[aeoman]

I got my 23 ZL1 M6 last year, and immediately found that I had a serious drivability issue. The rear end consistently kicks out to the right under load and fishtails. Occasionally it will kick to the left if the surface is tilted significantly that way. WOT is basically an impossibility except in 4th or higher gears due to squirrelyness. I love the car, but want to be able to actually use its capabilities. I generally use the car as a daily driver but would like to be able to take it to the track occasionally.

Had the alignment checked. Had the dealer look at it, and after keeping it for a week, they said the car is "perfect" even though I reproduced the issue for them on a test drive.

So now after reading the forum and all the posts on suspension issues I am planning to put the BMR rear cradle kit in it to try and fix the issue. I am wondering what else I should get done at the same time.

I live in Oman, so it is not as simple as going to a local performance shop. I have to order parts from the States, get them through customs, then go to the local performance shop for install. Thankfully there are some good shops here to do the work and can put a good tune on the car if needed. Even so it is a hassle to do all the logistics so I prefer to batch everything together at once. My questions are:

1) If anyone has any ideas about other ways to fix the problem, well, I am all ears. Its on relatively new Pilot Sport 4S and only has 12K miles.

2) What other suspension upgrades should I consider based on daily driver and occasional track use? Arms? Sway Bars? etc.

3) Are there any other upgrades to be considered? I am not chasing more power yet as I can't even use the stock power effectively. I bought the car used with a Corsa Carbon Fibre CAI. That said, no reason not to use the shop time for relatively simple upgrades.

Thanks in advance for any advice!

[arpad_m]

Hi aeoman, to the forums

I can't help you directly, but here is a thread describing a very similar problem Ted Jannetty was having, with tons of tips and his solution: https://www.camaro6.com/forums/showthread.php?t=525356

The BMR rear cradle lockout kit is very helpful in terms of added launch stability and body roll control, I have it installed as well, but you shouldn't have much (if any) wiggling and fishtailing on a stock ZL1 with good tires to begin with. If the reason you're looking at suspension upgrades is to fix your rear end stability problem, you're going in the wrong direction, the suspension should be fine for these basic requirements.

My SS has much more than stock ZL1 power, yet it's rock stable under load even with its slightly inferior FE3 suspension and its simple mechanical LSD (although I do have MRC, too). This is the norm for the 6th gen, don't stop troubleshooting until you can mash the skinny pedal and have the car accelerate straight as an arrow.

[Patriot Motorsports USA]

Originally Posted by aeoman

I got my 23 ZL1 M6 last year, and immediately found that I had a serious drivability issue. The rear end consistently kicks out to the right under load and fishtails. Occasionally it will kick to the left if the surface is tilted significantly that way. WOT is basically an impossibility except in 4th or higher gears due to squirrelyness. I love the car, but want to be able to actually use its capabilities. I generally use the car as a daily driver but would like to be able to take it to the track occasionally.

Had the alignment checked. Had the dealer look at it, and after keeping it for a week, they said the car is "perfect" even though I reproduced the issue for them on a test drive.

So now after reading the forum and all the posts on suspension issues I am planning to put the BMR rear cradle kit in it to try and fix the issue. I am wondering what else I should get done at the same time.

I live in Oman, so it is not as simple as going to a local performance shop. I have to order parts from the States, get them through customs, then go to the local performance shop for install. Thankfully there are some good shops here to do the work and can put a good tune on the car if needed. Even so it is a hassle to do all the logistics so I prefer to batch everything together at once. My questions are:

1) If anyone has any ideas about other ways to fix the problem, well, I am all ears. Its on relatively new Pilot Sport 4S and only has 12K miles.

2) What other suspension upgrades should I consider based on daily driver and occasional track use? Arms? Sway Bars? etc.

3) Are there any other upgrades to be considered? I am not chasing more power yet as I can't even use the stock power effectively. I bought the car used with a Corsa Carbon Fibre CAI. That said, no reason not to use the shop time for relatively simple upgrades.

Thanks in advance for any advice!

What options do you have for alignments in your region? I can walk you through what is needed to make the car go straight, where you point it, but you will need an alignment shop willing to do the work to make it right.

Is your ZL1 a Left or Right-hand drive?

Send me a DM or email me directly for guide on how to get this right: PatriotMotorsportsUSA@gmail.com

[Mark R]

I don't think you can go wrong with a bunch of BMR stuff. Cradle lockout, cradle braces, upper rear control arm, trailing arms, toe rods, chassis brace, strut tower brace. I have them all.

Remember to get all replacement bolts for your alignment, as they are one-time-use.

These straightened out my rear squiggle problems.

[SOCAL.M6.ZLE]

Originally Posted by aeoman

I got my 23 ZL1 M6 last year, and immediately found that I had a serious drivability issue. The rear end consistently kicks out to the right under load and fishtails. Occasionally it will kick to the left if the surface is tilted significantly that way. WOT is basically an impossibility except in 4th or higher gears due to squirrelyness. I love the car, but want to be able to actually use its capabilities. I generally use the car as a daily driver but would like to be able to take it to the track occasionally.

Had the alignment checked. Had the dealer look at it, and after keeping it for a week, they said the car is "perfect" even though I reproduced the issue for them on a test drive.

So now after reading the forum and all the posts on suspension issues I am planning to put the BMR rear cradle kit in it to try and fix the issue. I am wondering what else I should get done at the same time.

I live in Oman, so it is not as simple as going to a local performance shop. I have to order parts from the States, get them through customs, then go to the local performance shop for install. Thankfully there are some good shops here to do the work and can put a good tune on the car if needed. Even so it is a hassle to do all the logistics so I prefer to batch everything together at once. My questions are:

1) If anyone has any ideas about other ways to fix the problem, well, I am all ears. Its on relatively new Pilot Sport 4S and only has 12K miles.

2) What other suspension upgrades should I consider based on daily driver and occasional track use? Arms? Sway Bars? etc.

3) Are there any other upgrades to be considered? I am not chasing more power yet as I can't even use the stock power effectively. I bought the car used with a Corsa Carbon Fibre CAI. That said, no reason not to use the shop time for relatively simple upgrades.

Thanks in advance for any advice!

Hey Buddy... First off, welcome to the Forum and congrats on picking up the ZL1, these are amazing cars, this great platform, and you found a great spot to search for old conversations, ask questions and learn from dozens of super knowledgeable guys on here.

1. Like you, was not happy with several things on my ZL1 1LE after purchasing new. First thing I noticed was the latency and lazy throttle response. Two things helped that.... a remote tune using HP tuners, and removing the factory oil filled engine mounts for the BMR versions with poly bushings. Combined, the engine now felt so much more connected to the chassis... night and day difference.

2. Not related to your topic, but being here in California with crappy 91 octane fuel, it didn't take long to install a Flex Fuel Sensor, in order to take advantage of readily available E85 for more power, better detonation protection, and a much more responsive car.

3. Like you, found the rear suspension soft, unpredictable, and impossible to tame. Unfortunately, I cannot tell you which component made the most improvement, but combined made a night and day difference.... along with a quality alignment. Although I have several newer items now, but before upgrading to these Ridetech Coilovers... The first round of rear suspension upgrades included the BMR Front of Rear cradle braces, BMR Upper and lower trailing / traction arms, and the BMR Toe Links.

Those combined made a dramatic improvement... down the road, I installed the Ridetech Coilovers, BMR Upper & Lower Control Arms, to round out the package... and BOY do they help!

Like you suspect, no harm in starting small... perhaps the lockout kit, and trailing arm package to start... then add more later if you see the need.

Cheers to going faster and staying cooler!

[Knightfall50th]

If you are on street tires then there's only so much improvement that can be made with a high-horsepower car losing traction under heavy throttle. Even the lowly SS can be a handful on the street.

[WhiteMale]

Just about everything BMR you can put under the rear helps, starting with like the others, the cradle lockout. I've done that, upper control arm, upper/lower trailing arms, front of cradle braces and it all makes a huge difference.

[Gunkk]

Originally Posted by aeoman

I got my 23 ZL1 M6 last year, and immediately found that I had a serious drivability issue. The rear end consistently kicks out to the right under load and fishtails.
...
1) If anyone has any ideas about other ways to fix the problem, well, I am all ears. Its on relatively new Pilot Sport 4S and only has 12K miles.

Try new tires.

[Mark R]

This illustrates perfectly why the BMR arms provide much needed stiffness.

[radz28]

I have to say do all of what's been posted here. It's been my experience, after adding more power, I was getting BAD sway. Even on MT ET SSs, it could get bad. Even after I realized I was contributing to what was happening and correcting that, the sway can still be there. I don't think it's the roads in Mexico, but I couldn't say there's some crown I can't see or something. It's free of ruts and such, but I wouldn't guarantee anything.

I have the full BMR rear suspension catalog, minus their newer lower control arms. I have rod ends on everything and their rear cradle front brace, along with ZLE cradle bushings. An alignment was performed after all of that was installed, but I could still get alarming sway. The DRs didn't make it anymore consistent either.

I think if you have sway, tires might be the first thing to look at on a stock car. I haven't noticed many people comment about this that tires didn't seem to fix. Even factory GYs didn't seem immune (like JRE had posted about and was referenced above). Maybe earlier cars could benefit from the GM Drag Race e'LSD calibration, but there's not a lot of information from people that have done that. I would have paid to try that, but I don't think it was offered for cars after 2019 or something - I know mine fell outside of that window.

IMHO - start with fresh quality tires and alignment. If that doesn't help, maybe start focusing on arms and consider cradle bushings after that.

[arpad_m]

You guys are trying to sell OP a whole suspension catalog even though it fixed nothing for radz28 ("...I could still get alarming sway."). That's not troubleshooting but parts cannon fireworks. I only have the BMR rear cradle lockout and the car still goes straight under power at 700+ rwhp on a suspension that's worse than that of a ZL1.

The first thing to check would be the tires IMO, say, see if the swaying behavior changes when they're swapped side to side. If yes, then there's the answer, if not, then it's something else.

A stock ZL1 is not supposed to have this problem, let's not act like he needs a ton of aftermarket assistance just for the car to stay stable at WOT.

[radz28]

Originally Posted by arpad_m

You guys are trying to sell OP a whole suspension catalog even though it fixed nothing for radz28 ("...I could still get alarming sway."). That's not troubleshooting but parts cannon fireworks. I only have the BMR rear cradle lockout and the car still goes straight under power at 700+ rwhp on a suspension that's worse than that of a ZL1.

The first thing to check would be the tires IMO, say, see if the swaying behavior changes when they're swapped side to side. If yes, then there's the answer, if not, then it's something else.

A stock ZL1 is not supposed to have this problem, let's not act like he needs a ton of aftermarket assistance just for the car to stay stable at WOT.

I'm not trying to argue this point, but I was only addressing the sway-part.

I will say that I don't have any trace of wheelhop or anything like that, too. AND - I have aftermarket sway bars (because of, incorrectly, trying to help with something else) but those didn't help the sway, either.

If you have much road crown, I'm not sure there's much that can be done, OP. I'm not sure it's too reasonable to expect to compensate for that without effecting something else. I wouldn't purport that's your issue, but I'm fairly positive that's not helping.

To arpad's point - even though ZL1 toe links are spherical (if I recall correctly - I replaced mine almost 5-years ago now), they're a little flimsy stampings, too. Before throwing the catalog at it, if tires and verifying the alignment doesn't help, these relatively inexpensive arms might be helpful. There ARE rubber bushings in the knuckles, too (not all if I recall, but of the several per side, I think ZL1s have rubber ones), which could have worn out. I'm not sure how likely, but all of these rubber bushings are under tension when the car is on the wheels on the ground, so it's not impossible for them to wear-out or tear over time. Maybe get a look ALL of the bushings on all of the arms, too.

[NG329]

Originally Posted by arpad_m

You guys are trying to sell OP a whole suspension catalog even though it fixed nothing for radz28 ("...I could still get alarming sway."). That's not troubleshooting but parts cannon fireworks. I only have the BMR rear cradle lockout and the car still goes straight under power at 700+ rwhp on a suspension that's worse than that of a ZL1.

The first thing to check would be the tires IMO, say, see if the swaying behavior changes when they're swapped side to side. If yes, then there's the answer, if not, then it's something else.

A stock ZL1 is not supposed to have this problem, let's not act like he needs a ton of aftermarket assistance just for the car to stay stable at WOT.

I thought it was just me thinking this....... there's so much to unpack here. Including how the throttle is applied. So many variables.... because the stock components definitely are not trash.

If anything, the BMR components are very rigid, which would in effect make things break loose quicker. I'm not judging, but something doesn't add up here. Need to see a video of what the OP is referring to, including views showing the shifter, and pedals.

[Mark R]

Originally Posted by NG329

I thought it was just me thinking this....... there's so much to unpack here. Including how the throttle is applied. So many variables.... because the stock components definitely are not trash.

If anything, the BMR components are very rigid, which would in effect make things break loose quicker. I'm not judging, but something doesn't add up here. Need to see a video of what the OP is referring to, including views showing the shifter, and pedals.

It's definitely a puzzle. What might be a better way to think about this problem would be "In what order should I diagnose this problem?"

I definitely threw a bunch of BMR parts on my car. I also got the drag update from the dealer. The dealer who services the car replaces all the TTY bolts during an alignment. It still sometimes gets squirrely.