questions about my rear axle

[Surrey]

Okay I have a 7.5 I pulled out of my old truck that went to the JY like 2 years ago.

According to the door tag from the old truck, its a 4.10 LS.
I have read the post in the tech library about IDing axles by their axle tag, but my tag doesn't quite match the one shown (I assume the one shown is a 8.8 tag, and the 7.5 is just a bit different, but dont really know)

My tag looks like this



It says [ S602D ]
[ 4 5 7 5 8E31]

I can make sense of everything but the 4 5. I assume its a code for the gear ratio?

Two other questions... Can someone tell me wether or not this thing has a limited slip? And possibly post a picture of what one with (or without, whatever is opposite of what I've got) looks like so I know for the future?

Also, there is a tiny bit of surface rust on the ring gear in a few spots, what should I do about them? They practically wipe off with me rubbing my thumb on 'em...

 

[cvar]

Yours looks like it's open, certainly not limited slip.
You can tell by the spider gears, and between them is missing an S-spring that would press against clutch discs on a LS.

Here's what my Dana 35 limited slip 8.8 looks like: http://imgur.com/a/Z8jr1

For parts info, see here:
http://broncograveyard.com/bronco/b-1019
http://broncograveyard.com/bronco/b-1020-rear-axle-8-8-.html

 

[70roadrunner]

the rust is not a problem. just wipe off as much as u can with a rag. do not use any kind of abrasive.
that looks like an open diff to me. an easy to check is to grab the yoke with one hand and try to turn one axle with the other hand. if you can turn the axle without the yoke turning it is an open diff. if you cant turn one axle without turning the yoke, it is a l/s or other form of locking diff

 

[Mac]

It's also a 3.45 ratio, the first number is often under the attachment bolts or disfigured. Very common ratio in a 7.5.
Dave

 

[Surrey]

Seriously?! they are a 3.45 ratio???

the door stated 4.10s, LS(d7 I think?)... SO this is not the original axle then....?

Now I need to go check the front axle I pulled form that truck. son of a bitch.

 

[Surrey]

It's also a 3.45 ratio, the first number is often under the attachment bolts or disfigured. Very common ratio in a 7.5.
Dave

If you look beside the 4 5 on that axle tag, you can clearly see a large portion of empty space on the tag before the bolt hole starts. Would they have THAT big of a gap between the 3 and the 4 5?

 

[Surrey]

the rust is not a problem. just wipe off as much as u can with a rag. do not use any kind of abrasive.
that looks like an open diff to me. an easy to check is to grab the yoke with one hand and try to turn one axle with the other hand. if you can turn the axle without the yoke turning it is an open diff. if you cant turn one axle without turning the yoke, it is a l/s or other form of locking diff

I figured if it was a stock LS it would be long-blown by now anyways, being that they are clutch based and all...

 

[alwaysFlOoReD]

The gear ratio will be stamped on the ring gear along with a bunch of other numbers. You could also count teeth and divide one into the other, I think it's pinion divided into ring.

Richard

 

[Surrey]

The gear ratio will be stamped on the ring gear along with a bunch of other numbers. You could also count teeth and divide one into the other, I think it's pinion divided into ring.

Richard

There is the info I needed. 3.45 gears it is. Well Crap.

I guess that changes my build plan significantly.

Now to start replanning wtf Im doing with those axles, as I assume the front axle I have is the original axle from that truck, and actually DOES have 4.10 gears, but I can't find the ID sticker or anything

 

[4x4junkie]

Yep, 3.45 open for sure.

They keep a space between the 3 and the 45 because a L/S axle would read 3L45 or 3SL45 to designate it a limited slip.

Front axle will have either a metal tag on a cover bolt (similar to your 7.5) or it may have a yellow/white sticker on the backside of the passengerside beam (may or may not be present after however many odd years it's been since it was made).

You could do a spin test on it to find the ratio...
Fix the axle shaft on one side so that it cannot rotate, then give the other side TWO full exact rotations while counting the number of times the pinion rotates.
3½ turns = 3.45 (D28) or 3.55 (D35), 3¾ turns = 3.73, just over 4 turns = 4.10 and so on.