Grey Gearbox

[Ken's 57]

With my FE now running well I’ve turned my attention to the FJ. Motor and box almost ready to go back into the car.
I note that FJ boxes are fitted with a bronze bush in the rear extension housing and the FJ workshop manual states that an acceptable clearance between propellor shaft yoke and bushing is between 0.002” - 0.004”. As I only had my FE manual with me down in the shed later on that day, I opened it up at the exploded view of the gearbox and low and behold...no bushing in the diagram. According to the Master Parts Catalogue it was only used in the 48 and 50’s and some FJ’s. To remove the bush requires a couple of specialised tools and I’m assuming I’ll have to get bush and tools machined up somewhere. Questions... why was the bush deleted from the extension housing? Should I leave the old bush in situ (which has a clearance of around 0.022”) because it was found to be unnecessary? Also, I found the inside of the bell housing coated in sticky old oil which required a stiff brush and petrol to remove it. It seemed too thick for engine oil but it did not have the distinctive smell of gear oil. The rear main was definitely leaking so I’d appreciate suggestions as to likely causes. Lastly, one of the retainer plugs in the housing has a hole below it with a small ball evident. Why? Thanks for any suggestions or opinions.
Cheers, Ken 

[ardiesse]

Ken,

48s and early FJs were fitted with a welded steel rear extension housing. In this type of housing, the bush for the driveshaft yoke is a two-piece assembly, with a bronze insert pressed into a steel carrier.  The bushing assembly was available as a service item (and I've still got a couple).  This kind of rear extension housing was superseded by a cast aluminium rear extension housing with an inserted bronze bush, which is what you have.  In this type of rear extension housing, when the bush wore out, you were supposed to replace the entire rear extension housing.  Bit of a problem for service.  Holden later relented and made the bronze bush available as a separate item ("Liner").

You say you've got 22 thou clearance?  Most of that will probably be wear in the driveshaft yoke.  Measure its outside diameter right down the back end, just before the shoulder for the uni-joint.

Replacing the rear extension housing bushing will require a drift to be machined up, and then you'll have to get the new bush reamed to size, parallel with the mainshaft.  But replacing the bush will only make sense if you have a new driveshaft yoke to go with it.  I've sometimes wondered if a hard-chroming or metal-spraying shop can recondition the front yoke.

Retainer plug with a hole and small ball?  Did you use a 3/8" Allen key to unscrew the plug?  That would have been one of the gearshift detent balls.  Its job is to hold the gearbox in gear.  But there should have been a coil spring between plug and ball.

Rob

[Rip]

G'day Rob
Looking at the picture of the bell housing I think the ball that Ken is referring to is the ball in the end of the cluster gear shaft which prevents the shaft from turning in the gearbox housing.
Cheers Rip

[Ken's 57]

Thanks so much for the reply Rob. Unfortunately I only have a 0-1 micrometer but using verniers on the yoke I’m consistently getting 1.375”. Measuring the inside of the bush is a little more problematic as I had to make do with a telescopic gauge which I then measure with my verniers. I’m getting around 20 - 22 thou more. My main concern is that a worn bush may put more pressure on the functioning of the seal thus causing oil to leak from the back of the extension housing.....again  . It’s interesting to note that the parts catalogue gives cut-off serial numbers for the deletion of the bushing during the FJ series. Mine is a March 56 build still with original engine, #261443, and the box number begins with #262... so I’m pretty sure it’s the original box as well.

Re the ball question. If you look at the photo of the bell housing, the welch plug(?) at the bottom of the picture has a small hole with the ball blocking it off. Just confused as to its purpose.
Cheers, Ken.

[ardiesse]

Ken,

So your driveshaft yoke's not worn that much.  Given it's 1-3/8" OD, the rear extension housing bushing is likely to be a standard size, available from a bearing supply place.

Oh, and Rip (post above) identified the ball.

Rob

[Ken's 57]

Thanks Rip and Rob 

[geebeefc]

The thick oil in the bell housing could be engine oil that is contaminated with dust from the clutch plate linings over a long time. Or the same result from gearbox oil and clutch dust.
Cheers, Glenn

[Ken's 57]

Thanks Glenn. A plausible explanation for it possibly being engine oil. I hope you’re right. If it’s gear box oil it should have had that distinctive smell and more worryingly, where did it leak from?   

[ardiesse]

Gear oil can leak into the bellhousing from at least three places: the cluster gear shaft, the welch plug for the reverse idler gear shaft, and the input shaft.  Holdens don't have a seal on the input shaft, so if you park the car on a steep enough downhill slope, gear oil will leak out the throwout bearing tube.

Rob

[Ken's 57]

Thanks Rob.