Al.B

Specifically with the C6Z in A street autocross in mind and ignoreing the adjustability benefit of koni yellows. I wonder how competitive are the DRMs and how much better would the koni yellows perform? Wondering if the konis are worth the extra 700. I'm not a tinkerer so would set and forget the konis. I do see that the konis are heavily utilized but is that because of the adjustability or are they also far superior.

smitty2919

How competitive/serious are you?

Always nice to have some adjustment once you get a feel for the car and learn more about shock settings etc.

Al.B

I take this pretty serious and am fairly competitive, but only Ax at the local level for the foreseeable future. Only 2 years into the sport and just starting with a Vette. I don't mind spending more for shocks, I just want to know it's worth it. I read a lot of great things about the DRM but not from anyone that autocrosses them. Maybe that's my answer, if no one's autocrossing them maybe they aren't that competitive.

smitty2919

DRM may be more popular for the road course guys since they may run the same course over and over. Local autocross always has different courses so the ability to "tighten" or "loosen" each end of the car via shock adjustment is nice.

However similar adjustments could be made with adjustable swaybars and to a lesser extent, tire pressures.

I have the Konis on my car and have them set to Sam's initial specs. I have run them only twice since and since I'm still getting used to what the car can do coming from a 95 Camaro Z28. I have yet to adjust them personally but knowing I CAN is nice.

I plan to hit GoodGuy Columbus which is notoriously a tight course. I have no adj swaybars so shocks will be my only option. Strano or Vansteel front bar will come eventually and MAYBE an adj rear bar if I feel the need.

Monks

I have the same questions, I know lots of autocrossers using the DRM and C4 bilsteins re valved by Bilstein for autocross. I am sure the Konis would be better for National caliber drivers, but for me?, Maybe not.
I had both a C4 and C5's with DRM coilovers, and both were great cars and were very competitive. I never even changed spring rates, just ran them as I got them from Rippie.

DRM have VERY good reviews from almost everyone that has them, and hold their value very good. You could give them a try and if you feel you need more shock, sell them and get most of you money back....to buy some Koni's

Consider Ridetech HQ's ?, I heard they are pretty good and only $1000 a set for a very high quality damper. Much better than DRM , or worse than KONI ?

smitty2919

I think you need to decide whether or not you want/need adjust-ability. Then go from there.

crimlwC6

If you don't really, really understand what changing settings does to the car then it can be more of a hamper than a bonus.I put myself in that category after doing this for almost a decade. I now run penske DAs but I ran pfadt adjustables and then DRMs for years. It is not as simple as front push turn a **** on the front. Go with the DRMs. I had my penskes set up by a suspension guy; I wasn't faster on the 5k shocks until he adjusted then vs the DRMs.

Al.B

Thanks for the feedback. I think starting with the DRMs as I'm learning the car is a good way to go and when I want to take my competitiveness to the next level i can upgrade. My initial concern was just getting a more competant shock than stock to control transitions. Coming from an AWD car I have some bad habits of overdriving a forgiving AWD car.

MarkAVette

Why are DRMs considered better than stock? I was initially looking at C5 Z06 and the 2004 shocks were supposed to be very well tuned from the factory. I ended up with a 2012 GS. Did they lose that factory tuning with the C6 Z06 and C6 GS? Do people find they have better lap times with DRM over stock? This assumes non-worn stock shocks. I would be giving a hard look at DRMs if I had worn shocks, but what about if stock shocks are still good?

smitty2919

From what I gather the DRM are a monotube design since they are Bilstein (better then twin tube designes....but Konis for C5 are monotube as well) and have adjusted fixed valving better suited for race use.

Keep in mind, just because it came on the car stock does not mean it's "the best". OEM may have A LOT more resources and engineering to produce a shock, they are still handcuffed in certain aspects to meet ride quality/Noise Vibration Harshness testing and the cost it takes to produce the unit on a mass production scale. So while the stock 04 C5Z shocks or C6Z shocks may be a GOOD shock for a off the assembly line car, there is better aftermarket once you get into higher spring rates or swaybar rates. DRM shocks would have likely been considered "too stiff" or "too harsh" for the majority of the consumers buying the car when in reality it's a "better" shock than what came with the car.

It's a system designed together factoring in the wheel weights, spring rates, swaybar rates, unsprung weight, wheel motion ratio etc etc. You CAN over spring a shock...the point spring rates are too much for the shock and the shock simply can not control the spring any longer. This is when an "even better" Koni/JRi/Penske/Ohlins shock is needed.

You will inherently learn things as you mod/race. You have your own driving style that you will try to do "best practice" movements when driving asking other faster drivers opinions but also feel the car. You will start tweaking accordingly to make the car feel predictable TO YOU. Confidence in the car and knowing what it will do in every situation allows you to push it to the limit. When the limit is set too low for you, you start modding to better parts raising that limit bar and the you somewhat relearn the car. Rinse and repeat.

acrace

Late to the discussion as I don't check out the Forums as much as I used to.

Some miscellaneous thoughts:
1) I ran my '09 C6 Z06 "seriously" for a year (2011). Back then there weren't the "Street" classes, so my car was run in Super Stock, on Hoosiers (what is now SSR). I ran the car the first half of the year on DRMs and then found some used single adjustable Penskes for the balance of the year. I ran only two SCCA National level events - finished 2nd at a tour in Blytheville early in the year (on the DRMs) and finished in the trophies (barely) at Solo Nationals (on the Penskes).
2) I did want the adjustability of the Penskes. I got my set used at a very reasonable price, and the "plan" was to convert them to double adjustable for 2012. Alas, I decided to take a break from autox, from which I am only now deciding to come out and play again. I decided on the Penskes as I had dyno curves from others in the class and had really liked their set-up, so the thought was to replicate.
3) When I look at dyno curves for autox purposes, I look at 2 in/sec (50 mm/sec) velocity area, as I think that most replicates transitions. If you run regularly on surfaces that are really bumpy or with lots of surface changes that would mean higher shock shaft speeds, then you may need to re-prioritize data. A learning for me is that the person who dyno'ed my shocks started his data collection at 2 in/sec, and ran out to pretty high shaft speeds, so I had to remind him to take extra data at lower shaft speeds for my interpretation.
4) I had Konis for my '03 C5 Z06 (and actually that's what is on that car now). The set I had was an early build set (higher gas pressure than what is now sold) and is an orange tube, but the internal valving is very close to the current Sport shocks (supposedly). What I didn't like about the Konis for adjustability, for the rear shocks, is that under 2 in/sec, no matter where the shocks are set, there is very very little difference in the damping characteristics. They do nicely diverge above about 70 mm/sec. I actually never ran the Konis at SCCA Solo Nationals; I had some custom built Sachs front shocks that I really liked, but now that they're damaged, I can't get them rebuilt. I ran the custom Sachs front/'04 factory rear shock combo at SCCA Nationals a few times and took trophies each time.
5) The DRMs, as compared to the '09 FE4 (GM speak for the Z06 package), have this difference: front shocks at 50 mm/sec has about twice as much compression force and 2-1/2 times as much rebound force. When you get to about 10 in/sec (250 mm/sec) shaft speed, there is very little (less than 15%) difference. Rear shocks have about 50 to 60% more force at 50 mm/sec. Compression/rebound is interesting in that compression starts to be identical between DRMs and FE4 at about 5 in/sec, whereas there is still a good 20% difference in rebound. When you get to about 10 in/sec, rebound forces between the two are very very close. So this "data" confirmed my seat of the pants feel where I didn't like the body control at low roll rates in the rear and I felt that the DRMs improved it.
6) A previous post that discussed the importance of learning the car and learning where/how to turn the ***** . . . I couldn't agree more. One of my frustrations when I was running in the late 2000s into 2011 was that I just didn't have the time to properly test stuff, so although I had Konis and Penskes, I didn't take full advantage of their adjustability . . . when I was younger I had the time and ability to test, but then I didn't have the (financial) resources to have all the "toys" that I wanted to experiment with.
6a) I never did manage to do an A-B-A test session with my C6 Z06 w.r.t. shocks. I can say that with my C5 Z06, comparing the factory '04 front shocks to the custom Sachs fronts (with higher low shaft speed forces), there was a time difference between the two, consistent between multiple drivers.

So I put a lot of stuff here . . . my thoughts? I think that the DRMs (which I put back on my C6 Z06 after the 2011 autocross season - the Penskes had way too much rebound force for street driving) are very good for autox. "Serious business" would mean that I would put on Koni Sports or rebuild my Penskes. The nice thing about the Koni is that, as pointed out earlier, as you gain more experience in your Z06 and/or decide you want to step up, it's pretty much a shock that can be ultra competitive at any level, in a stock car. Oh, if you want to convert to double adjustable (one of my friends did that), you can do so with the Konis. As pointed out in the above post, if you start to make a lot of mods such as different spring rates, then the boutique shocks will offer advantages.

Hope that this helps.

Al.B

Great write-up. Very informative. Much appreciated!

fuggles

Having a 2004 Z06 I would say the Bilstein Sports without the DRM valving are significantly better than the stock z06 shocks. The ride is much stiffer and the car is planted like on rails. The Bilstein shocks are much, much faster.

smitty2919

I think the Konis can be used in a wider range of setups than the DRM's. The adjust ability allows for changes for varying course designs, concrete vs asphalt and different car setups. They may be shocks that you keep/use longer on the car given their flexibility though having an adjustment feature.

But like someone mentioned, you could buy the DRM's and try them. If you don't like them, sell the for close to what you paid then go Koni. It's up to you if you are willing to do the work twice...but a shock swap is not very difficult anyways.

RedTRex

Hey Guys, Sorry to Necro this thread but running a C5 in BS and I need a shock change - currently have the C6 Z06 shocks (not '04s). I have read the opinions on DRMs vs Konis but wanted to throw in Vikings as well. Anyone running them successfully on Corvettes?

Have been researching quite a bit - saw RideTech mentioned previously and QA1 is out there as well.

Hitman227

Some food for thought, is that you should really know how different courses/tracks change the targeted setup of the konis, otherwise, you are kind of shooting in the dark, and might actually hinder your progress. Akin to setting the *wrong* settings for given situations, it will slow you down.

Also, an option, you don't necessarily *have* to fiddle with the konis, find a nice setting and run with it. I ran koni yellows on my LS2 GTO that was setup as a street-gt car, and I ran them stiff all around (9/10). It worked very well with the springs I had at the time (B&G progressive) and didn't need to change the shock settings for my driving (which was pretty aggressive). Personally, I did *not* find them *too* stiff for even street driving, however, as you might expect the dampening control of the car in aggressive situations was vastly improved, car was fantastic planted.

andersnor

Bang for buck with DRM is hard to beat, superfast to install as well, superhappy with mine, disclaimerI mostly roadrace.

Most cars will have worn shocks, so going to be a huge upgrade no matter what

RedTRex

Thanks to those few that replied, it has helped. I feel the lean is towards DRM. I looked at the sales in C5 and C6 and it appears DRMs resell rather quickly. So might be worth a shot.

MX621

sorry to bump a old thread. I had my new to me c5zo6 on track last week ( njmp lightning ) and I was pretty unhappy with the car ( I believe I know why ). I used the vette for the NASA instructor clinic vs my race car for simplicity sake. After the clinic was over we got two sessions on track and the car was a hand full. It’s bone stock 73k miles, lowered on stock bolts and alignment. Recently rebuilt the entire rear suspension ( upper/lower ball joints, inner/outer tie rods and wheel bearings ). But the car was very unsettled and very springy In high speed sections that required steering input. I’m blaming the 73000 mile stock 02 shocks and hoping some new ( most likely DRM bilstiens ) will help/solve the issue.

Not looking to make this a track car, but wouldn’t mind it being capable of some light duty track work.

romandian

what toe are you running in the rear?

my personal experience with various shocks over time and on different cars is quite marginal. they dont make as much difference as other components. (yes, if you have them set up on a dyno by an engineer it might be different.)