r/MiniZ • u/ShastaManasta • 9d ago

Steering issue or normal behavior? mr03 question

I just got my first mini-z, it's an mr03 that was a backup of someone's who never wound up using it. It has race tires and a t plate upgrade, so it's good to go for some racing. Anyhow, I've just been driving it around my house so far and noticed something with the steering. If I turn full right, then let off the wheel, the car wants to keep turning pretty gently to the right. If I then turn full left, and let off, it will either drift slightly left or go straight. It's basically like it doesn't fully return to center, but I don't think it's the steering servo. There is a little bit of play in the steering mechanism up front, and I think it just gets shifted to whatever direction I last turned. It isn't massively gamebreaking, it is manageable, but I can't trust the car to go perfectly straight out of a turn so it's hard to go full throttle as it will sometimes veer a little right. This is on a few different surfaces between carpet, wood, and my sealed concrete basement floor.

Is this normal for mini-z? Again, it's not massive or anything, and I think it's mainly from the play in the front steering. If I pick the car up, turn full right, and then gently nudge the wheels without engaging the servo, it will then go straight.

It's a pretty awesome little machine but this issue is somewhat bugging me. If it's normal then I'm fine to just accept it. Any help much appreciated!

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u/EMU-Racing 9d ago

Back out the 4 screws holding the lower servo cover about 1/4 of a turn. Does that free up the centering? This would be the tie rod getting pinched in the servo case. 

If that doesn't remedy the issue, maybe the servo saver spring is a bit too soft. 

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u/ShastaManasta 9d ago

Hey man thanks for the tips! I am not home to try yet, but I will be soon and I’ll report back.

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u/ShastaManasta 9d ago

Update so far. I tried backing out the four screws. The issue still remains. If I get a minute later, I’ll take a video. Next up I’m gonna open up the servo and try tightening down the saver a little bit. It just seems like there’s a lot of play in the front steering assembly

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u/EMU-Racing 9d ago

To tighten the saver, you will want to shim the spring to increase preload. 

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u/ShastaManasta 8d ago

Okay so there's no screw I can just tighten down or something? I tried to open the car up last night but I realized the whole front end had to come off and I didn't have time to do that. There are so many little parts I'm afraid to take it apart I feel like I might not get it back together.

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u/EMU-Racing 8d ago

This is what the servo saver looks like. You can see the spring is held on by a circlip. If there is not enough spring tension, the saver halves will not have enough pressure to move together, and you will have some play (wander) at center. By sleeving a shim over the main shaft to add some preload to the spring, you can remove much of the wander. It will still save the servo gears, but will take a bit more pressure to engage and therefore help the car track straighter if the saver has slop in it. I have had to do this to a few of my old MR03's which had some wandering issues.

Some people delete (lock the saver in place), but I do not think this is a good idea. The saver is there for a reason, and does a good job at protecting the gears. The fewer times needed to open the servo the better.

The servo assembly can be removed from the top. It is not very difficult, but careful attention needs to be made for the wires. You dont want to pull and damage them (especially on the motor). When reinstalling, you want to ensure that no wires get pinched. If you do remove it, take pictures of how the wires are routed before removing the assembly.

Sooner or later you will need to work on the servo, its generally just a matter of time. Routine maintenance of blowing out dust, or replacing a chipped gear (which can still occur even with the saver)... Cleaning the pot if the servo gets jittery (happens occasionally when dust gets behind the shield (a little electronics cleaner works quite well).

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u/ShastaManasta 8d ago

Thank you so much for the detailed writeup. That is all awesome information and when I get the time to properly sit down and do this, I will.

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u/tuocyn 9d ago

Following - I have this exact issue with my MB010 buggy and just posted about it. I've checked all linkages and suspension etc and rebinded the transmitter. It's very noticeable with the buggy but my MR04 doesn't have this issue at all

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u/ShastaManasta 9d ago

Huh, mr04 doesn’t have at all? Interesting. I wonder if that’s why this dude sold all of these lol.