UPDATE: Help with SM420 (1 Viewer)

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No, there is no obvious loose metal inside. From the videos I’ve seem, it seems to me that they could fall out forward toward the clutch and not fall into the tranny housing….. Is that not correct?
No. No way.

It is more likely a problem in the adaptor or transfer case. It the input gear pilot needle bearings fell out, there would probably be a problem shifting into 4th gear or popping out of gear.
 
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I’m totally perplexed. I refilled the gear oil (using a GL1, Mineral Oil), and drove the vehicle with the tunnel off for 5 miles or so, running it up to 50+mph. I’m in Arizona so it’s plenty hot and it amazing how much heat that comes off that BH and Tranny. I ran through all gears with no issues. No noise. Got back and I couldn’t hear any of the noise I heard on Saturday.

I don’t know what to think. I wasn’t imagining the noise. All I can think of is to run it longer at higher speed and see if I can duplicate it.

It’s possible the problem is on the TC or adapter, but I don’t understand what brings it on. The only difference was that I had driven about 20 miles at 60+mph speeds on two occasions. If prolonged high speed operation causes something the come loose or shift??
 
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My driveline will make a noise and vib at certain speeds, the shifter on the 420 will rattle as you described in 3rd gear, did it happen in 3rd when it was making the noise, FWIW it wouldnt hurt to pull the inspection cover on tcase and have a look. My 420 has lots of miles, rebuilt it in 2003, they just keep going.
 
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My driveline will make a noise and vib at certain speeds, the shifter on the 420 will rattle as you described in 3rd gear, did it happen in 3rd when it was making the noise, FWIW it wouldnt hurt to pull the inspection cover on tcase and have a look. My 420 has lots of miles, rebuilt it in 2003, they just keep going.

There shouldn’t be any issues with the TC since is was rebuilt by Mark’s Off-Road in January, but then you never know. I had to re-do the double seal in the Double Seal Speedo Hub he installed, and seal the shaft splines to keep the oil from leaking into the parking brake, so……I guess it wouldn’t shock me if I discovered problems in the TC too. I’m not sure I’m qualified to know what to look for taking the tcase inspection cover off (I’m assuming you mean the PTO cover), unless there is something obviously loose.
 
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Major mechanical problems don't just go away, so it is probably something strange, like something got in the clutch and bell housing and was banging around in there and then made its way out. It is either that or ghosts.
 

pjohnson

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Major mechanical problems don't just go away, so it is probably something strange, like something got in the clutch and bell housing and was banging around in there and then made its way out. It is either that or ghosts.
I was thinking the same thing. Something rattled around the bell housing and has now settled or fallen out.
 

middlecalf

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Clutch throwout bearing dragging?
 
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I love guys who say: “one of the easier trans to work on” and assume every person on this list has the tools and the mechanical knowledge to work on a transmission. That kind of thinking is what got me in this situation in the first place. THANKS for your deep insight!
Really @Poser? Everyone on this list should have the tools and be able to rebuild a Transmission?
 

Poser

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Did YOU install this 420 trans and transfer case?

If so, what did the pilot bearing look like in the end of the crankshaft?

The input shaft on the SM420s, (civilian truck/Gama Goat does not matter) is SHORTER than that of the Toyota three speed transmissions, so, you need a different pilot bearing. If you do not have the correct pilot bearing installed, your input shaft will not be supported properly and could cause the 'clutch wobble' you mentioned earlier in the thread.


BTW,

Pin_Head knows that of which he speaks.
 

Poser

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THANKS for your deep insight!

It was commentary on you being a douche out here, to people who have substantially more experience and knowledge about your transmission and are trying to HELP YOU.

Further, very similar to the Land Cruiser being reliable and not requiring A LOT of specialized tooling to keep it living and rolling along, the SM420 can be disassembled and rebuilt with very little special tooling, provided you have a little mechanical experience and the Interwebs.

:beer:
 
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Did YOU install this 420 trans and transfer case?

If so, what did the pilot bearing look like in the end of the crankshaft?

The input shaft on the SM420s, (civilian truck/Gama Goat does not matter) is SHORTER than that of the Toyota three speed transmissions, so, you need a different pilot bearing. If you do not have the correct pilot bearing installed, your input shaft will not be supported properly and could cause the 'clutch wobble' you mentioned earlier in the thread.


BTW,

Pin_Head knows that of which he speaks.
Yes, I installed ithe Tranny and TC. I have driven this Transmission for 20 years with the pilot bearing. It is the longer version pilot bearing to address the shorter input shaft. I have never had a problem with it.

The noise I heard was coming from the Tranny. I could hear it with a screwdriver set up to the transmission and without. Unfortunately I couldn’t record it because my phone overheated.

It’s sweet that you to feel you have to defend Pin Head.
 
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It was commentary on you being a douche out here, to people who have substantially more experience and knowledge about your transmission and are trying to HELP YOU.

Further, very similar to the Land Cruiser being reliable and not requiring A LOT of specialized tooling to keep it living and rolling along, the SM420 can be disassembled and rebuilt with very little special tooling, provided you have a little mechanical experience and the Interwebs.

:beer:
Oh, durka, durka durka durka!
 

Poser

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If the needle bearings in the input gear pilot got loose, they would end up inside the transmission and probably be stuck to the magnet. There is no way for them to get outside without a big hole in the tranny case. The 420 is reasonable easy to work on, but I wouldn’t assume it is responsible for the noise If there is no obvious loose metal inside

It’s sweet that you to feel you have to defend Pin Head.

Damn dude.

Keep 'em coming.

:beer:
 
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I love how trolls like @Poser and @OGBeno jump in, not to be of help or to offer any real expertise, but instead to attempt to belittle members on the list who they consider beneath their technical prowess. It’s the epitome of arrogance. It’s what really hurts this site as a place to get help.
 

pjohnson

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So, is the noise still there?

If not, just run it until it comes back 🍺
 

pjohnson

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$hit dude, you really don't want help do you...
 

DangerNoodle

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