Axle length??

[RMATTZZ4]

Are the 5 lug axles from a 71, 12 bolt the same length and size as a 70, 6 lug rear end? Can they be interchanged?

Thanks....

[SactoJim]

The earlier rear ends are narrower....not sure how much, but I'm sure someone with chime in pretty quick.

[GREASEMONKEY72]

im not sure but i think the 67-71 axles are the same width and the 72 is wider but i dont know for sure

[bagged7185]

yep six lug axles are shorter dont know how much though

[Bus Ted Knuckle]

6 lug 67-70(ish 'cause somewhere in 70 they got longer) are 3/4 inch shorter on each side. 71-72 axles are 3/4 inch longer than earlier ones.

[OLDIRON69]

RMMATTZZ4--I used 73 or 74 (what I was told it was) axles for my rear end swap. Before I pulled anything, I measured from backing plate to backing plate. They were the same for my '69 C-10. I had never swapped axles out before and was surprised HOW EASY it was. It was almost scary it was so easy. I had to double check everything a few times to make sure everything was right, just to make sure I didn't miss anything.
As far as the measurements, when I put them side by side they were the same.

[RMATTZZ4]

Thanks guys! I already gotta 5 lug unit on the truck but came across a six lug posi unit that I want to swap to and was wondering what options I had. Thanks again........

[Jim_PA]

You can put the longer axles in the narrower rear -- Just put on the larger brake drums from a 73-80. I've been running mine that way for over a year with 0 problems.

[Longhorn Man]

Doing what Jim did will put the bearings in a less hardened (or even non-hardened) part of the axle shaft. You can do it, and even get away with it, but if that axle snaps... hold on. Your wheel will exit the fenderwell, and probably do $2500 of body damage if your rig is nice, then, you'll be sliding down the road on the rear axle, becouse the backing plate will fold almost instantly.
Not to mention what will happen to the front of the truck from sliding around uncontrolably fishtailing left to right... You hit the brakes, but all the fluid will squirt out the brake cylinder that just blew up, so now you can only hold on, and TRY to steer it.
Now, I got balls of cast iron, I'll call the boss man a fat lazy bum, but I wouldn't do this personally.

67 - early 70 rear axles were 56 inches from backing plate to backing plate.
late 70 - 72 were 57 1/2 inches.

[OLDIRON69]

Weird....Got lucky some where I guess...my axles that I swapped in were from ???? year 5 lug and were the same length as my '69. Damn I should have got some numbers off it before I scrapped it!

[StingRay]

A 70 rear end could be a transitional piece. I have a 70 housing in my truck that had 6 bolt axles but was 71-72 length. I swaped in my 72 axles and brakes no problem. Measure if the length is correct you are good to go. 67-69 are going to be the short ones, 70 could be either and 71-72 are the longer ones. This has been discussed here many times over the years and proven true. On the late 70 housing the brake line brackes will be early style but everything from the 71-72 will swap on fine.

[Jim_PA]

Originally Posted by Longhorn Man

Doing what Jim did will put the bearings in a less hardened (or even non-hardened) part of the axle shaft.

How can you determine that the outer surface of where the bearing originally rides is hardened, whereas the inner part of where the bearing rides (3/4 of an inch away from the original surface) is less-hardened (or not hardened at all)?

[OLDIRON69]

I thought the axle as in "entire" was hardened.

[Bus Ted Knuckle]

Originally Posted by OLDIRON69

I thought the axle as in "entire" was hardened.

It is hardened, BUT only a certain area at the end of the axle is machined and sized for the bearing to ride on.

Here is the deal. Sure you can swap axles that way, but it is just not the best way to do it. The last time this discussion came up some guy said that he did the longer axle swap into the earlier housing and the "only" problem he had was that the brake shoes did not fit all the way in the brake drum ...

I mean, come on, buy a new set of aftermarket axles @ $250 or so, or swap out an ENTIRE rear end assembly from a 71-72 truck. OR, grab a 73-87 rear end and fab up the trailing arm perches by cutting them off of your 6-lug housing and welding them on the new housing. Price a 73-87 rear end at the junk yard next time. I would be supprised if you did not leave with one.

There are SO MANY ways of doing it right, why would anyone want to do it the one wrong way!?!

Now, I am a big boy...I can take a little flamin. Give it to me

[Jim_PA]

Originally Posted by Bus Ted Knuckle

It is hardened, BUT only a certain area at the end of the axle is machined and sized for the bearing to ride on.

Here is the deal. Sure you can swap axles that way, but it is just not the best way to do it. The last time this discussion came up some guy said that he did the longer axle swap into the earlier housing and the "only" problem he had was that the brake shoes did not fit all the way in the brake drum ...

I mean, come on, buy a new set of aftermarket axles @ $250 or so, or swap out an ENTIRE rear end assembly from a 71-72 truck. OR, grab a 73-87 rear end and fab up the trailing arm perches by cutting them off of your 6-lug housing and welding them on the new housing. Price a 73-87 rear end at the junk yard next time. I would be supprised if you did not leave with one.

There are SO MANY ways of doing it right, why would anyone want to do it the one wrong way!?!

Now, I am a big boy...I can take a little flamin. Give it to me

Your opinion says it's the wrong way, but you haven't given me any reason to believe swapping the axles is the wrong way. The bearing is still contacting the axle on the machined surface. Until someone presents me with information that says "only the outermost 3/4 inch of the machined axle surface is hardened", I say BS. For many of us, the best way is the cheapest way, unless it risks safety.

Until you can bring more than an opinion to the table, I still say swapping axles and drums is perfectly safe, and I am open to being proven wrong.

[OLDIRON69]

My axles were the same length, so this is not an issue for me. I was just wondering about the hardened issue. I replaced my rear drums, with the light duty $28 each at O'rielly auto parts. They fit like they should and stops even better, I will eventually pull all the rear drum stuff off my truck anyway, so I can do a 4 wheel disc. I WON'T go cheap! Aflac dosen't cover my arse THAT much! Damn DUCK!

[Bus Ted Knuckle]

Originally Posted by Jim_PA

Your opinion says it's the wrong way, but you haven't given me any reason to believe swapping the axles is the wrong way. The bearing is still contacting the axle on the machined surface. Until someone presents me with information that says "only the outermost 3/4 inch of the machined axle surface is hardened", I say BS. For many of us, the best way is the cheapest way, unless it risks safety.

Until you can bring more than an opinion to the table, I still say swapping axles and drums is perfectly safe, and I am open to being proven wrong.

5 lug axles axles are the WRONG LENGTH for 67-69 (and some 70) housings.

They are too long, they are not the correct part. They are not designed to go in the shorter housing. They are for a later, wider housing. how much more proof do you need?

Where is your proof that it is safe?

I see nothing but opinion in your response as well. My statements are backed by part number and year differences that are known and can be measured.

Old iron, you did it one right way because you used the correct length axles out of a (apperently) 70 axle that are the correct length.

Edit by ME:

Jim, everything that I do is the cheapest and safest way (I don't have the $$$ to do it any other way). You are not talking to a guy that does high budget rebuilds or trick fancy trucks. I am an old fashioned knuckle buster that was taught by one of the finest of the old time mechanics.

[Jim_PA]

Originally Posted by Bus Ted Knuckle

5 lug axles axles are the WRONG LENGTH for 67-69 (and some 70) housings.

They are too long, they are not the correct part. They are not designed to go in the shorter housing. They are for a later, wider housing. how much more proof do you need?

Where is your proof that it is safe?

I see nothing but opinion in your response as well. My statements are backed by part number and year differences that are known and can be measured.

Old iron, you did it one right way because you used the correct length axles out of a (apperently) 70 axle that are the correct length.

Been running them for over a year with 400 horse and a 4 speed. Goes down the road smooth as silk. There's your proof.

Part numbers mean nothing. I've got 71 front suspension under my truck, and had to use different tie rod ends with different part numbers. Guess those are all the wrong parts too.

I can go home and measure if you'd like, but there's plenty of machined surface for the bearing to contact the axle with. 3/4 of an inch isn't going to blow up your truck while going down the road.

[Bus Ted Knuckle]

Originally Posted by Jim_PA

Been running them for over a year with 400 horse and a 4 speed. Goes down the road smooth as silk. There's your proof.

Part numbers mean nothing. I've got 71 front suspension under my truck, and had to use different tie rod ends with different part numbers. Guess those are all the wrong parts too.

I can go home and measure if you'd like, but there's plenty of machined surface for the bearing to contact the axle with. 3/4 of an inch isn't going to blow up your truck while going down the road.

OK, so you have ran them for a year, who is to say that they won't fail tomorrow? I am glad it is working for you.

Sometimes people have to agree to dissagree.

[Jim_PA]

Originally Posted by Bus Ted Knuckle

OK, so you have ran them for a year, who is to say that they won't fail tomorrow? I am glad it is working for you.

Sometimes people have to agree to dissagree.

Lots of things can fail. I think the point is that there's no proof/data one way or the other... OTHER THAN... I've never heard of anyone having a problem

[Bus Ted Knuckle]

[OLDIRON69]

My axles came out of a leaf spring rear, what year?? I do not know. I bought it with a trailer load of parts. He thought is was a 73-87 ?? Either way the axles were the same length and the axles actually required me to use larger diameter wheel studs. I still wish I knew what year!!

I agree that if a swap of any kind is not safe, it should not be done. I would worry more about premature bearing wear than the axle to break, or high hp going to stock axles. I'm not trying to argue with anyone here, I value the information that is on the site, I just wish it wouldn't have taken me so long to find it!

[cooters]

so what about axle saver bearings, they move the bearing over if your axle is damaged. They wouldnt sell them if they caused problems would they?

[Bus Ted Knuckle]

Originally Posted by cooters

so what about axle saver bearings, they move the bearing over if your axle is damaged. They wouldnt sell them if they caused problems would they?

Well, they sold the ford focus, and asbestos didn't they?

[Longhorn Man]

and foam air filkers, fram oil filters, and flex fans.... oh hell, they STILL sell them, and everyone knows (or should know) that these items can mess up your day.