how well will a dana 60 dodge 1980,s dodge rear end and a 1980,s dodge 60 front end hold up to 47 inch ltb swampers. i plan on building them up if need be, this blazer will not be a serious rock crawler. but more like a really stout dune and trail rig. do i have to tear the axles apart to check if its got 35 spline shafts.
CK5
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47 ltb,s and dana 60 axles
- Thread starter rancid
- Start date
01maroonz71
1/2 ton status
well, being a dodge axle...i believe it's got 19spline inners, which is no bueno. your gonna need some serious beefiness for those heavy ass tires. my buddy breaks shafts with his 40in hawgs...and that's in the mud. if your goin that big i would go rockwells...or upgrade your shafts and ujoints, and get some SLUGS. also, that's kinda big for a trail rig, well, that is if your gonna lift it alot. i dunno though, just my 1/50th of a dollar.
I would use something other than a rear 60, here's why:
The rear 60 shafts are you first weak link by quite a bit. It will have 1.31" 30 spline shafts (the same size as most 1/2 ton rear end). I wouldn't be surprised if you snapped one of those backing out of the driveway on 47's. You can upgrade most rear dana 60's to 1.5" 35 spline shafts by having a machine shop bore the spindles bigger and then using a front dana 60 locker and custom shafts. The spindles on some dana 60 rear ends are too small to be bored for the bigger shafts and there is some question as to how much weaker the spindles become once you bore them out.
Starting with a dana 70 or a FF 14 bolt is a much better choice, they already have all that good stuff.
The front will have 1.5" 35 spline inner shafts which may or may not break. Since you have a 1980 axle the shafts may "neck down" in the middle. You will break those easily, if you have the early style shaft upgrade to the non neckdown shafts (or better yet aftermarket 4340 shafts). The 1480 axle u-joints are probably a little stronger than the stock shafts. The 30 spline outers are also weak (dana 70 35 spline outers are a direct swap but you need new hubs or drive flanges too).
Basically, if you use a better rear axle and upgrade a couple things in the front you may get to marginal reliability. To get them to survive, you would need to spend big $$ on chromo stuff.
The rear 60 shafts are you first weak link by quite a bit. It will have 1.31" 30 spline shafts (the same size as most 1/2 ton rear end). I wouldn't be surprised if you snapped one of those backing out of the driveway on 47's. You can upgrade most rear dana 60's to 1.5" 35 spline shafts by having a machine shop bore the spindles bigger and then using a front dana 60 locker and custom shafts. The spindles on some dana 60 rear ends are too small to be bored for the bigger shafts and there is some question as to how much weaker the spindles become once you bore them out.
Starting with a dana 70 or a FF 14 bolt is a much better choice, they already have all that good stuff.
The front will have 1.5" 35 spline inner shafts which may or may not break. Since you have a 1980 axle the shafts may "neck down" in the middle. You will break those easily, if you have the early style shaft upgrade to the non neckdown shafts (or better yet aftermarket 4340 shafts). The 1480 axle u-joints are probably a little stronger than the stock shafts. The 30 spline outers are also weak (dana 70 35 spline outers are a direct swap but you need new hubs or drive flanges too).
Basically, if you use a better rear axle and upgrade a couple things in the front you may get to marginal reliability. To get them to survive, you would need to spend big $$ on chromo stuff.
My bet is the rear will have 1.31" 30 spline axles and the front will no doubt have 35 spline inners and 30 spline outers.
As for how well they'll hold up... not for long. I have seen 47's in person and they are some huge parts breaking tires. To make a front 60 last it would need the best axles and joints along with aftermarket knuckles.
I really liked the 47's when I saw them and I would love to have a set but I don't think my 35 spline front 60 or rear D70HD could handle them. Too big and too heavy.
Footnote, the one I saw were on a 2.5 ton buggy getting a broken axle replaced.
As for how well they'll hold up... not for long. I have seen 47's in person and they are some huge parts breaking tires. To make a front 60 last it would need the best axles and joints along with aftermarket knuckles.
I really liked the 47's when I saw them and I would love to have a set but I don't think my 35 spline front 60 or rear D70HD could handle them. Too big and too heavy.
Footnote, the one I saw were on a 2.5 ton buggy getting a broken axle replaced.
With a 14 bolt or D70 rear + your front 60 you should be ok with 42's. 44's are doable also just expect some breakage occaisionally. On paper there's only 3" between 44's & 47's but the difference is very dramatic.
sandawgk5
3/4 ton status
Willyswanter had Chromos front and rear with his 47s and he was twisting the splines on the shafts. He never broke one but he said the splines where going.
I have been told that Bobby Longs CVs will hold up to 47s.
Dik
I have been told that Bobby Longs CVs will hold up to 47s.
Dik
Hossbaby50
3/4 ton status
sandawgk5 said:
ya, but will the R&P hold up to 47's
.47's are asking alot even from a D60 front even beefed and even more from a rear D60. If you gonna try it get a 14bff, D70, D80, 10.25" Sterling, etc somthing with some beef for the rear.
Harley
If in doubt seems like you should go rocks 
Save yourself some time and money and just go big the first time around...
Save yourself some time and money and just go big the first time around...
Hossbaby50 said:ya, but will the R&P hold up to 47's
I have seen a couple dana 60 gearsets break with 42's.
In general, the rear end sees a lot more stress than the front which is why I said that dana 60's have a relatively weak ring and pinion setup. It could be the weakest rear end ever put under a 1 ton truck.
sandawgk5 said:
Twisted splines means very close to breaking. Wouldn't surprise me if he would have broken them the next time out. That's why he was swapping 'mogs in.
I wouldn't doubt that Bobby Longs CV's will hold up but what about knuckles, ring and pinion, kingpins, etc.
He would be running this in the sand and mud, not the rocks though so maybe he can make it survive without putting $4K into the front axle.
Avery4jc said:If in doubt seems like you should go rocks
I have heard that many of the rockwell axles break easier than one tons (from people that have switched). Everything on the rocks' are bigger, but they have been used MUCH harder than civilian axles and likely for much longer.
The worst part of that? You can't really find new parts for rockwells (I don't think you can buy new shafts at all) and even the few parts that can be bought new are really expensive.
The aftermarket stuff is stupid strong and stupid expensive.
Big tires = big strength = big $$$
True but rocks are comparably cheap for their strength even in stock form...
But iono... I'd think that if they did break easier than 1 tons you wouldn't see so many BIG tire wheelers switching from 14ff/d60 or d70/d60 combos to rocks...
But iono... I'd think that if they did break easier than 1 tons you wouldn't see so many BIG tire wheelers switching from 14ff/d60 or d70/d60 combos to rocks...
Avery4jc said:
And again, everything on rocks are bigger compared to one tons.
You just don't know what you have. Using 50 year old axle shafts that have carried who knows how much weight for who knows how long under who knows how much torque using inferior 50 year old mettalurgy means that you may or may not have a strong setup.
There are obviously tons of people running rocks on big tires with lots of success, but I have also heard of people having trouble with breaking shafts and the only replacements are used (and just as questionable).
I bought new "big" Spicer inner shafts for my 60 new for ~$50 a side (a few years ago). You can't buy new shafts for rocks and $50 a side would probably be a good deal for used shafts for them.
Are rocks stronger than one tons? IMO, yes. But in stock form they are far from the perfect answer for really big tires.
With the best axles for the 60- Superiors/CTM's or Bobby Longs 60 CV's, a kingpin D60 front will hold up just fine. Willyswanter Ran the 47"s on his heaaavy 7500k lb rig wih the Superiors/CTM's. Other than the spline twisting, which I believe his heavy rig contributed too, you'll be fine. You're blazer is aloot lighter that his crewcab was, and you probably don't run a bigblock. Jason also ran the 14b. Dunno 'bout what shafts he ran, but he never had any problems with it. It'll cost ya, but it's do-able.
TruckNutzDude
1/2 ton status
I know they're not 47's but my 44's are doing just fine on my D60/14, only thing I had to do was upgrade the stubs in the '60 because I kept twisting the splines off where they machined for the inner c-clip. I'm running a spool up front and a welded rear, stock rear shafts and stock non-neck inners on the front. I think you could do it with 47's on a D60/14 or D60/D70 without breaking every trip. 
I've considered 'Rocks but only for the 6.72 gears, I'd like a little deeper than 5.13 sometimes, even with the SM465.
I've considered 'Rocks but only for the 6.72 gears, I'd like a little deeper than 5.13 sometimes, even with the SM465.
Hossbaby50
3/4 ton status
I am not sure 47's are a great choice but I will say you will never find out it won't work unless you do it. Worst case is you break stuff to often for your taste and you trade someone for a set of 42's or 44's.
I know that 37's on my 10bolt front with a locker isn't a great idea but I just keep that in mind when I am wheeling and try and drive smart. Push it as much as I can but try and keep it from breaking is the way alot of the AZ guys run. Eventually it catches up to us but hey, sh*t happens and that wheelin.
Harley
I know that 37's on my 10bolt front with a locker isn't a great idea but I just keep that in mind when I am wheeling and try and drive smart. Push it as much as I can but try and keep it from breaking is the way alot of the AZ guys run. Eventually it catches up to us but hey, sh*t happens and that wheelin.
Harley
chromo it and have at it man. breaking it is half the fun and it helps you understand your rig better. hell i can change a u-joint in mere minutes now. I personally think chromos and some beefy joints and the front should last. But deff a full floater rear( 14 bolt ff or D70) and chromo that if you feel the need. If you break a shaft buy a replacement and if you resale them they axles will bring in a hefty downpayment on some rocks or mogs if you choose to go bigger. What would be the ground clearance difference b/t rocks with the "angry" cover)and a 60/14 combo? Just kinda curious on that one, even though they are damn 47s
very nicely put.
