Identify Dana 25 Vs 27?

If I take a look at my front axle, how do I tell if it's a Dana 25 or 27? Visually, whats the difference?

 

No number on the 27?

 

I thought the breather location helps to tell them apart? I know Dana 25s are on the cover and I'm pretty sure a Dana 27 has it on the top of the cast housing.

 

My 27 has the breather on the housing and it also has a 27 cast into it

 

Mine has a 27 cast into it as well

 

so does mine.

 

x2

 

The Jeep you have pictured appears to be pre-'64 due to the lid on the top of the cowl, so if your front axle is original, it should be a D25.
-Donny

 

Yep, that was a '53 M38A1. I don't have that one anymore. But the CJ5 I have now has the breather on the cover, so probably a 25. I'll look for a number on the housing.

 

What's the difference in the internal components? There has to be some differences ,other than the housing!

 

A Dana 27 ring gear is smaller than a Dana 25.

Dana 25 vs 27 -- strength?

 

The only differences are:
The ring and pinion (D-27 has smaller diameter ring)
The differential case itself
The differential case bearings and shims
The pinion inner bearing. (the cone and cup) plus the pinion depth shims
Outer pinion bearing and seal and preload shims are same as D25
The housing and the cover are different.

Also the wheel spindle bearings (D27 is slightly wider/ larger)
The D27 hubs and hub seals (same as drum brake D30 hubs and seals)

 

In my experience, the ring and pinions in either the D25 or D27 are generally adequate for a somewhat stock Jeep and maybe tires up to 33's. That can not be said for corresponding spider gears and axle shafts which seemingly sometimes disintegrate without much cause. But looking at a D25 ring gear more suggests a go-cart component than one for a Jeep------

 

I think the 33" tires are beyond the capabilities of a Dana 25 unless it is used very gently. I have a Willys Wagon down in the yard with an exploded 25. Its got a pile of teeth shucked off in the bottom of the housing, and this was running 31" tires when that happened.
-Donny

 

What year did the Dana 27 come into production,for the CJ5?

 

The model 27 came into production for a very short time in 1961.
That was the model 27 and it only came with 5.38 gears.

I re- emerge in late 1962 (early 63 model year) as the 27 AF and was then standard with 4.27 gears and 5.38 optional.