Tekno issues

[RC Steve]

My daughter's Tekno MT410 steering sucks.

Sitting still the steering is full range and fast.
Backwards the steering is full range and fast.
Forward the steering is limited to about 10 degrees and the servo struggles.
Wiggle the steering wheel back and forth with the truck still and the steering frees up.
With the wheels off sitting on the ground nothing changes.

Replaced the servo, no change.
Rebuilt the bellcrank, no change.
Installed a Castle BEC, no change.
Replaced the C and steering blocks, no change.
Replaced the driveshaft, CVs, and axles, no change.

The front drive cups are heavily worn, could the dog bones be binding in the cups?
New drive cups have been ordered.

I'm running out of ideas.

 

[Shadows]

My daughter's Tekno MT410 steering sucks.

Sitting still the steering is full range and fast.
Backwards the steering is full range and fast.
Forward the steering is limited to about 10 degrees and the servo struggles.
Wiggle the steering wheel back and forth with the truck still and the steering frees up.
With the wheels off sitting on the ground nothing changes.

Replaced the servo, no change.
Rebuilt the bellcrank, no change.
Installed a Castle BEC, no change.
Replaced the C and steering blocks, no change.
Replaced the driveshaft, CVs, and axles, no change.

The front drive cups are heavily worn, could the dog bones be binding in the cups?
New drive cups have been ordered.

I'm running out of ideas.

That's a lot of effort to remedy that. I don't know Tekno or a whole lot of anything else, really; but it looks like that's the best course of action.

 

[Just a hobby]

Yes that worn cups will do that. My Baja Rey did the same. I tried just switching the cups from side to side. And ran fine, save a buck and run the cups till that side wore out. Your cups must be worn deep. Won't affect reverse.

 

[KnowAir]

I guess at this point you might as well change out the drive cups if they're heavily worn. In my experience worn drive cups will effect suspension travel more than anything else, but I suppose it can affect steering too. I've seen situations where the cups are worn so deeply it'll actually cause the suspension to bind up under power, also, a telltale sign is to run the vehicle while the wheels are off the ground and the suspension is fully unloaded. Really worn cups will cause the suspension to go up when the axle binds in the cup. The tires will be "jumping" up and down while spinning. That's a pretty severe case of worn cups and definitely need replacement.
What servo and tires are you running?
It is possible that something is mechanically binding up the steering when the suspension is traveling. Disconnect the shocks and work the steering with the suspension at different positions and see if you can notice a certain point where the steering is binding.

 

[Hector_Fisher]

Some good thoughts here so far. Tekno is pretty good at this among other manufacturers, but the ball ends of the driveshafts do still move in and out slightly under left-to-right steering movement. And overtime with slop in the suspension, the in/out movement of the ball end increases a little bit more. It's entirely possible that the seeming randomness of the steering is the driveshaft "catching" on the worn cup. This would make sense in that my kraton was the opposite: when i would pop a driveshaft out and it would get stuck on the outside of the drive cup (rotated 90 degrees) steering would be almost non-existent. So a binding driveshaft could certainly be causing steering issues.

It sounds like you've replaced basically all of the front of the truck (involved with steering). I would surprised if your new drive cups don't fix the issue.

 

[RC Steve]

Swapping the drive cups didn't do anything.

The next step for the Tekno is a complete teardown and rebuild. This has got me beat. I keep blaming it's MAX6 V2 ESC. I don't remember the truck doing this before I installed it's new ESC but I don't drive it very often. I'm grasping for straws at this point.

 

[razorrc]

Just tighten your servo saver almost all the way. Leave about 1/4 from full tight. Don't overcompress the spring.

 

[KnowAir]

Just tighten your servo saver almost all the way. Leave about 1/4 from full tight. Don't overcompress the spring.

Good call, I didn't think to mention the saver spring.

 

[Just a hobby]

Bad servo saver spring will definitely cause lack of steering. That is your issue. Easy simple fix

 

[RC Steve]

The final clue!!!!!!

I installed my daughter's radio system in my Sledge so she would have something to drive today. Now my Sledge does the same thing.

 

[RC Steve]

I replaced the receiver in the Tekno and now the truck works perfectly. Turns out I was running the BEC voltage too high and fried the receiver.

 

[RC Steve]

Sorry, I forgot a picture of it running perfectly. I understand pictures are mandatory on this site.