Dana 25 vs 27 -- strength?

I'm thinking about some major work on the jeepster real soon. It has to have a new engine and trans, which I am currently building. I would like to do a spring over and put 35's or 36's on it. I'll need to change to a 4.88 or 5.38 axle ratio. This brings my question about the 25/27. I have two 25's with 5.38's. Is the 27 stronger than the 25 or was the move from the 25 to the 27 simply to accommodate higher (numerically lower) gear ratios?

 

Thanks Mike, I plan to upgrade to a Dana 44 front (I have a Scout II front end in the barn) when I can afford to have it narrowed and regear it.

 

The dana 25 uses 8 bolts to hold the ring gear to the carrier and the 27 uses 10 bolts and the 27 gear in the same ration is a thicker gear (more meat on it) so that makes the ring gear in the 25 slighlty weaker in my opinion.
Sean the size of a ring gears diameter is only part of its strength, the strongest gear is the one closest to the carrier break.
The housing on the 27 is larger on the ends where the axle tubes are pressed in, if you look closely you will notice that the 27 is longer in this area and larger in diameter, I bet that if you weighed the 2 empty housings you would find that the 27 has about another 6-8 lbs of iron in the housing section.

 

4" suspension and 1" body would be a better and safer combo. (less axle twist) Also the under mount springs keep rocks away from the frame.

 

Seems like you would break an axle before you break the gears. A lot of these guys have run the 25 for years. On a personal note the 25 that was in my 69 had a lot of metal shavings in it when I took it out, but it still worked.

 

My '60 CJ5 was bought new by my father and has had a plow on it since 1962. For the last 10 years, I've been plowing with it commercially doing a route of 45 driveways. My buddies with their powerstokes call me up all the time for their tricky driveways cus they slide around and with chains on my rear tires, I go pretty much everywhere. Anyway, the stock 25 front axle lasted until last season (thats 43 years of abuse). The bolts which hold the ring gear to the carrier backed off and the gear got wedged in there making a big mess. I found a used 25 with the 5.38 gears I needed. I picked it up and rebuilt it. During the rebuild, I looked into the option of putting a powerlock unit in the front (the rear 44 had one in it from a donor scout). The very early scouts came with dana 27 front and rears both with powerlock units. I found a powerlock out of a dana 27 front end from a scout for 50 bucks. I'd figure I'd buy it and see if I could make it work in my dana 25. the 27 ring gear is smaller diameter, but is thicker, as stated above by mcruff. However, I was able to bolt the 25 ring gear up to the 27 powerlock no problem. It had the same number of bolts and the same pattern. This is in contrast to what mcruff says. maybe the scout 27's had a different carrier than the jeep 27's???? I doubt it though. I just know the 27 carrier I got from a scout accepted my 25 ring gear. All I had to do was remove the bearings and shims from the 27 and replace it with 25 bearings. I then had to machine down the races very slightly to get the 27 carrier to fit into the 25 housings. And now i got front an rear powerlocks. Long story short, the stock 25 lasted over 40 years and was subjected to a ton of plowing abuse. It would have gone longer if the carrier bolts were ever tightned down but to be honest, I don't think the differential cover was ever removed to inspect things. As for the carrier bolt count being different, I didn't find that to be the case.... And another thing, no matter what front axle you have, get a set of warn manuel full turn locking hubs. These hubs will greatly increase the life of any front axle and makes for easier driving on paved roads.

 

sounds like it had a 27 carrier already. 25 should have 8 bolts, 27 has 10.

 

I don't see how it could have had a 27 carrier in it already. It's definetly a 25 housing (it has 25 stamped on it with big numbers). But like I said, I got a complete 25 axle to replace my original as the original was completley shot after the ring gear backed off. Maybe sometime in its life, the 25 I picked up was swapped out to a 27 carrier??? But that doesnt make sense for 2 reasons. 1) it had a 5.38 ring gear (i didnt think 27's came in that ratio - i maybe wrong). and 2) it definetly has a 25 ring gear cus it was a larger diameter (5.75") than the 27 ring gear (5.20") that was still bolted to the 27 powerlock I bought....... I don't remember if it had 8 bolts or 10, but I still have the stock open carrier that came out of the 25 i bought. I'm gonna dig it up and count the bolt holes in the carrier. i also have the 27 ring gear that came on the 27 powerlock i bought. i'll check that out too.

 

That might get 35's or 36's under the front ok. But no chance on the back. I don't want to cut the rear fender's. See below...... (btw i'm running 235's on 1980's factory chrome cj wheels w/ a 2.5" shackle lift in the back and they barely clear) .........


Here's where I got the idea.......



Notice the rear fender issue......



This jeep is soa + 4" springs/blocks I'm thinking soa + 2" springs + 1.5" body and keep the rear shackle lift to help at the rear fenders.

 

Thanks Lynn, lots of good info there!! I've seen his jeep over at the Off-road.com/ jeepster club BBS. 8)