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Last Post 22 Feb 2009 06:14 PM by  DFWmiata
Vorshlag Tester Jarrett's 1st Gen Miata/STS car
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Fair
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20 Feb 2009 09:51 AM

    Update from Dec 9, 2008:

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    Jarrett's car in EStock form

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    Initial weighing/corner balance check

    Wanted to share this thread for Jarret's Miata. He is a local (to us) racer that been running his NA generation MX5 Miata car in EStock for the past few years and was ready for the move up to STS2 (now STS). We are working with him via our [URL="http://www.vorshlag.com/vtpp.php"]Vorshlag Test Pilot Program[/URL] to help fine tune existing AST 4100 shocks for the NA/NB chassis in the United States. AST has made many hundreds of sets of coilovers for these cars in the past for the European and Japanese markets, but we here at Vorshlag have not sold them in 4100 form yet to U.S. customer's (we have only sold 4300s). Here are a few pictures of the shocks then we'll move on to the install, initial test impressions, and setup discussion.

    [URL="http://vorshlag.smugmug.com/photos/419715160_njxxy-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/419715278_q6cbA-L.jpg"]SCCAForums Image[/URL]
    [I]L: Long shocks are the fronts, short are the rears. Knob is for rebound adjustment[/I]
    [I]R: Lower bushings are spherical. Upper is made to work with the stock NA/NB upper mounts[/I]

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    [I]This was one of the ride height iterations, which was eventually lowered more at the rear.[/I]

    SCCAForums Image SCCAForums Image
    [I]Left: OEM front is 14" long and 150#/in, rear spring is 11" and 90#/in (SOFT!). We started testing with 7" x 60mm ID Hypercos, 550 #/in front, 350#/in rear[/I]

    The dyno plots of these 4100s were textbook perfect. We dyno'd the Brand K singles that were on here before and were... not surprised at the results. [;)] We dyno'd some Brand K doubles the week before that had some pretty... interesting results ("non-adjusting adjustment knobs").

    [URL="http://vorshlag.smugmug.com/photos/433456760_rUiKZ-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/433455258_Z4SQp-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/433456393_DHLWR-L.jpg"]SCCAForums Image[/URL]
    [I]click to enlarge[/I]

    Above left you can see the AST 4100 Miata rear shock being tested on our Roehrig 2VS shock dyno. Middle, you can see Hanchey making a CVP plot. Notice the large force changes over the range of rebound adjustments - this valving package can deal with a nice spread of spring rates (we later revalved them for much higher rates that the car seemed to work better on). Right, new dyno fixtures had to be built for the lower eye mount (1.800" width)

    [url]http://vorshlag.smugmug.com/gallery/6717983_45S6v[/url] = Miata 4100 Install Gallery

    More soon!

    Fair
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    20 Feb 2009 09:52 AM

    Stock Spring Rating:

    If you've ever driven a stock suspended Miata you know how soft the factory springs are. We went the extra step and put the front and rear springs from Jarrett's Miata on our Spring Rater and checked them over 4" of travel. Here's the numbers:

    [URL="http://vorshlag.smugmug.com/photos/433473421_SCcrc-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/433474176_4WgCz-L.jpg"]SCCAForums Image[/URL]
    [I]Above: The testing of the rear OEM spring, from 0" to 4" of compression. At 4.000" of travel there was 348 pounds of load.[/I]

    [LIST]
    [*]OEM front springs = 14" long x 150 #/in (from our testing)
    [*]OEM rear springs = 11" long x 90 #/in (from our testing)
    [*]The new front springs = 7" long x 550#/in
    [*]The new rear springs = 7" long x 350#/in
    [/LIST]
    [URL="http://vorshlag.smugmug.com/photos/433472750_MU2wj-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/433475484_PjydB-L.jpg"]SCCAForums Image[/URL]

    [I]Left, above: The Miata's OEM rear spring had a staggering 14" Overall Length (OAL). When installed they had almost 4" of preload, just sitting at ride height!
    Right, above: The OEM rear spring was 3.9 pounds. 7" long, 60mm ID Hyperco OBD coilover springs are 2 pounds[/I]

    Fair
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    20 Feb 2009 10:04 AM

    Some shock install pics:

    [URL="http://vorshlag.smugmug.com/photos/429715968_JY2eq-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/429734461_QRRW7-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/429723278_Gb8v3-L.jpg"]SCCAForums Image[/URL]

    [URL="http://vorshlag.smugmug.com/photos/429725718_JrHuu-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/429714377_jrsoV-L.jpg"]SCCAForums Image[/URL]

    Corner weighing
    [URL="http://vorshlag.smugmug.com/photos/433493844_x7rEV-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/433493392_r9Svk-L.jpg"]SCCAForums Image[/URL]
    [I]Left: 50.1% cross weights with driver. Right: Locking down the spring platform[/I]

    Quick alignment check:
    [URL="http://vorshlag.smugmug.com/photos/433499879_BZUxG-L.jpg"]SCCAForums Image[/URL] [URL="http://vorshlag.smugmug.com/photos/433500189_sNCg6-L.jpg"]SCCAForums Image[/URL]
    [I]Most corners were set at -3° degrees for initial testing[/I]

    Jarrett and Thomas turned the camber down to -2° all around for the first event, but both the skidpad pyrometer numbers and the outside edge tire wear suggest that more static negative camber would make probably the car faster and wear the tires more evenly. More testing will determine if its -2.5 or closer to the intial guesstimate of -3 that's the magic number. Caution: There is no perfect alignment that works on all setups. A change in spring rate, tire model/compound, or other tweak might make new alignment settings necessary.

    Fair
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    20 Feb 2009 10:07 AM

    Jan 31, 2009 update from co-driver and logn time Miata racer Thomas H:

    [quote]We had to roll the fenders today for the 15x7.5 Rota Slipstreams and 205/50/15 Toyo R1Rs. The car feels great but I think we could use some higher springs rates.

    I can't wait to try out the car at College Station. See you guys there.

    Thomas was right - additional spring rate did prove faster, but luckily (with a revalve) it didn't impair ride comfort.

    Fair
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    20 Feb 2009 10:09 AM

    [B]Update after Feb 7-8, 2009 Test/Race weekend:[/B]


    Here are Jarrett's thoughts after the first Test event / Race weekend in the car with the AST 4100s. We made some changes after the test event (see below) and improved the setup further. We like what we've seen and are moving to make this our default valving package and start production on 4100s soon.

    [QUOTE]Okay, we finally got an event under our belt with the new AST shocks and stiffer springs. I have good news, but first, let me give a quick run-down of myself and the car.

    I started autocrossing in my 1993 Mazda Miata at the beginning of the 2006 season. Since we have five clubs in DFW hosting AX events, I was able to get a lot of seat time. I raced in a local tire class (based on E-stock) for 2006 and 2007, switched to R-comps (and regular ES) in 2008, and decided to give STS (formerly STS2) a try for 2009.

    I started with an SCCA stock-classed Miata and made the following changes in the off-season to prepare for my assault on STS: Racing Beat front sway bar and end links (replaced FM sway bar with stock end links), Borla cat-back exhaust (replaced cheapie exhaust), Sutton Spec Miata Straight 1.6 Intake, K&N filter, aluminum underdrive pulley, Raceland 4-2-1 header, TDR heat shield, HP+ pads in the rear, HPS pads in the front, timing bumped 4 degrees, and most importantly, [B]AST 4100 shocks and coil-over springs[/B]. We are currently running Toyo R1R tires on 15x7.5 Rota Slipsteam wheels (the tires came on the wheels), but we plan to switch to Bridgestone RE11 tires before the Houston National Tour.

    One of the rules for converting the car to STS2 was that I had to keep it drivable on the street. Not only do I drive this car to events several hundred miles away, but my future fiancé and I enjoy occasional day-trips in the car. So, I could not make any modification that would compromise this rule. With that in mind, we originally went with 550 lb springs in the front and 350 lb in the rear when we initially installed the AST shocks. Based on my experience with my previous Koni Sport shocks (great shocks, for the price), I was concerned that even this would compromise my ride. However, I was floored by the ride with the new setup. Even with the stiffer springs, the AST shocks made the car ride better than stock!

    We used the autocross school hosted by the Texas A&M Sports Car Club on Saturday (Feb 7, 2009) and Sunday’s (Feb 8th) autocross event to test the car on a course for the first time. After testing on Saturday, we decided that moving to 700/450 springs would yield an even bigger improvement for Sunday’s event. Again, I was very apprehensive about the ride quality, but I again turned my car over to Terry and Brian’s (of Vorshlag Motorsports) capable hands on Saturday night to make the changes before Sunday. When switching to the new springs, Vorshlag also revalved my shocks so I only needed to run them at the half-stiffness level for competition. (I will let Terry or Brian speak to that, since I would only look foolish.) I could tell right away that the stiffer springs and revalved shocks did not hurt my ride quality on the street. It was the same, if not better. Again, I was just ecstatic that I could run such stiff springs with the AST setup and still have a great ride on the street. There is no way that I could have accomplished this with my old Konis.

    The car was incredible at the event on Sunday. While my normal co-driver (Thomas) was not able to make the Sunday event, I was able to pick up an abnormal co-driver (Brad) that morning. Watching Brad’s first run, I could not believe how flat the car was! Once behind the wheel, I was impressed by how responsive the car was and the sharpness through corners. It just felt so right and it was so much more fun to drive than my old “stock” setup, even on street tires versus my old R-comps. We won our class (I was less than a tenth faster than Brad). Since I had so many people tell me how great the car looked on the course it was not just my overzealous impressions of the car.

    The drive home was very comfortable and I have no regrets about my change to the heavier springs. At this point, I highly recommend the revalved (Jerrett-valving?) AST 4100 shocks with 700/450 springs on any NA Miata used in autocross competition. Just incredible, and I can only imagine how much better it will get with additional testing and seat time.
    ------------------
    Jerrett Jan


    Thanks for the report, Jarrett. Nice job on the 1-2 finish at the car's first event in STS prep!

    Big thanks to TurboTodd (a National level CPrepared racer) for loaning the Vorshlag crew and testers access to his shop the night of Feb 7th, which we were in College Station for the test/race weekend. We were able to revalve shocks and swap springs on several cars that night. The test facility at the TAMSCC event site is about as close to Nebraska's site (Nationals) as one could hope fore - the same vintage & size concrete airfield - and we'll be doing more testing and races there throughout the year.

    We were busy testing/prepping with about 8 cars and even racing in the event ourselves so we didn't get as many pictures at this event as we would have liked, but here are a few below we managed to snap the morning of the event, in the pits. As with all of our Vorshlag Test Pilots that send us pictures, this car has its own picture gallery on our website: [url]http://vorshlag.smugmug.com/gallery...;/url]

    SCCAForums Image

    SCCAForums Image

    Its so nice to see a car like this, that once had marshmallow springs & shocks and huge amounts of roll/pitch/dive, and turn it into a flat cornering, cone carving machine with just the right selection of parts - yet keep it civilized and usable for daily use. The myth is that you can't have both, but with higher end monotube shocks and proper valving you [I]can [/I]have your cake and eat it too.

    We'll make a point of putting the data logger in this car and snapping more pics and/or video of this one at the next event. The fresh Toyo R1R tires on the Miata felt SUPER SOFT - me thinks someone at Toyo has changed the compound. :-?

    Fair
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    20 Feb 2009 06:03 PM

    Just a few pictures of some new Miata shocks we're developing for 949Racing:

    SCCAForums Image

    SCCAForums Image

    SCCAForums Image

    These should be in production soon, along with AST 5300 triples and 5100 Singles. The 5000 series are modular and upgradable from single to double to triple adjustables. The doubles and triples have remotes and the Miata singles have remotes on the rear. More details soon.

    www.949Racing.com
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    22 Feb 2009 05:14 PM

    Terry,

    Got the Hyperco's last week. Anxiously awaiting my babies! They'll go right onto the car straight to the track. Anyone interested in the singles or doubles, shoot me an email or visit our homepage for more info. Once testing is complete and the Vorshlag guys tell me they're ready, we fire up production. Really excited that the modular project is coming together. I may just have to put triples on the OGK now.

    DFWmiata
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    22 Feb 2009 06:14 PM

    After driving the car on the 550/350 springs I'm really looking forward to driving the car on the new, higher spring rates. We'll be at the Texas A&M event on March 1st.

    It looks like we may be on 225/45/15 Toyo R1Rs for the Houston Tour. We've been doing all of our setup and testing on R1Rs and we don't want to rock the boat too much with a tire change right before the tour. I'm sure we'll try a set of RE11s this season sometime though.

    Emilio, I'm jealous, that setup looks great!

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