T-maxx idle speed

gs39t

I dug out my t-maxx today to try and tune it (again!) but made a horrible mistake somewhere, because the first time it started, it jumped to full rev and tried to drive up my leg :eek: . Then, it just died 2 seconds later. Same thing happened 3 times

Anyway, i somehow turned the fast idle ALL the way clockwise (to speed it up) but i dont know how far to turn it BACK to get to a decent idle speed; the manual doesnt seem to say this and alll my attempts at guessing failed as i still cant start it!

So how far from fully clockwise do i turn it back?

Thanks in advance

Gary

vectra

READ ME TUNING TIPS

gs39t

Thanks, ive read that and applied some things, BUT - and this is the kicker - ive found the cause of my problem. for some reason, the controller is now working in reverse . Pushing the lever forward to brake, is now throttle and pulling back is now brake - how did THAT happen?! :eek:

g5hn710m4xpdwy

is there 2 switches on the bottem of your controler? mind does and it can do things like that (i think) fiddle with it and hope it gets better if it doesnt sorry:D thre will be anotehr reply with better info tho

no leaf clover

thats the only thing i could think of aswell flunked, id say tahts the case as they get changed fairly easily!

gs39t

There's only the 3 'channel' switches, but ive never changed them, could that be the cause?

That issue is just ONE. I can finally get the truck to idle properly but only by using the throttle trim to the extreme on the controller, something which according to the manual isnt recommended. BUT, even when its idling fine, if i hit the BRAKE, the linkage PULLS the throttle position BELOW the idle speed and the truck shuts off. To explain that a bit better - start truck, truck idles fine. Applying the brakes will close the carb, slowing the idle too low for the truck to run. I cant see how to sort that out at all, and even looking at the linkage i cant see how to even adjust anything to stop it.

g5hn710m4xpdwy

well at this stage i think its the channel swith (just check) and move a way from the idle too try other combos with other needeles, my car was a an asshóle to me so i pretty much handed it back to greenhobby to see if they can get it working right (too many trips over back)

no leaf clover

im guessing you've re adjusted ur idle screw yeh?
after that one of the switches will say throttle "normal, reverse" or n, r change and try it,
also have you played with the servo, is it set so that wheen it turns on, the arm holding the linkages is at 90* and the two are in line, i dont know tmaxxs but they're my guesses!!

gs39t

I've left it for now as ive run down the EZ start battery. I'll have another look tommorrow, but now i remember why i put it away in the first place.

Ebay here i come!

vectra

gs39t wrote:

Ebay here i come!

Dont give up just yet.
Persevere..
It can only be something obvious but you are jut not spotting it.
Without starting the engine, take the shell off and turn on all switches (both)
then ensure the throttle and brake are working smoothly and not getting stuck anywhere.

As NLC said. Make sure the servo arm is returning to 90*
Use the idle screw so as there is about 1mm ( I think ) of a gap between the carb piston and body.

other than that..
Hmmm.
Call on Coolwings

gs39t

I have tried everything, but this linkage thing is the worst of it, because i dont see how to solve it. Hitting the brakes basically causes the truck to die!

no leaf clover

wer r u based man?

vectra

gs39t wrote:

Hitting the brakes basically causes the truck to die!

That deffo points to wrong tuning.;)

g5hn710m4xpdwy

yeah im sure if anybody can, they will help you out ;-) my buggy is in greenhobby to get her patched up and actualy get used after all my troubles but its great for the 5 mins she is running:D nah get it fixed and tell fleeebay to walk away:eek:

no leaf clover

my savvy is sitting idle just because o lack of spur gear....i h8 not having somewhere that stocks hpi...actually...wats the name of that place in liffey valley..haplins or something...just thought o that!! woo!! wonder would they have it.. thatd be nice.. race er tomorrow..

gs39t

vectra wrote:

That deffo points to wrong tuning.;)

Thats because for some reason, applying the brakes causes the linkage to pull the carb closed fully, despite idling fine. Read above

no leaf clover

i temporarily had that problem, but mine was ALSO wrongly tuned thank god for that, i just had to touch the brake and the bad sound, taht was my engine full blast was calmed by the brakes shutting the carb!
sorry, mind wandered, em ok, adjust the idle screw and the linkages, u able to post a pic o the linkage? and the servo?

tallus

gs39t wrote:

Thats because for some reason, applying the brakes causes the linkage to pull the carb closed fully, despite idling fine. Read above

Had the same prob with my Savage, you need to take the air filter off, make sure the servo/throttle is set at it's lowest setting, and turn the idle screw clockwise until you have at least a 1mm opening. Or apply the brakes when you set it, if the throttle closes fully.... then start turning the idle screw clockwise and applying the brakes until you see that gap appear. It's as simple as that.

no leaf clover

tallus wrote:

Had the same prob with my Savage, you need to take the air filter off, make sure the servo/throttle is set at it's lowest setting, and turn the idle screw clockwise until you have at least a 1mm opening. Or apply the brakes when you set it, if the throttle closes fully.... then start turning the idle screw clockwise and applying the brakes until you see that gap appear. It's as simple as that.

nicely put!!! i had to do it, but am so bad at just saying it point by point!!

g5hn710m4xpdwy

NLC you are talking about a store called "maplins" there is also "peats" and neither are in liffey valley, they are in blancherstown

gs39t

SOME progress at least! I changed two of the switches on the controller and the throttle/brake is now operating normally again. I dont get how that happened in the first place, as i needed a small flathead screwdriver to move them into position so its not like i accidentally changed their positions before Somehow it changed all by itself.

My EZ start battery is still charging, but i did what you suggested about the servo and idle screw and i now have what look like good settings, but ill have to wait to start it later to see how that goes.

Looking good so far, thanks guys

tallus

Hope it goes well for you mate, thinking of taking my Savage out for a bash in a while... weather looks ok

coolwings

gs39t wrote:

.... Somehow it changed all by itself.....

You'll get used to that after a while !

With RC models - if you can spot the problem as it comes loose/begins to go wrong. You get to fix it before the (whatever it is), breaks, wears out, falls off, gets lost, etc....
Model maintenance takes a bit of getting used to.
Payoff is - you buy less replacement bits, get fewer failures, have more fun

T-Maxx

Make sure the throttle/brake linkage looks like this:

http://www.traxxas.com/support/index.php?action=artikel&cat=143&id=459&artlang=en (Linkage Set-up, about 1/3 down the page)

Reset carb settings to factory, i.e.

HSN 4 turns out
LSN flush with slide
Idle setting 0.7-1.0mm (you need to take the air filter off)

Make sure the servos directions are correct and the trims are at neutral (adjust on transmitter accordingly).

With a little bit of luck she should fire up and idle reasonable now. Tune and enjoy!

gs39t

One thing i cant figure out - if im supposed to have the trims at neutral, how do i adjust the linkage to get the 0.7-1 mm gap, because there is no other way can get this gap by adjusting the needles, and its not from lack of trying. Anything else i do, i can set the gap with the needles, but after applying the brake, the linkage returns to center pulling the carb open to about 2.5mm, which of course means the truck tries to leave...

g5hn710m4xpdwy

turn the idle screw the right way to close it enough (not sure which way:D )

gs39t

Flunked wrote:

turn the idle screw the right way to close it enough (not sure which way:D )

The idle screw has no effect on this issue, the linkage is pulling it away from the needle

g5hn710m4xpdwy

yeah i fad that problem, my brother ended up taking it apart almost to get it to normal, tho it can be fixed \9eithout that hassle as it wasnt even moving for me)
the throtle return spring i think its called could be off, but i dont really know much about that

T-Maxx

gs39t wrote:

... but after applying the brake, the linkage returns to center pulling the carb open to about 2.5mm...

If you apply the brake the throttle should close all the way up to the idle set screw (which is BTW clockwise for a faster idle and vice versa).

I'd say check the linkages again, maybe the spring retaining collars need adjustment. It could also be that the idle screw stripped out the carb and that's why no turning it in any direction seems to have any effect. Also if you're way too lean on the LSN, the idle doesn't have any effect either.

gs39t

T-Maxx wrote:

If you apply the brake the throttle should close all the way up to the idle set screw (which is BTW clockwise for a faster idle and vice versa).

I'd say check the linkages again, maybe the spring retaining collars need adjustment. It could also be that the idle screw stripped out the carb and that's why no turning it in any direction seems to have any effect. Also if you're way too lean on the LSN, the idle doesn't have any effect either.

The fast idle screw IS 'working' - when i turn it clockwise the gap increases, but whats happening is when i brake, the carb closes all the way up to the needle, but then as i release the brake, the linkage returns and pulls the carb open. I CAN sort this by messing with the throttle trim on the controller. Is it ok to use this method? The manual seems to strongly recommend NOT doing this

vectra

gs39t wrote:

I CAN sort this by messing with the throttle trim on the controller. Is it ok to use this method? The manual seems to strongly recommend NOT doing this

Just a thought.
But, Would the linkage from the servo to the Carb/Brake need adjusting ?

T-Maxx

It's definitely a linkage setup issue then. You might need to unscrew the servo horn from the servo and turn it one or more splines back/forward. The horn needs to be perpendicular to the servo itself with the throttle (and trim) at neutral.