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73 620 rear end issues!


DatsunKaua'i

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So I've removed my rear diff to find that the cross shafts have earthier broke or come loose. So I've taken off bearing covers and ring gear assembly will not pop out,it's literally stuck in? Any suggestions and anyone have an old diff they wanna ship to hawaii!!?? Thanks guys I'll add some photos also. And here's a video link to see what I'm talking about.

 

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The pinion mate shaft is simply held in with a roll pin that has sheared off. Replacing it may fix the problem. Well it will lock the shaft in place but what ever caused this problem may shear this pin as well???

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So this piece is called a pinion mate shaft? Do you know of a breakdown of the differential? Like a schematic or whatever you call it?... thx for such a quick reply too by the way! I can't even get the ring and spider gear assembly out?

 

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Remove the bearing caps and then give it a  whack with a hammer and block of wood. it should come out. remove the ring gear and the pin should slide out. you will be able to see if the pin is broken or just the roll pin broke off. those small roll pins can be very difficult o remove sometimes, Your video looks like the pin is broken, still need to get the roll pin out to remove both parts of the pin. That is probably all you need to fix the rear end 

Edited by Rick-rat
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Rick-rat thx brother. Do you know where I could buy the parts needed to repair this? I'm having a hard time finding them online. 

Also the pinion gear is a little banged up but still mates well with ring gear and does not seem to make any noise or bind up just cosmetics.

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 Did you get it apart? I don't know where to get new parts, maybe someone has an old differential lying around that could have a good pin the roll pin should be available at any parts store. Try an ad in the classifieds, maybe you will get lucky

Edited by Rick-rat
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So I got everything apart the bearing caps had no shims ? And the roll pin will not budge when hammering.?? Any suggestions? Pretty frustrating also can't find the parts to buy anywhere. Kinda have to just go to a parts store and see what'll match up.if anyone  

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They can be a bear to get out, get some penetrating oil, I like Kroil, get a good quality punch or 2, the same size as the roll pin. Did part of the pinion mate shaft come out when you removed the ring gear?

 

When you get the roll p[in out finally you won't believe the small thing that is kicking your ass, don't let it win!!!!!!!!!!!!

Edited by Rick-rat
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8 minutes ago, Rick-rat said:

 

get a good quality punch or 2, the same size as the roll pin.

 

 

This! Spend the money on a good punch.

 

Punch has to go all the way through to drive it out. Roll pins are compressed like a spring.  

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Yeah that pinion mate shaft is broken and in at least one place and maybe two. It's got to go. That thing in the middle is the thrust block. Replace the pinion mate shaft or swap in a new third member.

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That roll pin has to come out, sometimes they do not want to move but the roll pin in that is a lot easier to remove than the pin in a 320 pumpkin/gearset, they are solid pins and are a BITCH to get out(they come out shaped like a banana), I normally use as large a nail that will fit in the hole with the end ground flat, I just keep tapping away till it starts moving, a good punch made out of harder metal should work WAY better than a nail. an old drill bit might also work.

You cannot use it the way it is, what will happen is the hole that the pin is still in holding that center block in will start to oval, once that happens the whole thing is garbage, I had that pin break on my C200 dually axle and it destroyed the carrier, lucky for me the C200 carrier in the late 4wd Nissan 720 is the same thing and I was able to fix my dually axle with them parts.

Just keep tapping away at that roll pin till it starts moving, I have bent a few large nails over the years but have always got that pin out.

I am sure it would be easier to just buy another pumpkin/gearset, but it will likely cost a lot for shipping.

Edited by wayno
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The pinion mate shaft came loose on my new 70 340 Dart. It went into the crown and tore half the teeth off. So no you can't run it like it is.

 

 

OR...

 

I have a center section , 4.37 gears. 100.00 plus the ride.

 

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14 hours ago, DatsunKaua'i said:

So I got everything apart the bearing caps had no shims ?   

 

I know, a little late to the party, as I don't come here much after the change to the new & improved forum format.

You won't see the shims, as they are between the bearing & the diff, not between the outer race & housing like modern diffs.

Don't mix up the races, as it may change the gear mesh.

 

Want quick & cheap, have the diff welded up (locked diff).

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