[T-Maxx 2.5] Clicking & Idle problem

[jay3]

Hello, its me again :yes:
When my T-Maxx gets warmed up this problem occurs. When idling the T-Maxx will constantly jerk forward in increments with a "clicking" sound. The warmer the engine gets, the faster it moves and clicks forward without any throttle applied. I tried many different idle-screw/trim settings and it still does this. Eventually the t-maxx will keep driving after you let go of the throttle at about the same speed as you had it going until you apply the breaks!

Sometimes when I apply the throttle slower from a complete stop it will jerk forward while clicking than drive normally.

What could be the problem? This is limiting my driving time to about 5 minutes or less before I need to let the engine cool down. I dont think its over-heating or too lean either since a lot of blue smoke is coming out, etc.

 

[olds97_lss]

The clicking is normal. The 2.5 maxx had a safety clutch in it for forward/reverse. It takes a few RPM's to get the clutch to fully engage inside the trans.

It sounds like your idle is just too high, or your throttle trim is holding the carb open. Or, it's lean on the LSN

 

[benjman420]

mine does the same thing, but after lowering the idle and messing with the LSN the clicking and jerking mostly stops.

 

[jay3]

will try

The clicking is normal. The 2.5 maxx had a safety clutch in it for forward/reverse. It takes a few RPM's to get the clutch to fully engage inside the trans.

It sounds like your idle is just too high, or your throttle trim is holding the carb open. Or, it's lean on the LSN

I see...
I will have to try to lower the idle screw, (counterclockwise right?) and richening the LSN. Is this going to stop my t-maxx from driving forward when in idle and switch it to neutral (idle) once the throttle is let go of? After its warmed up it basically drives without jerks, it just continues to drive... I havent ever really got it to stand still when idling once warmed up...

 

[jon2]

The clicking and jerking are due to the transmission. It takes some time for it to settle down. Doing Foward ONLY conversion can help to reduce that a lot. My last Tmaxx project I did for someone netted the clicking and jerking but after the FOC it went bye bye.

 

[NCNitro]

Something else you may want to check, you may have your linkage set up incorrectly. If the linkage holds the carb open even slightly, lowering the idle is not going to do anything, since the barrell is being held open by the linkage rather than the idle screw. When you are on the breaks is it ok or is it still idling high? I would remove the carb, look down the throat of the carb while holding the brake on, you should have no more than 1-2mm of an opening on the carb barrell, any more than that and it will cause what you are describing.

As far as the forward clicking and jerking, unfortunately that is normal for the maxx, just do a forward only conversion and it will go away completely, and will take off much better than it does now.

 

[Rolex]

In the post right above this, by NCNitro, I think he meant to say "remove the air cleaner" not the carb.

 

[jay3]

In the post right above this, by NCNitro, I think he meant to say "remove the air cleaner" not the carb.

Ahh! I think I might know the problem. Since the new carb was installed it was put in in an angle and the throttle linkage part right near where the air-filter connects to the carb (a small plastic piece with a screw in the middle) isnt 90degrees with the linkage rod and is slightly resting against the filter. This must be holding it open a bit and causing it to not idle when warmed up. I will have to adjust this!

 

[NCNitro]

Thanks Rolex, that is exactly what I meant, lol.

 

[jay3]

Alright I took a look at it. I was able to slow down the movement and jerking speed when idling. But I think the problem is with the servo linkage settings. When the engine is off and i look into the carb through air-filter inlet while pulling the throttle to full it opens all the way up, but once its released it doesn't quite go shut against the idle screw settings. It remains open slightly more. Once the break is applied goes back to the idle screw rest setting... This is whats causing my t-maxx to sometimes keep driving after the throttle is released until breaks are applied. When i unscrew the linkage form the servo and adjust it I either get strong breaking power but the carb wont totally open (about 1/2 way at full throttle) or weak breaking power and full throttle opening...

Any ideas? Do I need to adjust the linkage springs/tubes or something?

 

[NCNitro]

Yep, the little barrell stops on the linkage rods that have the set screw in them will need to be adjusted. Take a pic of your linkage and I can tell you exactly which ones to adjust and how.

 

[jay3]

Here are some pictures I took from my t-maxx's servo/linkage and inside the carb. Notice the creaking sound when the breaks are applied. It is coming from the metal piece at the end of the throttle linkage spring. (Probly needs oil?)

Look at the pics and the 2 videos I attached. Use Quick Time player to view these small video files (press No if a message comes up when opening)

Tell me what you think...

Click below to download the .rar file (megaupload. Enter the 3characters it shows to download)

http://www.megaupload.com/?d=ZCX38DJ8


BY THE WAY:

I am thinking about buying a humpack/power pack to power my servos. The Traxxas one is a bit too expensive for my budget at the moment after I had bought a resonator and carb.
Is it these 2 items that I would need?

http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&Item=190194472355&Category=34061&_trksid=p3907.m29
http://cgi.ebay.com/Traxxas-T-Maxx-...475980QQcmdZViewItem?IMSfp=TL0803230860a18759

 

[abadk9420]

Here is a link to the traxxas site http://www.traxxas.com/support/pub/Tune-2-356kb.pdf where there are pictures of how the linkage should be, you want all of your linkage for throtle and brakes to be at 90 degree angles. I also used the spring setup on the brakes and works great, how ever I didn't move the position of the pivot point for the carb I just made sure every thing was at 90 degree angles good luck...

 

[jay3]

I had a look at the pdf above... It doesn't help me out too much since it only tells you what to do, not troubleshooting. The problem is simply that I cannot get the carb to close and rest against the idle-screw setting after it has been opened without applying the brakes which rests it again. The throttle linkage just doesn't push back in hard enough, or is limited...

This makes it VERY hard and unpredictable to drive since it can keep driving after you let go of the throttle! NCNitro, what do I have to adjust? Does the "horn" or what ever its called (where the link rod connects to near the carb) need to be adjusted or the spring/tube settings?

 

[NCNitro]

sorry, but I am not joining mega whatever just to view the vid.

Take a pic and I will let you know exactly what to do.

 

[jay3]

sorry, but I am not joining mega whatever just to view the vid.

Take a pic and I will let you know exactly what to do.

Uhh.. You dont need to join it, just enter the security verification code thats on the page in the box and click download and you'll be able to download it after 45secs, I took a few pics and a video of the servos moving. I dont know where else I could upload it. No sign-up/registration is required...
If you still dont believe me or dont trust me for what ever reason I will attach the images here...

 

[NCNitro]

Ok, the two barrell stops on the linkage to the carb is where your problem is. First you will need to loosen the one on the backside of the servo horn, the side without the spring. Make sure your throttle trim is at 0, the truck receiver and radio are on, and then push that linkage rod towards the carb until it closes against the idle screw. I do this by backing my idle screw out so it wont effect the barrel closing all the way. That way the carb barrell will close completely and then I set the idle using the idle screw to open it back to where I want it. Once the carb is closed completely, tighten that set screw back up.

Next, the one with the spring needs to be loosened and then move it towards the servo horn to about where the spring is halfway compressed, then tighten that set screw back up.

That should take care of your problem.

 

[jay3]

Alright, I'm going to try it out. I attached a pic, is this what you mean?

--------

Loosen screw under the GREEN circle

Loosen screw with allen wrench in the RED circle and compress spring 1/2 way.

Thanks for helping me out, I hope I dont look to dumb :breakdown

 

[NCNitro]

no, not the one under the green circle, the one that looks just like the one under the red circle, but on the outside of the linkage slider to the right of the green circle in your pic. But you got the rest right.

Thats the one that pulls the throttle open, and most likely it is holding the carb partially open causing your high idle no matter where you set the idle screw.

 

[jay3]

Your totally right! I did what you said and now it stays in position!
Unfortunately fixing this problem aroused another problem! Now my brakes barely work! They are very weak. The servo isnt pulling the break lever hard enough. I tried setting the barrels on the break linkage to different positions, making it tighter on the brake so it wont have to pull as far etc... and it still isnt anywhere near as strong as it should be.

Is this story ever gonna come to an end? I bet if one of you were here it would be fixed in a minute.

This is how it looks now.