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I am currently building a 2002 RCSB 4.8 4l60e. It currently has 3.42 (GU6), LSD (G80), disc brakesand 245/55R18 tires (28.6” tall). I was set on Yukon LSD and 4.10 swap since the G80 is dead and this will be a mild street strip. I just acquired a parts truck and it has GT4 (3.73), LSD (G80) and disc brakes. It is in good working order.
I will be refreshing (gaskets/bearings/rings/hone) the 4.8 using crank/rods from the parts truck over the winter then install a mild cam and spring and mill the heads .020-.030. So it’ll be a mild 5.3 in the spring.
So the questions are;
Do I settle for the bolt on swap of the 3.73 or do I sell it off a put that towards my 4.10/yukon LSD?
Is the 4.10 too much gear for the mild 5.3?
I had 31.1” tires factory and switched to 28.6” so 8% difference which is about the same as going from 3.42 to 3.73 mathematically speaking?
No harm in running the 3.73 rear right now. If you still think you need more gear, then you can change it at that point. That will also leave you some $$$ cushion to build your engine.
I'd swap to the "new" complete axle and build up the "old" one at your leisure. The disc brakes will require a bit of extra work butt shouldn't be too brutal. I think I'd want to swap them over to the other axle later. Maybe even change them out to the Av/Burb/Caddy rotors & calipers. I would also recommend against the Yukon carrier in your build-up; not that it's "bad" or "wrong" or "inferior" or any such, just, it's 2024 now, almost 2025, and clutch type those are obsolete. For the same money you can get a worm-gear type instead.
I'd swap to the "new" complete axle and build up the "old" one at your leisure. The disc brakes will require a bit of extra work butt shouldn't be too brutal. I think I'd want to swap them over to the other axle later. Maybe even change them out to the Av/Burb/Caddy rotors & calipers. I would also recommend against the Yukon carrier in your build-up; not that it's "bad" or "wrong" or "inferior" or any such, just, it's 2024 now, almost 2025, and clutch type those are obsolete. For the same money you can get a worm-gear type instead.
Worm gear? Like the Detroit tru-trac? I was only going with Yukon since they have it on Amazon next day shipping. And I know how to rebuild/repair clutch lsd.
Thanks
If you swap the other axle in complete, a day or 2 of extra shipping while the one is sitting around and you're doing other things anyway, won't matter so much. You can afford to wait.
I know how to rebuild/repair clutch lsd
And I know how to repair / rebuild mechanical alarm clocks... I use my phone to wake me up anyway, and it doesn't create the need for repair / rebuild.
I vote for the 3.73 and LSD of your choice with a mild NA 5.3L. Nothing wrong with a clutch style like the Eaton or Yukon for a mild build. Just set up the backlash on the spider gears and it will give you many years of trouble free service. As for gear ratio, 4.10 may work well with a high reving, low torque 4.8 or 5.3 but if you keep the cam and compression right on your 5.3 build, the first gear multiplication may be too much to be useful with a 4l60. If going to a 4l80, may change things a bit with the taller first gear but will tach higher on the highway with the lower OD. My 2000 has always had 3.73 and an Eaton Posi most of it's life. No complaints with that ratio on my early NA and N20 5.3 and 5.7 setups.
If you swap the other axle in complete, a day or 2 of extra shipping while the one is sitting around and you're doing other things anyway, won't matter so much. You can afford to wait.
And I know how to repair / rebuild mechanical alarm clocks... I use my phone to wake me up anyway, and it doesn't create the need for repair / rebuild.
I vote for the 3.73 and LSD of your choice with a mild NA 5.3L. Nothing wrong with a clutch style like the Eaton or Yukon for a mild build. Just set up the backlash on the spider gears and it will give you many years of trouble free service. As for gear ratio, 4.10 may work well with a high reving, low torque 4.8 or 5.3 but if you keep the cam and compression right on your 5.3 build, the first gear multiplication may be too much to be useful with a 4l60. If going to a 4l80, may change things a bit with the taller first gear but will tach higher on the highway with the lower OD. My 2000 has always had 3.73 and an Eaton Posi most of its life. No complaints with that ratio on my early NA and N20 5.3 and 5.7 setups.
it’ll be a mild 5.3 build, I’m keeping the 4l60 it’ll get a mild converter and shift kit. Already has a corvette servo. I like the gear spread of 4l80 much better but the 4l60 isn’t bad I’ve had them last a long time in light cars/trucks. Especially 2wd.
The 5.3 I’d like to build would be;
4.8 flat tops new rings gapped .030
5.3 rods
5.3 crank polished
new bearings (rod, crank, cam)
862 heads refreshed (valve job if needed) new springs
Complete cam kit (cam, lifters, push rods)
new gaskets.
if I can put 300 to the wheels would be great but I don’t have a set number just an idea of parts and whatever it runs great.
The ultimate goal is to take my 2 boys on a power tour or equivalent trip. So Reliability is 1st, Drive-ability 2nd and performance 3rd. I use it daily.
After plugging in the numbers 3.73 would be right about where I want my revs for the speeds I drive. I was concerned 4.10 would be too much. I’m gonna swap in the 3.73 and see how I like it if I need more I’ll get the 4.10
Either way I’ll get a Tru-trac or equivalent installed but for 3.73 and G80 are going in.
Thank you all for replies your input is greatly appreciated!!
08-05-2024, 11:07 PM
Advice on 3.42 to 3.73 axle swap
