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'77 Pacer ring & pinion question

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Seann View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Seann Quote  Post ReplyReply Direct Link To This Post Topic: '77 Pacer ring & pinion question
    Posted: Aug/12/2019 at 4:47pm
I'm looking to change the ratio in my Pacer after engine swap. Aftermarket parts suppliers show the Pacer axle as a Dana 35, but this car has tapered axles/separate hubs meaning it could be an AMC rear end, not a Dana. My question is, will Dana 35 parts fit it? I've been told Dana axles have flange shafts...can anyone clear this up?
Thanks,
Seann
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Trader View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Aug/12/2019 at 6:52pm
Dana20 or Dana35  parts are not interchangeable with AMC15 or AMC20.
That stated, if the cover is round and axles are 2 piece, you have an AMC differential. Now over the years someone could have put a Dana from a Jeep in it or an AMC20.
 In 1977 the six should have an AMC15 but, being an AMC, an AMC20 may have been put in it right from the factory.
As memory serves, Pacer wagons got an AMC20 if the tow package was ordered.
That would have to be fact checked!  

Should add that my 78 Pacer wagon 258 with tow and cold weather packages came with an AMC20. That fact I can verify.


Edited by Trader - Aug/12/2019 at 7:34pm
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Ken_Parkman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Aug/12/2019 at 10:10pm
https://en.wikipedia.org/wiki/Dana_35

Info from wikipedia says Dana bought the AMC 15 and made it the Dana 35
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Aug/12/2019 at 10:45pm
Yes the Dana did buy the AMC15 and may be the same in some parts and years. This older thread will get your head spinning:

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farna View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Aug/13/2019 at 6:27am
The ring and pinion from a Dana 35 should fit an AMC 15 with no issues. The axle shafts are different though. Even the non- c-clip axles are a bit different from the AMC 15 axles. AFAIK the differentials are the same as well, but I'm not sure about the spline count or diameter of the axle hole in the spider gears. I think those are the same, but there was an HD axle version of the D35 that had a larger diameter on the hub end (larger bearing and seal).
Frank Swygert
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Seann View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Seann Quote  Post ReplyReply Direct Link To This Post Posted: Aug/13/2019 at 8:41am
OK, thanks for this info. Next question, how do you tell the difference between an AMC 15 & a 20? Also, if the ring and pinion for a Dana 35 will  fit a 15, will it fit a 20? My cover is oval, like the one pictured in Ken's wikipedia link, without the Dana stamp.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Aug/13/2019 at 10:03am
The 15 (Dana 35) and AMC 20 are completely different. The AMC 20 has a simple round 12 bolt cover, and was used on 8 cyl cars and I believe a lot of bigger cars that did not have leaf springs.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Aug/13/2019 at 5:49pm
The AMC 15 has a 7.5" ring gear, AMC 20 has an 8.875" ring gear, so no, parts don't interchange.
Easy way to tell the difference is the AMC 15 has a fill plug in the back cover, the AMC 20 does not. The fill plug for the AMC 20 is on front to the right of the pinion shaft (right from driver's seat perspective). That AMC 20 cover has 12 bolts and is perfectly round. The AMC 15 cover has 10 bolts and is sort of a flattened circle ("squashed" a bit from top to bottom).


Edited by farna - Aug/13/2019 at 5:53pm
Frank Swygert
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Seann View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Seann Quote  Post ReplyReply Direct Link To This Post Posted: Aug/14/2019 at 9:24am
OK, thanks...ordering gears from Rock Auto today, will post results,
Seann
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Seann Quote  Post ReplyReply Direct Link To This Post Posted: Sep/05/2019 at 8:03am
2:73 to 4:88 gear change for Mazda 13b engine/transmission conversion worked out OK...had to find a diff carrier for the 3:55 and up gears, it's offset to move the ring gear closer to the smaller pinion gear. Also had to use my spider gears. The Pacer is driveable! Thanks for all the tips,
Seann 
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