Aussie Autocross EV

galderdi

galderdi

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.
 
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.

 
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.

 
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.
 
20180311_163136_resized_1.webp 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.
 
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.
 
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.
 
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.
 
I placed 21st of 55 competitors (excluding those who did not complete the day). All in all it is obviously not what I had hoped for. But I did manage to beat 6 of the 11 Porsche entries. The result was to be expected considering how bad the understeer is. Plus this is only the second outing for the car so I think it is doing ok considering the stage of it's development. I have a heap of modifications planned for the next 10 days before the next event on April 29. Hopefully I can get the car turning by then.
 
I had a ball at the Lotus day at Lakeside yesterday. The car was very unstable and not quick. But the main purpose was another opportunity to test the car. The great news is I have gone from massive/uncontrollable understeer to massive/uncontrollable oversteer. This is great because it proves that I can overcome the handling issues and eventually make the car competitive in the autocross/khanacross events at least.


I did have to retire early with a split CV boot. Not a big deal as I already had plenty of information to work with.


Even with the handling issues I managed to place 36th from 55 cars. So I am confident with a few tweaks I can be dicing with the leaders in no time.










 
I have attached a couple of pics. One clearly shows the front suspension giving great contact with the ground but the rear is favouring the outside edge. It also shows the rear tyre pressure was a touch low which was a tactic I applied to increase the rear contact with the ground, with some success.


FB_IMG_1525036996189.webp FB_IMG_1525037002589.webp
 
I will be competing in the car at the Noosa Winter Hill climb this weekend. June 9 & 10. It is my first time to this event so I do not expect to be particullarly quick.
I will be #62. I will post some videos shortly after the event.
 
galderdi said:
I have attached a couple of pics. One clearly shows the front suspension giving great contact with the ground but the rear is favouring the outside edge. It also shows the rear tyre pressure was a touch low which was a tactic I applied to increase the rear contact with the ground, with some success.


View attachment 968 View attachment 969
Click to expand...
Good effort so far!

Can you bring some batteries forward - say put them in the side pods?
 
Hi Stuart. The batteries are as far forward as I was willing to risk. They are already in the side pod up against the front firewall. I wasn't willing to have them in the nose for safety reasons. But after my recent changes I beleive I have the handling under control now.


I had an good weekend at Noosa. The car was ok. The batteries are on the way out but still manage to give me enough to keep going. The car is awesome off the start line. But it struggled to get any top end speed. The handling was terrible at the beginning of the weekend but I made some changes over the two days and at the end it was coming good. The first few runs were so bad I was 100% focused on not crashing so I couldn’t learn the track. The last few runs I was able to actually drive the car and start focusing on making the most of the track. My results are not great but also not embarrassing and it was a great experience.




 
Hi everyone. Appologies for not posting for a while. It has been a heck of a journey (not implying it is over).


The car is coming along nicely. But it still isn't competitive. I seem to be hovering around the mid field in most results. Not bad in itself as I am usually up against some seasoned competitors in some goo cars. So as I usually say I am happy but not content.


The second last event of 2018 was the Noosa Hill Climb. It was only my second time at the event and I improved by 4 seconds. The car was still understeering but was managable. But the understeer prevents me from gaining too much confidence and holding corner speed. So I am still focused on improving that aspect of the car. Here is a video from that event:





The last event of 2018 was an autocross/khanacross. But it was very very wet which emphasised the understeer to the point where is was not managable. I don't have a video for that event.


I started with a check of all the suspension geometry including Castor, camber, king pin inclination, roll centres, toe in and Ackerman angle.
Castor was about right on the driver side but significantly more aggressive on the passenger side. This will be resolved as I complete the new front contro...l arms.
Camber, king pin inclination and roll centres were about where they need to be.
Toe in was correct but will need to be adjusted again as it will be impacted by all the other changes.
Ackerman angle was a little out on the passenger side but not enough to warrant a change in the short term. The driver side was out by a bit more and I have now replaced the adaptor plate to bring it in line with the passenger side.
I have made some solid progress on a second nose for the car. The first nose is for lower speed events where it is an advantage for the tyres to be in front of the nose. The new nose is sleeker, and will include a wing for additional downforce (maybe). The two noses are interchangeable depending on the upcoming types of events. The nose and wing are structurally complete and just need the panels to be added.
I have created some ballast in the form of a 10kg lump of lead. This can be added or removed depending on conditions. I intend to only include it in wet weather where the understeer characteristics seemed to be pronounced.
I have made new front control arms. These are designed to address the inequality in caster from left to right. They are also designed with a slight bend in the front bar of each arm. The bend is to improve the angle of the rose joint attaching to the chassis mount. I was concerned about the bend creating a weak point in the control arm. So you can see I added some significant reinforcing to ensure it can handle the forces.
I am also part way through a modification of the hydraulic handbrake setup. The existing setup has a single master cylinder serving both rear wheels equally. The braking capacity was insufficient to overcome the grip of the rear tyres. The new setup will have dual master cylinders opposing each other with a handle in between the cylinders. Pushing the handle forward will operate the right rear brake and pulling it back will operate the left rear brake. Operating one of the rear brakes at the same time as some mild acceleration should enable the car to perform very tight turns when required (one of the requirements it has struggled to satisfy in the past). The car will retain the cable handbrake for parking and as an emergency brake. I have created the adaptor brackets required for the modification but I will need a full weekend to install system, rerun all the hydraulics and bleed the system.
progress.gif
 
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