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Old 10-03-2009, 10:12 PM   #1
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Default Rough day at ARC

Rough day at the track. Started off pretty humorous; we arrived a little after 3pm (I wanted to be there at 2 so I could put down some practice laps but the wife had to work). Practice usually ends at 3:30. Since we were late Ginny said she'd sign me in while I got everything ready. The car ran pretty good in practice. I was down on power but leaned it out a smidge and had it pretty good for the first qualifier. I start the warm up laps for the 1st heat, all seems well, good power (not great), suspension and diffs feel real nice, and I found a place I really like on the drivers stand. Throw down 2 of 3 laps and hear the announcer ask, "why is there a buggy on the track?" I look around and sure as chit, there is one buggy amongst a horde of truggies. Seems Ginny signed me up for Sportsman truggy vice buggy Pull the car off the track and get the class issue straightened out.

My heat comes up and I start to throw down the warm up laps (again...) and come in to top off the fuel. I run one lap and then the car starts handling oddly; I have no top end and I'm either getting some binding or the brakes are on. I make some adjustments on the radio and get full throttle back (or close) but I cant get ride of the binding/braking. I have to put down some laps so I stay out and actually run some really fast laps (good enough for 2nd qualifier for a while); .5 seconds quicker than my previous best at the track (30.6 to my previous 31.1). The car is a major handful, I have to hold half throttle going over the jumps or the car will do a half front flip off the jumps.

Once the heat is over I bring it into the pits and discover the servo horn for the throttle has either jumped some teeth or there is a problem with the servo its self. Since the servo has titanium gears I figure it's the horn. I replace the insert with another new unit and test it out again. Same problem happens. Thankfully the racer next to me has an aluminum unit that he is willing to part with so I get that installed for the main. Once again, I run a couple warm up laps and everything feels really good except I have way to much traction (track is pretty wet and I'm getting some traction rolls on some of the corners). After about 5 laps I start having problems again. At first I thought it was the same problem as before and figured the servo itself may have been the problem. After another lap it's obvious that something else is happening. The car will run great for a few feet and then fall on it's face. My car is a bit quieter than most on the track so I cant tell if it's revving and not moving (clutch issue) or it's just bogging. I limp it around another 2 laps and decide to pull it off so I'm not holding up the other drivers.

I havent ripped it apart yet but I'm thinking it may have been to lean; the outside temp dropped 15-20 degrees and I didnt make an adjustment because I was busy between rounds fixing problems. I'm going to pull the turbo button out and see how it runs. Last race it was super reliable, this trip was a disaster from start to finish
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Last edited by madweazl; 10-04-2009 at 07:28 AM.
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Old 10-03-2009, 10:18 PM   #2
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Possibly a clutch issue, maybe bad clutch bearings?
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Old 10-04-2009, 05:51 AM   #3
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Getting to the track late angers the nitro Gods.

-bury your broken servo arm in the track to appease them, spray Axe body spray around in the pit area.

-Hitec servo arms rule. Throw away or bury the darn changable insert type arms. (we call them DNF arms)

-check that clutch
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Old 10-04-2009, 07:22 AM   #4
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I'm hoping clutch but I'm doubting it right now. We'll see pretty soon, time to start weekly maintenance. On the one hand, it would be nice if I killed the motor (which I highly doubt) because I'll get to buy a new one , on the other hand, it would be nice to know I'm not a tuning retard.

I did fatten it up 1.5-2 hours (top) after a few laps in the main but it didnt make any difference.
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Old 10-04-2009, 07:29 AM   #5
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Clue #1; didnt have to dig very far. I did get t-boned on the first or second lap, not sure this was the whole problem though.
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Old 10-04-2009, 07:32 AM   #6
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My N21b deos the same thing, with a good race tune it will lean bog a little every once in a while.

I richened the mixture a little.


Could be fuel lines or your tank so watch for air bubbles in the fuel line.
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Old 10-04-2009, 09:07 AM   #7
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Quote:
Originally Posted by madweazl View Post
Clue #1; didnt have to dig very far. I did get t-boned on the first or second lap, not sure this was the whole problem though.
That looks like the problem.
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Old 10-04-2009, 10:50 AM   #8
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Didnt find anything else that looked suspect. Head looked good with no indications of being overly lean and the clutch looks great. So anti-climactic
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Old 10-04-2009, 12:23 PM   #9
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Well your Obviously pulling too much brake or throttle and stripping the insert's....I Only run "DNF" horns and cant say ive ever had an issue.....imo the Stock losi set-up is the best there is for buggy as it clear's the body nice and is easily adjustable...the bend linkage rod will definitely make the motor act up as im sure the arm wasn't being pushed by the spring very hard which is a common thing i see a lot.....i would replace that rod and Polish it before re-installing and it should be silky smooth....i polish my throttle side rod every so often as if its all gritty and binding in the plastic the linkage wont work very well.


Also madweazl 4mm shim's will take out a lot of the excessive slop in the losi plastics for the rods.
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Old 10-04-2009, 01:03 PM   #10
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Quote:
Originally Posted by Integra View Post
Well your Obviously pulling too much brake or throttle and stripping the insert's....I Only run "DNF" horns and cant say ive ever had an issue.....imo the Stock losi set-up is the best there is for buggy as it clear's the body nice and is easily adjustable...the bend linkage rod will definitely make the motor act up as im sure the arm wasn't being pushed by the spring very hard which is a common thing i see a lot.....i would replace that rod and Polish it before re-installing and it should be silky smooth....i polish my throttle side rod every so often as if its all gritty and binding in the plastic the linkage wont work very well.


Also madweazl 4mm shim's will take out a lot of the excessive slop in the losi plastics for the rods.
Mine was doing great prior to this. Something else noticed was the stop for the front brakes slid on the rod which probably led to the insert stripping. A double whammy.
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