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AST 4200's - Initial Thoughts

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  • AST 4200's - Initial Thoughts

    Hey Guys,

    Just wanted to give my feedback on the kit, so far:

    Open the box: Dampers look great, adjusters are nice and easy to use. Rear spring perches don't have any locking mechanism (I thought this was weird) and there is no upper spring perch in the back. I really don't like the latter - The spring falls out and doesn't reseat in the same place every time.

    Love the adjustable swaybar mount, rear shock mounts are great and the long studs were excellent as I've got a home-brew RSM reinforcement in the car that is about 1/4" thick total. Front shocks/adjusters/Vorshlag Camber plates are great quality and went in without any trouble. Really nice to make sure there's no preload in the swaybar, and the fine-thread adjustments are excellent as well.

    Installation: Pretty straightforward, I've done this before. The front dampers are short - As short as the AD DA's I owned previously. I think the droop travel ends at ~stock ride height. No big deal because the car sits down at !~12.75" ride height, so there's plenty of usable travel in both directions.

    The rears went in quickly as well. The 7mm flats on the top have not been adequate for me to get good torque on the RSM's. I have had them loosen up twice, as I just can't get a good grab on the small 7mm flats. The front 8mm's were no sweat. Maybe I just need better tools.

    The rear spring setup is my main complaint. Very simple to install, but with nothing holding the perch to the control arm and nothing to center the spring up top except the body nub, there's a lot of room for movement/error there. I'd really like to see an upper spring perch similar to the GC style that can be zip-tied to the top of the spring and centers on the little nub, just for my own peace of mind.

    Initial driving: Wow. Did they give me the wrong springs? The ride is fantastic for 9/11kg springs (503lb/615lb for those of us that don't do the metric system). I had both damper settings at the minimum. Car feels really smooth over undulations, has just a bit of overtravel on larger bump/rebounds. Considering the spring setup, very acceptable. And not in even in the same league as the Advance Design junk I've experienced.

    After driving the car a ways, the dampers seems to get just a touch stiffer. Still a fantastic ride, but they feel just a bit more damped after driving. Not a negative, just something I noticed.

    Went for a little midnight marathon romp on some of my favorite backcountry mountain roads, and started turning the damping up to see how the car responded. The particular road that I chose is just-resurfaced, and very smooth, so I was able to really dial in some damping and feel the changes. I was blown away by the range of adjustability with these. The compression adjusters in the rear are kinda tough to grab when your fingers are cold and the hot exhaust is in close proximity, but I would imagine these will loosen up over time.

    Autocross: We had a practice event this weekend at a site that is, more or less, somewhere between a parking lot and a dirt field. It was paved... sometime in the 70's... And not since. Very weathered and worn, with a lot of loose gravel for the first run groups. We ran 4 runs in the AM and 4 runs in the PM, and my afternoon runs were much faster/smoother than the morning. The surface was fairly slick, and I was amazed at how much grip I gained by dialing a lot of the damping out to allow some weight transfer to the wheels that needed it. I've gotta go recheck the settings, but I believe I ended up with the following:

    F: 1C 2R
    R: 2C 3R

    I'm still wrestling a bit with the car's setup and may go back to the stock rear swaybar. As it is now:

    F:
    AST 4200
    503lb Spring
    28mm H&R Bar - Full Soft

    R:
    AST 4200
    615lb Spring
    24mm H&R Bar - Full Soft

    I have a little trouble with losing the inside rear tire on corner exit and getting power-on oversteer. I'd rather dial that out with a softer rear bar, but I may try stiffening the front first. Any guidance there would be fine with me. I also considered going to the stock rear bar and bumping up to a 12kg/670lb spring instead. Any thoughts on that?

    Overall, I am extremely pleased with the setup. I PAX'ed #1 out of 71 drivers at the practice event.. But next weekend will be the real test, as all the fast guys (John and Russ) will be there in STU competing.

    Just my initial thoughts. I'm going to make the last two Rocky Mountain Summer Series Autocrosses and I'm doing my best to make it to the PDX/Time Trials in late October. I would really like to get out on track and run the ASTs and see how they compare to Brad Huseman's TCK Doubles. We've run there before and were very close.

    Comment away!
    Last edited by Chris; 09-10-2007, 05:27 PM.
    Chris
    97 M3/4 - STU
    06 Evo - SM
    00 S2000 - STR

  • #2
    Re: AST 4200's - Initial Thoughts

    Chris,
    Re: Rear springs/perches

    Put the adjuster on the top and run a stock spring pad on the bottom. You shouldn't have any issues with it unseating. We've put many miles on this setup and never heard a spring pop or move. Seems to work fine.

    The reason the perch doesn't have a set screw is that the screw actually ruins the threads over time. The perch on the rear won't move once loaded so they are fine. The fronts would move without a clamp since the strut body has to turn.


    I'd run more rebound front and rear, like 6-8 clicks in the front, 5 rear. Turn the compression down (like you have it) for bumpy lots and up 1/2 way for smoother road courses.

    Rear shock mounts don't need more than a 7mm and 22mm hand tools to be tightened. They don't need much torque.

    You shouldn't have issues "losing the inside tire" with that setup. Could be a tired diff? Make sure you run about 1/4" toe in in the rear too.

    Glad the setup is working. Thanks for the feedback!
    Last edited by hancheyb; 09-10-2007, 09:34 PM.
    Brian Hanchey
    AST Suspension - USA

    Comment


    • #3
      Re: AST 4200's - Initial Thoughts

      I don't think it's a tired diff, if anything it seems surprisingly tight for the mileage. The problem started when I went to the stiffer rear bar, it feels like it unloads the inside tire on-throttle and the back end starts to slide. Great for showing off, not so great for putting power down.

      I'll try flipping the adjusters. It still seems like there should be something there to center the spring a little better, but it will probably make more sense when I see it flipped, maybe it's unnecessary.

      I'm expecting to use more damping at the next event site, I'll try dialing in some extra rebound over this week and see how it feels.
      Chris
      97 M3/4 - STU
      06 Evo - SM
      00 S2000 - STR

      Comment


      • #4
        Re: AST 4200's - Initial Thoughts

        1/4" toe in for the rear will probably fix your issue. -2.0* of camber in the rear. Also, make sure that new bar isn't binding. Grease up the body side bushings.

        Adjuster won't be an issue once you swap it. The adjuster base has a mating conical shape that works well with the "nub" on the chassis. We've run daily drivers like this for 4+ years without any issues.
        Brian Hanchey
        AST Suspension - USA

        Comment


        • #5
          Re: AST 4200's - Initial Thoughts

          To check the effectiveness of the diff jack up one side of the car, and with the E-brake off and out of gear try to rotate the rear tire that is off the ground. You can use a torque wrench to check break-away torque as well. I'm sure there is a spec somewhere... but just rotating the wheel by hand and checking resistance should tell you a lot.

          If you car has any sort of miles on it and the diff has never been rebuilt...
          Terry Fair - www.vorshlag.com
          2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
          EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

          Comment


          • #6
            Re: AST 4200's - Initial Thoughts

            I had the car in the air tonight - I can't rotate one rear tire with the other on the ground, at least not with the amount of force that I can get on it.

            I swapped in the stock rear bar while I was flipping the ride height adjusters over. I like that setup better, but I would still really like to see something that locates the spring in exactly the same place on the bottom side as well - I have a suspicion that the corner weighting may change just from the spring sitting down in a different spot every time you jack the car up. Like I said, not a big deal, but it's something I would like to see.

            As for the handling - Putting the stock swaybar back in the rear fixed all my complaints about the car... The handling is absolutely FANTASTIC now. I have several problems with the H&R rear bar (the hole it was wearing in my spare tire well, the rub marks on the LCA's, etc) and it's certainly possible that it was binding too.

            I set the dampers up with a little more rebound (setting 6 front and rear) and left the compression alone, I believe it is on either 1 or 2 on both ends. Car feels great, balanced, and extremely driveable with no fear and I can put gobs of power down with no understeer.

            Now I'm really excited for this weekend's autocross!!

            edit: woops, didn't know there was a swear filter.
            Chris
            97 M3/4 - STU
            06 Evo - SM
            00 S2000 - STR

            Comment


            • #7
              Re: AST 4200's - Initial Thoughts

              Originally posted by Chris
              Now I'm really excited for this weekend's autocross!!

              edit: woops, didn't know there was a swear filter.
              It's a censorship filter on words they don't want others to use like Chevrolet C a p r i c e or C****** - "only my most favorite car in all the world."
              Toth: "I would sue Duck, but I don't know what I would do with 3 pennies and a hoopty GTO."
              Me: "I never finish anyth..."

              Comment


              • #8
                Re: AST 4200's - Initial Thoughts

                One more observation:

                I checked camber front and rear last night, and with the camber plates at their minimum setting, I currently have -2.5 F/-1.6 R Camber. With the plates pushed all the way in, I'm around 3-3.5 degrees I think (my gauge doesn't read that high, and I'm too lazy to measure and do the math).

                Is it worth losing the caster to gain even more negative camber up front?

                I don't feel like the car is missing grip in the rear, but you're suggesting more rear camber... Something I will experiment with in the future.
                Chris
                97 M3/4 - STU
                06 Evo - SM
                00 S2000 - STR

                Comment


                • #9
                  Re: AST 4200's - Initial Thoughts

                  Originally posted by Chris
                  Is it worth losing the caster to gain even more negative camber up front?
                  How much camber do you need going straight?


                  Costas

                  Comment


                  • #10
                    Re: AST 4200's - Initial Thoughts

                    Had my first real event on the coilovers this weekend. I'm definitely happy with the overall results:

                    T 1. 26/STU Russ Johnson Denver, CO 54.357 964 03 Mitsubishi Lancer Evolu
                    T 2. 94/STU Chris Mayfield Fort Collins, CO 54.772 957 97 BMW M3
                    T 3. 81/STU Gary LaRock Thornton, CO 55.565 943 04 Subaru WRX STi
                    T 4. 66/STU Rick Walford Colorado Spring, CO 55.785 940 95 BMW M3
                    T 5. 11/STU Wiggy Greacen 55.975 936 04 MITSUBISHI EVO
                    6. 111/STU Donour Sizemore 56.258 932 04 MITSUBISHI EVO
                    7. 106/STU Jon Pomrenke Taylorsville, UT 56.388 930 05 MITSUBISHI EVOLUTION
                    8. 194/STU Tyler Neff (N) Fort Collins, CO 56.525 927 97 Bimmer M3
                    9. 25/STU Robert Dillon (N) Canon City, CO 58.017 903 07 subaru WRX STI
                    10. 6/STU Robert Irish (N) Salt Lake City, UT 58.420 897 05 Mitsubishi Evo VIII RS
                    11. 68/STU Bob Parkin (N) Golden, CO 59.021 888 07 Subaru STi
                    12. 166/STU Pat Holmes , 59.582 880 95 BMW M3
                    13. 60/STU Steven Hahn (N) Denver, CO 60.794 862 95 BMW M3
                    14. 37/STU Jean Riley Edgewater, CO 61.371 854 04 Subaru STi

                    2nd in a sea of AWD Turbo buggies. I turned a 54.4xx my only fun-run after the event, and I'm really not prepped for the class... So I'm pretty pleased. There's usually 1.5 - 2.0 secs between Russ and I. I wish John hadn't blown up a rear shock on the way down, as I think he would've been faster than Russ on this course. It was a very BMW friendly course, lots of sweepers and only one big dragstrip for the turbos to stretch their legs.

                    The car was still pushing more than I'd like, but i discovered after the event that I was running less damping than I thought. I'm going to try stiffening up the swaybars front and rear and do some testing to see if I can find a little more balance in the setup without drastic changes. Eventually I think I'd like more spring under the car, but for now it works alright.

                    Very very happy. Its nice to finally see the car (and the driver) getting a little more competitive. I think with 255 or 265 rubber under the car and the extra weight loss from a new exhaust and seats, and I could probably put up a good fight. Right now I'm only running 245s on 8.5" wheels, and the car weighs 3090 without me, and with approx 6 gals of fuel. I also got fuel starvation at an autocross for the first time last weekend. These cars' fuel pickups really suck (not literally).
                    Chris
                    97 M3/4 - STU
                    06 Evo - SM
                    00 S2000 - STR

                    Comment


                    • #11
                      Re: AST 4200's - Initial Thoughts

                      Originally posted by Chris
                      I wish John hadn't blown up a rear shock on the way down, as I think he would've been faster than Russ on this course. It was a very BMW friendly course, lots of sweepers and only one big dragstrip for the turbos to stretch their legs.
                      I'll be there for the October event... either with new AST rear shocks or a co-funk-ulation of Koni / AST as I need one more event to make 7 for the series.

                      Good job ... although you still should have let me codrive

                      Comment


                      • #12
                        Re: AST 4200's - Initial Thoughts

                        Originally posted by John in Houston
                        I'll be there for the October event... either with new AST rear shocks or a co-funk-ulation of Koni / AST as I need one more event to make 7 for the series.

                        Good job ... although you still should have let me codrive
                        Had I not already committed to another driver, it wouldn't have been a problem. You should've asked Russ, he offered!

                        I need exactly 5 points to beat Rick for the season. I think I can do it.
                        Last edited by Chris; 09-18-2007, 10:08 AM.
                        Chris
                        97 M3/4 - STU
                        06 Evo - SM
                        00 S2000 - STR

                        Comment


                        • #13
                          Re: AST 4200's - Initial Thoughts

                          Originally posted by Chris
                          I need exactly 5 points to beat Rick for the season. I think I can do it.
                          And on Sunday I did just that. Hehe!

                          I beat John too Mostly because he adjusted his dampers backwards, I suspect.

                          Got a chance to try out some new shock and alignment settings this weekend. I'm much happier with the balance of the car now, and once I finally cranked the damping up some, they really have come alive. The car felt extremely tossable and easy to drive. I had a little too much rotation for anything faster than autocross, but it felt great there, very easy to drive fast and NO understeer.
                          Last edited by Chris; 10-08-2007, 08:02 PM.
                          Chris
                          97 M3/4 - STU
                          06 Evo - SM
                          00 S2000 - STR

                          Comment

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