AMC Eagle Den Forum

The Shop => Axle / Differential => Topic started by: amcfool1 on April 13, 2023, 12:04:22 PM

Title: AMC Eagle rear axle ratios interchange
Post by: amcfool1 on April 13, 2023, 12:04:22 PM
hi, I have a 1984 Eagle sedan, nice shape. I am trying to replace the 2:35 axles with 2:73 axles. I have both front and rear 2:73 axles from a parted out 85 wagon. The front is fine. The rear, however has a bent housing. I have a chance to purchase a complete 3:54 rear axle. My question is; will the 2:73 carrier, ring and pinion, etc, fit into the 3:54 housing/axle? In other words, what is the carrier break?  Thank you all.   gz
Title: Re: AMC Eagle rear axle ratios interchange
Post by: AMC of Houston on April 13, 2023, 03:16:05 PM
Educated guess says yes; it should work.   Reasoning being the AMC Eagle parts manual shows the same housing part number for all gear ratios.   Although the gear carriers show different part numbers for different ratios, the axle housing part number is the same for all.
Title: Re: AMC Eagle rear axle ratios interchange
Post by: amcfool1 on April 13, 2023, 11:34:08 PM
thank you!  gz
Title: Re: AMC Eagle rear axle ratios interchange
Post by: amcfool1 on April 13, 2023, 11:38:35 PM
but not the 2:35, correct? In other words, one can't put the 2:73 in the 2:35 housing, can one? I always though that the 2:35 was its own unique beast.  gz
Title: Re: AMC Eagle rear axle ratios interchange
Post by: vangremlin on April 14, 2023, 11:27:58 AM
but not the 2:35, correct? In other words, one can't put the 2:73 in the 2:35 housing, can one? I always though that the 2:35 was its own unique beast.  gz

That was kind of my understanding also.  May require some more digging to find out. 
Title: Re: AMC Eagle rear axle ratios interchange
Post by: amcfool1 on April 14, 2023, 01:59:12 PM
hi, gz again:) i have the 79/80 AMC parts catalog. Parsing it, it says the the EAGLE rear axle could take the 3:08, 3:31, and 3:54, though the books tooth count for 3:54 is confusing (11/39 which is the Amc 20 count) instead of 13/46 which is the Amc 15 count. (according to this book) However, looking at the Spirit/Concord rear axle, same part # for 4/6 cyl. cars, (though different from Eagle), book says axle can take any gear set from 2:37 to 3:58. Why would the Eagle axle housing be any different? got my fingers crossed on this one!  :) So, extrapolating a bit, if a 3:08 fits where a 3:54 goes, and the 2:73 goes where a 3:08 goes, it should work in a 3:54 case. If the Eagle housing is same as Spirit/Concord housing, then any gear set should fit. This would really solve my problem. Maybe most of the gear incompatibility issues regard the FRONT axle, not the rear?  Thoughts?   thanks,   gz
Title: Re: AMC Eagle rear axle ratios interchange
Post by: AMC of Houston on April 14, 2023, 02:51:30 PM
Y'all are confusing the gear carrier differences with the axle housing differences.   Different gear carriers are needed with different ratio gear sets, but the axle housings are the same for all carriers whatever the ratio -- i.e; any carrier/gear set combo will fit in the housing; you just need to have the correct carrier for your gear ratio.
Title: Re: AMC Eagle rear axle ratios interchange
Post by: amcfool1 on April 14, 2023, 11:50:56 PM
....so, the 2;73 complete setup, carrier with ring and pinion, axle shafts, backing plates, etc, should fit into a (originally) 2:35 axle housing assembly, correct?
and thank you so much for responding.  gz
Title: Re: AMC Eagle rear axle ratios interchange
Post by: AMC of Houston on April 15, 2023, 01:25:17 AM
Yes indeed!   You are correct.   I would also swap over the shim under the big pinion bearing race from the donor housing, so you'll be more likely to have the pinion depth where it should be.   Would be a good idea to check the pinion depth after the swap if at all possible - if not, just hope for the best.  If no clunking/whining, its probably close enough.
Title: Re: AMC Eagle rear axle ratios interchange
Post by: amcfool1 on April 15, 2023, 07:03:11 AM
well, ok then! The adventure continues.....Thanks again!  gz