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Diff rebuild


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After finally getting everything rite with the engine, gearbox and brakes I took it for a good drive today to pick up a few bits and pieces just to get some miles up on the old girl. 20 minutes into my drive I’m thinking the rear end is a little noisy and in need of adjustment. Obviously been concentrating on everything else other than the diff. A few minutes from home things got real bad I couldn’t accelerate or back off without thinking the gearbox was coming through the floor. 

Got her home ok and put it on the hoist and pulled the axles and diff out and found one of the tail shaft bearings had collapsed. 

Completely my own fault because the diff was so low on oil, I neglected to check it with everything else going on. Since I’ve bought the car I’ve probably only put 20km on it test driving it around my streets so today was it’s longes drive since I’ve had it. 

I neglected to check it because it was so clean and dry around it as if it had no leaks so pretty stupid of me not to at least check the level. I now know why it was so clean and dry looking. It had about a 100ml of oil in it. 

Lucky I have a spare diff that came with the wooden spoke wheels I got for it so I’ll make a good one out of the 2 with no trouble. With all new bearings in it she should be good again. 

At least it’s all done front to back now and it gets you familiar with it all. Lol

 

 

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There’s a bit of a knack to getting them set up right too.  I think mines probably a bit different from yours but the process is pretty similar.  Bob talked me through how to do it on mine and I think i May have put notes on my aaca build page but if not I can dig through my notes.  Hopefully your gear set is ok as trying to mix and match worn gears isn’t easy.

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1 minute ago, RichBad said:

There’s a bit of a knack to getting them set up right too.  I think mines probably a bit different from yours but the process is pretty similar.  Bob talked me through how to do it on mine and I think i May have put notes on my aaca build page but if not I can dig through my notes.  Hopefully your gear set is ok as trying to mix and match worn gears isn’t easy.

Yer mate I spoke to Bob today and he’s going to help me through the set up. The complete spare one I have looks good at first glance so I’ll probably put the whole thing into the housing in the car now. Going to pull it all to bits and clean it up, been sitting for a while. 

The engine has turned out really nice. 

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I can't see clearly from your posted photos how the crown wheel attaches to the carrier. In the Dodge Brothers Eight, locking tabs under pairs of bolts are bent up against a flat on the bolt head. Mine broke the head off one of those bolts one day while creeping gently over a nasty speed bump. I discovered that all the lock tabs were bent up in place but every single bolt was loose. The book calls them "axle drive gear screw" and "axle drive gear screw lock".

 

I replaced all those bolts with Unbrako cap screws (i.e. high strength) and drilled and wired them in pairs. Basically, look very carefully at those locking tabs and if dodgy, replace them! Also, look carefully at how they prevent the bolts undoing and set them up so they actually do that.

 

The instructions for setting it up are in my Instruction Book. Probably in yours too.

Edited by Spinneyhill (see edit history)
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Pictures of my rebuild here - few notes but if you talk to Bob should be all good 

first important step I remember was getting the pinion and diff carrier pre load set on the bearings.  Next step was setting the gear mesh correctly which was a combination of pinion in/out adjustment and carrier left/right adjustment - bluing the gears each time (this step took me ages).  Then the last adjustment was done after installing diff in axle to set the play/clearance between the two half shafts.

 

i changed my seals to modern ones at the same time - probably not necessary but means I don’t have to think about them again.

 

 

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1 minute ago, RichBad said:

i changed my seals to modern ones at the same time - probably not necessary but means I don’t have to think about them again.

Maybe not quite. If you have used lip seals, without a housing breather oil will come past the seals due to heating and cooling of the air inside the housing. It has to go somewhere!

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Still trying to get the propeller shaft bearing carrier out. It’s not letting go easily. 

I’ve removed the one out of my spare diff but this one is hanging on to 92 years of stuck. Lol

Had to make a tool to go on the 3/4 drive rattle gun to even get it to budge a little back and forth. 

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2 hours ago, Spinneyhill said:

Maybe not quite. If you have used lip seals, without a housing breather oil will come past the seals due to heating and cooling of the air inside the housing. It has to go somewhere!

Lucky I added a breather then:)

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Taken almost all day to get the pinion gear off and bearing carrier out. Man it was stuck in there. A lot of heat and 2000 taps with a ball pein hammer and the 3/4 drive rattle gun slowly got it out. 

Lucky I have a spare. 

All my new bearings will be in tomorrow so I can attempt to reassemble it with a bit of luck. 

Has anyone ever attempted to straighten their prop shaft or do we have to live with them like they are. Both the ones I have seem to be a little bent in the middle. I’m going to attempt to straighten the worst of the 2 and see what happens. 

 

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The bearing carrier for the propeller shaft has given me more grief than I wish to mention. Once it starts to go into the thread it gets to tight to adjust through the side cage section. I’ve cleaned it inside and out many times and finally got it in this afternoon without the bearings and prop shaft. It’s still a little tight but can be adjusted through the side.  So tomorrow I’ll fit it up properly once I pick up my other carrier bearings. 

The bearings for the diff are very expensive so if you come across any grab them. For all 6 of them it’s close to $900. They are getting pretty scarce apparently. 

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I’ve got some thread files if they are any help?

 

lots of bearings aren’t there!  I think most of mine weren’t too bad except for the rear outer bearings.  They were crazy! I think it’s because of the taper bore.

 

they’ll be good for another 90 years!

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24 minutes ago, RichBad said:

I’ve got some thread files if they are any help?

 

lots of bearings aren’t there!  I think most of mine weren’t too bad except for the rear outer bearings.  They were crazy! I think it’s because of the taper bore.

 

they’ll be good for another 90 years!

Yer mate ridiculously expensive. I was actually looking for my old thread file but couldn’t find it. Lost or lent haha. I have actually milled a 6mm grove across the treads in 3 spots and left the sharp edge on the cut and I think that’s what has cleaned it up enough to allow it to go in all the way. It’s the only thing that has allowed me to screw it all the way in. The male thread is pretty clean I think it’s the inside that’s given me the grief. I think a thread file would be a good investment in these old girls anyway wouldn’t it. If I can’t pick one up easy enough I might grab it off you thanks Rich. 

Yer I think it helps if there’s oil actually in the diff. Lol. I picked up some Penrite 250T for it yesterday. 

I just have to get that carrier moving freely enough so I can adjust it easily. It was so tight to get out. Probably the hardest thing I’ve ever had to remove without creating any damage to it. 

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After the mammoth job of getting the prop shaft bearing carrier back In freely it’s all back together and running, sounding and feeling great. It all went back together great except for the carrier. I took about a 6mm bend out of the prop shaft and that also has eliminated a lot of vibration. Sits on 70-75km  perfectly. 

After the first run down the road I had oil poring out of the brake arms everywhere. I wrapped them in felt and put a zip tie around them and fitted a breather in the top of the diff the same as Richard did. No leaks at all now. Must of had to come out the easiest path after I put new felt seals in the axles. I didn’t realise there was small holes behind them all.  

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1 minute ago, 2251DB said:

Hi Matt I usually seal the small with weld and lubricate the shafts when servicing the car

2251DB

To be honest I think I would of done the same if I knew about the little buggers. When I saw the oil coming out I had a look in the other diff housing and saw them. 

I’ll see how my little felt bandaids go and if they leak I’ll end up pulling it out again and weld them up. 

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