Fwd vs 4wd front differential

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Notmikeb
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My tercel:: 85 Tercel 5dr FWD
Location: Laurel, MD

Fwd vs 4wd front differential

Post by Notmikeb » Tue Nov 03, 2015 9:08 pm

Does anyone know if the front differentials are the same between automatic and manual as well as fwd and 4wd? I know the ratios are different but for a fwd car it shouldn't cause any issues. Are the housings themselves interchangeable?

I'm still getting an odd click when braking and accelerating that I think I've ruled out a bunch of other potential sources. I have new axles, ball joints, wheel bearings, tie rods and brakes. The sway bar ends looked fine when I pulled the rearmost bushing off each side to inspect (didn't disassemble further than that) and the control arm bushings seem to be in good shape.

I haven't gone through and made sure all the subframe bolts are tight so that was next on my list. A little afraid to open the differential until it's my last resort because that would mean I have to fix it if it's bad :D
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1985 Tercel 5dr Hatchback
2003 Chevy Suburban
2014 Ford Flex

"I don't get it! I've cut this thing FIVE times now and it's STILL too SHORT!"

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irowiki
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Re: Fwd vs 4wd front differential

Post by irowiki » Tue Nov 03, 2015 10:56 pm

Maybe too OCD about every little noise? It is a 30 year old car after all :lol:

The AT and MT front diffs are probably different internally (like the input/output parts) because it is part of the bellhousing?
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xirdneh
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My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
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Re: Fwd vs 4wd front differential

Post by xirdneh » Wed Nov 04, 2015 1:14 am

its been a while but if my memory is correct the bell housing for automatics is shaped differently than MT bell housing
there are some differential gear ratio differences between hatchbacks and wagons
the hatchbacks have higher gear ratios than the wagons
i converted a 1983 4wd tercel automatic to 4wd manual once, the gear ratio on that car was 3.73

all manual tranny "bellhousings" for FWD and 4WD manual transmissions are the same (the differential gear ratios can be different)
Love those Tercell 4x4 wagons but they sure suffer from road noise.

Notmikeb
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Posts: 235
Joined: Wed Jun 24, 2015 4:53 am
My tercel:: 85 Tercel 5dr FWD
Location: Laurel, MD

Re: Fwd vs 4wd front differential

Post by Notmikeb » Wed Nov 04, 2015 4:00 am

Maybe too OCD about every little noise? It is a 30 year old car after all :lol:
i know I know. Shut up and drive it :D
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1985 Tercel 5dr Hatchback
2003 Chevy Suburban
2014 Ford Flex

"I don't get it! I've cut this thing FIVE times now and it's STILL too SHORT!"

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83Whit3Hatch
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My tercel:: 1983 3 Door Stripper Model. Grey seats with red inserts. 5spd swap.100W 9003 bulb upgrade.
Location: Denver, CO

Re: Fwd vs 4wd front differential

Post by 83Whit3Hatch » Sat Jan 02, 2016 9:34 am

xirdneh wrote: all manual tranny "bellhousings" for FWD and 4WD manual transmissions are the same (the differential gear ratios can be different)
There is an exception to this, I found out the hard way and after 2.5 years of frustration.

The 4 speed bellhousings are cast the same as the others but not finish machined like the others. The 4 speed comes with a freeze plug where the front support bearing for the fifth gear cluster is. The hole that the 5th reverse shift shaft slides into when in reverse is not machined to accept the shaft. The 4 speed transmissions have a shorter shaft that is flush with the intermediate plate and does not protrude into the bellhousing side of the transmsission.

Disclaimer: 1983 transmission, may not be later 4 speeds.

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
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Re: Fwd vs 4wd front differential

Post by Petros » Mon Jan 04, 2016 7:21 pm

the auto trans tercels have a different and unique ring and pinion ratio, something like 3.9:1, vs either the 3.73 or 4.1 to 1 for early and late manual trans T4wd. I would think there would be differences in the belhousing, and certainly the front diff input shaft since the auto trans has a "regulator" that couples the trans out put and diff input shaft. Also, the manual trans shares gear lube with main gear box and rear transfer case, auto trans does not, has seals between front diff housing and main auto trans gear box with different fluids.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
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