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Rebuild 3AT?


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26 replies to this topic

#1 BratRod

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Posted 08 August 2013 - 08:49 PM

If everything goes as planned; I will be picking up another Brat Saturday. The 3AT has (as expected) died: Sheared the main shaft. Would it be cheaper to find another JATCO and rebuild it, or source a D/R 4? Mind you, I would have to pay for shipping on everything for the manual swap, but could probably find another automatic locally if they are as common as depicted. How difficult would it be to rebuild the 3AT given I have good inners?

All thoughts and opinions are welcome.
Thanks.

Edit: Update post/question. 8/15

Edited by BratRod, 15 August 2013 - 08:40 PM.


#2 Mykeys Toy

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Posted 08 August 2013 - 09:01 PM

Depends on what the parts cost you for a rebuild.  The 4 speed is possible but not worth it in the long run ...a 5 speed would be better all the same stuff is needed and some creativity if you cant get a 5 spd conversion kit like Jerry's. plus a lot of time swapping things over like the pedal box, driveline shortening, a different trans crossmember etc.



#3 BratRod

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Posted 08 August 2013 - 09:05 PM

Are the 3AT and 4spd D/R drive lines the same length?



#4 NorthWet

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Posted 09 August 2013 - 12:33 AM

From what I have heard from rebuilders, the insides tend to have little wear, and seldom need replacing.



#5 BratRod

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Posted 09 August 2013 - 12:35 AM

Then what am I rebuilding?

#6 NorthWet

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Posted 09 August 2013 - 02:14 AM

Exactly. Despite the 3AT (M41a)'s bad rep on this board, the core seems to be pretty durable.  Most of the more "vocal" members seem biased against automatics, so 3AT bashing draws a crowd...

 

The best thing you can do for the 3AT is clean/debur the governor valve and keep the ATF fresh.  If you are going to abuse it, put on an ATF cooler.



#7 BratRod

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Posted 09 August 2013 - 02:25 AM

I do not believe you understand. The big shaft in the center (turbine shaft- FSM) is stripped, rendering it useless except for when in park. Your other post today is what gave me hope about finding another M41a from a Nissan. Sorry, im a little confused here.

#8 silverhelme

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Posted 09 August 2013 - 09:43 AM

I am probably one of the few on the board who will use the 3at on a consistent basis. If you adjust the 2-3 band and keep the governor clean and deburred and change the fluid occasionally they tend to last a long time.

 

I have rebuilt them and they are quite simple and very similar to a Ford C4. They generally only need the 2-3 band,  new seals and any hard parts that are broken but be sure and check all the bands for correct thickness. They are not that hard to change out. I have done it in the yard in less than 4 hours.

 

If it was me I would source another trans or replace the broken main shaft and check everything else.



#9 NorthWet

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Posted 09 August 2013 - 10:37 AM

I do not believe you understand. The big shaft in the center (turbine shaft- FSM) is stripped, rendering it useless except for when in park. Your other post today is what gave me hope about finding another M41a from a Nissan. Sorry, im a little confused here.

Ahhh... my apologies for the confusion.  Your original post talked about finding another transmission and rebuilding it, giving the impression that you were writing-off your current tranny. 

 

Although the Subaru shares the same core as other makes, the case and input- (and output-?) shaft(s) are different.



#10 BratRod

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Posted 09 August 2013 - 11:45 AM

Ok, now I understand. Thank you for clarifying.



#11 Meeky Moose

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Posted 10 August 2013 - 07:11 PM

my 84 wagon has a cracked flex plate,   the 3at is perfect and has no issues or leaks..  i am sure i will be doing a swap, just not sure what kind of swap yet..  either way  when i get to pullin the car apart i will have a good 3at for sale..



#12 BratRod

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Posted 10 August 2013 - 08:13 PM

Cool. I will start putting away for that (shipping :rolleyes: ) send me a pm when you get to doing that, so we can work something out.

#13 BratRod

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Posted 15 August 2013 - 07:56 PM

Okay, so it's not the turbine shaft. It is infact the oil pump drive shaft. So... If the transmission wasn't receiving any fluid that would explain why it wasn't moving, correct? So, in theory, if I just replaced that shaft would the transmission be fine, or would ther be damage to the internals. If I move the governor, the trans still rotates without any problems. Thoughts?

#14 NorthWet

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Posted 16 August 2013 - 02:08 AM

Where did the shaft snap?  (As in, were you able to retrieve all the pieces?)


Edited by NorthWet, 16 August 2013 - 02:09 AM.


#15 BratRod

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Posted 16 August 2013 - 03:03 AM

It just ate the teeth at the end that goes into the trans. Pics later.

#16 ivans imports

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Posted 16 August 2013 - 08:59 AM

Have 2 4 speed deul ranges in pile both good



#17 ivans imports

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Posted 16 August 2013 - 09:00 AM

Is the shaft same as 2wd 3 speed ? have a core 2wd one on ground

#18 NorthWet

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Posted 16 August 2013 - 11:16 AM

It should be the same shaft, but if the splines got chewed off deep in the tranny, there is probably something very wrong back there... along with a ton of metal debris.



#19 BratRod

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Posted 16 August 2013 - 01:35 PM

 

I'll probably buy a know working tranny rather than gamble and be disappointed. That's the smaller of the two shafts. If I pull it towards me it will still catch and it pumps fluid up the shafts. I was able to get it to turn when in gear for a moment, but I doubt it was a "fix".



#20 ivans imports

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Posted 19 August 2013 - 11:32 AM

very comen new shaft will probly fix it if you look closer should be a nylon retaining bushing or clip is it damaged or shifted



#21 BratRod

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Posted 19 August 2013 - 12:04 PM

there is a metal bushing, but it doesn't look damaged. No retaining clip, though.

 

Edit: It is nylon/plastic-esq. It is not even on the roll pin anymore. Guess that confirms its cause of death.

 

Also here is the pic. dunno what happened to old one.

 

WP_001149_zps7caf41c3.jpg


Edited by BratRod, 19 August 2013 - 04:18 PM.


#22 ShawnW

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Posted 20 August 2013 - 12:30 PM

It isn't that the 3AT is really a bad trans its just a good trans by todays standards.  The new Ej 4EAT trans for example is known for being about twice as good.  There are other elements too, like the fact that the trans was installed in all the EA81 Turbo cars and that engine tends to generate a lot of heat and kills these trannys too.  

 

More often than not the real problem is the trans is known for hard parts dying.  Things like front differentials and governors are not common to die on modern auto trans cars.

 

Lastly, the real killer against this trans is the ease in swapping in a manual transmission.  But that "solution" isn't always a good one.  Some drivers really need or want the auto.  

 

Its like saying the 4 speed dual range is a bad transmission.  It isn't.  But the 5 speed is so much better in the areas that the 4 is weak that it gets that reputation.  Its the same with the autos too.  That extra gear really makes the car more desirable to drive.



#23 BratRod

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Posted 20 August 2013 - 12:48 PM

Thank you, Shawn. I had some of those suspicions as I find no problems driving my other brat that has a 4spd d/r. I took the governor out of this trans, and it did not catch at all, so I guess that's good. I guess im in the market for a new trans then.

#24 NorthWet

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Posted 21 August 2013 - 09:23 AM

Regarding the governor, general opinion is that you cannot tell the governor's condition by moving it by hand while still assembled.  The general description it that the separated parts need to slide "like butter". 



#25 ivans imports

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Posted 21 August 2013 - 09:45 AM

The ecvt justy used to do this to me all the time the clip for pump shaft wears out and shaft moves and strips spline of on those i remove pump and can install new shaft thru trans with no removal so trans is junk ? or will a new shaft fix it ?






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