Front Diff

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ColSwede
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My tercel:: 83 Tercel Wagon 4wd

Front Diff

Post by ColSwede » Wed Jul 03, 2019 9:48 pm

Sad times... Got word from my shop that my front diff has died... Fortunately, I have my donor car, which still has its in. How big of a pain is it to remove? What do I need to watch out for? And how can I tell if the one on the donor car is good? All help is appreciated. I cannot let my baby die now!

teranfirbt
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Re: Front Diff

Post by teranfirbt » Sat Jul 06, 2019 3:38 pm

The most straight forward thing to do is to split the differential from the transmission and swap the entire front half of the transaxle. This avoids having to set pinion depth between the pinion and the ring gear.
When you have the donor diff off the car, have your mechanic measure ring to pinion lash as well as side gear lash. Both specs are in the Toyota FSM and I'd bet that both are out of spec wide on the donor diff. Unfortunately the shims required to fix the lash on the ring gear are no longer available, it took me some clever machining and some McMaster shims to get mine back in spec :\ It looks like the side gear washers are also no longer available :(

Removing the transaxle isn't too bad, you can remove the entire thing as a unit. One key trick is to get everything disconnected, angle the transmission toward the ground, and then remove the input shaft by removing the cover on the backside of the bellhousing. This will make removing the transaxle from the car 1000x easier. It's also the way to put it back in, leave the input shaft out until you get the bellhousing bolted up to the block, then install the shaft and its cover.

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Petros
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Re: Front Diff

Post by Petros » Sat Jul 06, 2019 8:39 pm

several cautions to watch out when swapping out the front diff assemby: '83-84 front diff is 3.7:1 ratio, the later '85-88 is 4.1:1, you can change them out only if it matches. or you can change out the front and rear diffs as a set to the front and rear final drive ratio is the same.

you can inspect the condition of the front diff without removing it from the car, you pull off the front cover. You can also verify the gear ratio by counting the teeth. the face of the ring gear teeth should be evenly worn, smooth and shinny. no pits, no scratches, or bits of gear teeth missing at the edges.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

ColSwede
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Re: Front Diff

Post by ColSwede » Wed Jul 10, 2019 10:49 am

Toyota FSM? what is the likelihood of my diff having all the shims I may need to correct anything that could be off in the donor?

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Petros
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Re: Front Diff

Post by Petros » Wed Jul 10, 2019 8:14 pm

you could get lucky, and old diff in combo with the replacement one, may have what you need.

but it seems to me that there are a few remaining diff shops around the country that should have something that will work. the 4x4 shops will have a lot of experience with Toyota truck diffs, may know enough about the smaller toy diff to be able to help you with the shims you need.

if the gear lash on the replacement assembly is acceptable, just leave it. these diffs run more than 400k miles without issue. but sometimes they get out of spec. the factory used soft crushable "shims" that are compressed to spec during factory assembly. these will eventually go out of tolerance, when that happens you have to replace with the correct thickness hard shim to correctly set the ring and pinion gear lash. it is a very sensitive adjustment, that is why if it is good, do not try and fix it.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

ColSwede
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Re: Front Diff

Post by ColSwede » Wed Jul 10, 2019 8:37 pm

I really hope I'm not getting in over my head with doing most of this work myself. Once I know the condition of the replacement diff, as long as all is well, I intend to get a clutch kit and replace that while I'm in there (mine is on its way out). It's just strange how it went out with very little warning.

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Petros
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Re: Front Diff

Post by Petros » Thu Jul 11, 2019 12:13 am

replace the rear main seal on the engine while you are at it. it is a big job, but fairly straight forward.

do not be intimidated, forum member Xirdneh make a detailed description and a you tube video on removing the trans.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

ColSwede
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Re: Front Diff

Post by ColSwede » Fri Jul 12, 2019 4:47 am

That's not a bad idea, I think I noticed previously that it looked like the rear main seal was leaking... As long as I'm in there, guess I might as well knock out as much as I can.

ColSwede
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Re: Front Diff

Post by ColSwede » Sun Jul 14, 2019 7:33 pm

Petros, I've looked far and wide and cannot find any videos on removing the transmission. Do you have the link?

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NWMO
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Re: Front Diff

Post by NWMO » Sun Jul 14, 2019 10:17 pm

Colswede,

I found oodles of transmission videos, but not on removal. Here is a great write up however, and his other trans videos are great.

viewtopic.php?f=7&t=7148&hilit=Transmission+Removal


Chris
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T4WD augury?
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ColSwede
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Re: Front Diff

Post by ColSwede » Sun Jul 14, 2019 11:46 pm

Thank you for the help on this! That write up has helped me already and I haven't even stepped back outside!

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NWMO
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Re: Front Diff

Post by NWMO » Mon Jul 15, 2019 3:40 am

Robert’s videos are fantastic too. He even uses a transmission prop with cut-outs so you can see what is happening and gives great trouble shooting advise.
Wonderful stuff!

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain

ColSwede
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My tercel:: 83 Tercel Wagon 4wd

Re: Front Diff

Post by ColSwede » Mon Jul 15, 2019 8:16 am

Wait a second... The Robert Walker videos? That's how I learned to rebuild my carburetor and how to get the front axles out! That guy and his videos are awesome!

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NWMO
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Re: Front Diff

Post by NWMO » Mon Jul 15, 2019 11:03 am

That's the one (I believe). I sometimes get confused bouncing between Facebook and here, but I'm pretty certain Robert Walker and xirdneh are one and the same.

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain

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Petros
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Re: Front Diff

Post by Petros » Mon Jul 15, 2019 6:51 pm

NWMO wrote:
Mon Jul 15, 2019 11:03 am
That's the one (I believe). ... I'm pretty certain Robert Walker and xirdneh are one and the same.
that is correct. if you are anywhere near where he is located near Seabeck WA, pay him a visit. is a great guy too.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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