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Anyone have Aero questions?

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On 5/14/2019 at 3:14 PM, Alchemy Autosport said:

Here is a question, how are people managing spring rates with big aero?  Adding damper pots is off the table for cost reasons.  I have considered some homemade measuring devices but if anyone has a good rule of thumb for Splitter/Air Dam and Big (9libes) rear wing setups on a miata, I am all ears.


Agreed, damper pots would be $$$.

There's lots of variables to consider here too; tires, static weight, track, conditions, type of race, and of course aero. I'm a firm believer in A/B/A testing, but not many people are able to do this. Thankfully with the miata community there's lots of combined info of people who have been able to. Typical go-to for non-aero R-comp'd 2300lbs miata is 800/500 along with typical big front bar and ~14mm-ish rear bar.

In my particular case(the same setup mentioned), after I've added 9LR aero of splitter, airdam, and wang physical limitations of the car tell me I need more spring or higher ride-height. Meaning, the tire is slamming into the frame/shock tower more often now. I don't really want to sacrifice my ride-height(4.25"f/4.5"r) so I'll be moving up to 1000/550. This matches the typical go-to rates the miata community has seen good results on with type of setup and aero package. Think Supermiata S1 setups, which is one of the A/B tests done in the community.

So not to over simplify it, but the clock doesn't lie! I hope to do some spring testing myself at Road Atlanta at a TT event in June. 

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31 minutes ago, Marcus_NineLivesRacing said:


Agreed, damper pots would be $$$.

There's lots of variables to consider here too; tires, static weight, track, conditions, type of race, and of course aero. I'm a firm believer in A/B/A testing, but not many people are able to do this. Thankfully with the miata community there's lots of combined info of people who have been able to. Typical go-to for non-aero R-comp'd 2300lbs miata is 800/500 along with typical big front bar and ~14mm-ish rear bar.

In my particular case(the same setup mentioned), after I've added 9LR aero of splitter, airdam, and wang physical limitations of the car tell me I need more spring or higher ride-height. Meaning, the tire is slamming into the frame/shock tower more often now. I don't really want to sacrifice my ride-height(4.25"f/4.5"r) so I'll be moving up to 1000/550. This matches the typical go-to rates the miata community has seen good results on with type of setup and aero package. Think Supermiata S1 setups, which is one of the A/B tests done in the community.

So not to over simplify it, but the clock doesn't lie! I hope to do some spring testing myself at Road Atlanta at a TT event in June. 

Great info, Thanks.   

Brings up a couple questions, because I'm curious   When you say 2300lbs are you talking with driver?   Am I wrong to think that may be too stiff with 200tw tires?  What about in the rain, too stiff?

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1 hour ago, JDChristianson said:

Great info, Thanks.   

Brings up a couple questions, because I'm curious   When you say 2300lbs are you talking with driver?   Am I wrong to think that may be too stiff with 200tw tires?  What about in the rain, too stiff?



Yes wet weight, so with the driver, fuel, safety gear, etc.

Could be too stiff for 200tw, but is this super200 or typical 200tw? It also depends on the track too, silky smooth surface or wtfsodirtyandbumpy surface? I believe there's going to be some compromise there that you may actually have to drive around at times. Same with being in the rain. We're getting pretty deep into suspension optimization too.

Having more down-force in either of the situations you've mentioned certainly isn't a bad thing 😃. Though you'll need to weigh the trade-off of potential drag if you're cranking in more down-force. Getting data out to us grass-roots competitors is one of the main goals we're trying to accomplish here at 9LR as well. With the proper data you and your team will be able to make config decisions on the fly, more accurately.

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1 hour ago, Marcus_NineLivesRacing said:



Yes wet weight, so with the driver, fuel, safety gear, etc.

Could be too stiff for 200tw, but is this super200 or typical 200tw? It also depends on the track too, silky smooth surface or wtfsodirtyandbumpy surface? I believe there's going to be some compromise there that you may actually have to drive around at times. Same with being in the rain. We're getting pretty deep into suspension optimization too.

Having more down-force in either of the situations you've mentioned certainly isn't a bad thing 😃. Though you'll need to weigh the trade-off of potential drag if you're cranking in more down-force. Getting data out to us grass-roots competitors is one of the main goals we're trying to accomplish here at 9LR as well. With the proper data you and your team will be able to make config decisions on the fly, more accurately.

Thanks again!  I agree down force is good.   

 

My only other concern with getting real serious with heavy spring rates for what we do is reliability of things like hubs and suspension components.  It hard to know the perfect balance between lap times and lasting for endurance racing.   

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4 hours ago, JDChristianson said:

Thanks again!  I agree down force is good.   

 

My only other concern with getting real serious with heavy spring rates for what we do is reliability of things like hubs and suspension components.  It hard to know the perfect balance between lap times and lasting for endurance racing.   


I'm with you there, more grip = more wear/tear. Hubs are a weak point of miatas, thankfully.... the community has answers!

Front hub options:
- Expensive, but THE option for enduro NA/NB:  https://www.miatahubs.com/
- Relatively new E30 hub conversion kit: https://www.miataturbo.net/miata-parts-sale-trade-5/group-buy-e30-hub-conversion-100121/
- Repack, check, and replace Centric hubs part # 40645006 from RockAuto (this is what I do currently)

Rear hub options:
- SadFab MR-S conversion kit, I run these on my car: https://www.miataturbo.net/miata-parts-sale-trade-5/sadfab-mr2-s-rear-hubs-miata-96576/
- OEM replacement 


 

2 hours ago, JDChristianson said:

^^. Oh one more question. What shocks are guys running on time attack cars with jumbo aero and 1k springs?   


Xidas, of course. 

https://supermiata.com/xida-coilover-miata.aspx

 

 

Edited by Marcus_NineLivesRacing
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3 hours ago, Alchemy Autosport said:

Non-OE hubs are points, I think 5pts each.

 

We have always taken 10 points per corner.

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Curious @NineLivesJohnny if you think my "Daytona" trunk lid and fender extensions helped with drag reduction.

20190405_151224.jpg

20190405_151403.jpg

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10 hours ago, wvumtnbkr said:

I think a big piece of lexan bent to fit the back would make more of a difference.

 

Pretty much exactly what my next project is. First a full top, then a lexan fastback.

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On 5/15/2019 at 8:36 AM, wvumtnbkr said:

Zip ties on the shock shafts with and without aero.

Bad idea. As soon as you hit one bump, even in the paddock, it looks like you're making more downforce than you actually are.

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It's not a bad idea and it works.  You just need to be mindful of the limitations.  It is a pretty simple and mostly free tool.

 

Drive on a smooth surface.

 

Wouldn't anything that measures suspension travel and loading be affected by bumps unless you went to some GPS based system which is gonna be a bit involved.

Edited by wvumtnbkr
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1 hour ago, The Aero Man said:

Bad idea. As soon as you hit one bump, even in the paddock, it looks like you're making more downforce than you actually are.

You’re not using it to measure downforce directly, you’re using it to see maximum suspension travel when you clip the outside curb in a high speed sweeper. If it bottoms out, you need to change something (more spring / less wing / more ride height).

The comparison of zip tie positions after runs with and without aero will give you some info about the actual downforce you are making in the turn where you had your most extreme suspension movement. 

Edited by enginerd
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7 hours ago, enginerd said:

You’re not using it to measure downforce directly, you’re using it to see maximum suspension travel when you clip the outside curb in a high speed sweeper. If it bottoms out, you need to change something (more spring / less wing / more ride height).

The comparison of zip tie positions after runs with and without aero will give you some info about the actual downforce you are making in the turn where you had your most extreme suspension movement. 

Nah, I'm with Aero Man on this one.  The factors that provide the max travel on the shock are moderately varied.  Can be the amount of down force, but you don't know where your max travel happens, or how.  Could just be a quick bump as you hit the curb at a slightly steeper angle than previous.  Seems you would need to do several laps, checking each time, plot the various results, discount the outliers, then go back and try again with the aero.  Need to insure the driver is the same each time too.

 

If the car rides on the bump stops at all, the max travel won't tell you much, you'll be looking for data in areas you're not at max travel.

 

If you're trying to measure max travel, yes the ziptie works (do it on my mountain bike all the time), but it isn't a way to measure your downforce.

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8 hours ago, wvumtnbkr said:

It's not a bad idea and it works.  You just need to be mindful of the limitations.  It is a pretty simple and mostly free tool.

 

Drive on a smooth surface.

 

Wouldn't anything that measures suspension travel and loading be affected by bumps unless you went to some GPS based system which is gonna be a bit involved.

You are correct, anything that measures suspension travel will be affected by bumps. But, with an electronic measurement that can be logged along with all of the other data collected, you can get around this problem. By graphing the results over time, you can see spikes in the data and rule them out. You can also compare side by side with g-force data to tell where the bumps are. 

 

Compare two sets of data, with and without the aero. Do some math, and you've got yourself the exact amount of downforce you are making at each axle at any given speed or place on the track. 

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I agree that is the right way to do it.

 

It's just not feasible for 99.9% of us who race champcar.  Therefore, this is a cheap method to do it that does work if you keep in mind that the data is garbage if you hit curbs or bumps.

 

80% accurate data is usually better than no data.

 

If you are on the bumpstops every lap, I would say that how much downforce you are making is less of a concern.  Yes, I know people tune their bumpstops and a car can be set up that way.  I think it's a bad idea for endurance racing (imho).

 

If ya wanna verify if it was from a bump or curb, versus cornering (and aero load) just run a camera to watch the suspension move.  It will be obvious if it's a bump or a curb.

Edited by wvumtnbkr
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It can also be revealing in other ways. I just upgraded the Civic suspension recently from the as-purchased combo, and while doing the final corner weights and heights today I decided to put zip ties on for the track/test day this coming Monday. I was thinking about adding some aero later depending on what the car wanted.

 

Imagine my surprise when I set the car at the ride height that we had been running it at and found out that we only have about 1 3/4" of travel left on all the shocks. The bumpstops are part of that travel, so likely have been running on the bumpstops most of the time. I ended up raising the car a bit to get some more room and to get back into a slower part of the camber curve.

 

Hopefully the test day goes well!

Edited by mender
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On 5/15/2019 at 7:36 AM, wvumtnbkr said:

Zip ties on the shock shafts with and without aero.

 Chumpy 😀

 

15 hours ago, The Aero Man said:

 an electronic measurement that can be logged along with all of the other data collected, you can get around this problem. 

Not Chumpy 😪

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