ausmini :: View topic - Threaded my Sump Plug!

drmini in aust wrote:

OK today I started to machine up a few steel repair adaptors, as pioneered by 4myego on his Cooper S. (ta for the drawing Steve).

Outside diameter is 3/4 UNF, inside is 5/8 Whitworth.

Pic of the 1st one... (sorry about the crook flash job)
http://home.exetel.com.au/zoomini/zoomi ... GP2330.JPG

You drill and tap the gearbox to 3/4 UNF, clean the thread out and dry it, put some Loctite 262 on the outside of the adaptor, fit the sump plug and torque it up.

The factory may think 25lb/ft is OK, they were in the business of selling spare gearboxes. 15lb/ft would be plenty for a sump plug I reckon.

[edit] If anybody needs one, PM me. :wink:

Today I was able to tap my sump out to 3/4 in UNF (as above) and install the steel adapter made by Dr Mini from a design by 4myego.

Very happy with the result.

Big thankyou to 4myego for the original design and to Dr Mini for making up the adapter for me.

Pics.... sorry about the quality.

^^Sump drain drilled out to 17.5mm and tapped to 3/4 UNF ready to receive the steel adapter.^^

^^Original sump plug used to screw in adapter, Thread locker was applied to the thread before installing.^^

^^Adapter installed.^^

Author:	Mick [ Sat Dec 06, 2014 2:51 pm ]
Post subject:	Threaded my Sump Plug!
Mod Edit: Split this off from the other thread as it diverged and I want to ask a little bit more on the inserts... Went to change the oil out, and the sump plug won't unscrew! Its stripped in situ. I don't remember doing anything abnormal last time I did it up, so it must just be its time... I ordered the first Helicoil kit I could find for a 5/8 UNC .... Expensive oil change..

Author:	goodie [ Sat Dec 06, 2014 5:29 pm ]
Post subject:	Re: What did you do on your Mini today?
Mick wrote: Went to change the oil out, and the sump plug won't unscrew! Its stripped in situ. I don't remember doing anything abnormal last time I did it up, so it must just be its time... I ordered the first Helicoil kit I could find for a 5/8 UNC .... Expensive oil change.. Yuk , geez that sucks Mick , thats not a job i would envy . I've just changed the oil in my car and all is good , but a few changes back , i had a plug that didn't feel right , so i changed it out , so far so good , but i'm always anxious because there is a tight spot in the thread , more than likely in the alloy side me thinks .

Author:	boomini [ Sat Dec 06, 2014 5:56 pm ]
Post subject:	Re: What did you do on your Mini today?
Yeah I bet it was expensive....

Author:	Mick [ Sat Dec 06, 2014 6:38 pm ]
Post subject:	Re: What did you do on your Mini today?
About 120 for the kit delivered. Its an industrial helicoil kit, so is more than single use. However the last time I had to do it was 2002.. I will do it in-car, I had good success last time. I washed the engine through and used a really worn out bristly toothbrush to pull the swarf out. It doesn't go far when its tapped by hand.

Author:	4myego [ Sun Dec 07, 2014 1:03 pm ]
Post subject:	Re: What did you do on your Mini today?
My solution - Still OK since 2009

ausmini https://www.ausmini.com/forums/

Threaded my Sump Plug! https://www.ausmini.com/forums/viewtopic.php?f=2&t=87956	Page 1 of 2

Author:	Mick [ Sun Dec 07, 2014 2:28 pm ]
Post subject:	Re: Threaded my Sump Plug!
I like the idea of the insert. It takes the load and wear off the gearbox housing. That would take some work getting a UNF thread for the outer thread on the gearbox, did you get a machine shop to do it?

Author:	4myego [ Sun Dec 07, 2014 2:33 pm ]
Post subject:	Re: Threaded my Sump Plug!
Had the same problem with a stripped sump plug thread. Machined the insert. In Situ, Drilled out (stubby drill bit) and run a 3/4 UNF tap through. 30 minutes finished. Make sure to tap it square!

Author:	Mick [ Sun Dec 07, 2014 2:40 pm ]
Post subject:	Re: Threaded my Sump Plug!
4myego wrote: Make sure to tap it square! Yeah, that's the tricky one here, otherwise I get a permanent leak.. I'm not so great with hand tapping square. I have to be especially careful. The good thing with a recoil is that it uses the remnant of the original thread pitch to pull it through, but it can still be stuffed up. Was the bush a commercially available thread changer, or did you have it made up?

Author:	4myego [ Sun Dec 07, 2014 2:47 pm ]
Post subject:	Re: Threaded my Sump Plug!
I designed and made it myself. Easy if you have a lathe

Author:	mini_mad_matt [ Sun Dec 07, 2014 3:09 pm ]
Post subject:	Re: Threaded my Sump Plug!
Happened to me before, i paid $100 for a mobile thread guy to do it as it was cheaper then buying a kit. Instead of making it 5/8UNC though, he changed it to a metric thread which is a very common plug. Don't remember what size it was off the top of my head though. The reason he did that was because it didn't require taking as much meat out of the casing. I just drilled the centre of the plug so i could put a mini sump plug magnet into it. Unfortunately though, he didn't get it perfectly square as it had a slow leak, so i spent a little while filling the casing until it was square enough to the thread it wouldn't leak.

Author:	mickmini [ Sun Dec 07, 2014 8:32 pm ]
Post subject:	Re: Threaded my Sump Plug!
I also have an insert, but mine was made by Kev (dr mini). My case was also cracked where the thread was either by being dropped or hitting a kerb when in a car. I had to take it in to the guys in the metal fabrication shop in the dockyard to grind the crack out, weld it all up, drill a new hole and tap for the insert. These guys usually fix your occasional work transport, so they know what they are doing. Maybe a foreign order at FSU to get it all squared up? cheers michael Since the insert went in with a dab of loctite, the sump plug with a new copper washer, it has not even weeped.

Author:	drmini in aust [ Sun Dec 07, 2014 8:47 pm ]
Post subject:	Re: Threaded my Sump Plug!
Mick the one I made for you was the same as 4myego's he did one first. I still have the drawing, somewhere. Will look for it. [edit] found it. Now hosted with flickr. If I make any more inserts, they will be in brass, not steel. Easier to thread on my little Myford bench lathe. Ignore the copper washer shown, just Loctite the thread then screw it in.

Author:	phillb [ Sun Dec 07, 2014 9:22 pm ]
Post subject:	Re: Threaded my Sump Plug!
Thread from when I did mine, ....scariest part was drilling out the hole ready for recutting. Drilling into alloy with an electric hand drill not fun. viewtopic.php?f=2&t=71501&hilit=sump+plug phillb wrote: drmini in aust wrote: OK today I started to machine up a few steel repair adaptors, as pioneered by 4myego on his Cooper S. (ta for the drawing Steve). Outside diameter is 3/4 UNF, inside is 5/8 Whitworth. Pic of the 1st one... (sorry about the crook flash job) http://home.exetel.com.au/zoomini/zoomi ... GP2330.JPG You drill and tap the gearbox to 3/4 UNF, clean the thread out and dry it, put some Loctite 262 on the outside of the adaptor, fit the sump plug and torque it up. The factory may think 25lb/ft is OK, they were in the business of selling spare gearboxes. 15lb/ft would be plenty for a sump plug I reckon. [edit] If anybody needs one, PM me. Today I was able to tap my sump out to 3/4 in UNF (as above) and install the steel adapter made by Dr Mini from a design by 4myego. Very happy with the result. Big thankyou to 4myego for the original design and to Dr Mini for making up the adapter for me. Pics.... sorry about the quality. ^^Sump drain drilled out to 17.5mm and tapped to 3/4 UNF ready to receive the steel adapter.^^ ^^Original sump plug used to screw in adapter, Thread locker was applied to the thread before installing.^^ ^^Adapter installed.^^

Author:	Timbo [ Mon Dec 08, 2014 8:54 am ]
Post subject:	Re: Threaded my Sump Plug!
I bought a replacement engine and gearbox for my old Deluxe several years ago. When I got it ready to put in I found it had a stripped thread, so I rummaged through my Dad's box of spare bits and found a slightly larger plug out of something else. I took it to a machine shop who drilled and tapped it to the size of the new plug and it was sorted. I think they charged me $10. Tim

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Author:	Irish Yobbo [ Mon Dec 08, 2014 9:06 am ]
Post subject:	Re: Threaded my Sump Plug!
My sump plug has been helicoiled since I've owned it, but if it were to happens again I would go for the insert. My sump plug has always leaked despite trying many things, but I'm not brave enough to go over the factory torque settings. They say the helicoils are strong, but I'm not willing to push and see how strong.