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MG Midget and Sprite Technical - Stripped / Damaged gearbox filler thread (1275)

Hi Guys,

I changed the oil on my 1970 1275 this afternoon, and it was all going well until I went to put the filler bolt back in, and it appears that the thread is toast - the first few mm is stripped, so I can't get a 'purchase' with the bolt.
as a temprary fix, I've screwed in a big rubber bung :D but ideally, I'd like to do it properly.

have any of you guys had this happen, and if so, what did you do to fix it ? I've realised that i'm probably going to have to drop the gear box, even if i only refit the same plug, but are there helicoil kits, or something similar ?

the bottom bolt was also tricky, but went in ok with some PFTE, but access to that one is a little easier.

cheers :)
phil near bristol

Is it the plug that is stripped, or the casing?

They are bu99ers to fit, anyway, as you can't get a straight run at it...and it doesn't want to stay in the socket, unless you add some tape as packing!
Dave O'Neill2

Im assuming you mean the hole in the casing is stripped out !/?

If you want a nasty easy cheap fix that dosnt involve pulling the gear box....

There is always pipe thread plugs....pipe threaded plugs are tappered, so you just get it started then crank that baby in there till its good and tight, its a very southern red neck way of "gettin er dun" but it will work and will last for many years to come

A little more professional apporach on the same premise is the pipe threaded plug but with a threaded insert .... basically the plug stays in and a smaller threaded core is whats taken in and out for drainage ... that way if the thread ever goes bad agian on that inner core you just replace both parts and start over

but at least you now would have a decent common attachment on the plug to put a wrench on

Side note... dont use ptfe TAPE, you want ptfe PASTE, far better and easier to work with

Photos please...we love photos of nasty looking holes

Prop
Prop and the Blackhole Midget

Opps... this is the filler plug not the drainage plug

Nope ... your screwed, new case needed, haha

Nah, your fine... if your rubber bung is working, id say job well done, pat yourself on the back and call it a day, there will be many other issues just over the horizon that are going to steal your time and money of far more importance

when the day comes that you "HAVE" / "REQUIRED" / "NEED" ... to pull the gear box, then id fix this "minor in comparison to everything else" issue.

Till then... Have fun bleeding the brakes and clutch instead

Prop

Prop and the Blackhole Midget

yep, it's the hole that is stripped rather than the plug, I did have a hunt around for a big tapered bolt but couldn't find anything in my boxes of bits, but this:

"A little more professional apporach on the same premise is the pipe threaded plug but with a threaded insert"

is what I was thinking of, glad to know I didn't just imagine them :)

"Nah, your fine... if your rubber bung is working, id say job well done, pat yourself on the back and call it a day, there will be many other issues just over the horizon that are going to steal your time and money of far more importance

when the day comes that you "HAVE" / "REQUIRED" / "NEED" ... to pull the gear box, then id fix this "minor in comparison to everything else" issue.

Till then... Have fun bleeding the brakes and clutch instead"

true :D

phil near bristol

I wouldn't trust the rubber bung for long unless you know the material is resistant to oil. If I remember correctly the oil filler and drain plugs are BSP taper plugs and if so I would see if you can find a replacement which has a smaller diameter by virtue of being longer or at the lower end of tolerance size wise so it may have a chance of reaching some remaining thread.
David Billington

This thread was discussed between 05/05/2014 and 06/05/2014

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