Diff. rebuild, time to switch gears?
Thread Starter
Instructor
Joined: Dec 2007
Posts: 184
Likes: 0
From: Crystal Lake IL
Diff. rebuild, time to switch gears?
OK...so I'm being force to rebuild my trailing arms, so while I'm at it, I decided I might as well do all the rear suspension...and what the heck, the diff. should probably be gone through too. So my question is:
It's currently a stock '81 with the TH350c trans and stock gears. I'm hoping to change the engine and trans in the next 1-3 years. I will likely go with a 200R4 trans and an engine at 400-500HP.
If I'm rebuilding the diff. anyway, should I change the gears based on my future setup? What gear ratio would you recommend for a weekend cruiser (very little to no highway driving and no strip driving at all)?
It's currently a stock '81 with the TH350c trans and stock gears. I'm hoping to change the engine and trans in the next 1-3 years. I will likely go with a 200R4 trans and an engine at 400-500HP.
If I'm rebuilding the diff. anyway, should I change the gears based on my future setup? What gear ratio would you recommend for a weekend cruiser (very little to no highway driving and no strip driving at all)?
Burning Brakes
Joined: Nov 2006
Posts: 954
Likes: 40
2022 C3 of the Year Finalist - Modified
It's a question of in what RPM you want to cruise.
Go to this link and figure out your RPM.
http://www.differentials.com/calc.html
Avner
Go to this link and figure out your RPM.
http://www.differentials.com/calc.html
Avner
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
OK...so I'm being force to rebuild my trailing arms, so while I'm at it, I decided I might as well do all the rear suspension...and what the heck, the diff. should probably be gone through too. So my question is:
It's currently a stock '81 with the TH350c trans and stock gears. I'm hoping to change the engine and trans in the next 1-3 years. I will likely go with a 200R4 trans and an engine at 400-500HP.
If I'm rebuilding the diff. anyway, should I change the gears based on my future setup? What gear ratio would you recommend for a weekend cruiser (very little to no highway driving and no strip driving at all)?
It's currently a stock '81 with the TH350c trans and stock gears. I'm hoping to change the engine and trans in the next 1-3 years. I will likely go with a 200R4 trans and an engine at 400-500HP.
If I'm rebuilding the diff. anyway, should I change the gears based on my future setup? What gear ratio would you recommend for a weekend cruiser (very little to no highway driving and no strip driving at all)?
Thread Starter
Instructor
Joined: Dec 2007
Posts: 184
Likes: 0
From: Crystal Lake IL
The stock aluminum diffs are very weak. They cannot be made any better. In fact, there was just a thread on one unit where a guy broke one of his stock aluminum bearing caps - it cracked in half. If you are planning on running 400-500 HP, I suggest you look into upgrading the diff to an earlier iron unit. You can tune and polish the posi case, install socket head cap screws in the bearing caps, and even install ARP ring gear bolts for extra safety. It bolts up to the batwing, but will require some mods to the front bushing mount and maybe the half-shafts. I'm sure Gary and Mike will respond to this thread, as they are the experts on vette differentials.
I just saw that thread and it got paranoid. I'm thinking at this point I might leave it alone until I have more time to think about the best approach for the long run. The seals are leaking, but it's not making a ton of noise or anything that would push me to do it right now.
BTW, nice writeup on the diff rebuilt. You convinced me that with some time and patience I could probably do the work myself.
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
Safety Car
Joined: Oct 2004
Posts: 4,809
Likes: 237
From: Utah
The stock aluminum diffs are very weak. They cannot be made any better. In fact, there was just a thread on one unit where a guy broke one of his stock aluminum bearing caps - it cracked in half. If you are planning on running 400-500 HP, I suggest you look into upgrading the diff to an earlier iron unit. You can tune and polish the posi case, install socket head cap screws in the bearing caps, and even install ARP ring gear bolts for extra safety. It bolts up to the batwing, but will require some mods to the front bushing mount and maybe the half-shafts. I'm sure Gary and Mike will respond to this thread, as they are the experts on vette differentials.
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Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
I recently addressed this same issue when I went to change the gears in my diff. Gary did not recommend rebuilding my aluminum diff. As I had a new zz383. Instead, he built me a new diff using a 79 case. The batwing bolted right up to the 79 case. However, there are some parts that need to be changed. Mike Dyer (tracdogg2) can give you a complete list.
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Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,983
From: Connecticut, USA
I opened and looked through this fast and didn't see the poster's name. I saw the green witness marks on the Spicers and thought someone does that like I do !! LOL
Looks good, but bend those french lock tabs in more.
Enjoy the ride, Jeremy will be on the road soon too!
Looks good, but bend those french lock tabs in more.
Enjoy the ride, Jeremy will be on the road soon too!
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