The Stovebolt Site Forums The Parking Lot Big Bolts Front Axle swap? 6400 Dubl-Duti into 4400 series ?

Is this asking for grief ?


I have a '55.1 4400 series whose king-pin bores in the axle were hogged-out...

Found out this is the same axle as used in the 3/4 & 1-tons...the axle and knnuckles are just too small to carry 20" wheels, IMHO...

Would the heavy-duty front axle from a 5400 or 6400 Dubl-Duti swap right in?

I might put this dump truck back to work; if I do, I think I will want a beefier front-end...

Your thoughts ?

Frank54,

I have not done this swap..but I researched my manuals and resto-pack and it looks to me like it would be possible. The axle cross section is a little larger, which gives it the 4500# rating. King pins are larger and , of course, so are the spindles. I'm sure the final verdict would hinge on a look-see with a tape measure..

Stuart

The 6000 series front axle was available as a heavy-duty front axle RPO on the 4000 series, so it should be a bolt-in affair (as a complete unit with the corresponding spindles and hubs). The 5000 series axle was a slightly heavier I-beam than the 6000, and the track might be a little wider, but I think the spindles and hubs were the same as the 6000, so it would probably work too.

I think the axle you have is plenty strong. My 4400 has the standard axle and it hauls 4 ton of weight on it pushing and lifting an eight foot wide snowplow. I've been using this truck for 5 years now and never had a front end problem. BUT, I think to swap out a 2 ton front would be a direct bolt in since the fenders and the frame between the two are the same. The main drawback would be finding kingpins available for the bigger axle. I know the 1 1/2 tons are still available.
Just some food for thought,
Scott

Scott,

My '55 first was reasonably well-cared for...it was a one-owner truck prior to my acquiring it...belonged to a local builder...

It has what I presume to be 131,000 miles on it...

We knocked the front-end down because the front wheels were floppy, presuming bad king-pins...

Our first surprise was when the king pins amost flew right out on the first tap of the hammer...no pounding, no heat...

Once everything was off the truck, we discovered that the truck had been given a new set of king-pins shortly before it was retired, and the new pins were snug in the knuckles... the slop was from the pins themselves rocking in the bores of the axle itself.

A little research provided part numbers for the stock size kit, plus .010" and .020" oversize kits (requiring reaming of the axle).

When I tried to get an oversize set, I found from just about all the suppliers that the oversizes were depleted years ago...the standard size is the only one still available.

That said, we had a local machinist make up a pin and bushing set for us, .020" -over.

I was shocked to find that this is the same pin set for 3/4, 1 ton , AND the 1.5 ton...

There's a vast difference in the amount of "unsprung weight" those pins are supporting between a 3/4-ton with 15" split rims and a 4400 series with 14" brakes, heavy cast hub adapters and 20" wheels...that's why I'm suggesting that this axle is a little light for my particular application...

It may have been acceptable for the trucks with the 8-lug 18" & 19.5" wheels...

Both of my '41-47 big trucks have a heavier axle and knuckle set-up, with the bolt-on cap over the wheel bearing and bolt-on covers over the king-pin.

The first King pin set I got from Jim Carter was for the BIG truck...too big for my axle...

If your 4400 axle is working for you, then I guess you won't be worrying about an axle-swap...

I will run the stock axle for now...but I think I will keep my eyes open for a 6400 being parted, and grab the axle if one becomes available...


Thanks for all the replies guys !

Frank are your sure that truck is a 4400? A dump truck is often a shorter wheelbase, like a 4100. The 4100 did share the axle with the 1-ton truck, but I think the 4400 was a bigger axle.

Steve,

It's a 4400 "medium duty" alright...

Has the 4400 hood scripts, plus the Serial code P-55, and a 14,000 lb GVW rating...

I believe it is the 160" (I'm approximating!) WB, oufitted with a 10ft Galion low-side dump body...

It has the big single-speed rear with the 15x4 rear brakes...

My buddy has a '51 1-ton dump with eight-lug 18" wheels: the front hub adapters look very similar, with the screw-in hubcover...

I think GM was a little misguided putting the "medium-duty" axle in this big a truck, IMHO...

As long as I can fit the heavier axle under the existing front-end, I'm not too worried...

The truck is going back on the road with an antique tag for now, so no hauling until I switch to a regular plate.

Thanks...

Frank

160 inch wheel base is a 4400, so if it has the same axle as the 1-ton I think its been swapped at some time in the past. I think a 4100 has the same 137 (or whatever it is) wheelbase a 3800 has and that may be why it uses the same axle.

Does it have the same 5/10-lug wheels on the front as a 6400?

We're talking here about a '55 1st, and my resource on the axle applications is actually from a '51 or '52, but that kind of thing has seemed consistent across years.

I have both a '51 4400 and a '52 6400 and the axles look very similar, though I've never tried to measure either one.

You might look around and see if you can find another truck with a servicable axle. These old trucks with rusted bodies are hard to give away, but could still have some good parts like the axle.

I like the look of those wheels. My 1-ton is not a dually, and I've been thinking I'd like a set of these wheels to cut the centers out of and make a set of 16-inch wheels to run under my dually I'm building.

Same 20" ten-lug wheels as the Dubl-Duti...

The big giveaway on axle ID is the cover for the front wheel bearing...the medium-duty axle has that screw-on cover with the octagonal head; the Dubl-Duti axle has a "domed" cap secured with five 7/16" head bolts.

When you look at the king-pins, the medium duty have welch-plugs covering them, the Double-Duti have the oval flat cover with two bolts.

One of these days I think I will try to get a resto packet from GM on this buggy...

It looks just like a '54, except the grille is painted all-white ('54 was body-color on the outer bars, with light gray on the backsplashes).

Good luck with your wheel adaptage...sounds ambitious !


Frank

The '54 resto pack (should be the same for '55.1) shows that the 4400 axle is the same as the 36-38-4100. The dimensions of the I-beam, king pins, and spindle are all the same. The 4000 even uses the same wheel bearings as the 36-3800, though the hubs would obviously be different. The only other difference is that each series has a different weight capacity (2500, 3500, and 4000 lbs. for the 3600, 3800, 41-4400 series respectively). If the axles are all identical, I can't figure out how they have different capacities. The 6000 capacity is only 500 lbs. more, at 4500 lbs.

One note about using a '54 or '55.1 5000 or 6000 series axle--while the wheels may be the same size with the same bolt circle as the 4000, the wheel center holes are bigger. In '54, the front and rear hubs of the 5000 and 6000 series were beefed up, and the hub center diameter was increased 1/2".

Curt,

I have an extra set of 20 " wheels with decent tires from my '41 Dump that I was planning to put on the '55.1...

Sounds like the '41 rims won't fit the '55.1 hubs ?

Frank ,you still here?
If so maybe this can help.
Believe I have access to a 52 6400 complete I- beam takeout drum to drum.
Steve sr

If the '54 and '55 1st 4400 hundred axle is the same as the lighter trucks, when looking for a replacement you'll want to know what year truck you are looking at. Because in '51 (or '52, I don't recall which resto pack I read) the 4100 is the same as the 3800 and the 4400 is bigger.

I wonder why and when Chevrolet changed that.

I'm getting confused, now. The '49 resto pack, the '49 data book, and the '53 and '54 resto packs show common specs for the 36-38-41-4400 axles. However, the '51 resto pack shows the 41-4400 axle as having the same specs as the 6000. I think that is probably a misprint, unless it was changed for a year or two for whatever reason.

Looking thru the '54 parts manual, I see that, even though the axles have the same dimensional specs (for I-beam size and king pin and spindle diameters), there are many different I-beam forgings listed ( see here at the bottom of the page and on to the next). So there must be differences despite being the same (??). They could be slightly different lengths (the length isn't given in the specs), and/or they could be made of different alloys or heat treated differently to obtain the different weight capacities. :confused:

Frank, your '41 1.5 ton wheels would have a smaller center hole than the '54/'55.1 5000/6000 wheels, which have a center hole diameter of 5.25", up from 4.75" (I think these are correct numbers). It shouldn't be a problem if you get a 6000 front axle with '53 or earlier hubs, though you'll probably want to keep the '53 and later bendix brakes.