Rear Differential Gear Swap

[rosseich]

I'm planning to swap out my stock 3.45 gears for a 3.91 and have a question. Does the stock differential carrier work with any gear set? I'm hoping to avoid replacing my stock posi carrier.

Thanks.

[Starman]

From when I researched this some time back, I believe once you go past 3.73, a larger carrier is required.


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[Starman]

Next clutch change, I will move to Viper 4.10 set.


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[HAWAIIZR-1]

I'm planning to swap out my stock 3.45 gears for a 3.91 and have a question. Does the stock differential carrier work with any gear set? I'm hoping to avoid replacing my stock posi carrier.

Thanks.

Yes, you are good to go to change to lower gear ratios with our Dana 44 HD rear. You can do more research, but here is an example
of gear ratios available. It is the Dana 36 in base model autos that have limitations.

https://www.corvettepartsonline.net/corvette-differential-ring-pinions/

[1991 Corvette ZR-1]

You should be fine. I went from 3.45 to 3.90. Yukon brand pinion and gear and there was no issue.

[Matt B]

Has anyone ever produced a step by step guide or, even better, video on how to swap gears on a Dana?

[Jagdpanzer]

Factory Service Manual is what I use. It shows pinion preload using shims. Most modern replacement gears sets now use crush sleeves for pinion preload. Plenty of videos on YouTube showing crush sleeve pinion preload setups.


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[HAWAIIZR-1]

Factory Service Manual is what I use. It shows pinion preload using shims. Most modern replacement gears sets now use crush sleeves for pinion preload. Plenty of videos on YouTube showing crush sleeve pinion preload setups.


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Hey Prof Phil,
I remember you helped me out with the list of parts to rebuilt and do 4.10s in my 90Z many many moons ago. I took the assembly out to a machine shop back then to have a pro do the work. I am almost tempted to try this myself, but aren?t some special tool needed? I?ll see if I can find a shop here in Japan and did check out some YouTube videos. Thanks.

[Jagdpanzer]

Yes, several special tools are required. Case spreader, set bearings, inch pound torque wrench, 300 lb torque wrench, dial indicator, precision calipers, heavy duty snap ring pliers, pry bars, drifts, pinion bearing removal tool, differential case bearing removal tool, pinion depth setup tool, pinion bearing outer race install tool, side shaft bearing install tool, pinion and side shaft seal installation tools.
All are mentioned in the FSM write up. Most of these were made by Kent-Moore back in the day. FSM lists the KM part numbers. I picked up most by scouring eBay over a couple of years and made the rest in my shop.


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[Jagdpanzer]

I was lucky back then due GM shutting down a lot of the weaker Chevrolet dealerships. Tool liquidators came in and bought up up a lot of dealerships special tool inventory and many of them ended up on eBay.


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[HAWAIIZR-1]

Yes, several special tools are required. Case spreader, set bearings, inch pound torque wrench, 300 lb torque wrench, dial indicator, precision calipers, heavy duty snap ring pliers, pry bars, drifts, pinion bearing removal tool, differential case bearing removal tool, pinion depth setup tool, pinion bearing outer race install tool, side shaft bearing install tool, pinion and side shaft seal installation tools.
All are mentioned in the FSM write up. Most of these were made by Kent-Moore back in the day. FSM lists the KM part numbers. I picked up most by scouring eBay over a couple of years and made the rest in my shop.


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Thanks Prof Phil! I guess I'm out for sure. Maybe I can bring the assembly with me to Carlisle to have the 4.10 installed and carry back home to Japan. LOL :cheers:

[WARP TEN]

Thanks Prof Phil! I guess I'm out for sure. Maybe I can bring the assembly with me to Carlisle to have the 4.10 installed and carry back home to Japan. LOL :cheers:



Now that would be an impressive piece of carryon luggage Craig!-- Bob


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[HAWAIIZR-1]

Now that would be an impressive piece of carryon luggage Craig! ? Bob


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Ha ha! Not carry on, I do it all the time with car and motorcycle parts and tools. I have two tuff boxes with wheels. Two checked baggage up to 70 lbs are free.

[HAWAIIZR-1]

OP,
My apology for asking on your post but maybe someone else has the same question?

I found a shop in Japan to do the gear swap. What else do I need to provide the shop besides R&P gear set? I only have 30K miles so I don?t think I need a complete rebuild kit. Thanks.