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Old 08-31-2009, 06:33 AM   #1
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Default A bad day at the track is better than a good day at the office...

Or is it?

(Alternate title: Rookie mistakes!) Hopefully y'all can at least get a chuckle at my expense... and it WAS expensive, as you will soon see!!!

I had a fairly unfortunate chain of events (mostly self-created) that ended up being relatively expensive over the past week... We spent the past week getting ready for the RC Pro South round 3 race in Bossier City.

Since I was down to one good engine and wanted to try something different, I was breaking in a new modded Novarossi BF21 Limited. During break in we were having a little trouble getting it to idle well (just a VERY tight engine with a finicky tune... no big deal...) Unfortunately, every time I touched the throttle it would kill it also, so it was a bit frustrating.

My buddy Ron noticed that just a TINY amount of trigger was pulling about half throttle, so we thought the throttle servo was going bad. (It wasn't, but more on that in a bit...)

I bought a new Hitec 7955 TG, put it on steering, and put the 5955 that I've been running for steering on throttle. The old throttle servo was a Futaba 9351... so of course I had to reverse the the servo on the transmitter. (once again... more on this in a minute...) Reversing the servo was the only change I made on the transmitter... (Rookie mistake #1! Remember this one...)

Changing servos didn't make any difference... the potentiometer on my transmitter for throttle is evidently going bad. (Hmmm... maybe my finger isn't as bad as I thought it was!)

So, given that I had to work Friday, I got to the track late Friday evening and continued to work on breaking in that engine, which was intended to be my backup. It was getting better, but still very finicky on tune, and like most engines that you're breaking in, too much throttle will make them die. A little bit frustrating, but... it was coming along. NO practice time for me Friday, unfortunately, just running up and down the field in the back trying to break in and tune.

Saturday morning I tried to practice with / track tune the new engine... boggy, flameouts, and just generally not a good practice session- I made a whole 3 laps in practice. Not good for me- I'm slow to learn a track layout.

A quick engine change before round 1, and I was good to go... everything was back to normal, and round 1 became my practice session. I had a bad run (of course... 3 laps of practice? I need AT LEAST a fuel bottle to learn a new track layout... I'm slow to pick up on it.)

They called me done a little late, so I couldn't make the turnoff and simply pulled it off the end of the straight to not hinder other traffic...

My pit guy was pitting 2 of us, so he went down and temped me, and put my truck back down... I couldn't see him very well, and I THOUGHT since he put it down he had shut it off... so... (rookie mistake!) I turned off my radio and walked off the drivers stand. (I know better than that... I simply wasn't thinking... and he had NOT shut it off...) (Rookie mistake #2!)

Remember Rookie mistake #1? Now lets add Rookie mistake #1 + Rookie mistake #2:

I previously had set (as recommended) my radio failsafe to full brake... well, the receiver doesn't know the servo is reversed, only the transmitter does. So... when I shut off the radio, it of course went to failsafe mode, just like it is supposed to- in this case... FULL THROTTLE. The result, despite the best efforts of the marshal, was a blown VSPEC. (Like I said... expensive mistake.)

Now I'm down to 1 engine, and it just starting to break in... I got some help tuning from a guy who runs modded Novarossi engines, so we got that fairly well sorted out... but due to the transmitter issue it was bogging every time I'd touch the throttle, so I was having to "blip" to clear it every time I wanted to accelerate at all... pretty hard to drive like that! That + still not knowing the track well was of course hurting my driving. (Not that I can drive that well anyway...)

So, after round 2 I decided I had some time, I'd see if I could do anything to fix the radio. (Another bad move...) To keep it short, I'll just say I ended up breaking the antenna lead on my Spektrum module. Now I'm without a radio.

Fortunately Josh Glancy had a spare DX3.0, (Thank you VERY much for the load of the radio Josh!) so I bound it to that radio, set it all up, and was able to run the rest of the weekend with a borrowed radio- but of course it feels different from my M8, and the response time is somewhat slower, so everything was different, and I'm back to continuing to learn a track with a truck that now drives completely different.

The end result was $300 for an engine (VSPEC + ceramic bearings) and probably $10 for the antenna assembly... and 7th in the C-main. (I have to admit I probably would not have done much better under perfect conditions though.) Frustrating, but I still had a good time.

Ok, laugh away!
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Old 08-31-2009, 06:49 AM   #2
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Oh man, wow, that sucks.

I hope you learned your lesson about setting your failsafe full brake. That burns up servos, engines, and the occassional suspension part if you failsafe and someone rails you from behind as your vehicle squeals to a stop.

Did you try resetting your transmitter? Could it be a problem with the expo setting or perhaps you can relearn it somehow? I know on my Helios I can reset the potentiomiters by using VR Reset. If you cant fix it with a reset you should at least be able to see whats happening with it.
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Old 08-31-2009, 06:54 AM   #3
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Originally Posted by PTP Racing View Post
Oh man, wow, that sucks.

I hope you learned your lesson about setting your failsafe full brake. That burns up servos, engines, and the occassional suspension part if you failsafe and someone rails you from behind as your vehicle squeals to a stop.

Did you try resetting your transmitter? Could it be a problem with the expo setting or perhaps you can relearn it somehow? I know on my Helios I can reset the potentiomiters by using VR Reset. If you cant fix it with a reset you should at least be able to see whats happening with it.
I don't know how to do a reset... but I HAVE tried to create a new model from scratch, same behavior. I'm going to call Airtronics and see if they can tell me if there is something I need to do or if I need to send it in for service (and how much that will cost!)
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Old 08-31-2009, 06:58 AM   #4
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Sounds to me like a good reason to upgrade your radio system. Otherwise you may be out for a while.

I dont know how to do it on the M8 but most of the good radios have that. Scroll through all the settings on that thing. I bet you could figure it out.
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Old 08-31-2009, 07:07 AM   #5
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sounds like a painful day. i agree better than at the office no doubt lol
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Old 08-31-2009, 07:22 AM   #6
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When you said fail safe i was like. OH NO!
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Old 08-31-2009, 07:23 AM   #7
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Wow, that was a tough weekend. This hobby is lots of fun, but there are definitely days when it can be frustrating to no end.

I had a day a few months back where practice in the morning went well. things were looking good for a good finish that day.

Out of three heat races and a (low) main, I completed exactly ONE timed lap! Some of it was my fault (poor maintenance), and some was bad luck but it all added up to a very frustrating and long day at the track.
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Old 08-31-2009, 07:40 AM   #8
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As a side note... a VSPEC has an interesting failure mode. The rod split down the middle... leaving the brass bushing intact on both the crank and wristpin.
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Old 08-31-2009, 07:47 AM   #9
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Was the engine going to full throttle before you got to full throttle on the trigger? If so, it's just an end point problem. Make sure exp is zero or negative. If it's +20 or something like that, there is the problem.

Also, lean out the bottom on that bad boy, it can take it
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Old 08-31-2009, 07:48 AM   #10
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Quote:
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As a side note... a VSPEC has an interesting failure mode. The rod split down the middle... leaving the brass bushing intact on both the crank and wristpin.
Yep, I've seen that a time or two. Take a pic and post it up for us
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Old 08-31-2009, 07:53 AM   #11
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Originally Posted by wingracer View Post
Was the engine going to full throttle before you got to full throttle on the trigger? If so, it's just an end point problem. Make sure exp is zero or negative. If it's +20 or something like that, there is the problem.

Also, lean out the bottom on that bad boy, it can take it
Endpoint is correct and the exp = 0%

As for the Novarossi... it is already a little too lean on bottom. It was "singing" over jumps a bit if I was full throttle on runup, so the bottom is too lean. (If I was only 1/2-3/4 throttle it didn't sing...) Temp at the end of the main was 258... temp at the end of the last heat on Saturday was 274. A bit too warm for comfort, although I did have good smoke... top seems about right. The bottom needs to be fattened up a bit, but I was having trouble with it bogging and not wanting to idle if I did so. It only has maybe half a gallon on it now, and is still so tight I can't turn it over in the chassis when it is cold.
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Old 08-31-2009, 08:00 AM   #12
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Endpoint is correct and the exp = 0%

As for the Novarossi... it is already a little too lean on bottom. It was "singing" over jumps a bit if I was full throttle on runup, so the bottom is too lean. (If I was only 1/2-3/4 throttle it didn't sing...) Temp at the end of the main was 258... temp at the end of the last heat on Saturday was 274. A bit too warm for comfort, although I did have good smoke... top seems about right. The bottom needs to be fattened up a bit, but I was having trouble with it bogging and not wanting to idle if I did so. It only has maybe half a gallon on it now, and is still so tight I can't turn it over in the chassis when it is cold.
If richening the bottom makes it boggy, lean the bottom instead. Then back off the idle to get rid of the "zing"

May need to richen the top just a hair after doing this.
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Old 08-31-2009, 08:09 AM   #13
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Quote:
Originally Posted by DOMIT View Post
Endpoint is correct and the exp = 0%

As for the Novarossi... it is already a little too lean on bottom. It was "singing" over jumps a bit if I was full throttle on runup, so the bottom is too lean. (If I was only 1/2-3/4 throttle it didn't sing...) Temp at the end of the main was 258... temp at the end of the last heat on Saturday was 274. A bit too warm for comfort, although I did have good smoke... top seems about right. The bottom needs to be fattened up a bit, but I was having trouble with it bogging and not wanting to idle if I did so. It only has maybe half a gallon on it now, and is still so tight I can't turn it over in the chassis when it is cold.
I had that same exact problem with my engine but the temps got up to 298 once and every time you richened it just a little bit the engine would just bog down but that one time it hit 298 a guy i was using as a temporary pit man threw fuel on it and to cool it down and richened it so much on the top and bottom that i had to miss the next to heats to retune the engine but then the engine was working perfect and temped it at 224 but i only made it through half a race til someone hit me and cracked the crank case
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Old 08-31-2009, 12:25 PM   #14
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why whould full failsafe burn youru engine up if the electrics shut off and the car not moving i have my set to full brake but it only does it if my battery goes really dead or the speckum loses it bind i dont think the failsafe works on speckum inless you bind it with full brake
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Old 08-31-2009, 01:45 PM   #15
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why whould full failsafe burn youru engine up if the electrics shut off and the car not moving i have my set to full brake but it only does it if my battery goes really dead or the speckum loses it bind i dont think the failsafe works on speckum inless you bind it with full brake
where ever you have your radio dials set to when you bind the receiver to the radio is where your failsafe will be set at. it could be full throttle, neutral, or full brake.


personally i recommend full neutral on both the steering and throttle. before i have turned my transmitter off and left the car on which sent it into failsafe mode that i had set to full brake. i left it on the bench like this when i went out to turn marshall. while i was gone the throttle servo almost caught on fire because it was in full brake mode causing the servo to go into overload and heat up to the point where it was smoking bad and nearly on fire.

and it was a borrowed servo too
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