problems with new throtle linkage

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mrvern_04

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i have just replaced the rear diff, and performed a 3 speed upgrade, and the last thing i put on was the traxxas throtle linkage mod with switching the servo to the sf-2 servo instead of the sf-1. i couldnt get it to work the way they said. mainly the part about putting compression on the spring...when i go WOT, i have about half braking strenth...and excelent braking (does endo from high speed stop if i'm not careful). i havent had a chance to see if it is exacly the mod that has something to do with it cause i'm out of town and dont have those couple parts with me. i can get it to run ok, but sometimes at WOT, it seems like the servo cuts out, but then comes back. i think it has something to do with metal on metal contact between linkage and tvp. i've hear there can be problems with interference because of metal to metal contact. it is cold here...probably about 25 to 40 degrees...does this have something to do with no being able to get it to tune correctly? i am just very frustrated. newer motor(less than a gal on it), new clutch, spur and 3 speed converson. i got this thing used off my bro, and he got it used. i have about $800 in this darn thing including the cost of truck...and no major mods! just resurecting it. i had absolutely no experience with rc's before this. i really enjoy it, but it has gotten frustrating, and my LHS guy is not cool...ripped us off in the first place. if someone could be patient enough to be sort of a mentor with my salvage (official savage nickname) i would be eternally grateful!:bow: :surrender HELP!!!
 
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Do you have a decent close up photo of the throttle linkage?

Tuning is an art form. Colder ambiant temps make things harder to tune. Partly because colder air is more dense and partly because the engine cools off faster.

Weak batteries also cause glitching which is what it sounds like you have. Or, your going too far or you don't have your antenna extended fully on the truck or remote.

What radio/receiver are you using? Are you using AA alkilines or a NiMH receiver pack in the truck for batteries? What engine are you running? What exhaust are you running? Did you run it in wet conditions?

Answering a few of these questions will help us to help you.
 
Do you have a decent close up photo of the throttle linkage?

Tuning is an art form. Colder ambiant temps make things harder to tune. Partly because colder air is more dense and partly because the engine cools off faster.

Weak batteries also cause glitching which is what it sounds like you have. Or, your going too far or you don't have your antenna extended fully on the truck or remote.

What radio/receiver are you using? Are you using AA alkilines or a NiMH receiver pack in the truck for batteries? What engine are you running? What exhaust are you running? Did you run it in wet conditions?

Answering a few of these questions will help us to help you.

ok, can do...i have a new motor from a savage X, the exhaust that came on the truck (used...could be ok or not), i am just using regular AA batteries, i had both atennas all the way out, i have tried in dry and damp conditions. i am using a 3 channel radio, i'm not sure of the brand (sorry its packed away at the moment due to frustration) but i know i wasn't out of range. i did switch to the stronger sf-2 for the throttle too...so i will double check the batteries and see if that will help. if that doesn't help, then i will try the old linkage. i will get a pic on of the linkage when i get it installed properly. the kit didnt have enough of the correct sized fuel tube, so i had to improvise while i was out of town.

thanks guys for all your help, and especially for your patience with a struggling newbie

the SALVAGE thanks you!:surrender
 
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Did you get a photo of the linkage yet? Just curious. Your radio issue does sound like a glitch of sorts. I've had servo's that were dieing do that and I've had batteries that were dieing do that. I've also had a crystal in the receiver wiggle loose and cause issues.
 
If he's getting brakes at half throttle, it sounds like a binding linkage. Try adjusting the brake link so you have zero brakes at neutral, and adjust the EPA on your radio (if it has it) for more throw if needed.
 
finally got some pics

hey guys, sorry it took so long to get pics on...anyway. i was trying to do some of my own experimentation. today i got it running pretty good, but if i mashed the throttle, it would want to cut out or just instantly die. i did some reading and checked the idle setting, and reset it to what i thought it should be, but it idled high, and by the time i was done with my short tune session before work (bout 30 mins or so) i had the idle set so the carb was almost closed...this i believe is wrong. also, at WOT, the slide is not visible at all when you look down the carb...is this, in conjuction with the faster, old steering servo, causing too much fuel or air to kill the motor? could it be the crappy old stock filter...probably original to the .21bb that came with the truck new (not when i got it). or could i have possibly damage the engine some how? too low of gear ratio for a 3 speed tranny? something wrong with the clutch in the tranny (i rebuilt the 2 speed myself - 13T CB and 52T spur) the servo didnt seem to be glitching today, as i could get it to run on blocks, through all 3 gears while smoothly increasing throttle. i backed off and waited 5 or 10 seconds, and mashed it, and instantly died. i am going to go back to the old brake linkage, the only thin i upgraded was the brake part of the throttle setup. should i just wait for warmer weather and less frustration? here are the pictures...all are taken with trim set to zero while radio and reciever are on...or the obvious other are taken at WOT. the last one is the carb slide with idle screw set to where i think it should be (the about 1mm i've heard so much about, but makes for high idle) sorry to ramble, but i just want to give you guys all the info i can while i have the time. thanks to all!
the "SALVAGE" thanks you! :surrender
 

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PS...i didnt get enough of the fuel tubing with my kit, so i had to make due with what the LHS had, and a spring from a ball point pen...the tape and some extra tubing was for trying to shield against metal on metal and glitching i was having.
 

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Well, there's your problem. I run mine with nothing between the horn and the brake lever; only the stuff that it puts pressure on when applying brakes. Remove all the stuff that "pushes" the brakes open (the ball point pen spring), and that should eliminate the binding problem.
 
Try this set-up, this is how I ran my Savage when I had one. I ran the brake linkage through the brake arm and bent it at the end so that it would hit the base of the L arm if extended too far. Takes a little tinkering but it ensured that brakes would never be applied with throttle.
 

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i also forgot to mention that when i did have it workin good that it ended up running up to about 315 degrees. i suspect that the filter is causing problems with air flow- ie: runs ok at idle or lower speeds and first few mins of running, then heats up and doesn't like taking quick throttle movements. like if i bob around with blirps of throttle. just thought of that, and thought i would add some insight...cause i'm basically clueless!
 
Sounds like you have an airleak. Seal the backplate and carb with sensor safe RTV. Also check that the engine head screws are tight and that the copper head shims are not distorted. You need to retune after checking for leaks and richen your needles. 315 is way too hot for any mill.
 
Also, with the linkage mod, you should super glue the stock servo horn so it doesn't give from top to bottom or replace it with a solid horn. The stock horn has a servo saver build to it that is making it difficult to adjust right.

You can see my "normal" servo horn with my slider/spring setup:
2005-0626-SavageThrottleLinkageBearings.jpg
 
Clutch shoes...

i removed the eninge to install some parts and check for problems with air leaks...i wanted to adjust the weight of my clutch shoes, and i think i discovered a problem. i had just bought a clutch tool (very hard to install a 3 shoe setup with out one, impossible to remove also), and when i compared my shoe orientation to the instructions provided with my clutch tool, i discovered that my shoes were installed backwars. i guess i forgot which direction the old ones were facing, and try to use my lack of physics knowlege to guess the direction. i havent re-installed my motor yet, but i bet that was a big problem...and why it didnt like to start, and sounded funny decellerating from high speeds. also, anyone know any good tricks for aligning your engine and spur gear, so they have a good square mesh, and lower the amount of abnormal wear.

...'nother question- i have a bit of wobble in my spur gear, even after getting an aluminum and steel set. is this normal, or do i have a bent shaft in my tranny?

the "Salvage" thanks you! :surrender
 
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