servo trouble I THINK

[greenwing7]

Ok here is the deal I am NEW to nirto and RC bought a used car off e-bay and believe it or not the engine has >46psi. it is a highly "rigged" up RS4 3 I think from what i can tell basically i bought it to keep me entertained til the new savage came out I got it started no problem but the throttle servo (Futaba 3003) i know its junk, seems to be traveling too far, it has the nitro star T-15 engine with a rotary carb, when the throttle is at full it seems to torque the engine and chasis quite a bit and i was wondering if this is normal, how I can adjust this, or if I can adjust this. it has the stock radio and reciever but the throttle trim does not seem to help. My friend and I spent quite a bit of time on this and we are both pretty good at this sort of mechanical problem solving but this one is really killing us. if there is any more INFO that i need to post to help with this problem please let me know I will work on getting a pic of it its just that I'm not really sure how to yet
thanks all

 

[lykan]

A pic would really help but anywas here goes..

#1 Would it be possible to use a shorter servo arm? The longer the arm is on the servo, the more throw, or travel it will have, you could also possibly move the lingae on the servo arm closer in toward the center of the arm, that will make it loose some travel too.
#2 is the linkage like hard linked with no adjustment collets? If it has collect, you can loosen them, move them up a bit? it may cause some slop, as in you hit the throttle and it doesn't instantly go, but then that slack can be taken up with the trim..

let me know if that helps, and post a pic if you can get one up ..gluck

 

[craig-uk]

i have the rs4-3 evo and i think i know wot u mean, have u centerd ur servo??

 

[olds97_lss]

Depending on the radio, the cheaper ones don't let you set the end point adjustment, so your stuck with dealing with full servo throw, and you have to compensate with the linkage.

On my HPI RS4 Nitro MT, the stock servo saver on the throttle sucked and I replaced it with a normal horn and used OFNA slider parts with springs and collars to give me more solid brake engagement. My radio allows me to set up the EPA though, so I don't have to worry about it pushing the throttle to far.

If your going to be getting a new savage down the line, get a new radio now and buy a savage kit without one. That way, you can use the new features on your current car and not deal with either "stock" radio on either vehicle.

Most aftermarket radios allow the use of more than one vehicle (normally 4-10). You may have to swap out crystals, like I do, but then you just hit a button or two to change from model to model so the trim and epa settings are correct for the vehicle your running.

 

[jon2]

OK It seems that the best solution in the long run IMO is to get a Radio with EPA options. Members above have pointed it out. I have the same thing occur to my engines but I use the EPA option to control the servo throw. I have the JR XS3 Synthesized and it has that option. IT is pricey but worth it. You can also try the MX3. It has the EPA options and its around 100 bux. Look in the F/S forum. You may find something there. I do... I am Broke!

 

[bigfreak]

My son uses an JR XR3i. It's the same radio as the XS3 just it isn't synth. I picked it up for $65 on ebay without any servos.

Anyway, olds97_lss and jon2 hit the nail on the head when you get a better radio you can fix this problem easily with your end point adjustments.

For now, there is a something you can do. You say it's pushing the throttle too far. I don't really know the rs4 vehicle, but if it uses a rotary carb, the chances are the throttle lever thingy has a series of holes running down the length of it. Your throttle linkage is in one of theses holes currently. To do a temp fix on the over throw, you can drop the throttle linkage down one hole closer to the center of the roatry carb. This will should help the problem. You want to make sure it's opening the carb all the way at wide open throttle so you may have to remove the air filter to check.

Also, if it's a slide carb, the only option you have is adjust the throw with the throttle servo horn. Move the throttle linkage closer to the center of the servo for less throw.

 

[lykan]

A pic would really help but anywas here goes..

#1 Would it be possible to use a shorter servo arm? The longer the arm is on the servo, the more throw, or travel it will have, you could also possibly move the lingae on the servo arm closer in toward the center of the arm, that will make it loose some travel too.
#2 is the linkage like hard linked with no adjustment collets? If it has collect, you can loosen them, move them up a bit? it may cause some slop, as in you hit the throttle and it doesn't instantly go, but then that slack can be taken up with the trim..

let me know if that helps, and post a pic if you can get one up ..gluck

 

[greenwing7]

ok i will TRY to have a pic up tonight i just am not having any luck ulpoading the image as i am new i did get them re-sized down to the mandatory 800x600 but from there i could not move them from the computer to the forum, i may try moving the linkage in one, and yes the points are adjustable with a llittle allen or collet as you called itand as i have it setup right now there is about 2mm of slop in the throttle where i have it just waiting to see if that is ok to run it. I really want to get the JR XR3i my LHS has it for 89.99. I heard so many horror stories about them I was really worried about going in there but i seems like everything that they carry is competitive with internet prices. thanks again pic will hopefully be soon to follow

 

[Rolex]

ok i will TRY to have a pic up tonight i just am not having any luck ulpoading the image as i am new i did get them re-sized down to the mandatory 800x600

Pic sizes are 640x480. Make note of where they are located in your computer, then upload them to your gallery and paste the link in your post.

 

[greenwing7]

I Will Have Pics Up Around 11:30pm Central Time Thats When I Get Off Work Ohh And Tomorrow I Get To Go Pick Up An M3 Body To Match The One In The Garage And Some Other Small Things

 

[greenwing7]

here are pics and i hope that they work all i could figure to do is get them on my callery and post a link to there

 

[lykan]

Ok I saw your pics..

What you need to do is move the collet forward, so when the servo reaches full throttle position, it's not pushing on the carb.

Because of this you will have some slop when the servo is in it's neutral position. Move the trim on the transmitter forward until it touches the collet you just adjusted when your finger is off the trigger. Adjust your brake collet to match.

If this still is enough, there is one other option. If you have enough skills with a pair of pliers and some snips, you can snip the linkage a bit shorter, and put a new z bend in it for the carb..

Is it possible that anything is backwards? Or not installed correctly? I hope this helps..

One solution would be a nice controller, but myself i can't justify one yet.

 

[greenwing7]

I was considering the hack and burn method and i am not worried about cutting and bending thats no problem but I am worried that I might mess something up If you look the Throttle is in the out most position and the brake is in the third hole in I might try and move the throttle in one hole is this a viable option?

and to commemt on your comment that is the problem with the trim it will NOT move the servo arm far enough forward in the neutral position, i have tried taking the white thing off and moving that around and resetting where that goes but then it moves too far forward and torques the carb, engine and body and I am worried this will mess with how the tranny lines up or burn out the servo (maybe thats what I need so I can get a new one) oh and does the car look like a decient way into the hobby I mean I've already taken it ALL apart and had A BLAST!! I will keep all posted on how this problem is comming.

 

[lykan]

It looks like a decent ride..
Linkages can be a pain in the ass if you over think them.

Have you centered the servo yet? If not, this is what you do. You take off the white thing (servo horn or arm) turn on the transmitter and the reciever, center the trims. when the servo is centered put the horn back on.

Play with it a little bit, and don't overthink it. You are righ tho, that servo is putting wya too much stress on thecarb, which will screw up your gear mesh. I did that on my tamxx, and cpouldn't figure oput why I was eating through the big spur gear. Give it gas, and it would torque it and strip.

Ok ok I see now.. an Idea on how to adjust this thing right.

Turn on transmitter and reciever.
center trim
Give TX full throttle and hold (will push on the engine and tranny)
Loosen collet
Rod should slide back until pressure is off while collet is loose.
Tighten collet.
Release throttle trigger, check for proper operation, adjust brake.

See if that works

 

[greenwing7]

better look

this is what happens when I move the collet I get the slop in the throttle. now I'm going to see what happens when I move the throttle linkage one hole in.

wish me luck and for warmer weather

 

[bigfreak]

I once put a RTR radio in an 8th scale buggy (I know I know shame on me, but it was a long time ago). I ended up using sever servo arms and drilling several different holes until I got it close to to correct. Even then it wasn't perfect. May the force be with you.

 

[greenwing7]

well i moved the collet so that at WOT there is no torque and at neutral servo position (with the servo trim maxed out) there is less than a cooter hair of throttle and it has hardly any effect on the idle i know this is BAD but it still idles fine when i hit the brakes.