Aussie Autocross EV

Discussion in 'Other EV Racing' started by galderdi, Mar 12, 2018.

  1. galderdi

    galderdi New Member

    Hi,

    I have been watching the forum for a while and decided I should introduce myself.
    I have recently built my second EV for short ditance time trial style racing. Mostly this is Motorkhana (similar to Gymkhana), Khanacross (similar to Autocross) and bitumen hill climbs.

    I am the only EV competing in my sport here in Australia (at this time)

    The first car was pretty good but I was losing a lot of the advantage due to wheel spin resulting from it being front wheel drive.

    The new car solves that problem but I still need to sort out the handling and braking as the weight distribution is significantly towards the back. I have only had the new car at one event so far. The brake bias is wrong and it was understeering significantly.

    The car is a home made chassis with an advanced DC 8 inch motor, Zeva 1000amp controller and 7kwh of Chevy Volt batteries. It runs through a 5 speed front wheel drive gearbox but mounted just in front of the rear wheels.

    I'll post some pictures and videos shortly.
     
    Domenick likes this.
  2. galderdi

    galderdi New Member

    20180211_052654_resized.jpg

    Ignore the front wheels. I was just using these during the build.
     
  3. galderdi

    galderdi New Member

    I am still working out how to post an embedded video but here is a link until I work it out:

    This is from the first event in this new car. On this day I had not yet installed a clutch pedal so I was forced to launch in 2nd gear. The car is understeering quite badly and will require some adjustment to make it handle correctly. The next event is on April 15 so I should have it performing a bit better by then.

     
  4. galderdi

    galderdi New Member

    Well that worked better than I expected. So here is another video from the same day:

     
  5. galderdi

    galderdi New Member

    and one more video for good measure.

    This one is a 360 degree video and is best viewed from a mobile device. You should be able to point the view in any direction. If it looks like the wheels are pointing in odd directions it means your device/browser can't handle 360 degree videos.

    There are plenty more videos from that day and previous events but I will leave it at that for the moment.

     
  6. Domenick

    Domenick Administrator Staff Member

    Welcome to the Forum, and thanks for sharing all that.

    I have to say, yours is the first car I've seen that uses a katana for a brake lever.
     
    galderdi likes this.
  7. galderdi

    galderdi New Member

    20180311_163136_resized_1.jpg Thanks Domenick. It turns out it was really only designed for show. It snapped the first time I tried to test it. The handle was made from flimsy balsa like wood.
    I am in the process of making a replacement handle from solid steel. I am confident I can replicate the effect by reusing the cover over the top of the steel once I finish shaping it. I'll post some pics of the finished product in a couple of weeks.
     
    Domenick likes this.
  8. galderdi

    galderdi New Member

    Just a quick update. During the first outing the new car demonstrated noticable understeer, front brake lockups, slow steering and slightly reduced launch speeds. All of these were expected at this stage in the development.
    • The understeer and front brake lockups are due to the lack of weight over the front wheels.
    • The reduced launch speed was because I have not yet installed a clutch pedal and master cylinder resulting in the need to launch in a higher gear.
    • The slow steering is because I have not yet modified the steering to speed it up.

    I can't do too much about the weight distribution, although I have added a second auxillary battery in the nose. This adds another 7kg to the front of the car.
    This past wekend I altered the front suspension pivots to substantially soften the front. I added some more caster and some more negative camber to the front both of which should increase front grip during cornering.

    I still need to:
    • Reinforce the panels around the brake pedal to give a stiffer feel
    • Add a brake bias adjustment to send more pressure to the back brakes and eliminate the front brake lockups
    • Add a steering quickener to speed the steering rate
    • Make and install a hydraulic clutch conversion
    • Finish and install the replacement handbrake handle
    • Make an adjustment to the ackerman angle
    The first 5 of these modifications must be complete before my next event on April 15th. I will provide another update before then.
     
    Domenick likes this.
  9. galderdi

    galderdi New Member

    I still have some fairly significant adjustments to complete. I have made some progress but have stumbed on a few items like having a bolt stuck in an awkward spot and needing to "easy out" it. Plus this little issue has meant I needed to order in some replacement bolts. I have also had some clearance and width issues etc with the latest steering rack. I have finished the new handbrake handle. I have also finished the brake bias except I have not filled the fluid, adjusted or tested the system (due to the missing bolt).

    I only have one more weekend to sort it all out before my next event. The next event is a motorkhana on Apr 15. Followed by a khanacross hosted by the Lotus club on Apr 29. The lotus day in 2017 was my favourite event so I am really looking forward to this day. But I really need to have the car dialled in to have a good showing. There will be some top end Lotus and Porsche cars competing so I will be very happy with any place in the top 25% of the field.
     
    Cypress and Domenick like this.
  10. galderdi

    galderdi New Member

    We had an interesting event yesterday. It was the Motorkhana round of the Interclub challenge. We ended up with 60 entries which was our biggest in a very long time. We had a good turn out from the Porsche, Lotus, MG and MX5 clubs. But we were off to a rocky start as the Venue management had double booked us. So we had to alter our plans. It meant that the complex tests I had been memorising for the past 3 weeks were off the agenda.

    My car was a real handful. I had run out of front steering adjustment during the wheel alignment last week. This left the car with significant Toe in on the front. This made it very twitchy and added to the understeer issues. It also became quite clear the handbrake will not be able to break traction as there is too much weight over the rear wheels. This isn’t an issue for the sweeping style tests but for the tighter ones it makes it very difficult and uncompetitive. You can see this in the 5th video. On the positive side the car’s acceleration was awesome as you will see in the 3rd and 4th videos. Plus I can now see that solving the steering properly may make all the difference to the car.

    So the short term plans are:
    • Complete the Ackerman angle modification and shorten the steering arms prior to the Lotus Lakeside day on April 29.
    • Connect the Clutch pedal so I can change gears for the Lotus Lakeside day on April 29.
    Long term:
    • Make new upper control arms for the front to provide more caster adjustment and improved range of movement.
    • Install fiddle brakes to enable separate left and right braking to swing the car around the really tight corners.
    The results from yesterday will probably be released tomorrow morning.
     
  11. galderdi

    galderdi New Member









     

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