Changes to wheel hubs

[Chris Lloyd-Staples]

Apologies, I'm a CMP-newbie!

There appear to be two types of wheel hubs that I've noticed on CMPs. The first type is a simple dome


and the other type has flanges


Are these related to particular dates or production batches?

Chris

[rob love]

The flanges are on the 44-45 dated trucks. They may have come out late in 43, others on the site will know. The flanges provided an attachment point to crane the trucks onto ships.

[Grant Bowker]

You are correct that there are two setups.
The version with the flanges is later and as you probably already know intended to make it easier to sling load the truck on/off ships.
The flange at the rear is a simple flat sheet that is held in place by the rear axle flange nuts between the nuts and the wedge washers that stop the drive flange from rotating relative to the hub.(I'm not sure if there were longer studs on the flange equipped trucks.)
The flange at the front is deceptive. It looks like the cast hub cap with the built-in flange should just be a bolt on replacement for the earlier cast hub cap. My experience is that this is not the case.
I'm not sure whether once the flanged setup became available all trucks were equipped with it or whether the plain setup continued in production (doesn't make sense to me but possible).
Another thing for me to check in the parts books.

[m606paz]

I have two parts manual with both Caps/Flange Hubs #1131

[Lynn Eades]

The obvious difference will be because the early one has a cap with 3 small screws. and was designed to only hold the cap on. The later design has to carry the weight of the vehicle.

[Grant Bowker]

The three screws don't carry the complete load of the truck, there's a machined step on the cap with matching surfaces on the hub to take most of the shear load with the screws serving largely to hold the cap and hub securely in place. I'm not sure if I have easy access to samples to photograph.

[Bob Phillips]

So in other words, the early vs late style front drums and caps are matched due to the different bolt size holding the caps on. If you wanted to change a truck from early to late style hubs ( or vice versa) you would need to change the drums and the caps together as a set. I do seem to recall (as per Grants comment) the the wheel studs on the back of a late model truck ( with flange) are longer to accommodate the extra width of the flange.

[Jacques Reed]

The sling caps are held on by the three studs part No. C 380304-S which are 1/2" dia with 1/2 UNF and 1/2 UNC threads either end. My NOS hubs shown have these drilled and tapped holes.

The front hubs on mine have both the small, tapped holes for the standard cap and the larger holes for the sling cap studs. One size fits all as often is the case so perhaps some late war trucks had either cap, or it was just to keep parts inventory down.

I put 1/2-13 UNC grub screws with Permatex into mine to seal the stud holes as my earlier truck should have the standard caps.

Cheers,