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Tuned Class AR (My first build in 20 years)

Discussion in 'AR / FMAR' started by ltr74, Nov 24, 2017.

  1. ltr74

    ltr74 FRP H-Bar

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    This is a work in progress as I have been figuring out what parts are available and watching lots of Youtube. But it's been a while since I did anything Mini 4wd. I picked up the AR Speed Spec starter pack about a month ago and between old parts and a couple of purchases, I'm hopefully going in the right direction. There are a few upgrades I already know I need based on some brief testing a few weeks ago, but here's the pics. Hopefully I get some more track time tomorrow to see how it performs.

    IMG_1574.jpg IMG_1575.jpg IMG_1571.jpg IMG_1573.jpg
     
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  2. ltr74

    ltr74 FRP H-Bar

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    Managed to get some time in at DXN Provisions today. Great shop and super nice people, apparently we raced at the same places in the 90s. Got the kinks worked out of the handling and it seems really stable, maybe too stable. I think it's a bit slow though(I really should have timed it) and I'll likely chalk that up to new batteries that have not hit the charger to top off.

    Next up is pulling it all apart and making sure everything is running smooth and some drivetrain improvements.
     
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  3. Dxn Provisions

    Dxn Provisions Moderator

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    Thanks for swinging by and showing me your high speed monster truck ! Giving me ideas.... haha
     
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  4. ltr74

    ltr74 FRP H-Bar

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    No problem. I want to get mine running again just for some fun. Since i'll likely need a new chassis to get the battery clip, I may just build a new one. With the newer parts, I'm sure I can work out something stronger than gluing the battery box.
     
  5. ltr74

    ltr74 FRP H-Bar

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    I should really start a Wild Mini thread, but browsing eBay, I saw the one way wheel set you need to make the special gearing. The auction is horribly over priced, but those mustard one ways have the 16 tooth gear you need.
    https://www.ebay.com/itm/Tamiya-Min...777559?hash=item1a3afc85d7:g:QmMAAOSwopRYlqDM
     
  6. ltr74

    ltr74 FRP H-Bar

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    Well, first race came and went. I'm relatively happy with the results, got to the semifinals before being eliminated. Checked out some my competitors and figured a few things to improve.

    One thing I noticed was my car was heavier than what I've seen on some videos, I know Tamiya class allows cutting everything so that is some of the weight savings, but I still had room for improvement.

    Weight savings included:
    switching front under guard from rear FRP stay to carbon 13/19 popsicle
    removing unnecessary screws and nuts
    Removing aluminum spacers on front stabilizers
    reducing weight of front mass damper
    replacing plastic body with poly body

    This managed to drop the weight of the car from 142 to 121 grams (my scale kinda sucks for 1 to 2 gram changes so weights are approximate). The last two weight savings were the biggest, but even the first three saved somewhere around 5 grams.

    In addition, I need to corner faster. The car is already really stable so not too worried about changes. I've brought the rear rollers forward and tried to move the front rollers back, but the under guard will likely hit the track so I need to sort something out. I also upgraded to carbon wheels and went with a set that makes the width from wheel to wheel the narrowest, again hoping to improve corner speed. The rest of the changes will have to wait until after the holidays.

    Onto the next race at DXN this weekend!

    Current setup:
    IMG_1606.jpg
     
  7. warwick

    warwick Spacer

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    Nice. For faster cornering use smaller roller and make sure your roller closer to your wheel
     
  8. ltr74

    ltr74 FRP H-Bar

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    That is the plan. I have a box of parts including everything I need to make those changes waiting for me when I go to Japan for the holidays. Don't really want to spend the $35 or $40 to make the changes when it's only one more race before I can get the parts I already bought.
     
  9. Drew

    Drew Carbon Fiber Dust

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    I really need to make simpler builds like this rather than keep messing around with the cars I keep making...
     
  10. ltr74

    ltr74 FRP H-Bar

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    I like the more advanced Tamiya class cars and the complexity as well, but I'm just getting back in and somewhat time and resource limited right now so focusing on this one car until the new year. After New Years, I have several projects I want to work on including a Tamiya class car.`

    The tuned class is one where you can almost go all out without having to hold back in certain areas. I don't really have brakes on the car. There is brake sponge, but all of it is covered with Tamiya tape to act as a cushion more than a brake. My car started out as nearly copying Mad Tang's AR chassis videos without the frp/carbon cutting. His videos were Tamiya class so there seemed to be a bit of concern with strength and stability with the faster motors. I'm really just taking his ideas and going minimalist, lighter weight and trading stability for speed since I'm motor limited.
     
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  11. ltr74

    ltr74 FRP H-Bar

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    Well, much more competitive at the DXN race. 5 lane race with digital turn and a beast of a bouncing jump. Easily won my first race then in the semifinals was leading until I crashed out on the digital turn(first crash out there in maybe 25 practice/race laps).

    Was really happy with the performance of the car. The jump was the biggest problem and it was rather unpredictable each time. Sometimes landing perfectly, others less perfect, but it was the same for everyone. Digital turn really posed no problem until I crashed out. Two things I could see causing it. First, I should not have topped off my batteries before the semi, they were higher voltage than my first race. Second, I'm using a slightly smaller than ideal white disc for my front stabilizer. The correct size may have made a difference. Third, I could have used slightly more weight on the front mass dampness which may have helped keep the front end down.

    Anyways, that's it for my racing for the year. Off on a couple of vacations then back for 2018 with new parts and another couple cars.
     
  12. ltr74

    ltr74 FRP H-Bar

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    Well, I thought I was taking a break until after the holidays, but after seeing the pictures from the race, I decided to start a project I wanted to try with tuned class rules, making a body damper system. There were examples of both front and rear systems in the tuned class winners picture, though both were MA/MS chassis. Setting up a front system on the AR chassis was actually super easy and only a couple extra pieces were needed from the standard side mass damper set.

    IMG_1724.jpg

    IMG_1729.jpg

    IMG_1728.jpg

    IMG_1731.jpg

    I still need to pick up another pack of lock nuts to secure some parts and trim/mount the body, but I think it will work out well. Also, will likely get longer screws to add the weight as I still have about 3mm until I'm at the minimum ground clearance. With these pieces, there are two choices for mounting the FRP at the back, I'm currently using the slightly further forward but single screw. After testing, I may have to move it back a millimeter or two and use the double screw mount to keep the bar from shifting to the side. On the other end, the mounting point to the chassis is slightly higher than level but I don't know how much of a difference it makes. Once I add a little padding to where the FRP sits on the chassis, it should even itself out though.
     
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  13. ltr74

    ltr74 FRP H-Bar

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    Third race and this car is definitely quick! Only managed the semi-final again, I really should have charged the batteries. It was a speed tech track with a tabletop with two straights then the drop and two more straights before the corner. You either needed to clear the tabletop and land on the downslope or land really early so your car was settled for the drop and the turn. If you landed close to the drop, you were unsettled and likely to come off the track, which was my trouble in the semifinal, I was clearing the tabletop before my batteries dropped in performance.

    The body damper worked great. The body is not the best on it, but not sure if I want to stick with it as I see so few Astute cars out there or switch to the most standard Thundershot which sits better with the damper. Even without getting to the final, I'm super happy with the performance, not sure I'll change anything else.

    IMG_2098.jpg IMG_2097.jpg
     
    Last edited: Jan 20, 2018
    Drew likes this.
  14. Lucky Lou

    Lucky Lou Screw

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    When I get some time I want to do some racing over at Dxn. Is this version of your build still considered tuned class at Dxn?
     
  15. ltr74

    ltr74 FRP H-Bar

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    Hi, so rules have changed a little and body dampers and car catcher material has been banned from tuned class. This helps make the class much more of an intermediate class and makes it different from Open/Tamiya class.

    I have not raced tuned recently due to focusing on the points series for open class. but the pictures below is my tuned car. It is very close in design to another racer who has been doing very well in tuned recently. The nice thing is that it is simple and straightforward to build and runs well on a variety of tracks.
    IMG_2441.jpg IMG_2442.jpg IMG_2443.jpg
     
  16. Lucky Lou

    Lucky Lou Screw

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    Nice build. Love the simplicity. Looks like no chassis cuts either.
     
  17. Corweena

    Corweena Spacer

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    Similar you say? LOL

    [​IMG]
    [​IMG][
    [​IMG]
     
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  18. ltr74

    ltr74 FRP H-Bar

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    Thanks, I've tried some other chassis, but the AR chassis is super simple to set up so less time making sure everything is correctly set and not damaged. An no cutting at all, I could trim a little but it's not needed for roller clearance anywhere.

    Once I start racing tuned again, it will likely look even more similar. I just need \some dedicated track time to test the different tire compounds and such. We need someone else to make an AR vanquish tuned so we can have 3 copy cars on the podium!
     
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  19. Corweena

    Corweena Spacer

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    Down! If you want to do side by side runs, let me know!

    This is my 3rd attempt at a Tuned AR chassis, and finally hit the sweet spot with it. 3 podium finishes in 4 races with it since its rebuild. There is very little I change between races now. First is tire compound. I'll mix and match between gray hard tires, Super Hards, low friction, and the new silver super hard/low friction combination, depending on the amount of grip/slip I need.

    Only other thing I change is the brake setup. Adjust the height of the rear, and swap between either a plastic front underguard, or frp with brake sponge as shown. Pretty much everything else stays the same.
     
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  20. Lucky Lou

    Lucky Lou Screw

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    When would you choose plastic under guard over frp with brake sponge?
     

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