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MG Midget and Sprite Technical - Gearbox nut has me stuck again

Feels like I can't move two steps forward without coming up on a problem.

Working on the 1275 gearbox, and just received a batch of fresh parts from Moss. Trying to replace the bearing (Moss 127-040)on the first motion shaft, and I can't get the nut off.

Seems to me I'm bringing enough force to the game to twist the input shaft itself, but the nut won't budge. I saw in the archives that a used clutch plate in the vise would be ideal, but I don't think I have that. Pretty sure I resurfaced the clutch plate during the restoration 16 years ago.

I've tried heating the nut with a heat gun, tapping around with a small drift to try to let some PB release spray in. The locking washer is definitely out of the way, and I've tapped on that to try to release the nut from the washer.

The gears are clamped in the vise with softwood, really tightly, and the tight-fitting adjustable wrench just walks the wood within the vise. <picture> And it's really cranked in there.

Unless I just need to be more patient, and work on it for a week, I'm ready to give up and let the bearing stay. I'm replacing it at 113k miles because it's a good idea, not because I know there's a problem with it.

Any suggestions? Thank you.



Mark 1275

113,000 miles on a ribby 4 speed, WOW, that's some kind of wonderful

I'm dumb on transmissions ... but I'd probably replace it being I already put some force to it

I would go to harbor freight and get a box end wrench for extra grip of the nut and cut off the other end and slide on a 6 foot long piece of steel pipe and give that a heave hoe and see what happens

That will break something
1 Paper

Walking the wood...now i see what you mean

As you apply force to the wrench it wants to spin the wood out the side

In that case remove screws that hold the gripping jaws to the clamp

Next drill matching holes and same size into the wood and get longer screws and reattach to the jaws of the vice

If the wood splits try redrirefilling agian again and use some metal tubing (forced ) into the new hole of the wood to act as a bearing for the screw to fit snug thur

Copper plumbing tubing, old metal brake line ECT ect
1 Paper

I've got the torque on the nut. I put a short length of pipe on the adjustable wrench, and I've also tapped it a bit, first with a rubber mallet and then a hammer. The part where I'm failing is holding the shaft in place.

I know I've already said it, but that vise is tight! The gears just slide the wood each way within the vise.


Mark 1275

Just saw your second post.

Maybe I do need do find a better way to secure the wood in the vise. Or use harder wood.

Curious what experiences others have had.

Thank you for the responses.

(Did you used to be Prop?)
Mark 1275

You could attach some more pieces to the ends of the wooden battens to prevent them from moving.

The used clutch plate is good - if you have one.

I think I may have just gripped the shaft directly in the vice, in the past. Horizontally, so there is a greater surface area.

There may be a risk of damage, so you would need to decide whether to risk it, or not.
Dave O'Neill 2

I remember doing it the way Dave did, clamping the shaft in the vise though its been years since I did one. I seem to remember that I lined the splines up in the vise so that the jaws lined up with the cut out part and not the high sections hope that's clear). If you do any damage to the splines you can always clean it up with a file. And when your doing that take, the clutch disc and slide it on to make sure you've done it right.
Martin

You do know it is a LEFT hand thread, don't you....
Chris at Octarine Services

"You do know it is a LEFT hand thread, don't you.... "

Not on a midget.

MGA/MGB 3-synchro first motion shaft has a LH threaded nut. In fact, it's the same nut that is used on the Spridget LH rear hub.
Dave O'Neill 2

I've just attempted to undo the nut on my broken first motion shaft and it didn't want to co-operate.

It might be easier to drill a couple of radial holes in the nut and break it with a chisel. Moss charge 39c for a new one.

The other option, assuming that your clutch plate is still attached to your engine, is to push the shaft into place in the clutch plate and lock the flywheel so that it can't turn.

In case you're wondering why I keep a first motion shaft with two teeth missing, it makes a very good clutch alignment tool.



Dave O'Neill 2

I would have thought the nut is case hardened ... but if the nut is that cheap and can be broken up ...

then drill baby drill it


I wonder if you can make some wooden wedges and place them between the wood planks on the vice jaws on the end where the wood kicks out ... creating a wooden open end wrench effect so the more force you apply the more resistance the wood would provide

I wouldn't be to excited about using hard wood besides the soft wood will allow the gear teeth to really dig in once your able to keep the soft wood from spinning out, were the hard wood will probably be more ept at letting the gear teeth spin between the wood ... depending on how hard and the grain structure of the wood is

Btw... make sure the wood grain is horizontal and not vertical or the gear teeth will chop up the wood along it's grain pattern

Prop

1 Paper

Thank you for the responses and ideas.

Chris, your note made my heart skip a few beats this morning.

I'll try altering the fixture so there's a better grip in the vise before I cut the nut or just leave the bearing as is.

Dave, I did try inserting the shaft in the clutch on the engine stand before trying the vise. I held the clutch plate with a 6' 2x4 (baulk?) braced against the engine stand, and it held, but it felt like all that force was going to bring harm somewhere. I'll give the vise some more effort.

Any ideas why it's so unmoveable? Doesn't look the least bit corroded. Was it torqued at superhuman levels when installed?

Frustrating, but I guess I'm not the only one to have come up against this.



Mark 1275

You might get a better grip by replacing the wood in the vice with some aluminium angle or flatstock. I keep several short ends of ally angle as homemade softjaws for just this sort of thing.
If you can achieve a really tight grip then a tight fitting ring spanner on the nut might shift it if you give it a good old British whack the other end with a mallet. Hint: tie the spanner loosely to the vice first to limit how far it can fly. Don't ask how I know - it's a secret between me and my dentist haha!

(I wouldn't want to try it with the adjustable though).
Greybeard

I'm with matt, I'm not a fan of using the adjustable cresant wrench for this... dangerous and damaging plus you can't get enough leverage on that short of handle

That's why I say a $3.00 box end wrench (ring spanner) and just cut the other end off and a 6 foot piece of steel pipe... that's going to move something
1 Paper

I've removed two different ones in the last few years but don't remember it being a struggle. I think I probably gripped the shaft in the vice, like Dave, and kept tapping at the spanner with a hammer.
Bill Bretherton

Mark
Pulling up on that shifter at that angle, you'll never get it to move
I'd be getting the spanner over the other side and fit it snug to the nut with the adjustable jaw on the bottom
Put (jam) something like a block of wood under the gear to support it
Set the spanner so it is roughly horizontal Try pushing down on it to undo it but if still no go, get someone to hold it in place and then stamp on the spanner with your boot
The shock will move it
willy
William Revit

That's the stuff Willie. Short sharp shock.
Greybeard

I use a flat spanner used for removing mini suspension ball joints. The ist motion shaft is mounted in a vice and the spanner rapped sharply with a hammer. I have never failed to remove the nut in this way on several occasions.
Bob Beaumont

Willy,

So a Size 10.5 boot up the ass works in more then one way for motivation?

Haha

Prop
1 Paper

I'm at work now, but wanted to mention the photo of the attempt with the shaft in the engine was staged. Wanted to show Dave what I'd tried, and it was a great reason to head out to the garage with my 8 year old granddaughter as the photographer. Perfect activity for a rainy day in New England.

My next step is to go further with the vise. I think the wedge shaped pieces, maybe even with C-clamps to hold them in the vise, should bring a lot more force where it's needed.

I have definitely been using a short pipe on the wrench, maybe 18" long, and it's the holding of the shaft that's not working for me so far. If I did have a box wrench that large I would use it, but I'm pretty sure this adjustable is all I've got. And I've given sharp raps to the wrench to try to break it free. It moves my whole workbench, which is fastened to the wall.

Can't recall bringing this much torque to a problem without a result, but haven't given up yet.

Thank you for the responses. Hope I can post some progress soon.
Mark 1275

Mark,
If you use the "short, hard shock" treatment on a spanner, as described by William then the shaft is very much less likely to squirm its way out of the wood. The vise needs to clamp it tightly so that you can strike it hard but it is the shock of the impact which will free it.

Small taps may work for a rusted or corroded nut but when its just very tight on clean metal then its the shock that will free it. Make sure the spanner is firmly in place, and anchored with a rope. Then strike it hard and sharp with a heavy lump hammer. Hitting it as if the point of impacft is 6" beyond where it actually is will give the best impact force and should free it.
GuyW

You need to clamp the shaft directly and TIGHT in the vice on a non machined area. Then you need either a wrench and a LONG lever or a wrench and a HEAVY hammer (aka BFH). No holds barred and it will give.
Dominic Clancy

What Guy and Dominic said, Mark. Although I'd still recommend some scrap ally instead of wood. If you are going to buy a spanner for it take the shaft with you to the tool store and choose the closest fitting one you can find, bearing in mind it might not be the nominally correct size. You might quite feasibly find a metric or Whitworth that fits tightly, even if it needs to be tapped on. But the shifter spanner is not helping you I'm afraid.
As the nut is quite shallow you may find advantage in grinding one side of the spanner flat for maximum engagement.
And sorry to say the hot air gun is unlikely to be effective for heating the nut. Not hot enough or localised enough. It needs a flame or the old-fashioned (scary) method with a turn of steel fence wire and a battery. (I wouldn't want my little granddaughter too close to that though).

By the way I like your vice, with the flat table at the back and the swivelly turntable mount. It's a thing of beauty and I covet it like mad, it's much nicer than mine.
Greybeard

I would grip in the vice the full length of the clutch splines - more likely to damage the gears the other way.
For soft jaws thin wood/ alloy as Greybeard has suggested or a thinish leather wrap should do the trick. Soft jaws are available which are usually steel backed with a dense fibre material, however they may well not take the torque without the shaft turning.
If you get an odd burr on the shaft it should be fairly easy to clean up to ensure a smooth slide for the clutch plate.
richard b

Might get out to the garage tonight, and I wonder about heating the nut. I went with the heat gun because I was concerned my propane torch might be too hot for the adjacent bearing. If I have to throw in the towel and leave the bearing for another time, won't I ruin it by putting that much heat that close?

The advice here has me more motivated, so the giving up option is less and less likely.
Mark 1275

Okay. My tools and methods just aren't up to it.

The wedge clamped to the vise held pretty well.

Started with shock and awe, using a 2 lb fist maul, but still with the adjustable crescent wrench. I just don't have a box or even open end big enough.



Mark 1275

The result was damage to the nut.

Now I'm out the $0.39, and need to build another order with Moss.

I'll try to borrow a proper wrench from my work, and failing that start drilling per Dave's earlier advice.

Grrr.


Mark 1275

If you can't afford box wrench from harbor fraigfreight

Go to a pawn shop, they will have em all day for under $5.00

But you will need to cut the open end off to put a piece of pipe on it

Hang in there... we are behind you, God knows we have all been there with a stripped screw or a buggered nut

Trust me wait till you take the nut off the crank shaft pully, now there is a fun nut to crack

Prop
1 Paper

Either drill and split the nut as per Dave method. Or, do you not have a friendly Engineer's shop you can take it to and see if they can give it a good talking to.
GuyW

Yep looks like you're out the 39¢ but on the bright side look at all the fun you've had😎

In fairness I probably wouldn't want to use that nut again anyway; I suspect the thread will be pretty distorted. The shaft should be OK though - it's easy enough to clean up the male threads.

Good luck Mark.
Greybeard

Well, if it is a RH thread then I would place a cold chisel on the corner of one of the flats and hit the chisel hard with a heavy hammer to rotate it anticlockwise.

You may need to do it on more than one flat as it is likely to chisel off the corner but then you won't be reusing it anyway.
Chris at Octarine Services

Mark, If you can, take a look at the 3-part series on rebuilding one of these gearboxes which appeared in the July/August/September 2008 issues of 'Practical Classics'. Part 3 alone contained FORTY steps and I have attached a copy of Part3/STEP3 which may(?) solve your problem. The information in these articles comes from Hardy Engineering (Leatherhead, Surrey) who are acknowledged experts on the subject. Good luck with it all.


J.E. Davies

Are you sure that's not Lawrence?

It looks a bit brutal.
Dave O'Neill 2

Wow, I'm surprised they're gripping the dog teeth! If I tried that I'd wreck them. I'm sure that, like others, I gripped the shaft in the vice, tightly, and probably gave the spanner a few hard whacks rather than taps. You do need a spanner with a bit of heft and a lump hammer.
Bill Bretherton

For the same gripping force, the turning moment (physics: force x distance) will be much greater if the dog teeth are gripped rather the shaft. And when gripping the teeth, there should be no slipping ...
J.E. Davies

I think gripping the dog teeth is OK but I would want some soft metal packing in there between the Stilson jaws and the teeth to prevent possible damage from hardened steel against hardened steel.
David Billington

Amen David, Amen.... preach it brother, preach

I like this soft wood approach, I wouldn't be so excited to abandon this idea ... The gear teeth can dig into the soft wood without damage to the teeth

The aluminum is a good idea... but hardened metal to hardened metal
1 Paper

Tried the 'Practical Classics' method today on an old Minor shaft - it worked OK - a little bit of initial graunch as the stilson engaged ! but visually no damage to gear, does the bearing have to be pressed off ?

Thanks John for reminding me of those articles - only not sure where I safely stored them !

Mark - on another thread you mentioned a friend inserted bearings into the laygear (in place of the originals)which if I understood corectly are a cartridge and do not run directly on the inner surface of the laygear.

Did he have to carry out any machining to get them to fit ? i.e cylindrical grinding ? - I've found a basically good laygear but I was advised the inner surface was not good enough to run the normal bearing cages so it went into the pending bin !

R.
richard b

"Does the bearing have to be pressed off ? "

Yes, it's an interference fit.
Dave O'Neill 2

Richard, yes, he did what he called "cleaning up" the inside of the laygear. I have the feeling it was just a few thousandths to true it up and restore a good surface. I'll ask when I next see him what he figures he took off.

So, maybe I'm in deeper than I should be. I guess I assumed the bearing would just slide right off the shaft once I get Lucifer's nut off. I have a small arbor press, but too small to use for this without some very creative fixturing.

Will the main shaft bearing also need to be pressed off? Maybe it's time to enlist more capable help.

I do have to admit, Greybeard, that even though the process has been disheartening and frustrating, this thread has been a bright spot.
Mark 1275

If you're careful, the bearing can be levered off using two large screwdrivers.

You could also invest in a bearing puller, such as this...

http://www.ebay.co.uk/itm/112693676850
Dave O'Neill 2

Mark,

Yes, the main shaft bearing is also a press on. But both bearings have a short area that is actually press fit. The way I got them off, since I don't have a press (and I know that this sounds Mickey Mouse) was to drop the shaft hard against a piece of wood so as not to damage the tip. It would take a number of tries but eventually they came off. The input shaft is easy since it is short and there is nothing on it but with the main shaft you have to be careful that the first/second slider doesnt't come apart with the spring loaded balls flying into parts unknown. I would take a jubilee hose clamp and tighten it around the part that the slider moves on after moving the slider into second gear position. I would also leave the retaining nut holding the spacer on loosely so that nothing goes crashing down. Re-assembly is easy since all you have to do is tap the bearings in place and tighten the nuts. Hope this doesn't sound too complicated but you get creative when you don't have tools that you need once every 20 years.
Martin

Removing the bearings in question isn't the main issue as you're replacing them you can press/hammer/puller on the outer race so any damage caused is irrelevant, when fitting the new bearings pressure should only be placed on the inner race as that is the one being fitted to the shaft, load should never be transferred across the bearing to fit a race.
David Billington

Here's 'Part 3 / Step4' which shows how Hardy Engineering Release the shaft ...


J.E. Davies

... and here is 'Part 3 / Step 5' which shows how to re-insert the shaft in a new bearing. I repeat, this 3-part series is a gold-mine of information for anyone attempting to recondition one of these boxes for the 1st time. The experts at Hardy have seen more A-series gearboxes than I have had hot dinners. And Gentlemen, I am 70 years old!


J.E. Davies

Or you could use the old inner race as a drift, and tap it gently home.
Nick and Cherry Scoop

Mark
Could you take another picture of the nut and shaft from the side-
In that last one you put up of the damaged nut,-I've looked and looked at it and from that angle it could be either lh or rh thread
A pic from the side will show it up better
Good move getting the Granddaughter involved with the camera, I like that
willy
William Revit

Willy

If you look at the photo I put up on the 11th, you can see it is a RH thread.

Dave O'Neill 2

All the A series ones I have ever worked on were RH thread. Certainly the 1275 one's with a 88g 229 part number
Bob Beaumont

If you take a hacksaw to the other side if the thread and take the cut down to the tab washer, you'll have the nut off in 5 minutes. Most probably someone use Loctite on the threads - some of the high strength ones have to be cut off.


f pollock

What's the cost of a replacement shaft.

There is always another way to skin a dead cat

Prop
1 Paper

A bit more than $0.39
Dave O'Neill 2

Willy, hope this confirms it's RH thread.


Mark 1275

All good, it just looked a little strange in the other pic.
Cheers
William Revit

Put it in the vice, place a cold chisel on the nut where i have drawn the yellow line and hit it hard with a heavy hammer.....


Chris at Octarine Services

Mark,

I've done what Chris suggests with the cold chisel quite a few times when I didn't have a large enough wrench, and it certainly works.

I think your adjustable wrench is soaking up all the impact because its jaws are not ridged enough. You might have better luck with a pipe wrench.

Charley
C R Huff

Success!

Put a new 32 tpi blade in the hacksaw, carefully made parallel cuts, used a nail set at the corners, and it separated just fine.



Mark 1275

Makes me wonder why I was so committed to unscrewing the nut. Should have heeded the advice here sooner.

The bearing levered off just fine. Started by driving in a putty knife, then screwdrivers.

Now I feel prepared for the main shaft adventure.

Much appreciate all the advice and support here.


Mark 1275

Congratulations!

Half way there. But now that you know what you're doing things will be easier. And putting it back together is much easier. You just have to make sure that you get the bearings on in the right direction.

While you're getting new nuts you probably should get new locking washers if they're available.
Martin

Mark - on behalf of the dozens of us who have followed your thread with mounting excitement, but have had nothing useful to contribute, CONGRATULATIONS!
Nick and Cherry Scoop

Well done Mark. You've solved the problem of "should I reuse this old nut or not"! Did you find any residue of Loctite or similar? I can't see any reason for it with the lockwasher but POs do funny things sometimes.
Greybeard

The international nightmare is over ... haha

Well done buddy good going, I have to admit, now I'm a little depressed, for me this was a daily adventure like a day time tv soap oprea

But I'm glad it worked out for you.... I have to agree buy the other little parts to go with it... You know how karma gets jealous around good luck
1 Paper

Appreciate the comments!

Did not find a good reason for the nut to be so stubborn. Didn't seem to be adhered to the lockwasher, no traces of Loctite. There was a slight deformation of one thread on the shaft, but I can't imagine it was enough to put up such a fight.

But it keeps getting better and better. I had a few minutes in the garage today, set up the output shaft preparing for a similar battle. Flattened out the lockwasher, and presto! The nut was practically finger tight. Came right off.

Next I'll get the bearing off, and new nuts ordered from Moss. Hope to be able to make some progress next weekend.

Thanks again for the interest.



Mark 1275

" Thanks again for the interest"

We always enjoy a challenging rebuild.
Dave O'Neill 2

The main shaft nut always seems to be loose. Not sure the reason. I have had cases when the speedo drive, which is not keyed, is so loose on the shaft the speedo fluctuates or does not work at all.
Bob Beaumont

I've never had an issue with undoing the mainshaft nut, either.

My spare (broken) first motion shaft didn't want to undo when I tried it the other day. If my stilsons are big enough, I may experiment with that method this afternoon.
Dave O'Neill 2

This thread was discussed between 10/02/2018 and 18/02/2018

MG Midget and Sprite Technical index

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