lost 5th gear

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NWMO
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lost 5th gear

Post by NWMO »

Good morning all,

I was driving down the highway when I heard a slight rattle from the transmission. I coasted to listen and then shifted down to 4th. When I shifted back into 5th after accelerating, the trans acted like it's in neutral, no additional noises, just no 5th gear. I drove it 240 miles home. Here are some pics after changing the gear oil: first 3 pics are the rear drain plug and what I expect is a piece of one of the 5th gear teeth? Pics 4 and 5 are the front drain plug and “dust/gunk” from the magnet.

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AD4E790A-BAD7-4800-AD3C-AC6CB795E596.jpeg

Pic 6 is a possible fill port on the driver’s side of the trans that has easier access. I filled through this port until “full”. Pic 7 shows the rear passenger side fill port after filling, pic 8 shows the bolt needing backed out 7-8 turns. After filling my pump bottle and finishing filling through the rear plug (per the FSM), the last pic shows the remaining gear oil. The driver’s side fill plug is easier, which is nice, but make sure you finish the fill job per the FSM (additional 1/2 to 3/4 liter).

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I drove the car some yesterday and to work this morning (45 miles one-way). I assume the transmission is a bit of a "time bomb" now, in that a piece of the damaged gear? etc. could find its' way into some of the other gears while driving. If not too risky, I would like to continue driving it as-is while I possibly repair the original transmission that spun the main idler bearing. I've never worked on the transmissions before, but Robert's videos are great and I believe I could do the job. Ideally, I'll coordinate with Robert in the future and take a trans and my rebuild kit (all new syncros, etc.) for a road trip to learn and see the master in action.
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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."
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: lost 5th gear

Post by Petros »

the fifth gear is on the front side of the main gear box, they do fail (usually from abuse by towing or pulling too hard in loaded up hill in 5th), but will disintegrate in the forward chamber, separate from the gear clusters, so it can be driven without noticeable issues.

I highly advise NOT to drive it until you can pull the trans and flush it out. the broken pieces will circulate throughout the diff and transmission and slowly grind it all away. It can be fixed now, once you clear away all the other gears and ring and pinon until failure, it will be all scrap metal.

you can either clean up the broken parts, and flush out the rest of the trans, and install it without a 5th gear, so you can safely drive it. or find a 5th gear out of either the 5 speed FWD trans, or another T4wd trans. or replace the whole 4wd trans with a good one and keep your existing one for parts.

if you keep driving it without cleaning it out you will almost certainly destroy all of it. these 4wd transmissions are getting scarce and you would be best advised to not risk further damage to yours.

Good luck.
'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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Toyotise
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My tercel:: 1986 SR5
Location: Arizona

Re: lost 5th gear

Post by Toyotise »

That is a huge bummer. Maybe was that rattle you heard before losing 5th gear a bearing getting loose and rattley. Too much play on the shaft wiped out whatever gear you were in. Or the works chewing up a gear tooth. Probably not the best idea to drive on it until you can disassemble and inspect the situation. All speculation. Maybe at least run a few cans of brake cleaner through the fill ports when changing gear oil. Sorry for the loss, surprises like these are not fun. Do you have a good one you can swap in?

Always interested in hearing all the data points of a transmission failure. How many miles are on the unit? Gear oil change history and type? Other than stock tire size?

All mechanical stuff will eventually meet its end, rust, or wear, but it is nice when it all keeps working good for as long as possible. Hope you find a good solution to keep the green one running through the winter.
Keep it Stock; Live Long.
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NWMO
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Re: lost 5th gear

Post by NWMO »

Hey Eric,

The original trans had the main idler gear bearing fail late summer 2020 and I swapped the trans from my "unknown" parts car right before the 2020 Meet & Greet. I hit a deer in March that did extensive damage and the car had been sitting until I got it together for this year's Meet & Greet (I see a pattern here :)) I put new oil in when I swapped the trans and changed it after the first Meet & Greet because we played in some deep water (see avatar pic). I expect I put a little over 15,000 miles on the transmission prior to failure. No knowledge of prior maintenance or abuse?? It was still full when I changed fluid last weekend.

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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NWMO
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Posts: 1208
Joined: Wed May 20, 2015 1:08 pm

Re: lost 5th gear

Post by NWMO »

Hey friends,

I know I need to drop/clean the trans (don’t know when yet). I did not pull the plug under the diff (should have). So, I understand the front diff and trans are a shared sump, I assume my pic shows a hole next to the “shoulder” for 5th gear into yhe diff? I believe I am pointing at 5th gear on the other transmission I pulled last year, presumably, this is the most likely failure point?


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DECDFC43-8E8F-436C-9978-644BC9D7DF22.jpeg
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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
User avatar
Petros
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Posts: 11761
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: lost 5th gear

Post by Petros »

yes, that is the fifth gear. on the front side of the front housing wall of the main gear box. if you have replacement parts, as I recall, this is as far as you need to strip it down to replace the broken 5th gear parts (presuming nothing else is damaged).
'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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