gear ratio

[maddog]

i have been trying to figure out what gear ratio i have in Eagle Eyes but don't know how to tell which one i have can someone please tell me how to tell what one i have.

[BenM]

If everything is unmolested, the easiest way is to clean off the front differential and find the tag bolted between two cover bolts. It'll have the tooth count for both gears and the ratio stamped on it clear as day. That's what I try to do in the junkyard.

There's a letter code on the back axle that's easier to get to, but sometimes it's not clear or hidden by the cover.

[shaggimo]

http://www.amceaglenest.com/~iowaeagl/guide/index.php?title=Group_9_Axles_--_Propeller_Shafts

In the eaglepedia, parts catalog, under axles.

[ammachine390]

According to the sales brochure, there were 2 axle ratios availible in 1980, 3.08, and 3.54. The 3.08 was standard for the 49 state models with the 3.54 optional., the 3.54 was standard for high altitude areas. Does your car have the high altitude option, I think it would say on the emission sticker under the hood, either "for use above 4000 feet" or "for use below 4000 feet."

[maddog]

well my rear went out today and i think it is the gears now i have looked at the front diff for a tag but can't find one. the rear diff has an arrow pointing at a 3 and then a ring of bumps with an arrow in the middle that arrow going clockwise is pointing almost halfway between the fifth and sixth bumps. now i'm thinking that means i have 3.54 gears or am i completely off.

[eaglebeek]

maddog, you're looking for a letter code on the rear axle. If should be stamped into the back of the axle next to the cover on the passenger side. It will be more or less in line with the axle shaft. If you don't see the letter you may have to take off the cover.

[maddog]

alright i finally found the marking on the rear and it has an F stamped into it and in the link shaggimo posted it says that is 3.08 so i'm guessing Eagle Eyes isn't a high altitude car.

[eaglefreek]

alright i finally found the marking on the rear and it has an F stamped into it and in the link shaggimo posted it says that is 3.08 so i'm guessing Eagle Eyes isn't a high altitude car.

 Both Eagles that I have bought were sold at Denver dealerships. One had 2.35's and the other 2.73's. I don't know how common it was to actually have the high altitude package available from the dealer.

[maddog]

i was on rockauto to see how much they want for their 3.08 ring and pinion gears but they don't have them listed instead they have 3.07. so i was wondering if there is any real difference between the two?

[eaglefreek]

Not enough to worry about. Manufactures have been known to put different ratio's front and rear. Like mixing 3.07 and 3.08. Wow, I just looked at Rock Auto and those are some great prices on those gears.

[BenM]

i was on rockauto to see how much they want for their 3.08 ring and pinion gears but they don't have them listed instead they have 3.07. so i was wondering if there is any real difference between the two?

The front is technically 3.071429... and the rear 3.076923... so it depends a little on how you round them. If you're double checking the front 3.08 gear tooth count is 14:43 and the rear is 13:40.

[carnuck]

i was on rockauto to see how much they want for their 3.08 ring and pinion gears but they don't have them listed instead they have 3.07. so i was wondering if there is any real difference between the two?

It all depends whether they round up or down when they figure the ratio. Less than 5% is within parameters for the viscous coupler. 1/300th is really no difference

[captspillane]

If you're double checking the front 3.08 gear tooth count is 14:43 and the rear is 13:40.

Does anyone know where a quick and concise list of tooth counts are? I'd like to have these notated in case I ever encounter a 3.31 differential.

If we make our own list I'd figure we'd need tooth counts for these ratios. I included some possible swap ratios or AMC Spirit ratios for the rear.

Front: 2.35, 2.73, 3.07, 3.31, 3.54.

Rear: 2.35, 2.73, 3.08, 3.31, 3.54, 3.73, 4.10, 4.54.

[carnuck]

I posted a pic of the 3.31 I had

[BenM]

If you're double checking the front 3.08 gear tooth count is 14:43 and the rear is 13:40.

Does anyone know where a quick and concise list of tooth counts are? I'd like to have these notated in case I ever encounter a 3.31 differential.

I posted a list here of some I had from a spreadsheet of everything I could find on the AMC 15, 20, and Dana 35. I have the rest at work.