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Hi Richard,

We've met before on SBG.  I am also doing the PBSRC this year.

I have been watching your videos and it looks to me like you have a problem with lift from that body (you may already know that).  That rear wing might be helping with a little downforce at the rear, but I suspect you are getting lift at the front that is making the car go unstable at speed.  (The air flow is probably separating over the rear window at speed and making the rear wing less effective also).

Years ago I had a Ford Escort body that behaved the same way.  I never could get it up to speed without spinning out.  At the time I didn't know why, but later in life I discovered the reason.  This is also a problem that faces 1:1 race cars too.

You might try raising up the rear of the body a little to give it some more rake.  Maybe also raise up the rear wing to get it above the disturbed air flow over the body.  Another possibility, perhaps a crude solution, but maybe add some ballast to the car to keep it on the ground.

Hopefully you can get it figured out and get the most out of that car.  Right now you are running about 20mph faster than me, so I have some catching up to do.

Nick.

Hi Nick!

Great to see you here!

I had several issues that I think have causes my crashes.
#1. Bearing failure at right front wheel. This caused the chassis to rotate to the right at certain speed. Before that it was left side every time
#2. My rear wheels/hexes did not run true. I suspect the vibrations made it fly off when it vibrated too much, and maybe made the tire to grove at the same time.
#3. And recently I found the front upper arms (M chassis to move about 3mm on top as it only hinged through one bolt. I got parts today to add a second upper arm to form a A like suspension arm. I hope this will prevent the suspension to move front to back.
#4. Also found that the drag brake did not work at all for me. All first times I crashed the drag brake was on. As soon as I removed that it started to go straight (my 70mph run).
#5. Brakes too strong, or rather the ABS. It's now adjusted to -1 on my Radiolink RC6GS. (negative is for low grip surface, or too strong brakes in my case). I will adjust this to -3 which is the highest value for low friction surface in hope it will not lock the tires. In my 70mph video you can see it got my speed down then the rear end slid out and I ended in the ditch at low speed.
#6. My brakes are set to 20% at the moment. If it still locks up at -3 ABS I will try 15% brakes. If that works I might add brakes sooner and brake near full trigger without slide out.
#7. If the above still makes the the car liftoff I will add canards on the front (from the spoiler cut off, which is a grey area, but should be allowed as it was part of my body.

In the end I hope to do 100mph+ if it stays on the ground and I have enough brakes. More brakes are out of the question, But I can turn down the ABS pulses to make the ABS weaker if I need to.

Good luck Nick and I hope you will get the speed up.
Please leave your YT channel link here so I can follow you 

Yesterday I recived the M05 C parts.
Mainly needed the long body post for the rear since I can't raise the rear of the body any more.
And also the rear upper links..


I needed those upper arms to build a sort of A arm to support the c-hub. Now there is next to zero slack.
Stabilizer is also M05


Need a bit more downforce on this body.
This the wing for the Zakspeed body.


From the off cut of that wing I made canards. A bit hard to capture.




These mods should make it more planted and stable.

My lower back is no good today so it might take a few days before I attempt another run with this.


 

Keep safe my friend. 

It will be interesting to see what effect those changes make.  Hope your back gets better soon - that's no fun.

My videos are posted here, in case you want to see them:
@fab1ten at youtube  (it won't let me post the actual link yet, as I am a newbie)

I tried a new motor yesterday, but it seemed to be only a little faster.  I also had trouble keeping it straight under braking and rolled into the bushes on my fastest run, so I didn't even get an official run to post.  I will try again tomorrow...if I can get up the nerve.

Nick.

What a contraption!
Love it!
Would never got the idea of making a ORV chassis a 3 wheeler in million years.
Clever stuff!

Back is a bit better today.
Due the current heat (31-32C, 88-90F) there will be no run today or tomorrow. Maybe on Friday.

Glad you like it.  I tried to be a bit different.

I managed to break into the 50+ mph bracket yesterday with a 52.5 mph run on 2S brushed.  The car ran straight and true this time - no encounters with vegetation.

Nick.

Time for an update.

Before the run on last Friday I did a few changes.
# Replaced the rear body post as the hole for body clip was ripped apart. Without knowing it the M05 rear body post is not the same as I used before. After cutting off the bottom hole it would not fit the chassis so I swapped for TL01 short angled ones.
# Rear hexes removed and replaced with the Toomod 15mm ones I used on Hornet last year. The old wheelhexes was not straight enough.
# Replaced the HPI 31MM wheel and tire with HUDY touring wheel tire combo with 36 shore rubber as HPI ones was bent.
# Replaced the servo for a Power HD 15kg alloy servo as I suspected it was glitching at certain power draw.
# Adjusted BEC on esc to 7.4V.
# Swapped to to 49/19 Frog gears.
# Locked diff (glued with green Loctite)
# Fitted front wing up front. The old rear Zakspeed wing.

Together with proper rake and the installed front spoiler I was ready for a new run.


Lower part of spoiler was installed at same hight as the body front spoiler to keep the airflow going over the body, hence no lifting of the front.


Used the shortest leaf springs I had as I needed the spoiler to go forward and down a bit.


And installed support rods to stiffen the body. Because of all the cracks/splits the body had become a bit floppy.


Then the run.
Car did go much much straighter than before and the front end kept down for once!!!
But there was a lot of wind and I did not want to steer too much, and before I konw it, it was too late and car took epic forward flips, at 73mph that is!
Would be a new PB if I did not crash...



From that crash it take out the whole spur gear and bent the body support rods and ripped off the wires for the front ledlist.

Here is what the 49t Frog spur looked like


Gears and servo savers so far this year...


Supports are now fixed and the spoiler is now installed again.




There is cracks where the rods for the the spoiler goes so I used the bent leaf springs from the earlier spoiler mounting as spacer to spread the load.
Spoiler is now secured by leaf spring shackles.


And it's ready again!
Last deadline is Friday 9.00 PM Oslo time (12.00 PM LA time), so hopefully I get some good runs this last week of Poor Boys RC speedrun challenge.
Currently I sit with 70mph (112.65kph) and 9th place. I would like to improve on that.
With the current 63mm tires the top speed is calculated to 108.6mph (174.8kph). 3 digits would be nice, but I hope at least 90mph+ in the end of the day...

That looked a lot more stable this time.  Hopefully you can keep it on the ground for a valid run.

My week 4 runs all ended up in the weeds, so I had nothing valid to submit.  I am not sure exactly what the issue was, but my car was very unstable at speed, which it hadn't been before.  It might have been the aerodynamic changes I made, or I messed up the gyro setting unintentionally.  Anyway, I hope to make it better this week - last chance (not that I am anywhere close to winning!).

Nick.

Yeah this challenge has been difficult.
Saw you new PB run with the new rear section. Looked very good!


On Wednesday was going to one of my last attempts.
Found a new section of road being made about 30min or so from me...




Should have known better...
You can bet if there is curb or rockbed like the above along the road, I will hit it!
And I sure did!
First one I slid off at low speed, no damage...
Second one tho...
Crashed at 60mph ish...
Motorfan broke and smelled burnt.
Also broke the bodypost support (rod end that goes over the post)


I lost my last short gearbox joint, so I had to run with hex driveshaft at one side to be able to run again...


Thursday night I took the whole chassis apart to replace the frame rails as it now would not track right after the last crashes.


Hard to see but there is stress damage. More livid in real life.


Replacement chassis, thankfully I have several sets of those in my parts bin 


Everything looked straight afterwards


Then it was ready again after 1.5 hours of wrenching...


Very early in the morning on Friday I traveled 1 hour to the a spot I knew has perfect asphalt and little to no traffic.
First issue was that I had not put the driveshaft into the wheelaxle so I had to take off the trailing arm, easy and quick fix.
Next I did some testing to see it worked as it should after the repairs..
First pass and it slid off the road right after it started so I had to walk for a bit.
Was just 9C so it was freezing in a thin hoody.
Then I tried again and it got up to speed and as it passed me it nearly become a nasty ankle biter and hit the only object in the ditch. A raised manhole for water valves I belive.
My speed during that crash was 70mph, which is same as my previous PB.
Bent front spoiler and body, bent body support rods and broke the battery holder for my lights (lower part of TT02 receiver box).
Support rods was bent back to shape then I noticed both of the metal rod ends of those support rods that mounts to the front spoiler was bent.
As I tried to bend it, it snapped. Ofcourse in my spare part box there was no extra rod end. So I had to drive home again.
Being up all night ment I hit the bed as soon as I came home.

Friday night was my last chance, so I thought at that moment.
Did several passes, and the first pass was new PB, but I did crash.
80mph was my new PB


And here is the crash video at 80mph which is 128.75kph.


I missunderstod the deadline so instead of being 09.00 in the evening Friday, the actual deadline was 12 hours later, 09.00 in the morning Saturday local time (12.00 midnight pacific time was the deadline at the host end).
So I stayed up all night again, repaired the car and headed out 7 in the morning.
Another morning with sub 10 degrees, was cold.
Sadly all my attempts ended in crash. It was unstable, body has become bendy due all the crashes so it needs a fresh roll of drywall tape and a coat of HUDY bodyfix to fix that.
Did not have time to fix it and my current drywall tape is no good.


Since my 80mph run is not approved due to the crash, I'm standing with 70mph as PB on the scoreboard in brushless class.
That was just enough for 9th place in brushless class of 33 drivers.

And here is the final scoreboard Sunday video


Next year I'm thinking of moving to open class as there is next to no rules and you can make your own parts. Just need to use the chassis specified for that year...