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What is the best balance of feel versus excessive NVH for a street C5Z?
My latest change was to go with Pfadt featherlights, oconnell swaybars and I did a 18x11 square setup (mpss 295's). The character of the car was VASTLY improved, much better feel, turn in response, etc. I just added a 350mm steering wheel to speed up the ratio a tad, so now what I am thinking about getting rid of some of the mushy nature the car has. It has a much higher degree of sharpness now, which I like, but with more front grip, and more roll stiffness, the bushings seem like they will start to become the disconnect point of road surface to steering wheel.
The car has 61k miles on it and I'm considering the next step to really make the car feel connected to the ground through the steering wheel.
I was told about a doug rippie steering rack bushing, which I think I will do, but on the other bushings...what's the best route? I don't want monoball of course, and I have seen delrin talked about. Is there a slightly higher durometer poly bushing that is slightly more aggressive than stock? What's that perfect balance?
I don't want to take my car into the land of TOO harsh, but as of now, it feels fantastic...better than it ever has by far. I had BMW's, a 993 Porsche, 2 late 90's clunker Ferrari's and the Z06 currently feels close to what I want....much sharper like many of those cars were, with still a degree of compliance for the street.
Delrin is going to feel the same as monoballs from an NVH perspective. There is basically no compliance in delrin. If it's a street car then poly will firm things up a bit without knocking your teeth out. As much as I like to sell monoballs I say it's overkill for a street car.
Monoballs or Delrin should be first mod in all vettes IMO. Leave the rear lower shock mount rubber. On the street suspension is free. People usually do solid bushings with nasty shocks & springs & then blame the bushings. A softly sprung & shocked car with monoballs is smooth going down the street. Straight. In corners yes you feel more.
Get monoballs over poly. The Poly's bind like crazy. It doesn't matter how much you grease them. It's the design that is poor.
The binding is definitely what I don't want. I just would hate to lay out 2500.00 and realize i went a step too far.
I look at my C5Z as a 996 GT3RS'esque approach. I want a C5Z but in a "club sport" edition. Very sharp feel, very connected, understandable to have a bit less compliance and more harshness, but not enough that it's TOO much.
I intend to do a bit more track days here this year also so, just want to find a nice balance that makes me happy.
The binding is definitely what I don't want. I just would hate to lay out 2500.00 and realize i went a step too far.
I look at my C5Z as a 996 GT3RS'esque approach. I want a C5Z but in a "club sport" edition. Very sharp feel, very connected, understandable to have a bit less compliance and more harshness, but not enough that it's TOO much.
I intend to do a bit more track days here this year also so, just want to find a nice balance that makes me happy.
Where are you located? If you're in a warmer climate with generally smooth roads then monoballs with good dampers aren't too harsh (as mentioned above). If you're in the Northeast and driving through pot holes and frost heaves then you're definitely going to be feeling all of them!
I've got Mark's monoballs on my C6Z. It also has coilovers, huge sways, AMT Vulcan motor mounts, AMT camber kit, race seats, harness etc etc and is a dedicated track/race car. That said, I have been driving it around town the last 30 days or so dodging snowflakes in the Northeast and breaking in the car best I can.
There is a definitive increase to NVH, but it is manageable. Car feels like a slot car. The way it should. Sharp and connected. If not for the race seats I would have no problem driving this car regularly on the street.
I will also add that Mark's monoballs fit PERFECTLY. Required zero modifications. Control arms lined right up neatly and exactly.
Where are you located? If you're in a warmer climate with generally smooth roads then monoballs with good dampers aren't too harsh (as mentioned above). If you're in the Northeast and driving through pot holes and frost heaves then you're definitely going to be feeling all of them!
After 14yrs in Pittsburgh, I threw in the towel on snow, rust, potholes, landslides, blizzards, rain, clouds, scum and moved on to ATL....movin again now to LasVegas here in 2 months. I am doing a driving series on YT with the car...it's well produced, etc. Canyon roads, the HelenRing in the east, etc.
Gotta think about it. Wasn't prepared to go that level of coin on "bushings" in the sense that, that's the location modification my mind was looking at...lol. Like I said, I am really seeking that balance of feel without going too "racecar" on the street. The car is being built also with detachable/quick release aero and a one off wide body.
It's my 4th build phase for this car...it's been a lot of different things, had a lot of different looks, wraps, etc. Right now, I have a "one car, do it all" mission in place with a huge injection of analog feel combined with adequate comfort....if that makes any sense.
Currently own a base C5/f41, off the shelf Bilsteins, stock leaf springs and bars, Pfadt urethane bushings. Pretty damn harsh over the bumps, but the bushings didn't change that one bit.
Also have a C6Z with LG coilovers, JOC bars, full monoball suspension. 600/700 lb springs... still rides like glass in comparison. Other than the cost, the only downside I can see to the monoballs is the rattle. Doesn't take very long before they develop enough play to be annoying.
I've got the Borg Motorsport offset delrin bushings in the STU car. Stiffer leaf springs and bars. Race seat. I drive it on the street often and have zero complaints. The bushings didn't change the NVH much in my opinion.
I'm in the process of swapping delrin bushings into my STU car that I drove ~7500 miles last year (stiffer springs/bars/shocks, race seat, etc.), and will be driving to Mid-Ohio this weekend from Detroit with the same spring/bar/shock setup, but adding the delrin control arm bushings. I'll be able to report back on how NVH changed after this weekend.
Please do...I don't want the squeaking of the polys and don't want the rattles of mono's (the cost is a bit also for a street car).
Definitely let me know...delrin could be nice.
FYI the monoball rattle usually comes from junky bearings. We use the best in the business and they don't rattle. We guarantee them for 5 years so if you ever have a problem we'll send you replacements.
I've had a similar goal with my car (the "clubsport" thing). I went to delrin control arm bushings almost right away and they are definitely a bit harsher over sharp bumps like misaligned concrete segments on the highway but in general are not bad at all. Its the sound more than anything, kinda like a crashing sound or a bang. Its not like riding in a racecar. As was mentioned a few times before, they don't affect the "ride" per se. Meaning they don't make the car handle bumps differently. Springs and dampers will ruin your ride if you don't pick them right. I have Hyperco HPT/HPS spring combo with Koni shocks and the ride is still pretty alright for me to drive to work most of the time.
I've actually gotten a lot of feedback from our customers that the NVH with Delrin isn't as bad as they were expecting. I know they don't have the squeak of poly, that's just a function of the material itself. Personally, I wouldn't put Delrin bushings on a street only car, but I also didn't street drive my Street class car back in the day. For a split purpose car, I might; especially back when I was in college and didn't care about NVH. Not so much now in my old age.
A lot of people say Delrin is as stiff as aluminum, steel, metal, etc. but in reality, it isn't. Here's a run down of some approximate stiffnesses (Young's modulus) for various materials:
Steel - 200 GPa
Aluminum - 69 GPa
Delrin - 2.7 GPa
Poly - 0.005-0.02 GPa (changes dramatically with load and depends on the stiffness of poly you specify)
Rubber is obviously lower than poly (in most cases). As you can see, Delrin is much less stiff than metal, but it's still over 100 times stiffer than typical poly. Everyone reacts a little bit differently to the NVH characteristics as their level of sensitivity will be based on their level of perception, sensitive to certain frequencies, body composition, etc. Basically at some point, you stop being able to tell a difference. Steel is about three times as stiff as aluminum, yet the vast majority of people wouldn't notice the change. Delrin seems to be about at the level where the transition from being able to tell a difference is for the average person.
TLDR: Rubber is best for NVH, poly will ride better, but Delrin will likely be quieter. All will be less stiff than sphericals.
FYI the monoball rattle usually comes from junky bearings. We use the best in the business and they don't rattle. We guarantee them for 5 years so if you ever have a problem we'll send you replacements.
...Got the same spiel (sans guaranty) from LG. After paying a premium for their super-duper-extra-high-quality bearings, they were nothing fancy.
What brand do you use?
Last edited by Nowanker; 04-09-2018 at 09:04 PM.
Reason: grammar!
Here are some pics of the monoballs that Mark (AMT) did for me on my C6Z control arms. They are of extremely high quality and again fitment was perfect and dead-on. A shame they are hidden under the car.
...Got the same spiel (sans guaranty) from LG. After paying a premium for their super-duper-extra-high-quality bearings, they were nothing fancy.
What brand do you use?
We use a Radial RWT-10. I went with them after a buddy who works for Action Express said they use the same bearings on their LMP cars and they last all season. Hundreds of hours at 3+GS was enough of an endorsement for me. They're made in Connecticut. I buy 160 at a time and my cost is $18.50 each.
Last bearing I saw come out of LG arms was a low grade COM bearing that I found for about $6. Don't know if they still use that bearing or not.
Where are you located? If you're in a warmer climate with generally smooth roads then monoballs with good dampers aren't too harsh (as mentioned above). If you're in the Northeast and driving through pot holes and frost heaves then you're definitely going to be feeling all of them!
I'm not sure where the decent streets are anymore. SoCal you would think, but "they" repave one & the "manhole" covers are always about an inch to high or low and I end up swerving down the street like you know what. Or the street/freeway hasn't been touched in 20 years. Don't get me started about Bott's dots.
04-07-2018, 12:27 PM
What is the best balance of feel versus excessive NVH for a street C5Z?
