Front Differential ID assistance.

[Brett M]

G'day All, I have an early 42 WC56 & has developed oil leaks on the inside of the steering knuckles, I intend to rectify this problem ASAP.
When looking at parts from VPW it asks whether the Diff is 8 3/4" or 9 5/8". I'm unsure of the type on my vehicle & would like assistance if possible on how to identify the diff correctly.
Cheers
Brett

[ng19delta]

Easy way, theoretically, is to look at the front cover- If it has studs/bolts holding the cover on, it is most likely an 8 3/4". If it has studs/bolts and a spacer, it may be a 9 5/8" retrofit. If the cover is welded on, it is probably a 9 5/8".

Based on the year, it should be an 8 3/4" if not refit to the later differential. Usually they would simply modify the axle housing, and fit the later center member in, using 3 gaskets on the carrier side, and a spacer and two gaskets on the cover side.

Scott

[Brett M]

Hi Scott Thanks mate, The cover has no bolts on it apart from a small bolt at the bottom for drain. The diff centre itself only looks to have a gasket between the 2 surfaces & bolted.
Brett

[ng19delta]

Hi Scott Thanks mate, The cover has no bolts on it apart from a small bolt at the bottom for drain. The diff centre itself only looks to have a gasket between the 2 surfaces & bolted.
Brett

Sounds like a 9 5/8"...

Scott

[Fred Coldwell]

Brett:

I just gave a friend a partial front axle assembly from a WC 1-1/2 ton 6x6 truck. It has a deep dish cover bolted to the front of the axle housing and a 9-5/8" diameter third member in it, so the presence or absence of bolts on the axle housing front cover is not a sure-fire way of identifying the ring gear diameter in the third member (which you call a "Diff" and I call a "third member"). A more direct way to identify the ring gear diameter in the third member it to look at the third member itself.

A third member with a 8-3/4 ring gear uses 2 tapered roller bearings to hold the drive pinon in place. Its case above the drive pinon oil seal is round and smooth, with no protrusions.

A third member with a 9-5/8 ring gear uses three tapered roller bearings. To hold the third bearing in place in place there is a small set screw on the top of its round case just above and very slightly (1" or so) aft of the oil seal for the drive pinon. This small set screw protrudes from the top of the third member case and can be felt there with your finger. [This area is the top of the round (tubular) area on the third member case just behind the U joint from the front drive shaft, before the ribs on the case begin to expand towards its large round base that bolts into the front axle housing].

If your "Diff" is smooth above the drive pinon oil seal, you have a 8-3/4 ring gear third member. If there is a small set screw on your "Diff" above the drive pinon oil seal, you have a 9-5/8" diameter third member. Hope this helps.

[Kaegi]

welded cover is 9 5/8"