Morris Minor Owners Club

Hi all,

So, having had the Minor serviced and a few bits overhauled, driving from Bristol to London this evening I noticed a weird rattle that wasn't there a week ago. Thought I should probably find out what it was soon but had the issue forced for me when the gearstick fell over and gave up doing its job on the A4 near Hammersmith! Luckily I had a screwdriver in the glovebox and was able to dismantle the gaiter thing and take a look.

Turns out someone has had the stick out in the past, crossthreaded one of the bolts holding the retaining plate thing on and just chosen to leave it out rather than repair the damage - this seems to have caused some looseness in the plate and thereby the other two bolts to work very loose (almost right out).

I screwed the two remaining bolts back in and went on my way but am worried this may happen again. It also looks like, from checking the parts catalogue, our chum hasn't replaced the O-ring or nylon thingie that sit at the bottom of the stick.

I can get hold of the necessary parts to rectify this issue from the usual suppliers but I need to re-tap the hole for the bolt as the first 1mm or so is coarsely crossthreaded and the usual 'line up the bolt nicely and twist' poor-man's-tap trick isn't (forgive the pun) cutting it.

Does anyone know what tool I need?

Any and all advice gratefully received.

-Tom

I would think you'd just get a tap the next larger size (whichever size that may be), and a bolt that size also, and tap it out that way. You may have to drill out one of the holes in the circular plate a bit. Perhaps I'm missing what you're asking...

It's an aluminium casting - so the thread is coarse - 5/16" UNC. A 5/16" Whitworth tap will be very nearly the same - for this very low tech purpose if you have one, just use it. But if you have buy a tap - get the UNC - it has plenty of other uses.
Edit - Ooooops Sorry to say ^^^^^ this is wrong - I was confusing with Mini arrangements. The thread is 1/4" UNF as others point out later in the thread.

I'd have expected it to be a coarse thread, too, but the Moss catalogue shows all three set screws as 1/4" UNF x 5/8" on the later gearboxes, and a part number I can't recognise on the 803.

Since the OP didn't share with us what car he's on about, we'll have to assume he's got the nous to order a set screw like his other two, and measure them up to see which tap to use. I'd certainly try a taper tap first, used very carefully. It may be worth checking the depth of the tapped hole to see whether a longer set screw would help, particularly if the first few threads are completely stripped. It may even be worth cleaning out just the damaged part of the thread with a drill of the screw's nominal size, i.e. a 1/4" drill for the later gearbox, which will make it easier to run a tap down straight.

If it's a remote housing, I doubt if the world will end if a bit of swarf falls through, but it would be good practice to use a blob of grease to catch as much as possible.

Or just put it back together with two screws and a drop of loctite on each. This is a bodge.

Kevin

I had a mk3 ford cortina (k reg )and the stick came out into my hand in the Snowdonia area ,Araldite used as temp fix ,which was still working long after i sold the car,at lease three years

one of the worst cars i have ever owned ,not a patch on the mk 1 or 2 ,no wonder the Japan firms gained ground so quickly

Thanks - all this is very helpful.

Fingolfin - I was basically hoping to avoid doing what you suggest as it's only the first couple of turns of thread that're messed up and it seems a pity to make the component non-standard if there's a way of tidying up the problem. Also, I was a bit afraid of dropping drilling chips into the mechanism. I suppose there's nothing to lose by trying other methods first, as your suggestion will always work as a backup if I fail.

bmcecosse / Kevin - I didn't share the car model with you because I am a bit dim and didn't think my question through very thoroughly! It's a late-model 1098 (1969 I think) - original as far as I know, ribbed housing etc. - the various suppliers I was aware of (I hadn't come across Moss yet) have the screw but don't divulge its spec and I wasn't sure which thread system to buy a gauge for to find it out. I'm essentially using your brains to do my work for me and am very grateful for the detailed responses. I've ordered a UNC/UNF gauge and will double-check your suggestions using that. I'm glad to hear you think it's worth at least trying to chase the crossed threads with an appropriate tap - that seemed like a good idea to me but I don't know much about such things and was nervous of going at it without wiser heads' blessing.

I've got it screwed down nice and tight with just the two extant chaps for now and am being extra kind to it. I appreciate the Loctite suggestion but think I'll try to do something more proper-like if I can - despite lambrettalad's past successes with Araldite.

Thanks again - I'll update here when I've tried some things out.

-Tom

From memory the thread is 1/4 inch UNF. As mentioned, good thought to drill out the top couple of threads but be careful doing that as the drill will tend to be 'pulled' into the hole taking out more than you want. If you can, get a piece of timber about 3/4 inch square and shorter in length than the drill you use, drill down the length so that the amount the drill sticks out the end is the depth you want to drill. You then stop the drill being pulled any further. Maybe worth trying to pick up the thread before attempting above.

tomti wrote: I am a bit dim

sorry i do not agree, hope you get your box sorted soon by the way

Hello Les,

personally I wouldn't use a drill first but try and re tap it to the original size. Failing that fit a 1/4" UNF Recoil (Helicoil type repair, cheaper and easier to get than Helicoils). With that no drilling is needed.
To prevent unwanted swarf getting where it shouldn't, grease the tap to retain the chips.

Alec

PS Here's the kit, http://www.powertoolsdirect.com/recoil- ... m=merchant. I know it includes a drill in this kit but in practice for small diameters it is not required.

Ooooops - just checked with a spare box and indeed the thread is 1/4" UNF as others have kindly pointed out. I was confusing with Mini arrangements in my head. Unusual to have a fine thread in an Aly casting - but that's what it is. Sorry for any confusion I caused!

Hello BMCE,

normal engineering practice is to use a coarse thread in casting, but BMC and Triumph use fine threads in lots of cases even in aluminium?

Alec

Similar story to lambrettalad, parked in the mayor’s parking space outside the Town hall in my relatively new GPO Bedford HA van as normal and the doorman ran out and said he is on the way move the van and hurrying to lift and push into reverse the lever came of in my hand.
The Town Hall staff had to push me out the way.

Hi Alec, you may have mis-read my post, I was suggesting just removing the damaged top threads with a drill, then using the 1/4'' unf tap for the remaining threads. Not drilling for an oversize screw, if that was your thought.

Les and I both meant that only the top few (damaged) threads might need drilling out, depending on how badly damaged they are and how confident the OP is that he can keep a tap upright. I think that a Helicoil or similar is a bit OTT for this, particularly if you really are going to whack it in without drilling.

Anyone who's doing more than the very occasional job on these cars needs to build up a collection of UNF nuts, bolts, and set screws, at least in the most common sizes (1/4", 5/16", 3/8"). Just buy a few spares when you have to buy one, and the collection builds up. Autojumbles still yield the odd mixed bag bargain, and some fastener suppliers still stock UNF - it's just that the grumpy old sud behind the counter won't admit to it.

And talking of recalcitrant gearboxes, I once had an FGK40 van stuck in two gears in the middle of a seven-point turn in a narrow street while delivering groceries. It was then totally unmovable until a fitter came out with a long slim crowbar to poke into the innards of the box and heave.

Kevin

Hello Les/Kevin,

trying to drill a couple of damaged threads with a hand drill, especially in aluminium, is likely to end up causing more damage.
Possibly if the drill is ground negative rake you may get away with it, but it's likely to snatch and drag itself into the hole.
A proper sized tap to clean the threads would be my way and if it fails I would put a Recoil in. Smaller sizes, especially in aluminium don't need drilling out, if the thread is already stripped. I've used them for years and they are very effective.

Alec

The wooden 'jig' I mentioned is designed to prevent just such 'dragging into the hole' effect. If the threads can be picked up without drilling so much the better!

Hello all,

An update - sorry for the gap but I got married last Friday so became slightly distracted from my Minor adventures!

Having thought I might go for the suggestion of re-tapping with the original thread, trying to pick up the good bit by careful starting and alignment, I then went and had one last look at the hole and thought I might be able to tidy up the crossed thread by simply chasing with a nail. My thinking was that, if I was careful and took my time, I could stop before doing any real damage and move onto the whole business of sourcing a tap and trying that option. The fact that I also had a broken alternator to replace and a wedding to organise (and carry out!) will also have slightly affected my patience, I suspect.

I bunged a bit of grease in to catch any stray chips and very carefully ran the tip of a nail 'round the good threads, working my way up to the top of the hole without applying too much pressure. I did this a few times 'til there seemed to be a decently defined thread all the way to the top of the hole and tried one of the remaining two screws in it. With a bit of careful guiding-in, it took to the thread and I was able to begin turning it into the hole. I backed out after a couple of turns to check where it was going (i.e. not following the horrible old crossed thread) and it seemed good, so I carried on and it went all the way in no problem!

I've now replaced the missing screw, cup, o-ring and (crucially, I suspect) the spring washers shown on the Moss site's exploded diagram which were completely absent from the situation as I found it. All seems well so far, which is nice.

I wouldn't recommend my slightly lazy solution to anyone but it's worked for me and I'm very grateful for all the info and advice here, as always.

-Tom

Well done ! And commiserations on the wedding.......

Thanks!

-Tom

Nice to hear of your methodical approach.