904 low gear- which vehicles and which internal parts?

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mshred

mshred

The Green Manalishi
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Hey guys,

I would like to do the low gear swap on my 72 year 904 transmission. My transmission currently has aluminum 4 pinion planets front and rear.

My first question- what vehicles have low gear set transmissions? My local wreckers is scarce for 80's year chryslers, so later model stuff like dakota trucks, 6cyl jeeps, late model rams, etc. is all I really have to pick from. What year vehicles would have the transmissions I am looking for?

Second- when I get the transmission apart, what parts am I looking for from it? I have read that the planetaries are steel in these transmissions- can I swap both in to my current 72 year aluminum planet trans? Are there any other mods to get the low gear set to work?

Thanks!
 
later 70s to mid 80s A999, (lock up tranny's) for sure. Maybe a500 overdrives ? A&A transmissions have new one but they are $300
 
AdamR said:
later 70s to mid 80s A999, (lock up tranny's) for sure. Maybe a500 overdrives ? A&A transmissions have new one but they are $300
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Just called the local u-pull it yard and its $160 for a transmission, minus $25 for a core. I need to upgrade to steel planets in my current trans anyways, which are $100 alone for the pair from the local trans parts house- if I can swap the steel planets from the later lockup models in, then the price for a whole trans with the low gear set would be ideal, otherwise it may not be.

I thought I read somewhere that all jeep/amc's use low gear transmissions, but im not sure what vehicles they are behind or how to identify.

Finding info about interchangeability of 904's seems pretty damn hard from all the searching I have been doing
 
The problem with trying to build a low gear 904 is there were numerous versions of 904/998/999 transmissions with minor differences in clutch pack carriers, pumps, etc. that won't mate up properly so it's hard to find info that covers all the bases. Your best bet is when you find a trans with the low gear set (easily identified by the sun gear having different diameter splines on each side vs. same splines on both sides of a std. ratio) and just rebuild it.
 
I found an A-500 locally. Apparently these trans have steel planets and the low gear set, which would be nice since i wanted to replace my aluminum front planet at the very least.

What parts do I absolutely have to replace when doing the low gear set swap? Automatics are very new to me since I have been using manuals for the past 3 years
 
Have you verified the A500 has the low gear set? I know all over the internet you read all A500's had the low gear set but I rebuilt a 87 A500 for a buddy and it did not have the low gear set.

If your trying to piece together a low gear 904 you need everything from the sun shell/gear forward to make sure it'll all mate up. And verify that the output shaft is the same design/size where the back end of the input shaft mates up with it. I'm not sure on 904's I know on 727's there were a few designs.

BTW: have you checked out www.wittrans.com for parts? They scrap out and refurb a lot of trans. parts and sell them at decent prices. You'd have some shipping charges but considering how much time and gas you could save you would probably be way ahead buying the parts you need there.

BTW2: you mention you want to replace your front planetary. JFYI you will definetly have to do that as it is part of the low gear set.
 
fishy68 said:
Have you verified the A500 has the low gear set? I know all over the internet you read all A500's had the low gear set but I rebuilt a 87 A500 for a buddy and it did not have the low gear set.

If your trying to piece together a low gear 904 you need everything from the sun shell/gear forward to make sure it'll all mate up. And verify that the output shaft is the same design/size where the back end of the input shaft mates up with it. I'm not sure on 904's I know on 727's there were a few designs.

BTW: have you checked out www.wittrans.com for parts? They scrap out and refurb a lot of trans. parts and sell them at decent prices. You'd have some shipping charges but considering how much time and gas you could save you would probably be way ahead buying the parts you need there.

BTW2: you mention you want to replace your front planetary. JFYI you will definetly have to do that as it is part of the low gear set.
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Is there a way to verify the trans as a low gearset externally? All I know is it came out of a 89 Ram D150 2 wheel drive truck...On another forum a torqueflite guru said that all 82' and later 904's used low gear sets....now you have me worried:?

I believe on 904's the outshaft where the low gear set rides is the same regardless of year.

Thanks for that web link by the way man! Have you ever ordered from them before? I ship stuff stateside all the time and then just pick it up, so shipping is not an issue...What is the quality like? They just refurbish old used stuff?
 
Good to see you back,shred.Your ride cranked,with the 4 speed.
 
mshred said:
Is there a way to verify the trans as a low gearset externally? All I know is it came out of a 89 Ram D150 2 wheel drive truck...On another forum a torqueflite guru said that all 82' and later 904's used low gear sets....now you have me worried:?

Not that I know of. Chances are good it has a low gear set but I've found NOTHING is written in stone.
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I believe on 904's the outshaft where the low gear set rides is the same regardless of year.

The issue isn't where the front planetary slips on. It's how the output shaft engages into the input shaft. Sometimes the button is a different diameter.
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Thanks for that web link by the way man! Have you ever ordered from them before? I ship stuff stateside all the time and then just pick it up, so shipping is not an issue...What is the quality like? They just refurbish old used stuff?
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I've ordered twice from them. 1st time everything went perfect. 2nd time I had 1 small issue with them. I needed a speedometer housing and I did the internet order thing and it showed they had it but when I got the order it said out of stock on the invoice. Luckily I was able to file the threads on the old one and use it but I would have much rather paid the $3 for a good used one rather than file threads for 20 minutes. From now on I'm going to call my orders in to make sure they have everything in stock.

They have a few new parts too but I believe their main service is with used parts. I just bought a set of 4 pinion planetaries that they refurbed and they looked like new.
 
fishy68 said:
I've ordered twice from them. 1st time everything went perfect. 2nd time I had 1 small issue with them. I needed a speedometer housing and I did the internet order thing and it showed they had it but when I got the order it said out of stock on the invoice. Luckily I was able to file the threads on the old one and use it but I would have much rather paid the $3 for a good used one rather than file threads for 20 minutes. From now on I'm going to call my orders in to make sure they have everything in stock.

They have a few new parts too but I believe their main service is with used parts. I just bought a set of 4 pinion planetaries that they refurbed and they looked like new.
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Ok, I hear you on the input shaft and output shaft thing. I guess it looks like the only way I will know is to buy the damn thing and find out the hard (I really hope it is a low gear and will work).

As for the parts place, I will definitely use them in the future if I need hard parts- im hoping this trans im picking up will have all I need to convert (I already checked that website for late model A-500 pump gears but no luck and I know the trans I am looking at does not have the pump gears I need either)
 
Another place I order from regulary is www.bulkpart.com They should have pump gears. They have more newer parts such as complete overhaul kits or most any wear item type part and a few hard parts but for hard parts I usually use WITT cause their a bunch cheaper. That's not to say Bulkpart is expensive because their not. WITT is just unusually cheap on hard parts.
 
fishy68 said:
Another place I order from regulary is www.bulkpart.com They should have pump gears. They have more newer parts such as complete overhaul kits or most any wear item type part and a few hard parts but for hard parts I usually use WITT cause their a bunch cheaper. That's not to say Bulkpart is expensive because their not. WITT is just unusually cheap on hard parts.
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There is a local trans parts house here that I called before that is not bad on prices either. If they don't have what I need, I will try WITT for the hard parts. I have been on the bulkpart site quite a bit now, thanks for suggesting though
 
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