General Throttle Springs

Anyone use these on their truck/cars?

Throttle Return Spring (2) by Traxxas [TRA4045] | Cars & Trucks

Yes, it is a must have with nitro. Make sure the spring can close the carb and overpower the servo when the switch is turned off.

Tin fore. I'll get a set of these then. These would have been very nice to have the other day when my batteries died in my truck. Never again will I use harbor freight batteries in my truck. I'm going to convert my 2.5 to the rechargeable pack later.

I thought you already put rechargeables in it?

In my new truck. Not the used one.

Ah

I use return springs on everything with an IC engine in it. Especially with the helicopters. If I have signal failure, servo failure, or crash it...I want it to shut off.

How can I be sure I'm ordering the right springs for the Tmaxx? The Traxxas part 4056 states it's for the Jato. I suppose it could be used on a Tmaxx but do you just put it directly on the carb or do I connect it to the servo somehow?

Put it directly on the carb. If the linkage comes off, then you are in trouble. WOT with a 12lb truck running full tilt is not fun.

I can imagine. I got lucky that day my batteries died. I was just putting around trying to run my tank empty.

I just realized my 3.3 truck has one but the other doesnt.

This is the other one. I'll have to get creative with it.

Quick and dirty but it works.

You need to put some tension on that spring and make sure it can close the throttle. Just leave the truck off, manually move the servo to WOT and see if it will close the throttle. Then do it at half and 1/4 and make sure it closes then as well.

Ok. I didn't test that but did notice it helps close while power is on. Thanks.

I think I may put a small wire tie on there and see if the spring seats better. I don't really like the way it is connected to the rid. I thought about bending it but don't want to break it.

I have always bent out a loop or two to make it cleaner. It shouldn't break, but there is always that chance.

I performed a power loss test on the throttle return spring. The test failed. At no point would the spring pull the servo back to a neutral state. The spring has enough force to return the throttle back to closed but not while the servo was involved. I removed the servo and opened the case. It was in fact the one I had cleaned out previously and applied lithium grease to the gears. A little research turned up that the traxxas 2018 servo is a standard servo and the 2055 is a high torque. I just happened to have a spare 2055 laying around and proceeded to take it apart and clean the gears and re-grease. The difference between the two is night and day. Not only do I have faster throttle response but now the throttle return spring works as intended. I powered the Tx an Rx. I adjusted the throttle trim so that it had about half a mm of gap. I gave it full throttle and powered off the Rx. The spring pulled the throttle back and stopped. I grabbed the servo horn and turned it so-as to close the throttle. The throttle linkage did not move at all proving it was fully closed. I performed this test many times with all results the same. I was able to use minimal tension on the spring whereas before I had major tension on it and it was unable to perform its task on the 2018 servo.

That being said, what is the major difference between the 2018 and 2055 servos that is causing the issue above? Is it the gearing? The motor torque?

You shouldn't use the servo to adjust the throttle opening. It will die when you hit the brakes. But sweet deal that you got it working. Better safe than sorry. And the high torque should be harder to return over a standard since it probably has a deeper gear reduction. But, it may have a more free gear train and motor allowing easier movement. Like these BK servos for example, they are ultra smooth and easy to move. Way easier than any other servo I have had my hands on. So smooth!

I only used the servo to adjust the gap so I could know that when the spring pulled back that it was as far back as it was able to go. As for throttle gap that is done on the carb.