gearing

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JDNightFox
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gearing

Post by JDNightFox » Wed Feb 28, 2018 10:23 am

So as I currently stand, my car has 3.73 in front and 4.11 in back

I have the front hub assembly from the blown up transmission sitting on the floor in my garage. How hard is it to swap out the gears in the front axle? I don't have a rear assembly so I can't swap the rear axle gears

rocketscience
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Re: gearing

Post by rocketscience » Wed Feb 28, 2018 10:58 am

By front hub assembly do you mean the front differential housing?

You can separate the front diff/bellhousing part of the transmission and put it on the transmission in your car now as long as the gears weren't damaged when the transmission blew up, but you need to pull the transmission. I don't know how hard it would be to swap the gears into your current housing but you'd need to know how to set up the gear lash.

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JDNightFox
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Re: gearing

Post by JDNightFox » Wed Feb 28, 2018 3:51 pm

rocketscience wrote:
Wed Feb 28, 2018 10:58 am
By front hub assembly do you mean the front differential housing?

You can separate the front diff/bellhousing part of the transmission and put it on the transmission in your car now as long as the gears weren't damaged when the transmission blew up, but you need to pull the transmission. I don't know how hard it would be to swap the gears into your current housing but you'd need to know how to set up the gear lash.
Yeah I have the entire front hub assembly in one piece

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Petros
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Re: gearing

Post by Petros » Wed Feb 28, 2018 4:22 pm

I would not trade out just the gears, requires setting the lash correctly or you will blow it too. but you can change out the whole front diff assembly as a unit.

you can separate the front bellhousing/diff assembly from the gear box, pull the front cover on the diff, and clean it out really good with solvent, compressed air, etc. Than carefully inspect the faces of the gears, and look for metal shavings. If your trans went all at once, the front assembly is likely okay to reuse because it likely did not spread the metal fragements to the front diff, but if the ring and pinion gears are damaged from metal fragments (scratched up, changing colors-bluish-yellowish, missing teeth or parts of teeth), better look for another diff. you could not use these even you just took out the gears.

So if the gears are good likely you can swap over the whole assembly (including the housing) without removing the gears and bearings, that would disturb their sensitive clearance setting (known as gear lash). Swapping out the front diff assbly/bellhousing is straight forward, simple job, just unbolt the old one and bolt on the new one.
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'85 Tercel 4wd DLX auto(daughter's daily driver)
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rer233
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Re: gearing

Post by rer233 » Wed Feb 28, 2018 5:27 pm

If I were you, I'd look for a 3.73 rear "pumpkin"- lots easier to swap out (unless of course you already have a clutch related problem that requires tranny removal.) Also 3.73's are more highway-friendly (10% less RPMs than 4.10's.) Meanwhile, I'd remove the rear section of the driveshaft so at least the EL function can be used (and prevent possible damage if someone inadvertently engages 4WD.) Just my 2 cents...
if it aint there, there's a good chance it won't break!
83 SR5 Silver/Blue (Snowmobile/work beater)-totaled but drivable
85 SR5 Blue
88 SR5 White (the 'good' one)-not anymore-totaled
87 fwd silver wagon a/t
87 4wd dx Cream (a/t- not anymore- now m/t)

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Petros
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Re: gearing

Post by Petros » Thu Mar 01, 2018 2:13 am

each of the different final drive gear ratios have advanages, the 3.73:1 is more quite at highway speeds since the engine is running at a lower RPM. The 4.10:1 is better for steep terrain and rough roads, it is especially nice for starting out on a steep hill, on pavement or off road.

Both appear to get a bout the same fuel economy based on reports on this forum and my own experience owing both. With a mildly built 4ac with more power I have come to appreciate the lower rpm and less noise at fwy speeds, with the extra power not having as good a low end is not as much as a problem as it might be with a stock under-powered 3ac. OTOH, if you intend to build up a powerful engine such as a 4age, 4afe, or even a built up 4ac, the 4.10:1 final drive puts the max torque RPM range in a better location on the power band where it is useful. high output engines tend to develop their best power at higher rpms than stock engines, so the lower ratio is better suited to the higher rpm output.
'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)
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JDNightFox
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Re: gearing

Post by JDNightFox » Thu Mar 01, 2018 12:06 pm

I like the lower gear ratio but I don't know where I would find a 3.73 rear end at, I just want to be able to use the 4wd again when I want to

I use this car for long distance road trips so the lower highway rpm is what I currently like, except that my top speed is 55 uphill

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rer233
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Re: gearing

Post by rer233 » Thu Mar 01, 2018 2:42 pm

So downshift to 4th!
if it aint there, there's a good chance it won't break!
83 SR5 Silver/Blue (Snowmobile/work beater)-totaled but drivable
85 SR5 Blue
88 SR5 White (the 'good' one)-not anymore-totaled
87 fwd silver wagon a/t
87 4wd dx Cream (a/t- not anymore- now m/t)

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