Power Antenna motor teardown/autopsy

[Pyral]

This will be a quick and dirty post, I'm not in the mood to write so this might not be my most eloquently written piece ever.

My motor is broken so with nothing to lose I decided to take it apart in a last ditch effort. I only took these photos half way through after taking out the nasty grease. My hands were too dirty to take many photos after I packed the grease.

Here is sort of what your greeted with upon opening the motor. I say sort of because I've removed part of the gear set (the motor worm gear wouldn't be visible), the antenna mast, and the antenna mast sleeve (shaped like a ring partially visible on the left). The main gears that also interact with the mast are also removed and would be in the very center.

Lets go over how it works because there was some small surprises.

It's easiest to start from the masts point of view. It has teeth on it, when it gets slid into the motor the first thing it interacts with is the main gear. The main gear grabs onto the mast and slides it up into it's holding chamber. The holding chamber is this plastic ring.

The main gear (above) is a 2 part gear (I think it's that way to allow some slop in teeth), one part interacts with the mast, the other half interacts with the drive train. These just slide apart and I thought I had broken it the first time.

The gear train takes power from the worm gear motor and transfers it into the main gear. I won't try and explain the drive train because it's hard to describe, plus I have a photo you can look at (above). In the diagram I call it gear cover because the gears in the photo would be facing down towards the worm gear, and the only thing you would see is a flat plastic face that keeps the mast and the gears from coming into contact. The drive train interacts with the motor via worm gear (below).

PS if you remove the metal cover on the antenna housing you will see the motor's stator.

All these parts were covered in dirty grease, but I cleaned some of it up before these photos were taken. If you look at the rest of the album (imgur thinks this is 18+ nsfw photos, it's not I promise)you can see me adding some new grease back. Unfortunately my hands were too dirty to take photos after I had gotten everything in place.

My motor has this issue where it will make a horrible grinding sound for the first 14 seconds when the radio is turned on, and it will fail to raise the antenna. I can help it raise by pulling on the antenna, but that was annoying. If the mast is retracting then there is zero problem with gear grinding. I didn't fix the problem after this and I'm looking for a replacement motor.

 

[octanejunkie]

Thankless filthy job, appreciate you documenting it



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[Auce]

I have the antenna conversion kit, you will not regret it.

 

[brillo_76]

Some of us, like me, prefer the retractable antenna. I keep looking for replacements at the pick and pulls. The last one was saw zalled off and destroyed.

The only issue I see if winter and sometimes they freeze.

I know lots of folks just convert and if that works for your needs great.

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[Pyral]

The taco whip conversion and the stubby conversions are good options. I just prefer the power antenna even if I have to go through hell to fix mine. If you live in an icy place turn the radio off before you turn the car off, I think that's how mine got broken.

There are a few things that I want to add:
1. The 2nd generation 4runner power antenna is different from the third generation one. The internals look different. The power connector looks similar to ours, so they might be interchangeable if you swap mounting brackets

2. Disabling the power antenna fully extended probably helps water get inside. The water will follow the antenna like a chain downspout on a house. The previous owner did this on mine, but it didn't kill the electronics because of the design. There wasn't too much water inside, but there was some. There is an o ring to prevent water from doing this, but it always finds a way in.

3. None of the gears in mine were obviously stripped, just extremely dirty. I can't say why it's not working, I expected it to have obvious damage but it's not the case. They might be plastic gears, but they don't feel flimsy. I tried to grease all the gears like I found them, but I wonder if the grease is helping the mast slip over the main gear.

4. The motor is sealed shut with RTV, it comes apart easily and is goopy like a molten cassette deck belt (sticky like melted marshmallow, stringy like melted cheese). You'll have to clean it up before resealing it with new gasket maker.

 

[brillo_76]

If you live in an icy place turn the radio off before you turn the car off, I think that's how mine got broken.

I can confirm the ice will not hurt them. Mine been freezing and sticking for over 5 years now and did not snap off. Still working fine

The motor will actually stop and not try if the resistance gets too high. As sometimes a section or the entire mast will freeze up.

I have been looking for a replacement for you but I have been striking out at the pick and pulls.. :-( I will keep my eye out.

I do not know if there are other power antennas that are interchangeable out there from other Toyota models. I never dug that deep into it.