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sm465 granny gear transmission rebuild

 
chevelle83
I mow my lawn and find Chevys
Posts: 2280
Joined: 11/09
Posted: 03/19/11 11:05 PM

I tore down and refreshed the transmission in my dads 4x4 and decided to take pics and post it just for the heck of it, enjoySmile this trans was used from 1968-1991 so there is a million of them.

first pressure wash it then mount the trans on an engine stand with the bolt holes on the side of the case,  makes the job WAAAAy easier.

then shift the transmission half way into reverse (it allows for top plate removal), then remove the shifter and top plate.
DSC02849

then remove the front bearing retainer, and rear bearing retainer or adapter (4x4)
DSC02850

inspect the shift forks for wear (the smaller one takes the most abuse from the 3rd gear shift)
DSC02851

now here are the tools that are absolutely necessary to work on this trans, you also MUST have a press or access to one
DSC02853

now remove the snap rings and remove the imput bearing, this may be very difficult and may require some heat with a propane torch, do NOT over heat if you want to save the bearing!
DSC02854

I didnt damage this bearing
DSC02856

remove the lock nut (4x4)now take the bearing knife and lock it into the snap ring groove and pry off the
DSC02855

with the PTO covers off there is a snap ring on the cluster gear holding 3rd gear slide it forward so the gear can be moved and allow you to lift the main shaft out
DSC02857

now with both top bearings removed there is a notch in the imput gear and that is to allow you to get it out of the case it takes some wrestling but it will roll out just barely
DSC02860
DSC02861
DSC02862

now watch out for the needle bearings and dont loose them
DSC02862

now lift this HEAVY main shaft out try not to mash your fingers Smile
DSC02863

now here is where reverse takes some abuse from grinding as you go into gear
DSC02864

now lets unstack the gears, I recommend laying everything out as removed if you are inexperienced.
DSC02866

thrust washer then the MASSIVE gears now we know why these trannys are basically indestructible
DSC02867

now the 1-2 slider,,,,, (note the groove is facing the rear of trans!
DSC02868
now move to the front of the shaft and unstack it,,,,,
first the 3-4 slider then the snap ring,,,,,,,
DSC02869
DSC02870


now the clutch collar,,, I have seen both slip fit and press fit collars if it wont move with a light rasp with a brass punch and hammer then it is press fit,,,, use the bearing knive to remove it.
DSC02871


now the syncro and 3rd gear,  it takes the most abuse and IF your trans was jumping out of 3rd it MUST be replaced along with the 3-4 slide ring
DSC02872

now second gear has to be pressed off cause the bearing sleeve is press fit, just catch the edge of the gear in the press
DSC02873

here is a pic of how it goes:
DSC02876

be dead sure to note this thrust washer!!
DSC02879

now with every thing apart change the syncro rings and reverse assembly

I will post pics of how to dissassemble the cluster gear when I get pics loaded.  

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tuffnuff
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Posts: 7841
Joined: 12/09
Posted: 03/19/11 11:39 PM

Great info Chevelle.,. I'll be doing a BW Super T-10 in the next couple of weeks, I should post pics of that rebuild, the Muncie is also very similar.

Smile  
When The Flag Drops.,.

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P. Engineer, Engine Builder

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redneckjoe69
I mow my lawn and find Chevys
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Posted: 03/20/11 07:06 AM

nice post chevelle!    you know your chit bud.  Cool  

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chevelle83
I mow my lawn and find Chevys
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Posted: 03/20/11 01:40 PM

thanks tuff, and joe!  I found some info that was foggy and not very in depth so I figured I would try to shed some light on some of this stuff.  most folks are terrified of stuff like this but it is not extremely difficult.  if you have the proper tools you can save a lot of money doing this your self.  

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ethelkilledfred-#001
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Posted: 03/21/11 12:09 AM

Very cool. Nice pics.  
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idrivejunk
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Posted: 03/21/11 06:15 PM

+1 Top notch post! Takes away lots of mystery  Cool  
idrivejunk

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chevelle83
I mow my lawn and find Chevys
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Posted: 03/21/11 09:10 PM

thanks junkman, and ekf, I enjoyed every minute of this rebuild, I like doing this stuff so much I would (almost) do it for free if the customer pulled and installed the unitsSmile  

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chevelle83
I mow my lawn and find Chevys
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Posted: 03/21/11 09:20 PM

I left out something,,,,, when installing the needle bearings in ANY situation all you need to do to keep them in position is greaseSmile
DSC02890  

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muddlover
I love my Chevy Chevette!
Posts: 1
Joined: 10/11
Posted: 10/25/11 06:18 PM

chevelle I'm having a slight problem with my 4x4 grant gear I bought a. 1978 short wheel base Chevy. 4x4 out the junk yard and brought it home had it running in thirty minutes drove it out to the road as soon as I started off I hit 2 gear and hit a pot hole the shifter slung out of gear and soon to fin out it will throw its self out of all gears haven't taken the transfer out yet but have pulled engineering any idea what could cause this problem I thought maybe the synchronizer?  

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chevelle83
I mow my lawn and find Chevys
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Joined: 11/09
Posted: 10/25/11 06:28 PM

mudd,,,, no it is not the syncros,,,,, they assist in getting it into gear.

the teeth where the collar slides wear on  a taper from years of shifting.

to make the trans work properly you need the "speed gear"(s) that is is jumping out of under load,  most of them jump out of 3rd but some will be bad enough to pop out of both 2nd and 3rd.

you need the speed gears, the 1-2 slide, and the 3-4 slide, and a bearing and syncro kit.. you will have to have the tools and a press handy to work on this trans!  so be ready for that.

it will cost you about $300 or so for the parts, if the price has not changed lately.  

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chevelle83
I mow my lawn and find Chevys
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Joined: 11/09
Posted: 10/25/11 06:34 PM

Icon Quotemuddlover:
chevelle I'm having a slight problem with my 4x4 grant gear I bought a. 1978 short wheel base Chevy. 4x4 out the junk yard and brought it home had it running in thirty minutes drove it out to the road as soon as I started off I hit 2 gear and hit a pot hole the shifter slung out of gear and soon to fin out it will throw its self out of all gears haven't taken the transfer out yet but have pulled engineering any idea what could cause this problem I thought maybe the synchronizer?

this is what the 3-4 slide looks like:
DSC02888

and the 1-2 slideDSC02885

these are the speed gears
this is 2nd speed gear:
DSC02878

and 3rd:

DSC02872

hope this helpsSmile  

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mike454hall
V-6 Camaros rule!
Posts: 37
Joined: 10/11
Posted: 11/07/11 11:15 AM

i have one of thses trannys in my 76 one ton and i love it the thing is bullet proof and shifts great awsome post  

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Smallblockman
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Posts: 1
Joined: 02/12
Posted: 02/26/12 11:05 PM

I have a sm465 alum top cover trans and I was wondering if I could change the granny gear in my trans to a higher gear ratio?  

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pepsi1
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Posted: 02/26/12 11:57 PM

Chevelle

Thats a great post, I did one of the Covette 4X3 4speed with the automatic. I'm glad it was brought to me. What a mess inside. Grin  Cool
Bob  

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chevelle83
I mow my lawn and find Chevys
Posts: 2280
Joined: 11/09
Posted: 02/28/12 12:51 PM

yeah those transmission were a disaster from the factory, I would probably can a busted 4+3 for a newer 5 speed and all the problems would go away.  

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