axle and drum questions.

[73stepside]

does anyone know if the axle shafts and drums will interchange to the 6 lug axles? i can find these for cheap compared to 71-72 axles and drums. thanks for any info, jason

[JimKshortstep4x4]

I am not sure what you are asking. Can you clarify?

Jim

[VTKidder]

Axles are a a direct swap from 6 lug to 5 lug, which I believe is what you are asking. The only stipulation is that you have the same number of splines on the pumpkin end of the axle, and they are held in the same way; usually C-clips. If the axles you are looking to swap are from the same era within a couple years, then I'd say you're fine, but wouldn't put my $$ on a swapping '68 and '98 axles.

I believe the drums are the same diameter and depth...but couldn't tell you for sure cause I've never done the swap.

[kaycee]

I took my 6 lug 69 and converted it to a 74 5on 5 setup front went together like a glove.The 74 rear was 1"wider than the 69 rear and I was trying to use the 69 housing soooo I made a 1/2" spacer plate to go on each axle between the rearend housing and the backing plate so far so good

[Longhorn Man]

The '70 axle shafts will be 6 lug, and swap right into your 73 & up rear. The 69 and older is, as indicated, not the same width.

[73stepside]

i was wanting to get axles and drums from a five lug 73-79 pick up and put them in my 70. i thought it would be an easier swap than tryin to find a 71-72 set up. i can get 73-79 stuff all day for real cheap

[Hardrock2]

Yep, '70 is the good rear for interchange. You can go either way with it. It will accept '71-'79 ('80) 12-bolt 5-lug axles, or 6-lug 4x4 axles from the same years, (if you are just looking to replace a bad one.) As far as the brakes go, I've been wanting to try this, too. From what I can tell, if you use everything including the backing plates and all hardware, you can end up with the bigger finned drums from the '73-up trucks. Should bolt right up!
Like Longhornmail says, anything '69 and back(1/2 ton) is a narrower rear, and you're stuck with 6-lugs, unless you want to re-drill the wheel pattern! Something to keep in mind, if you're trying to "tuck" some wild offset wheels under your truck, and you just need another 1/2" on either side!

[krue]

Does that include a 70 stepside axle? I thought they were narrower rearends than the fleetside rears.

[Hardrock2]

Yes, 1/2 stepside and fleetside trucks have the same width 12-bolt axle for any given year. I've noticed some folks claim to have swapped '71-up axles into pre-'70 trucks, but I'm willing to bet their trucks have had a rearend swap sometime in the past. As a rule, the earlier rearends (69-back) won't accomodate alot of wide tire/wheel combos. (especially anything with even moderate negitave offset) Too tight of inner wheelwell, bedside clearance, but with careful measuring, and alot of positive offset, you should be able to get some healthy rubber under there!
the '70-up rears don't have that problem, except in the most extreme cases. (read REALLY BIG TIRES) Plus, the rear of the truck will have the same track width as the front. The narrow rears were just a carry over from the '60-'66 trucks. Never really understood why it took GM 4 years to correct this.

Here's something I should know,but don't. I'm pretty familiar with the coilsprung chevys, but were the leaf/dana equipped GMCs
narrower from '69 back??? Something tells me they were, but I'm not real sure.

[73stepside]

cool thanks for the info guys. it will be much easier for me to swap these parts over. i know of a good yard here that has almost nothing but 73-80 chevy/gmc trucks.

[Southpa]

Whew, thanks from me too! Was just talking to my boss the other night about rotating tires. he asks me how often I rotate 'em. I had to say, "uhhh, never"? He says why and I say take a real close look. heheh 6 on the rear and 5 up front.

I might just go for a whole rearend swap tho. Spider gears have a little too much rotational play. I'll try to measure how much and then compare with any potential donors. Would like some midrange gears, 3.07 is nice on the hwy but still a bit slow on the starting line. What are the next higher ratios from there? And how rare?

[73stepside]

3:23, 3:42, 3:55, or 3:73 would be great gears for the street

[Hardrock2]

Common factory gears run 3:07, 3:42, 3:73, 4:10 (4:11) in the 70's trucks. I personally like the 3:42's! More fun than the 3:07's, and not as fuel hungry as the 3:73's or 4:10's !!
Assuming you have a strong mid range street motor, of course!
(or a solid big block)
With the 3:42's and a well built 700R4, you get the added benefit of a low first gear that leaves like a TH400 with around 3:73's-4:10's, AND an overdrive in top gear! Pretty good combo.
Oddest thing is, the 3:42's aren't all that common. I only seem to find them in the base "stripper" trucks, and only in 350-4V, 3-speed manual trans. trucks. I think that was the standard gear when optioned with a 350/3-speed! I know most all 6-cyl. 3-speeds were standard with 3:73's, and V-8 autos. were 3:07's, unless ordered otherwise.



Mike