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B4 diff in B3 box
Posted: Wed Dec 18, 2019 4:38 pm
by Mja75
Is it possible to fit a B4 diff in B3 box?
I've got two ball diffs for my B3 but want to swap over to a gear diff for carpet. Unless the B3 ever came with a gear diff will a B4 one fit?
Re: B4 diff in B3 box
Posted: Wed Dec 18, 2019 5:14 pm
by jwscab
No. The trans cases are very tightly designed to the diff gear and the diff gears are different sizes .
Re: B4 diff in B3 box
Posted: Sat Dec 21, 2019 7:06 pm
by Ronbo
I thought the B4/T4 top shaft could fit to use the newer slippers in the B3, or is that just for the stealth gearbox? i too am planning on running a b3 in 40+ mod for fun, 10.5 to start ... i havent tried it yet to see. i have a plain T4 gearbox to try...
Re: B4 diff in B3 box
Posted: Sat Dec 21, 2019 7:28 pm
by RS Chris
Top shaft is the same. The differential is different though. It will only fit B2, B3, T3 model trans case.
The final drive ratio is different also. 2:40 (b3) vs. 2:60 (b4).
Re: B4 diff in B3 box
Posted: Thu Dec 26, 2019 7:22 am
by Mja75
Ronbo wrote: ↑Sat Dec 21, 2019 7:06 pm
I thought the B4/T4 top shaft could fit to use the newer slippers in the B3, or is that just for the stealth gearbox? i too am planning on running a b3 in 40+ mod for fun, 10.5 to start ... i havent tried it yet to see. i have a plain T4 gearbox to try...
I've done the top shaft conversion on my B3 and T3, well worth doing. You can also then use a B4 gear cover, easier to find and more robust than the B3 one. At the moment I'm running a 13.5 in my B3.
Re: B4 diff in B3 box
Posted: Wed Jan 01, 2020 12:45 pm
by RS Chris
Mja75 wrote: ↑Thu Dec 26, 2019 7:22 am
Ronbo wrote: ↑Sat Dec 21, 2019 7:06 pm
I thought the B4/T4 top shaft could fit to use the newer slippers in the B3, or is that just for the stealth gearbox? i too am planning on running a b3 in 40+ mod for fun, 10.5 to start ... i havent tried it yet to see. i have a plain T4 gearbox to try...
I've done the top shaft conversion on my B3 and T3, well worth doing.
You can also then use a B4 gear cover, easier to find and more robust than the B3 one. At the moment I'm running a 13.5 in my B3.
Is that a direct fit? Need one for my T3.
Re: B4 diff in B3 box
Posted: Fri Jan 10, 2020 3:01 pm
by Mja75
Layshaft fits straight in, just don't put the spacer on like when it's fitted to a B4.
The gear cover won't fit over the T3 clutch though, but will of course fit if you use the B4 clutch.