Differential compatability questions

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LowBuckCanuck
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Differential compatability questions

Post by LowBuckCanuck »

Hello again.

Forgive me if this is a dumb question, but does anyone know how much, if any, parts compatibility there is between the front and rear differentials on our cars? The reason for asking is that my front diff seems to have excessive rotational play while in gear, and before tearing into it I would prefer to know if I can utilize parts from a spare rear axle I have (same year so same gear ratio.. presumably)

I do have a spare transmission as well that I can pull the front diff from if need be, but I would prefer to leave it as one unit if possible.

thanks.
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NWMO
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Re: Differential compatability questions

Post by NWMO »

LBC,

I can’t say for sure, but I would assume there wouldn’t be any swapping front/back, since I believe “drive” rotation is opposite directions. I’ve no experience, but it doesn’t work in my mind’s eye.

Chris
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In remembrance of my friend ARCHINSTL:

T4WD augury?
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dlb
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Re: Differential compatability questions

Post by dlb »

do you notice any symptoms while driving, LBC? I've noticed lots of rotational play in probably all of the t4's I've had and wondered about it, but once I replaced all the worn front end stuff I didn't notice any clunks or anything like that. So I think it might be normal, or at least acceptable. I'd sure love to ask someone with a brand new t4 though.
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LowBuckCanuck
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Re: Differential compatability questions

Post by LowBuckCanuck »

dlb wrote: Tue Mar 07, 2023 10:36 pm do you notice any symptoms while driving, LBC? I've noticed lots of rotational play in probably all of the t4's I've had and wondered about it, but once I replaced all the worn front end stuff I didn't notice any clunks or anything like that. So I think it might be normal, or at least acceptable. I'd sure love to ask someone with a brand new t4 though.
Symptoms include a "slam" feeling when not smoothly letting on or letting off the gas, speed doesn't seem to matter, nor does it seem to matter if I'm in 2wd or 4wd. I have previously replaced all front end components including the CVs, but those would be my next guess at the culprit. It is much worse than any other tercel I've driven.
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dlb
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Re: Differential compatability questions

Post by dlb »

Hmmm. I know what you're talking about, I've experienced it before and did most recently on my rust bucket. I hope xirdneh sees this, as he seems to be the most familiar with the internals of these transmissions/diffs. He is much more active on the t4 facebook page now though so you might want to try asking about this there.
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NWMO
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Re: Differential compatability questions

Post by NWMO »

It sounds like there may be excessive play in the front differential. This could be caused by wear or presumably a sloppy pinion shaft?

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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LowBuckCanuck
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Re: Differential compatability questions

Post by LowBuckCanuck »

NWMO wrote: Wed Mar 08, 2023 6:33 pm It sounds like there may be excessive play in the front differential. This could be caused by wear or presumably a sloppy pinion shaft?

Chris
Is a sloppy pinion shaft the usual suspect for what I'm describing? (And if it is can it be fixed?)
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Ace
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Re: Differential compatability questions

Post by Ace »

LowBuckCanuck wrote: Wed Mar 08, 2023 8:25 am
dlb wrote: Tue Mar 07, 2023 10:36 pm do you notice any symptoms while driving, LBC? I've noticed lots of rotational play in probably all of the t4's I've had and wondered about it, but once I replaced all the worn front end stuff I didn't notice any clunks or anything like that. So I think it might be normal, or at least acceptable. I'd sure love to ask someone with a brand new t4 though.
Symptoms include a "slam" feeling when not smoothly letting on or letting off the gas, speed doesn't seem to matter, nor does it seem to matter if I'm in 2wd or 4wd. I have previously replaced all front end components including the CVs, but those would be my next guess at the culprit. It is much worse than any other tercel I've driven.
I've had my 1983 Tercel since 1984 and have always noticed a 'bump' when going from deceleration to acceleration. I think it has to do with the carburetor fuel cutoff feature on deceleration and I simply learned to ease back into acceleration with a light foot, to minimize the 'bump'. But your symptom may be something different.
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LowBuckCanuck
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Re: Differential compatability questions

Post by LowBuckCanuck »

Ace wrote: Thu Mar 09, 2023 11:48 am
LowBuckCanuck wrote: Wed Mar 08, 2023 8:25 am
dlb wrote: Tue Mar 07, 2023 10:36 pm do you notice any symptoms while driving, LBC? I've noticed lots of rotational play in probably all of the t4's I've had and wondered about it, but once I replaced all the worn front end stuff I didn't notice any clunks or anything like that. So I think it might be normal, or at least acceptable. I'd sure love to ask someone with a brand new t4 though.
Symptoms include a "slam" feeling when not smoothly letting on or letting off the gas, speed doesn't seem to matter, nor does it seem to matter if I'm in 2wd or 4wd. I have previously replaced all front end components including the CVs, but those would be my next guess at the culprit. It is much worse than any other tercel I've driven.
I've had my 1983 Tercel since 1984 and have always noticed a 'bump' when going from deceleration to acceleration. I think it has to do with the carburetor fuel cutoff feature on deceleration and I simply learned to ease back into acceleration with a light foot, to minimize the 'bump'. But your symptom may be something different.
That's what I initially thought but there is a solid mechanical thunk that can be felt through the floorboards. I initially thought it might be a loose engine or transmission mount but they are still in good condition.
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NWMO
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Re: Differential compatability questions

Post by NWMO »

LBC,

I would jack up one side of the front, with the trans in gear, and see how much play was in the tire rotation. Here is a video of the front diff input shaft with minimal play. I assume a worn bearing and/or diff might allow mor play and “clunking”.

https://drive.google.com/file/d/1RWjhBZ ... p=drivesdk

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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