sport Controller. If I'm not happy with the BMR springs, I'll swap to something else. I think the springs are what you were referring to when you said it will be a mess? I just can't stand the monster truck ride on the stock MRC setup. Not just in looks, but it also feels like it has a high center of gravity.
I don't see the BMR arms/bushings and ZLE bushings having an adverse impact.

'Monster Truck' - that was funny.


Yeah, I'm a bit biased. I track and AutoX a lot and can't tell you how many times I see guys spend money they didn't need to spend and wind up with a worse handling car. Suspension setup is an art.


I have learned through my own painful and expensive lessons (on other cars) that you should make changes one at a time and only after you have a decent amount of seat time and a specific problem you are trying to solve.


I completely agree with the rear cradle work, tremendous benefit with only slight increase in NVH.


If you do decide on the DSC, make sure to go with someone that really knows how to set it up. The DSC by itself doesn't add any benefit.


Have fun!

[DaveC113]

All I did is ZLE cradle bushings, GMPP rear diff tune and Apex 19x11 w/305 RE71s and so far it seems competitive in CAM, and we have a few guys doing well at Nationals.

My driving OTOH could use some modifications!

[Msquared]

Sorry, been traveling the last couple days. The other suspension stuff I was thinking of was mainly aftermarket rear toe links so you can dial in more rear camber and possibly aftermarket coilovers...but I didn't realize you have MRC, so scratch the coilovers. Maybe eventually look at the DSC controller for your shocks, but not any time soon. I wouldn't go quite as far as saying your handling is going to be a mess, but there's definitely some things you added that probably didn't need to be. I'd start with a baseline of handling and then see if you really need an adjustable bar one end (the end that needs to break loose sooner needs the stiffer bar), and just that one. If the handling balance is fine as is, then you don't need to change either bar. Don't throw any other parts at it for now.

My friend I mentioned also has MRC and he's using some MRR M716 wheels. I find out what offsets he used and whether or not he's running any spacers up front. They don't poke out. I'll also verify whether he's using camber plates or not, but I don't think he is. I'll post back here when he lets me know.

[Msquared]

Okay, he replied faster than I expected:

Originally Posted by friend

19x11 +38 with a 25mm spacer. I had just ground the gusset initially, and was able to get 2.7* pretty safely. Poke was minimal. I’m now running camber plates with 3* camber, and the top of the wheel/tire is even with the fender.

So with that spacer, he's effectively running 13mm of offset up front. You could run a 19x11 with 11mm offset (ZLE fitment) and you wouldn't need a spacer at all. You also might not need to grind the gusset. The advantage of using the 38mm offset with 25mm spacer is that you can use the same offset in back (with no spacer) and rotate your tires. The disadvantage is having to replace the studs, but that's honestly not that big a project. Either way will work fine.

[bpflibsen]

Originally Posted by Msquared

Okay, he replied faster than I expected:

So with that spacer, he's effectively running 13mm of offset up front. You could run a 19x11 with 11mm offset (ZLE fitment) and you wouldn't need a spacer at all. You also might not need to grind the gusset. The advantage of using the 38mm offset with 25mm spacer is that you can use the same offset in back (with no spacer) and rotate your tires. The disadvantage is having to replace the studs, but that's honestly not that big a project. Either way will work fine.

This is my wheel setup that Matt's referencing. The picture is what the poke looked like with 2.7* camber. I've since added camber plates, and have run as much as 3.3* but have backed it down to 3.0* to balance outside edgewear from autocross and inside edgewear from street miles. Like you, I drive the car a couple thousand miles a year on my autocross tires. Having a rotatable square setup seems to help wear as well.

I'm also on BMR springs with the stock MRC module. their spring rates are close to 1LE spring rates. They're a little higher in the rear, but when you factor in wheel rate, I don't think it's a huge jump. The only other things I've done to the suspension are Hotchkis bars front and rear.

I've had a few experienced drivers drive the car, and all have agreed it didn't really possess any bad or unmanageable characteristics. They also seemed to place about where they normally would with their own cars. Its helped to remind me any poor results lie squarely on my shoulders! overall it's been a fun car to learn on, and is still comfortable enough on the street.

[DaveC113]

My 19x11s w/305/30/19 RE71s... The wheels are et35 and I use an Apex 26mm spacer up front. I plan on using 315s, got a half-used set of RT660 to try out next. I did grind the struts when I installed the longer wheel studs but I'm pretty sure I didn't have to, it's only 5 min worth of work so I just did it.

For me the ability to rotate tires was important. The car does oversteer a bit more, but the eDiff tune also locks on exit and makes it a little more spicy. Recently some comments on the other AX thread made me try a full tank of gas... this makes a big difference! Cheaper than anti-roll bars too.

[yourmomshouse]

So cool. Major thanks to the 3 of you: Msquared, bpflibsen, DaveC113.
So if I run Apex 19x11 ET35 SM10 all around on 305/30/19 RT660s, I would need the Apex 26mm spacers up front with extended studs and camber plates. And hopefully this will make it so that there won't be a need for grinding. Back will fit without any mods. Do I have this down?
Would I need new lug nuts to fit my OEM ZL1 wheels to park on for the winter?

[Msquared]

Originally Posted by yourmomshouse

So cool. Major thanks to the 3 of you: Msquared, bpflibsen, DaveC113.
So if I run Apex 19x11 ET35 SM10 all around on 305/30/19 RT660s, I would need the Apex 26mm spacers up front with extended studs and camber plates. And hopefully this will make it so that there won't be a need for grinding. Back will fit without any mods. Do I have this down?

Right, except I don't think you need camber plates. Without them, but with the stock camber adjustment maxed out, they'll just poke a teeny bit like in Brian's pic. They still won't rub.

Would I need new lug nuts to fit my OEM ZL1 wheels to park on for the winter?

Ahhh, yes you will want lug nuts with an open design so the extended stud length will go through. You'll want nuts with a 3/4" (19mm) hex anyway, so that the smaller sockets for them will fit in the smaller wells of aftermarket wheels. Vorshlag makes good quality ones for cheap, or a lot of us who change tires a lot use Gorilla 45048BC because they are long with a knurled end to facilitate easy threading by hand.

[yourmomshouse]

Originally Posted by Msquared

Right, except I don't think you need camber plates. Without them, but with the stock camber adjustment maxed out, they'll just poke a teeny bit like in Brian's pic. They still won't rub.


Ahhh, yes you will want lug nuts with an open design so the extended stud length will go through. You'll want nuts with a 3/4" (19mm) hex anyway, so that the smaller sockets for them will fit in the smaller wells of aftermarket wheels. Vorshlag makes good quality ones for cheap, or a lot of us who change tires a lot use Gorilla 45048BC because they are long with a knurled end to facilitate easy threading by hand.

If I can get by without doing the plates with 2.7* that'll save me 600 bucks. Is it worth that for an extra 0.3*?
I'm still a thousand bucks over budget. What else is new?
When I add up the amount of money I put into this thing, I want to shoot myself for not getting a ZL1.