64 replies to this topic

[Ethel]

All A+ Boxes/transfer cases had the larger bearings, so your 1990 will.

Yes you need to check the end float of both the primary and idler, different size thrusts are available for both. Key to getting the idler correct is using the orange gasket, these are the correct thickness. the only way to measure the float on the idler is to dry assemble the transfer case on the gearbox with no engine attached. when checking, us the gasket you are going to use.

You can assemble without the gasket, and allow for its compressed thickness in your calculations (4thou?), the gasket should really be replaced if you take it apart again, so buy at least 2 of the same type.

[Spider]

Yes, an old thread for sure, but just having read through this and in particular, the thread on the Turbo-Mini forum, quite interesting for sure to see what others hove found as issues (noting the Primary Gear Bushes getting a fair mention) and what they have done to try to improve on this issue.

 

I feel a large part of the under-lying issue that was touched on but not explored is the alignment between the Transfer Housing and the Gearbox cases. I've now measured loads of these and found none to be in what I would call, good alignment with most being way out.

 

The other part of the issue I see (that was discussed) is the hard Thrust Washers running against the Alloy of the Housings and this is exasperated with the mis-alignement issue, as this will increase spot loadings. Hard to say if the Thrust spin against the gear or against the case. Evidence from the cases and gears suggest that the washer spins against the case. As these spin up, with high spot loadings, the Oil Film gives way and the soft ally picks up on the hard thrust. Once that happens, it's all just a case of how fast the washer can eat it's way through the cases.

 

I feel that unless the mis-alignment is addressed, then nothing will give good life to the Idler Bearings and Thrusts, not even pressure feeding them with Oil. Once aligned, and without additional lubrication, for most applications the standard set up isn't too bad, however, with the A+ Gears, the Thrust Surface area is pretty small and in this regards the earlier gears fared better, but the needle rollers didn't last too well as they are a smaller set up. It's catch 22 here.

 

My own solution, after first aligning the housings is to go to a Tapered Roller Bearing set up. It has been suggested here and elsewhere a few times and sound simple, however, I assure you it is far from that. There is no off the shelf bearing that fits and has the required ratings. While it may seem odd to align the housings with the arrangement, I do so to square up the Idler Gear to it's brothers and also to obtain alignment for the Outrigger Bearing on the 1st Motion Shaft.

 

 

[Wiggy]

Out of interest, when you mention the alignment; do you mean the location of the dowels being correct, or do you mean the opposing bearings being aligned?

Or both?

What I'm trying to say is that if the dowels weren't correct in relation to each other, you'd struggle to get the transfer case on and the misalignment would be obvious.

On the other hand, if the dowels were in the wrong location, but correct in relation to themselves, getting the transfer case on would be OK, but the opposing bearings wouldn't be aligned properly.

Do you know what I mean?

[scoop-deluxe]

I was always told that the gearbox case was matched with a diff case and flywheel housing from the factory. All machining was line bored etc..

Nice work on the gear there Moke, I imagine that it wasn't easy. Is it a modified original idler gear?

Edited by scoop-deluxe, 12 December 2018 - 11:28 PM.

[DeadSquare]

I was always told that the gearbox case was matched with a diff case and flywheel housing from the factory. All machining was line bored etc..

Nice work on the gear there Moke, I imagine the wasn't easy. Is it a modified original idler gear?

 

The early (not sure until what date) transfer housings were clamped to the gearbox, the dowel holes were machined, the dowels were fitted and then both parts were transferred to another machine to be bored.

 

New tooling positioned the dowels accurately enough for transfer housings and gearboxes to be interchanged, so I am surprised that Moke found poor alignment.

 

As far as I know, diff housings and gearboxes were machined as matched pairs.

[Spider]

It did take me about a year to nut this out. Not much to show for that!

 

 

Out of interest, when you mention the alignment; do you mean the location of the dowels being correct, or do you mean the opposing bearings being aligned?

Or both?

What I'm trying to say is that if the dowels weren't correct in relation to each other, you'd struggle to get the transfer case on and the misalignment would be obvious.

On the other hand, if the dowels were in the wrong location, but correct in relation to themselves, getting the transfer case on would be OK, but the opposing bearings wouldn't be aligned properly.

Do you know what I mean?

 

Yeap, gotya Wiggy.

 

I really can't say which is out, the Dowels or the Bearing Tunnels from manufacture.

 

When I make something here from scratch that needs dowels, I dowel it first, then do all the other machining operations. I don't know how it was done in the factory, I would think the same way but ????

 

To correct for the misalignment, I start by taking the Dowels out, then fitting some dummy shafts;-

 

 

Then mount and clock up the Dowel Holes in the Gearbox Case in the Mill

 

 

Then fit the Transfer Case and check (though I don't waste my time checking now)

 

 

These Dowels are stepped, with the bigger side (7/16" dia) in the Gearbox Case. So once I have the Transfer Case fitted, I bore through the original Holes in the Transfer case (which were 3/8") and line them up to the Gearbox Case straight through at 7/16".

 

Then I know the alignment of theses - as a a pair - is spot on.

 

 

 

I was always told that the gearbox case was matched with a diff case and flywheel housing from the factory. All machining was line bored etc..

Nice work on the gear there Moke, I imagine the wasn't easy. Is it a modified original idler gear?

 

I've commented below on the first part here and yes, I've modified the original Idler Gear.

 

In fact, the whole set up, apart from the Idler Gear is 100% reversible, though, after running with one of these, I don't know why'd you'd want to.

 

 

 

I was always told that the gearbox case was matched with a diff case and flywheel housing from the factory. All machining was line bored etc..

Nice work on the gear there Moke, I imagine the wasn't easy. Is it a modified original idler gear?

 

The early (not sure until what date) transfer housings were clamped to the gearbox, the dowel holes were machined, the dowels were fitted and then both parts were transferred to another machine to be bored.

 

New tooling positioned the dowels accurately enough for transfer housings and gearboxes to be interchanged, so I am surprised that Moke found poor alignment.

 

As far as I know, diff housings and gearboxes were machined as matched pairs.

 

 

I'm actually quite sure the Transfer Housings are not matched in the factory.

 

Apart from what is evident from the Bearing and Thrust issue, the Transfer Housing was always sold as a spare part on it's own from the Gearbox Case. Each of these have their own part number. But say in the case of a Diff cap, as these were matched to the Case, they were not sold separate and when a new Gearbox Case was purchased, they always came with a Cap.

[Turbo Phil]

That’s dedication right there.

Phil.

[Retroman]

Seriously well done Spider some very good ideas and top engineering....wish you were in the UK

 

I have suspected for years that it must be a misalignment issue as wear indcates things not being 100% square

 

This 'wear' even happens in unmolested standard cars, not driven hard

 

Is there any reason why the gearbox side thrust washer cannot be fixed to the casing ?

 

Never done it, and not sure it has been done ?

 

It would mean two hard surfaces running together rather than alloy casing and hard thrust

 

Not sure if it would work what do you guys think ?

[Wiggy]

I just assumed that it was the helical nature of the gears with a poor choice of bearing types. I don't think the non axial load of the idler is catered for with needle roller bearings.

But I'm no engineering buff like some here.

[grizzler73]

I for one would love to see a step by step of what you do regarding the taper bearings and aligning the casings Moke. I am thinking I might try something on my race engine.

[Ethel]

Minimania/Minispares were flogging helicals with a bearing, same as the straight cut ones, at one point. Can't find them on their sites now.

 

Shame, it would seem more cost effective for all applications to make a better idler rather than a full set of trick tranny gears, even if you're not bothered about the noise.

[Spider]

Seriously well done Spider some very good ideas and top engineering....wish you were in the UK

 

I have suspected for years that it must be a misalignment issue as wear indcates things not being 100% square

 

This 'wear' even happens in unmolested standard cars, not driven hard

 

Is there any reason why the gearbox side thrust washer cannot be fixed to the casing ?

 

Never done it, and not sure it has been done ?

 

It would mean two hard surfaces running together rather than alloy casing and hard thrust

 

Not sure if it would work what do you guys think ?

 

Thanks for the kind comment    Yes, sometimes I wish I was in the UK, but I'd miss our Outback too much.

 

I think many of us have seen the Idler Gear in Old Mrs's Jones 's Mini let go for no obvious reason. I suspect this may have something to do with it in many cases.

 

I did look at fixing thrusts of some sort, the Gearbox side is easy enough, but the Transfer Housing side, well, I couldn't see a sensible way to do it, there's so little meat over there, but yes, I agree, for most suburban cars, this would the the way forward, but only if the cases had some reasonable alignment.

 

If they are out a bit, this is what you'll see

 

 

and so the Idler Bearings won't last too well, let alone the whine from the drop gears being so far out of kilter with each other.

 

Another 'thing' I've noticed with all the gearbox shaftings, including the Idler gear is that they are seriously undersized for the bearings, not under-sized in regards to ratings, but 'tolerances' or 'fits', with most being 0.002 to 0.005" undersize. This really does load up the shafts and the bearings as all the loadings are on a thin line rather than 1/3 the way around the shaft and bearing. I'm not sure if this was done to be sure everything fitted easy enough or for added clearances since the oil is shared with the engine.

[DeadSquare]

It did take me about a year to nut this out. Not much to show for that!

 

 

Out of interest, when you mention the alignment; do you mean the location of the dowels being correct, or do you mean the opposing bearings being aligned?

Or both?

What I'm trying to say is that if the dowels weren't correct in relation to each other, you'd struggle to get the transfer case on and the misalignment would be obvious.

On the other hand, if the dowels were in the wrong location, but correct in relation to themselves, getting the transfer case on would be OK, but the opposing bearings wouldn't be aligned properly.

Do you know what I mean?

 

Yeap, gotya Wiggy.

 

I really can't say which is out, the Dowels or the Bearing Tunnels from manufacture.

 

When I make something here from scratch that needs dowels, I dowel it first, then do all the other machining operations. I don't know how it was done in the factory, I would think the same way but ????

 

To correct for the misalignment, I start by taking the Dowels out, then fitting some dummy shafts;-

 

 

Then mount and clock up the Dowel Holes in the Gearbox Case in the Mill

 

 

Then fit the Transfer Case and check (though I don't waste my time checking now)

 

 

These Dowels are stepped, with the bigger side (7/16" dia) in the Gearbox Case. So once I have the Transfer Case fitted, I bore through the original Holes in the Transfer case (which were 3/8") and line them up to the Gearbox Case straight through at 7/16".

 

Then I know the alignment of theses - as a a pair - is spot on.

 

 

 

I was always told that the gearbox case was matched with a diff case and flywheel housing from the factory. All machining was line bored etc..

Nice work on the gear there Moke, I imagine the wasn't easy. Is it a modified original idler gear?

 

I've commented below on the first part here and yes, I've modified the original Idler Gear.

 

In fact, the whole set up, apart from the Idler Gear is 100% reversible, though, after running with one of these, I don't know why'd you'd want to.

 

 

 

I was always told that the gearbox case was matched with a diff case and flywheel housing from the factory. All machining was line bored etc..

Nice work on the gear there Moke, I imagine the wasn't easy. Is it a modified original idler gear?

 

The early (not sure until what date) transfer housings were clamped to the gearbox, the dowel holes were machined, the dowels were fitted and then both parts were transferred to another machine to be bored.

 

New tooling positioned the dowels accurately enough for transfer housings and gearboxes to be interchanged, so I am surprised that Moke found poor alignment.

 

As far as I know, diff housings and gearboxes were machined as matched pairs.

 

 

I'm actually quite sure the Transfer Housings are not matched in the factory.

 

Apart from what is evident from the Bearing and Thrust issue, the Transfer Housing was always sold as a spare part on it's own from the Gearbox Case. Each of these have their own part number. But say in the case of a Diff cap, as these were matched to the Case, they were not sold separate and when a new Gearbox Case was purchased, they always came with a Cap.

 

 

It was on a school trip in December 1960 that I saw the transfer housings being clamped to the gearbox for the dowel holes to be machined.

 

I only saw one machine.  Presumably it was drilling the holes in the same place each time so at that stage of the process, all housings and gearboxes would be interchangeable.

 

I don't remember seeing the gearbox flange to engine flange dowels being machined, but we know that engines and gearboxes all match up,....so.....if the gearbox flange dowels were used to position the the gearbox for the idler gear machining, at least all the pre my visit transfer housings and gearboxes should be transferable and perfectly aligned.

[Spider]

 

 

 

The early (not sure until what date) transfer housings were clamped to the gearbox, the dowel holes were machined, the dowels were fitted and then both parts were transferred to another machine to be bored.

 

I'm actually quite sure the Transfer Housings are not matched in the factory.

 

 

 

It was on a school trip in December 1960 that I saw the transfer housings being clamped to the gearbox for the dowel holes to be machined.

 

I only saw one machine.  Presumably it was drilling the holes in the same place each time so at that stage of the process, all housings and gearboxes would be interchangeable.

 

I don't remember seeing the gearbox flange to engine flange dowels being machined, but we know that engines and gearboxes all match up,....so.....if the gearbox flange dowels were used to position the the gearbox for the idler gear machining, at least all the pre my visit transfer housings and gearboxes should be transferable and perfectly aligned.

 

 

Sorry to drag up this old thread, but while looking for something today, I found the Factory Info on swapping Transfer Housings;-

 

 

I know it's come up a few times on the Forum regarding swapping these housings. As above, they are not matched to any particular Gearbox Case, but 100% interchangeable (depending on the era of it of course)

[Magneto]

Don't MED make a roller bearing idler gear - seems I saw a vid where they were showing it. I don't remember if it was for a helical gear or a straight cut but they had a shaft that pressed intot he trans case, then the idler which ran on a roller bearing and attached to the shaft, then a spacer that fit into the cover. I'll try and find the video.....

 

Edit - straight cut gears, but it's a slick idea.

 

 

Edited by Magneto, 28 December 2019 - 06:13 PM.