620 Differential busted

[bgmk106]

So I was teaching my girlfriend of six years how to drive stick today. It was a jerky experience to say the least. As i drove it out of the parking lot I noticed a faint but continuous clicking noise. So I started to head for home and realized the noise got much louder as i coasted and decelerated. Fast forward to getting home thinking it was just a U Joint, I crawl under and notice nothing odd about it. Spin the wheel and notice the noise is coming from the rear end. So I drain it and it was not a pretty sight. Lots of metal shavings on the plug and chunks sitting on the bottom that i could feel with my finger. Looking in the fill hole I see this

 

As you can see, the base of the spider gear/pinion gear is chunked out on every tooth. I have a feeling this is an easy fix though I have little experience with rear ends and even less knowledge on where I can find these particular gears.

 

So my questions are

1)are these gears the same for all sizes of rear ends?

2)do other rear ends share the same gears so I can acquire one quickly?

3)Where to find out what diff I even have? I can't find any markings on it nor any of the tags on the truck.

 

Any help is appreciated. And yes I have tried many searches, none of which help my problem.

Thanks

 

EDIT: on the diagrams for the rear end it lists the part # as 38425-71200

[datzenmike]

Hmmm title says 620 but profile says 280z. Well I'll assume it's a truck. The differential will have to come out so rather than taking it all apart why not just replace it. You'll have to get another one for the side/spider gears anyway.

 

All 620s had an H-190 differential in them with the follwing years and ratios...

 

'73-'78 4 and 5 speeds 4.375* chances are that you have the most common 4.375

'79 4 or 5 speeds 4.11

 

'73-'74 automatics 4.625

'75-'79 automatics 4.375*

 

Raise and drain.

Disconnect driveshaft.

Un-do both hydraulic brake lines from brake backing plates.

Remove the 4 bolts behind the brake backing plates that secure the axles and pull them outward with brakes attached.

Remove the ten? nuts around the third member (differential) and pull forward off their studs.

It's HEAVY so be ready for this.

 

Installation is the reverse.

Fill with GL-5 80w90 gear oil.

Clean the fill bung magnet

Bleed the rear brakes.

 

Don't let axles rest in the tubes.... they will pinch the grease seals. Pull out about 6" and support them. Ebrake cables should stretch enough.

Gaskets are NLA for the H-190 so get Permatex Gasket sealer. Not RTV get the thick blue stuff. Let set up and install.

Mark drive shaft so it goes back on in same position.

 

 

If set on swapping the gears then.... http://community.ratsun.net/topic/10748-h190-spider-gear-swap/

[bgmk106]

Great help DatzenMike, thank you. This is everything I need to know.

 

Now just out of curiosity, are the spider gears the same between all H190 rear ends? The only 620 in my area that I can get a rear end out of was destined for the scrap yard when I talked to the owner a couple weeks ago. Here's hoping I'm not too late...to make one last pull.

[datzenmike]

I believe they are. The gear ratio is stamped on the outer rim of the ring or crown gear. 35:8 divided is 4.375 which I assume is your ratio?

 

Gears are same part number through all years of 620

Pinion mate.. 38425-71200

Side gear.....  38423-73000

 

Rather than disturb the gear lash settings I would just swap the complete third member.

[bgmk106]

I believe they are. The gear ratio is stamped on the outer rim of the ring or crown gear. 35:8 divided is 4.375 which I assume is your ratio?

 

Gears are same part number through all years of 620

Pinion mate.. 38425-71200

Side gear.....  38423-73000

 

Rather than disturb the gear lash settings I would just swap the complete third member.

 

I was able to get the rear end yesterday 2 days before the truck was scrapped. Replaced the whole thing as suggested and all seems to be in order. I need to bleed the brakes today before a test drive but I'm sure everything will run well. Thanks again datzenmike!

[bgmk106]

Here is what I found in the bottom of the old one.