FE Holden gearbox extension housings

[DougT]

I have two crash boxes both FE going by the numbers, L293376 and L409584, but with different rear extension housings. One has four short webs at 90 degrees to each other, the other has only two long webs one on either side extending the full length of the housing and a metal guard over the seal boss. Both housings have the same part number, 7408348. My question is, did boxes fitted to commercial vehicles get a different extension housing or did the housings change at some point i.e. FJ to FE?

[mcl1959]

The housings changed - I think the early ones have the metal shield. I’ll see what I can find in the parts book sure dates.

Ken

[mcl1959]

According to parts book, in early FJ the rear bush was changed, this is probably when the casting changed and the shield was deleted. The earliest part book I have is FE and the metal shield is not listed as a separate part.

[weddo]

Just my two bobs worth Ken. I use the short ribbed ones in my FC race car, as I think they have a little more metal at the "bolted" end that I need. I turn the inside of the housing out to accept a support tube between the back of the rear race and the support in the housing.
Cheers Bill.

[Harv]

Three types of extension housing were manufactured for grey motor crashboxes. The first type, fitted to FX and some FJ Holdens is made from mild steel flanges and tubes which are welded together. The steel construction was replaced during the FJ production run as all cast alloy extension housing, which was used for all later models. The cast housing had two versions, one with short strengthening ribs, and one with longer strengthening ribs (see image below).




The Master Parts Catalogue (20 Years of Holden Production) lists the part number for extension housings assemblies for FX-EK Holden as 7408347. This assembly is the housing and bushings made up with the alloy casting. The alloy extension housings have either 7408348 cast into them (again one number higher than the parts list as this is a casting, not an assembly), or just plain “HOLDEN” and no part number. The dimensions (overall length, bushing length and diameter, bolt location, locating flange lip diameter) are identical, through the mild steel unit is 3/16” longer due to the use of an extra shroud at the rear of the extension (looks much bigger in the photograph above). A lip seal is press fitted into the rear of the extension and seals up against the main drive shaft as it exits the gearbox. The two units, including the seals, are fully interchangeable.

Cheers,
Harv

[mcl1959]

That’s great information Harv, do you have any idea when the aluminium versions changed and which one was first.

Ken

[DougT]

Thanks for the info, from Harv's photo the housing on the left (two long webs) is the type I have with the metal (tin) guard mounted on the larger rear boss. My example of this housing came from a box with serial number L409584 and a casting date of L 47 ( 04 Nov 57) and in addition to the cast part number and  HOLDEN the number 21. My other housing (centre housing in photo) came from a box with serial number L293376 and a casting date of H 38 (I assume from the early in the run serial number to be 03 Aug 48) with the additional cast number of 92. My questions are, do the additional numbers indicate different manufacturing locations or just different molds and could the housings have been used in different assembly plants or on different models i.e. utes and panelvans?

Doug

[ardiesse]

Ken,

The "two-long-rib" aluminium rear extension housing came first, and the "four-short-rib" rear extension housing would have arrived, I'm guessing, at about FB time.

Rob

[ardiesse]

The date code H38 is 1958.  A 1948 build gearbox would be rocking-horse-poo rare, would have a serial number in only four digits and no letter prefix, would have the extra ribs on the side of the bellhousing, and would have the welded steel rear extension housing.

Most gearboxes would have been rebuilt by now, and the rebuilder would have played mix-and-match with parts.  You'd be best off comparing the date code on the gearbox cases with those on the rear extension housings.

Rob

[ardiesse]

L293376 is only about ten thousand more than the end of FJ sedan production, so H38 would be H36: August 1956.

Rob

[DougT]

I have had another look at the date casting and agree it is more likely H36. Thanks for all the feedback, so when I re-build the box for my 57 FE I will use the two long rib extension. Can anyone suggest where I can get my hands on a set of new thrust washers?

Doug

[ardiesse]

Would these be the ones for the cluster gear and reverse idler gear?

What I have done in the past is to select the least worn two and use them with the cluster gear (if the shafts are the same diameter), but I've never yet had a gearbox where the cluster gear end float is less than double the maximum specification.

Track down a double-row mainshaft bearing if you can.  I've heard that a Mitsubishi Express uses the same bearing, but you need to get the groove machined in the outer race.

Rob

[DougT]

Thanks Rob, yes to the question both sets were worn beyond spec. I was thinking of making up some shims to put in behind the washers if I can't get new ones.

Thanks again.

Doug