Differential overhaul
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- Minor Legend
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Re: Differential overhaul
I doubt if it would last until Christmas. The same thing will happen again.
Regards
Declan
Regards
Declan
Regards
Declan
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- Minor Maniac
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Re: Differential overhaul
I am of the same opinion as Declan - leaving as it is and rebuilding is not the answer.
To get over the problem I would suggest filling the wear groove/lip with bronze weld and then grinding and lapping the carrier and washer together, you can then using an oversize thrust washer. It is going to take a bit of graft to get it back to a useable condition but it will be worth it and think of all that money you will have saved.
Finding a welder may be an easier option than finding a capable machinist.
To get over the problem I would suggest filling the wear groove/lip with bronze weld and then grinding and lapping the carrier and washer together, you can then using an oversize thrust washer. It is going to take a bit of graft to get it back to a useable condition but it will be worth it and think of all that money you will have saved.
Finding a welder may be an easier option than finding a capable machinist.
- ndevans
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Re: Differential overhaul
I did wonder whether it would be possible to fill the wear grove with weld! But surely I'd still need a machinist to clean up and smooth the weld?
Cheers N
Cheers N
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- Minor Maniac
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Re: Differential overhaul
If you are careful you can clean up the weld yourself with a burr/grindstone. Get the welder to only put as much weld to the wear as necessary. No need for overkill.
This will test your fitting skills
This will test your fitting skills
- ndevans
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Re: Differential overhaul
Ha ha, that it will!
I haven't seen any dimensions or clearances for the sun/planet wheels. Do you know of any? For example, what should be the distance between the thrust washer surfaces on either side of the cage? What free play, if any, should the planet wheels have?
Cheers N
I haven't seen any dimensions or clearances for the sun/planet wheels. Do you know of any? For example, what should be the distance between the thrust washer surfaces on either side of the cage? What free play, if any, should the planet wheels have?
Cheers N
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- Minor Maniac
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Re: Differential overhaul
The Marina diff which is very similar to the Minor states ZERO (in capitals) backlash (no play). The manual also states 'at ZERO backlash it will be tight - lubricate before assembly'.
Therefore to answer your question I would go for ZERO backlash.
The Marina/Ital workshop manuals give far more detail than the Morris Minor workshop manual for both the 1098cc and 1275cc engines.
It also goes into far more detail on setting the axle diff and how to do the job.
It also gives additional torque settings that are missing from the Minor wksp manual.
The Marina/Ital factory workshop manual is a valuable addition to the repair & how to do it owners library.
I would not be without mine.
https://www.ebay.co.uk/itm/Genuine-Aust ... SwmTddQrM2
Therefore to answer your question I would go for ZERO backlash.
The Marina/Ital workshop manuals give far more detail than the Morris Minor workshop manual for both the 1098cc and 1275cc engines.
It also goes into far more detail on setting the axle diff and how to do the job.
It also gives additional torque settings that are missing from the Minor wksp manual.
The Marina/Ital factory workshop manual is a valuable addition to the repair & how to do it owners library.
I would not be without mine.
https://www.ebay.co.uk/itm/Genuine-Aust ... SwmTddQrM2
- ndevans
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Re: Differential overhaul
Ok, here's the plan.
I'm going to chat to my local friendly machine shop, who re-bored my engine. I'll take the diff carrier and planet wheels down there, and explain in person what I want.
I'm going to ask him to machine or grind out the ridge around the centre hole, and the outer step, to the same level as the worn portion. I'm going to ask him to machine/grind it slightly larger than the diameter of the thrust washer.
I'm then going to ask him to clean up and smooth off the other end of the cage, and measure as accurately as possible the distance between the planet wheel centres along the shaft, and the distance from each side to the centre line. I'll also ask him to measure the depth of the machined area.
I'll then use oversize thrust washers and some valve grinding paste to lap then in and make them fit.
Does this sound a plan that will work?
Does anyone know what the distance between the back faces of the two planet wheels should be?
Cheers N
I'm going to chat to my local friendly machine shop, who re-bored my engine. I'll take the diff carrier and planet wheels down there, and explain in person what I want.
I'm going to ask him to machine or grind out the ridge around the centre hole, and the outer step, to the same level as the worn portion. I'm going to ask him to machine/grind it slightly larger than the diameter of the thrust washer.
I'm then going to ask him to clean up and smooth off the other end of the cage, and measure as accurately as possible the distance between the planet wheel centres along the shaft, and the distance from each side to the centre line. I'll also ask him to measure the depth of the machined area.
I'll then use oversize thrust washers and some valve grinding paste to lap then in and make them fit.
Does this sound a plan that will work?
Does anyone know what the distance between the back faces of the two planet wheels should be?
Cheers N
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- Minor Addict
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Re: Differential overhaul
Sorry I cannot help with dimensions, but as a machinist I would expect that job to end up quite expensive.
Machining a concave surface is difficult enough without it being on the inside face and difficult to get at, as Phil mentioned earlier it will require some special tooling to do that, and they probably will not have any without making it specially for this job.
Unless they are working at "mates rates" and it comes out very cheap, I would think your best option is to obtain another second hand diff or at least parts you need.
There is no shortage on ebay ( but no guarantee they will be any better either ).
https://www.ebay.co.uk/itm/AUSTIN-A30-A ... SwAGxdiIgl
https://www.ebay.co.uk/itm/Morris-Minor ... SwhEVdjiQs
Dont you already have a spare diff ?
I thought you had a 3.9 that you were rebuilding to replace the one from your car, maybe you could build one good one from the two.
I have not really been keeping up with the story, so am not sure which one you are working on.
Phil
Machining a concave surface is difficult enough without it being on the inside face and difficult to get at, as Phil mentioned earlier it will require some special tooling to do that, and they probably will not have any without making it specially for this job.
Unless they are working at "mates rates" and it comes out very cheap, I would think your best option is to obtain another second hand diff or at least parts you need.
There is no shortage on ebay ( but no guarantee they will be any better either ).
https://www.ebay.co.uk/itm/AUSTIN-A30-A ... SwAGxdiIgl
https://www.ebay.co.uk/itm/Morris-Minor ... SwhEVdjiQs
Dont you already have a spare diff ?
I thought you had a 3.9 that you were rebuilding to replace the one from your car, maybe you could build one good one from the two.
I have not really been keeping up with the story, so am not sure which one you are working on.
Phil
- ndevans
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Re: Differential overhaul
The diff I am working on is my spare, it's a 3.9:1. The 4.22:1 on the car is worn, and has probably had no attention since it was built, other than oil changes. I don't expect it to be much better when it gets stripped.
Cheers N
Cheers N
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- Minor Fan
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Re: Differential overhaul
I would have thought that the planet gear would revolve but the carrier and thrust would remain static. The fit would be more important than the grove as the two surfaces should not be moving much.
- ndevans
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Re: Differential overhaul
Having ummed and ahhed about it over the weekend, I decided tonight to get the diff cage on my 4.22:1 apart. I was worried that it'd be as bad, if not worse, than the 3.9, but happily it appears not! The planet wheels had about 2mm lateral play along the shaft, which didn't bode well, and I was expecting a non-existent thrust washer on one end.
There is wear in the thrust washer seats, but nowhere near as bad as the 3.9, and not as bad as it looks. The wear is hardly noticeable when I run my finger over it. The shaft is worn, much like on the 3.9. The bearings are a bit more worn than on the 3.9, but I'm loathe to pull them off and replace, as I don't have the special tool and gauge block that goes with it.
The only other thing is that the sun wheels don't have the fibre washer under them that the ones on the 3.9 do. I wonder if that would account for some of the play of the planet wheels along the shaft?
So my current thoughts are that I'm better off replacing the shaft and thrust washers, and oil seal, on the 4.22, putting it back on the car, and carrying on with it until I've either sorted the 3.9, or sourced one with a good diff cage.
Cheers N
There is wear in the thrust washer seats, but nowhere near as bad as the 3.9, and not as bad as it looks. The wear is hardly noticeable when I run my finger over it. The shaft is worn, much like on the 3.9. The bearings are a bit more worn than on the 3.9, but I'm loathe to pull them off and replace, as I don't have the special tool and gauge block that goes with it.
The only other thing is that the sun wheels don't have the fibre washer under them that the ones on the 3.9 do. I wonder if that would account for some of the play of the planet wheels along the shaft?
So my current thoughts are that I'm better off replacing the shaft and thrust washers, and oil seal, on the 4.22, putting it back on the car, and carrying on with it until I've either sorted the 3.9, or sourced one with a good diff cage.
Cheers N
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- Minor Addict
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Re: Differential overhaul
When you took the 4.22 apart was it evident where all the prop shaft free play was coming from shown in your original video ?
Was it purely due to the 2mm lateral movement of the planet wheels ?
Can you not build your 3.9 up using the good cage from the 4.22 ?
Phil
Was it purely due to the 2mm lateral movement of the planet wheels ?
Can you not build your 3.9 up using the good cage from the 4.22 ?
Phil
- ndevans
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Re: Differential overhaul
Not sure, might just be wear between the pinion & crown wheel. The splines on the sun wheels, which are what the half shafts locate in, look ok. Some of the play might be the wheel bearings, which were loose in the hubs.
Unfortunately, the diff cage on the 4.22 is an ATA type, on the 3.9 it's a BTA. Not sure what the difference is, but apparently they are not interchangeable.
Unfortunately, the diff cage on the 4.22 is an ATA type, on the 3.9 it's a BTA. Not sure what the difference is, but apparently they are not interchangeable.
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- Minor Addict
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Re: Differential overhaul
My understanding is that the cage is stronger (thicker construction?) but that doesn't necessarily mean that they are not interchangeable. Does anyone on here know?Not sure what the difference is
Don
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- Minor Maniac
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Re: Differential overhaul
As I have previously stated the ATA and BTA carriers are not interchangeable. There are differences in the carrier that do not allow the interchange.
To confirm the above statement I have just looked at various MG/Sprite articles/publications regarding the interchangeability of the differential parts and all state that the carrier is not interchangeable between ATA and BTA units. They also state that problems arise with the interchangeability of pinion, pinion bearings and spacer.
To confirm the above statement I have just looked at various MG/Sprite articles/publications regarding the interchangeability of the differential parts and all state that the carrier is not interchangeable between ATA and BTA units. They also state that problems arise with the interchangeability of pinion, pinion bearings and spacer.
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Re: Differential overhaul
OoopsAs I have previously stated...
Sorry Phil. I didn't remember reading that. But then I can't remember what I had for breakfast.
D
- ndevans
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Re: Differential overhaul
Are the sun and planet wheels interchangeable? They look it, and the ones off the 3.9 are in better nick.
Cheers N
Cheers N
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- Minor Maniac
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Re: Differential overhaul
According to the Moss web site they are interchangeable as they have the same part numbers for both the 1275cc and 1098cc axles.
Sun Wheel Pt No: ATA7037
Planet gear Pt No: 2A7037
Sun Wheel Pt No: ATA7037
Planet gear Pt No: 2A7037
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- Minor Addict
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Re: Differential overhaul
Phil
Just for future reference, would you clarify the significance of the ATA and BTA designations please.
I have not come across this before and would like to know how to recognise the difference when looking at spare diffs.
Thanks
Phil
Just for future reference, would you clarify the significance of the ATA and BTA designations please.
I have not come across this before and would like to know how to recognise the difference when looking at spare diffs.
Thanks
Phil
- ndevans
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Re: Differential overhaul
It'll be stamped ATA or BTA on the rim of the crown wheel. I think the outer casings are all ATA, but the cage & crown wheel assembly is either ATA or BTA.
I think, but not positive, that the BTA carrier was fitted to Midgets and Wolseleys.
Cheers N
I think, but not positive, that the BTA carrier was fitted to Midgets and Wolseleys.
Cheers N