Morris Minor Owners Club

Hi all,

Just a quick question, I will be pulling an engine & gearbox together next week (first time), I was always reluctant to pull the gearbox as I am aware there are captive nuts that are highly likely to give up! If this happens is it possible to replace them by removing the gearbox cover and using a rivnut or something similar? I don't currently have welding facilities, although if I had to there are neighbours I could ask. I also don't currently have a rivnut installer, so if anyone can recommend a reasonably priced one please let me know! I am trying to avoid a situation when the gearbox is out but I have nothing to reattach it to, so any tips would be very helpful.

Many thanks,

Edd

Whilst it is good to make provision - do not automatically assume that the gearbox cross member captive nuts will fail. At best they may have been out in the past and the person re-fitting them covered the threads in copper ease.
Give everything a good soak in proper release oil (not WD40) over a couple of days before attempting to remove them.
Try a spanner on the 5/16" BSF bolts and gently ease them backwards and forwards until they screw fully out.
Clean out the threads in the captive nuts with a 5/16" BSF tap and copper ease the threads.
If you have a small kitchen blow torch give the heads of the 5/16" BSF a good warm up (cherry red if possible) which will help - just be careful of the torch flame so it does not all go up in flames - have a bucket of water handy.
The 1/4" DSF Brass floor cover screws even if they fail can be replaced with plain nuts an bolt as they are all outside of the box section. Again clean the threads with a 1/4" BSF tap and cover with copper ease when re-fitting
As regards using rivet nuts - they are aluminium so I would not recommend them as a substitute for the steel gearbox cross member captive nuts whether they be the 1/4" or 5/16" ones.
If you do not want to disturb the gearbox cross member - remove the floor panel and remove the gearbox mountings (noting which way they were fitted) and slide the gearbox forward over the cross member.
If you do not have the respective taps there are plenty currently on 'e' bay for under a £5 each and they can be used for cleaning other 1/4" & 5/16" BSF thread on the Minor - so money well spent.
Phil

I have completely removed the captive nuts and their cages, and replaced them with a 1/4 inch steel plate with tapped holes in the appropriate positions. The plate can be free standing if you make it the width of the chassis channel, as this will prevent any turning. As a finishing touch, round the bottom edge to suit the radius of the chassis corners.

Les
How did you secure the plate in place to stop it moving fore and aft and upwards?
Phil

Ah well, i made it a snug fit, hence rounding the bottom edges to make sure the plate didn't 'cut' into the box section.

I suspect the others have answered the question you meant to ask - but you say 'pull an engine and gearbox together' - and this is NOT something you should ever need to do! They must slide easily together with the gearbox splines engaging nicely on the clutch plate (which you have already carefully centred..) perhaps turning the engine slightly as you do this, and the spigot then engaging in the bush in the flywheel. Only final obstacle then is the little alignment spigot at the top of the engine block which engages in the matching hole in the gearbox. Make SURE on the way in that the gearbox shaft doesn't knock the clutch operating plate/springs out of position. I'm not aware of any 'captive nuts' on the gearbox or engine.

BMC - Sorry this is my poor grammar!

What I meant was "remove the engine and gearbox, together"

Comma was missing!

I do apologise. If the gearbox removal was going to be tricky I would just split them and remove only the gearbox.

Thanks all,

Edd

covered the threads in copper ease

I can vouch for the effectiveness of 'copperslip' or copper grease - very good advice.

When our Minor was completely restored 18 years ago, I made sure that every thread on the body had copper grease either in the nut or on the bolt before it was assembled. I did take the opportunity to replace the wing bolts with 5/16" BSF stainless steel ones, and had any of the original fasteners that were to be re-used zinc and yellow passivated.

Fast forward 18 years and it was completely dismantled in January 2016 prior to a full respray - every single nut, bolt, screw and washer removed. In the whole dismantling process I had only one bolt that would not undo on one of the rear brake backplates (had to be drilled out) and one tight rear cylinder brake pipe fitting (some 3-in-1 oil gently worked in and the fitting spun free). Every other fitting undid as if it had only been on the car for a very short while - all wing bolts, gearbox x-mbr, rear spring front pins etc. etc.

The reassembly was completed 2 days ago on Wednesday and again all fasteners were treated to the same copper grease treatment.

So, are the captive nuts only present on the gearbox crossmember? If so I have removed the floor before and it was no biggie, although I did black-tack it to seal it up, so could be a right mess! I'll have a look at the bolts first.

Thanks,

Edd

edd_barker wrote:So, are the captive nuts only present on the gearbox crossmember? If so I have removed the floor before and it was no biggie, although I did black-tack it to seal it up, so could be a right mess! I'll have a look at the bolts first.

Thanks,

Edd

Yes, they are only present there - if you've already had the gearbox cover off, you'll be able to deal with the captive nuts with no trouble should you need to

Great thanks! I think I am going to go reconditioned box, as mine is incredibly whine-y at around 2500rpm upwards. Function-wise it is faultless, but the noise is a bit of a bugger, and there's a good transmission place down the road.

Thanks chaps,

Edd

EDIT - Yes I'm already a fan of the copper grease, I use it when replacing any nut or bolt. Apart from engine studs....Anything on the underside I try and replace with stainless, there's a great fasteners supplier in Hersham near me that I have yet to stump when requesting stainless items, even had Whitworth's so far!

NO - the stainless is a big mistake. They often don't have enough strength, but the BIG problem is that they make an electrolytic cell with the surrounding plain steel - and guess what - the plain steel rots away around the fixing.

The 1/4" BSF Brass screws that hold the gearbox cover in place also fit into captive nuts as well as the qty 4 5/16" BSF gearbox cross member ones.
The top of the gearbox cross member is secured either side by the longer 1/4" BSF brass screws again into captive nuts.
Phil

Just spent the afternoon repositioning or replacing the gearbox cover captive nuts on my new floors and chassis legs. Fiddly and slow, but good job I checked the fit before painting. If anyone else is this obsessive David Manners sell the nuts and cages.

Roy, I agree that stainless and mild steel are slightly apart in the electrochemical series, but not by very much, and in practice after 18 years and 55,000 miles I had no corrosion of any of the painted mild steel fixings at all. Maybe the copper grease acts as an electrical barrier? There was some corrosion of zinc plated shakeproof washers, but I suspect that may be more to do with the plating being partly removed on assembly, exposing the base metal to the elements.

Well - if both painted and greased - and kept reasonably dry there is likely to be good separation. It's a common problem on Minis - where the metal is thinner (a LOT thinner) and mugs are sold low grade 'stainless' packs - even for stressful applications such as subframe mounting.....

I should have said that I am only using stainless fixings in low stress body applications - ALL suspension and other load bearing uses are high tensile plated bolts, either original re-plated or new.

It doesn't get used very much if there is salt on the road, but 'reasonably dry' is not predictable and often, such as yesterday coming from Oxford to near Cardiff, it rained all the way down, so certainly not dry.

No - but I'm sure it's not standing in the rain 24/7 - nor do you get as much rain as good old Ecosseland.... And I dare say it's not the 'car of choice' on a wet day unless there is a special reason to use.