Z/28 suspension kit with 1LE F/R sway bars?

[MaverickLS7]

I have the Z/28 suspension kit (uninstalled) and wondering if I should keep my 1LE sway bars on or move to the kits smaller ones once installed. Any thoughts or experiences?

[Nick S]

I installed the Z/28 suspension with the Z/28 sway bars. With the increased spring rates on the Z/28 suspension the springs contribute a lot more to body roll control. GM could have kept the 1LE sway bar sizes if that would have worked better for the car but they chose to spend more money on different sizes to tune the suspension for better performance.

The one thing some people have done if they want the rear end to loosen up a bit is they have left the rear 1LE sway bar in (it's 1mm larger diameter) to make the car a little more prone to over steer. But I chose to first try the full Z/28 set up to see how I liked it and so far I'm happy with how it behaves.

Now you can run the 1LE sway bars and it's not like they car will be undriveable, but the Camaro team had a lot of data and lap times to prove the Z/28 sway bars were faster around the track.

[hkittrell]

[MaverickLS7]

Originally Posted by Nick S

I installed the Z/28 suspension with the Z/28 sway bars. With the increased spring rates on the Z/28 suspension the springs contribute a lot more to body roll control. GM could have kept the 1LE sway bar sizes if that would have worked better for the car but they chose to spend more money on different sizes to tune the suspension for better performance.

The one thing some people have done if they want the rear end to loosen up a bit is they have left the rear 1LE sway bar in (it's 1mm larger diameter) to make the car a little more prone to over steer. But I chose to first try the full Z/28 set up to see how I liked it and so far I'm happy with how it behaves.

Now you can run the 1LE sway bars and it's not like they car will be undriveable, but the Camaro team had a lot of data and lap times to prove the Z/28 sway bars were faster around the track.

That's what I was kinda thinking. What wheels and tires are you running with kit? The main reason I asked "I should've went into more details" is that I believe my 1LE is definitely heavier than the Z being a 2SS RS, also still running stock platform 285/20's vs the wider 305/19's. I am running Toyo RR tires though.

[cdb95z28]

I have the Z kit, I run my 1LE on the street and I track it.
Originally I ran with the Z front bar with the 1LE rear. Yes, this will balance the car towards oversteer, as expected. But it was a bit harder to put the power down on the exit of corners. RE-71 in 305.

I tried the Z front and rear together, definitely felt more "secure". I ran this way for a year. Again with the RE-71's. I then tried to "soften" the Z front bar by lubing the mounting bushings with a rubber compatible lubricant I use at work, Dow Corning Molykote 111. I was looking to get a bit more front bite. As you may know, the OE mounting bushings are designed to be installed dry as the bushing grips the bar super tight, adding to the bars effective stiffness. By lubing the mounts, the bar would lose some of the engineered in stiffness.

I ran like this for a year. I stepped up to the ZL1 1LE tire, Goodyear 3R in 305 on all 4. Car had more roll, so this year I'm going to try the front and rear 1LE bars. More roll is not necessarily all bad, but since I have the different bars, I thought I'd experiment.

This winter I have also removed the OE 1LE rear diff and I installed a TrueTrac diff, so that will help with putting the power down on the exit of corners.

[Mgizzle]

I am putting on the entire z kit too including bearings and rear knuckles on my 1LE and have decided to go z/28 bars too but will leave the 1LE ones for trying things out. My biggest headache is ride height with car so much lighter than a stock car. Uuugh, bout to put it together this month and am freaking out if it will look like a pick up lol. I dremmeled front struts and cut the tips of the knuckle to get camber. On 1LE struts I got up to 2.7 negative this way. I will keep the BMR lowering aprungs as back up but wish BMR made ines in z/28 rates but just lower.

I also wanted to buy the half shafts realizing the grease and boot are onlybdifference (higher temp grease in z/28) since my driver side one burped bad at track last year and greased my wheel very good. I am taking a risk since the damn halfshafts are $350 a pop.

[Nick S]

Originally Posted by Mgizzle

I am putting on the entire z kit too including bearings and rear knuckles on my 1LE and have decided to go z/28 bars too but will leave the 1LE ones for trying things out. My biggest headache is ride height with car so much lighter than a stock car. Uuugh, bout to put it together this month and am freaking out if it will look like a pick up lol. I dremmeled front struts and cut the tips of the knuckle to get camber. On 1LE struts I got up to 2.7 negative this way. I will keep the BMR lowering aprungs as back up but wish BMR made ines in z/28 rates but just lower.

I also wanted to buy the half shafts realizing the grease and boot are onlybdifference (higher temp grease in z/28) since my driver side one burped bad at track last year and greased my wheel very good. I am taking a risk since the damn halfshafts are $350 a pop.

I have thought about doing what you did on your front knuckles and struts as well. I was wondering how much more camber you could get this way. I currently have -2.15 on the left and -1.85 on the right. Both are maxed out. I'm not thrilled with the difference between the two sides but most of the tracks I frequent are also clockwise in direction so the left is a little more important than the right. I've also considered just biting the bullet and getting some camber plates. My biggest struggle right now is I think my rear camber is maxed out according to what the last alignment guy told me and I was only able to get -.85 in the rear. I was thinking I should be able to get more then that. I'm going to have to revisit the rear camber again.

[Nick S]

Originally Posted by MaverickLS7

That's what I was kinda thinking. What wheels and tires are you running with kit? The main reason I asked "I should've went into more details" is that I believe my 1LE is definitely heavier than the Z being a 2SS RS, also still running stock platform 285/20's vs the wider 305/19's. I am running Toyo RR tires though.

Currently I have only run the stock 1LE size tires in RE-71R and the stock Eagle F1 G2's. I think a wider tire in the 19" size will help the Z/28 suspension shine more. I think with the extra stiffness of the Z/28 springs and struts that you need more tire grip to make the suspension work a little hard and gain that extra speed. My car definitely does not roll much though. I even had a buddy drive my car that comes from a C5 ZO6 and he said my car stays flatter than his in the corners and transitions. I thought that was pretty impressive.

I'll slowly migrate over to 19" wheels and tires once I have a couple of sets to use.

[cdb95z28]

Originally Posted by Mgizzle

I am putting on the entire z kit too including bearings and rear knuckles on my 1LE and have decided to go z/28 bars too but will leave the 1LE ones for trying things out. My biggest headache is ride height with car so much lighter than a stock car. Uuugh, bout to put it together this month and am freaking out if it will look like a pick up lol. I dremmeled front struts and cut the tips of the knuckle to get camber. On 1LE struts I got up to 2.7 negative this way. I will keep the BMR lowering aprungs as back up but wish BMR made ines in z/28 rates but just lower.

I also wanted to buy the half shafts realizing the grease and boot are onlybdifference (higher temp grease in z/28) since my driver side one burped bad at track last year and greased my wheel very good. I am taking a risk since the damn halfshafts are $350 a pop.

I hear ya on the ride height desires with the Z suspension. I run 19's on track, while the look is not a primary factor, I do wish it sat lower. I did the BMR 1" springs early in my Z suspension upgrade. The DSSV's have less compression travel than the OE 1LE dampers. My concern was riding on the bumpstops more with the BMRs + DSSVs. I was changing so much that summer that I didn't get a definitive answer whether that combo was acceptable. A member here, aris, installed Detroit Speed's drop springs on his Z/28 and he has said it is a very good setup.

[cdb95z28]

Originally Posted by Nick S

I have thought about doing what you did on your front knuckles and struts as well. I was wondering how much more camber you could get this way. I currently have -2.15 on the left and -1.85 on the right. Both are maxed out. I'm not thrilled with the difference between the two sides but most of the tracks I frequent are also clockwise in direction so the left is a little more important than the right. I've also considered just biting the bullet and getting some camber plates. My biggest struggle right now is I think my rear camber is maxed out according to what the last alignment guy told me and I was only able to get -.85 in the rear. I was thinking I should be able to get more then that. I'm going to have to revisit the rear camber again.

I've opened up the upper slot on the struts for more camber, Without camber plates I had -2.4*

On the rear, your alignment guys needs to play with the toe also when trying to get more camber. I do my own alignments and I have achieved -1.3*. I might have gotten more but that is the max I ever wanted. The toe changes with the camber and vice versa. It's a chase, but you gotta be patient.

[Matty Ice]

Originally Posted by cdb95z28

I've opened up the upper slot on the struts for more camber, Without camber plates I had -2.4*

On the rear, your alignment guys needs to play with the toe also when trying to get more camber. I do my own alignments and I have achieved -1.3*. I might have gotten more but that is the max I ever wanted. The toe changes with the camber and vice versa. It's a chase, but you gotta be patient.

cd- Do you think there is that much difference, to justify the cost in the switch, between the Bilsteins B6's vs DSSV's. I have been thinking about going that route but was unsure how they well they would play with the softer BMR/DSE springs. The only reason I didn't originally go with the Z28 springs/struts is I can't stand the wheel gap and wanted to get rid of it. Like Mgizzle said wish there was a lowering spring in the Z28 rate. How is the BMR/DSSV combo?

Sorry to hijack, but it's been a really long time since we had a really good discussion on suspension. What about using a ZL1 front bar?

Also 19" vs 20" wheels/tires. Referring to the M/T article where they switched the tire/wheels between the Z28/1le. I don't think there is that much to gain as far as it pertains to help in the suspension. I think it helps with braking more, less rotation mass/weight. Tire compound definitely matters.

[cdb95z28]

Originally Posted by Matty Ice

cd- Do you think there is that much difference, to justify the cost in the switch, between the Bilsteins B6's vs DSSV's. I have been thinking about going that route but was unsure how they well they would play with the softer BMR/DSE springs. The only reason I didn't originally go with the Z28 springs/struts is I can't stand the wheel gap and wanted to get rid of it. Like Mgizzle said wish there was a lowering spring in the Z28 rate. How is the BMR/DSSV combo?

Sorry to hijack, but it's been a really long time since we had a really good discussion on suspension. What about using a ZL1 front bar?

Also 19" vs 20" wheels/tires. Referring to the M/T article where they switched the tire/wheels between the Z28/1le. I don't think there is that much to gain as far as it pertains to help in the suspension. I think it helps with braking more, less rotation mass/weight. Tire compound definitely matters.

I don't have any experience with the B6's and the only knowledge I have on them is guys like 'em. Yeah, the gap is the biggest downside to the Z setup. Even worse than the stiffness. Like I mentioned, my final word on the BMR/DSSV experiment is not complete. The car was a bit softer, but the DSSVs are stiff. And I was still on the 1LE Goodyear F1 G:2's. I was playing with alot of things at once, which is bad.

The ZL1 front bar is the same as the Z/28 front bar, 25mm.

That M/T article did touch on how each car is engineered (damper valving/tires) to work as a cohesive package. The Z dampers are tuned for the Trofeos (among other variables) and 1LE vice-versa. Beyond a tire compound variable, it is the sidewall stiffness too. The sidewall acts as a spring, so this plays a part in the damper tuning.

There is one big variable that us guys don't have in running the Z setup, the unsprung weight difference of the Z/28 CC rotors is huge. And the Z dampers are tuned with this mind. I would love to drive a Z/28 to see feel the difference is compared to my 1LE with the Z suspension. My setup is helped with the addition of lightweight Forgelines vs the heavier Z/28 wheels, but those rotors are very light compered to iron.

I can tell you with the Z springs/dampers, I can toss the car hard and the transitions are rock solid and stable.

[Mgizzle]

I ran 1" bmr drop on front amd 1.25" on rear. Could only get -1.8 front but rear had no issues with -1.5 even when car was stock. Nick something dont smell right that you cant get more..... I cut the slots longer on my 1LE fronts too but the knuckle bottomed out so without cutting the top off i couldnt budge more.

We shall see soon how it will do with z/28s and the mass..... A friend recommended some grinding and cutting of oem components to get the height but we ll see.

[Matty Ice]

Did you guys learn/decide anything with your suspension set ups this season?