66 Rear Axle #s (Help)

[Anthony P.]

Ok now I need some detective Help. I have a 66 rear axle the numbers don't seem to add up. they read as follows AB W 15 E 1 Can someone help decode this? AB is not in any chart. the W I believe is for the Warren Plant, lost after that, any help would be greatly appreciated. Tony

[John C.]

Re: 66 Rear Axle #s (Help)

Tony

It doesn't appear the rear axle is original to the car. The AB code was used on 1971-75 rear axles to denote a 3.70 posi unit. If it is from one of these years: W= Warren, 15 is the day of the year manufactured (no year was used), E = Eaton posi unit inside, and 1 would be the shift manufactured.

John

[Anthony P.]

Re: 66 Rear Axle #s (Help)

John Thanks! now I will Check casting dates, it seems that if it was changed it must have been in a small time window since I have owened the car since Aug of 74, at which time the unit was pretty rusted. 2000 RPMs at 60 MPH. seems I have a Frankenstien situation going on here!

[Jack P.]

Re: 66 Rear Axle #s (Help)

Your car probably came with a 3.36 and wide ratio M-20 Muncie, it was common to switch them out , when these cars were used to go fast between lights, when new.

My L79 (42 years) had the standard combo above, I have had the 3.70 since 71 . The engine will not mind the rpms. Put over 250,000 miles on it and still driving it 10,000 miles a year. Cruise control will make the car much more enjoyable on long trips. The cost of replacing the rear will take you 10 years at least to make up for gas savings with the lower rpms . If you hate the high rpms, then change it, but you would have to go back to at least the 3.36 to really notice a difference.

Jack

Jack

[Anthony P.]

Re: 66 Rear Axle #s (Help)

Thats what I'm trying to say is that now it only turns 2000 RPMs to go 60Mph. doubt if it is a 3.70:1 at this point. Let me ask this. did the 1971 axle have straps or caps to secure the halfshaft to the diff yoke?

[Jack P.]

Re: 66 Rear Axle #s (Help)

Here is a speed calculator Plug in your numbers and you will find out what you have http://www.corral.net/tech/gearcalc.html It looks like you have a 2.5 or less gears inside the case or and overdrive final transmission ratio , but you can do the input It your mph or rpm correct? Jack

[Joe L.]

Re: 66 Rear Axle #s (Help)

Thats what I'm trying to say is that now it only turns 2000 RPMs to go 60Mph. doubt if it is a 3.70:1 at this point. Let me ask this. did the 1971 axle have straps or caps to secure the halfshaft to the diff yoke?

Anthony-----

1971 carriers used both u-bolt and cap attachment for u-joints. I don't know, for sure, what an "AB"-coded unit used. However, I would suspect it originally used caps.

Also, just because the carrier housing is coded "AB" for a 3.70:1, that does not mean that's what's now inside. That could have been easily changed.

What is the date code on the carrier housing casting and the cover casting?

[Anthony P.]

Re: 66 Rear Axle #s (Help)

Joe the casting dates on both carrier and cover I still have to asertain maybe this weekend, The car is in a none heated garage And I'm located in northern MI. and the housing is quit rusted. I will post them when I can. The reason I ask about the caps and straps is this unit has one of each, I suspect it needs caps on both sides. keep in mind I have had the car since 1974 and never did much to it and drove it maybe ten times in the past 36 years. (busy with race boats) Now I would like to catalog all #s and see exacty what I have! to this point all #s are correct except the rear end and Carb! and that is discouraging! So any more insite on this rear end would be nice, I have no way at this point to find the original owner to verify any documentation on original options, (aka rear end). enough of my rambleing.

Tony

[Joe L.]

Re: 66 Rear Axle #s (Help)

Joe the casting dates on both carrier and cover I still have to asertain maybe this weekend, The car is in a none heated garage And I'm located in northern MI. and the housing is quit rusted. I will post them when I can. The reason I ask about the caps and straps is this unit has one of each, I suspect it needs caps on both sides. keep in mind I have had the car since 1974 and never did much to it and drove it maybe ten times in the past 36 years. (busy with race boats) Now I would like to catalog all #s and see exacty what I have! to this point all #s are correct except the rear end and Carb! and that is discouraging! So any more insite on this rear end would be nice, I have no way at this point to find the original owner to verify any documentation on original options, (aka rear end). enough of my rambleing.

Tony

Tony-----


I can absolutely assure you that as far as the stub axles go, they were never built with "one of each". So, from this we KNOW that someone has been in there at some point.

[Anthony P.]

Re: 66 Rear Axle #s (Help)

Joe yes that is very disturbing, I will have to remove it and teardown this spring, verify internals, Install new yoke(as I assume the straps are 3/8 which means the threads are gone) and generally referbish as needed. DARN IT!

Once again thanks to everyone on this one!!

Tony

[Joe L.]

Re: 66 Rear Axle #s (Help)

Joe yes that is very disturbing, I will have to remove it and teardown this spring, verify internals, Install new yoke(as I assume the straps are 3/8 which means the threads are gone) and generally referbish as needed. DARN IT!

Once again thanks to everyone on this one!!

Tony

Tony------


The cap-type axles have threads for the hex head bolts that retain the caps. The u-bolt type axles have no threads. The u-bolts are retained by nuts.

[Anthony P.]

Re: 66 Rear Axle #s (Help)

Ok I might try to pull that strap off this weekend as an exploritory exercise to see if if there are any signs of possaple stripped threads on an original yoke or if Bubba asembled it with two different yokes. "let the fun begin"

[Anthony P.]

Re: 66 Rear Axle #s (Help)

Here is a speed calculator Plug in your numbers and you will find out what you have http://www.corral.net/tech/gearcalc.html It looks like you have a 2.5 or less gears inside the case or and overdrive final transmission ratio , but you can do the input It your mph or rpm correct? Jack

Jack thanks for the Calculator I will use it in the spring when I can get the car out to drive it. Nice pics of your car!!

[Joe R.]

Re: 66 Rear Axle #s (Help)

Tony,

Here's another thread with some good info for you:

https://www.forums.ncrs.org/showthread.php?90765-what-s-my-rear-end-ratio&referrerid=2667

Joe

[Anthony P.]

Re: 66 Rear Axle #s (Help)

Thanks I will save and test it in the spring Thanks again