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stripped thread question
https://www.ausmini.com/forums/viewtopic.php?f=2&t=40178		 Page 1 of 1
Author:  mini-dunger [ Fri Mar 14, 2008 10:18 pm ]
Post subject:  stripped thread question
Hi guys

Mr dodgy from dodgy brothers mechanical repairs or the PO had stripped a thread on the drivers side diff case and neglected to

1) tell me

2) fix it

it felt strangely loose when I undid it to bolt my xtractors up. So then when I tightened it up I barely clamped the exhaust tab before it just span for a good length of time without moving in the inward direction.

I was visiting my local tool guru a while ago and he showed me these high tensile grub screw looking things with a thread on both the inside and the outside that you just screwed in and used a smaller bolt.

I think it cuts its own thread.

Anyone used em?

Failing that I will just tap it out with the next size metric bolt or something.

I could put a helicoil in but I would have to pull the cover off.

Has anyone else had the pleasure of doing this job?

thanks everyone :D
Author:  drmini in aust [ Sat Mar 15, 2008 5:50 am ]
Post subject: 
Now it's stripped the hole is 5/16" diameter, perfect size to tap out to 3/8 UNC.
Tap it out, drill the hole in the cover to 3/8, and Bob's yer auntie's husband. :wink:
3/8 thread is harder to strip next time.
Author:  mini-dunger [ Sat Mar 15, 2008 2:08 pm ]
Post subject: 
drmini in aust wrote:
Now it's stripped the hole is 5/16" diameter, perfect size to tap out to 3/8 UNC.
Tap it out, drill the hole in the cover to 3/8, and Bob's yer auntie's husband. :wink:
3/8 thread is harder to strip next time.


could I do it with the cover on?

provided I drill the cover first?
Author:  WantOne [ Sat Mar 15, 2008 2:16 pm ]
Post subject: 
Those things the tool guy was talking about are probably called a keen sert
http://www.circletrack.com/techarticles ... to_05.html

I found one at work yesterday on the floor and had to spend about an hour trying to find out where it was from...... Still haven't worked it out.
Author:  drmini in aust [ Sat Mar 15, 2008 2:22 pm ]
Post subject: 
mini-dunger wrote:
drmini in aust wrote:
Now it's stripped the hole is 5/16" diameter, perfect size to tap out to 3/8 UNC.
Tap it out, drill the hole in the cover to 3/8, and Bob's yer auntie's husband. :wink:
3/8 thread is harder to strip next time.


could I do it with the cover on?

provided I drill the cover first?

Yes you can, just don't drill too deep.... you just want the cover to be 3/8... :lol:
Author:  miquain57 [ Fri Mar 21, 2008 10:06 am ]
Post subject: 
Doc,

I am about to start my mini project and have been thinking about buying a tap and die set.

do i buy UNF or UNC or both?? :-S

Thanks
Author:  Mick [ Fri Mar 21, 2008 10:26 am ]
Post subject: 
You will need both UNF and UNC for the car. Although you can get a few individual ones of each type and not be too concerned with the rest.

1/4, 5/16 and 3/8 in both UNC and UNF will get you through the car no problems on their own. About 80 percent of all the threads you will encounter will be 5/16 UNC or UNF.

BTW: If you have a stripped 5/16 UNF thread, you can purchase the helicoil to fix this (about a dollar each from repco or bursons etc) and use a 3/8 UNF tap to prepare the hole for the insert. I believe this is the only size and thread size on a mini you can do this without a specialist tap, but 5/16 is a useful size being the most common.
Author:  drmini in aust [ Fri Mar 21, 2008 10:32 am ]
Post subject: 
All the gearbox threads are UNC. `Most' engine threads are UNF.
The thread you stripped is 5/16 UNC. Just go buy a decent 3/8 UNC 2nd (intermediate) tap, stay away from the crappy cheapo sets.
I only buy taps as I need em... :wink:
Author:  TheMiniMan [ Fri Mar 21, 2008 11:56 am ]
Post subject: 
The general "Rule of thumb" is to use the fine threads in steels ,,, & a slightly longer coarse thread type in alloys

Make sure it`s all nice & clean, spray both the new bolt & the tread in the case with lockquick primer & let sit for a while (as on the instructions written on the can of lockquick),,, then a dab of locktite "Nut lock",,, or "thread lock"

tighten it up & Bob`s your Aunty :-)

Some guys even drill a small hole in the botl head & use tie wire to make sure that it doesn`t come out even if it loosens at a later date & on my race cars i weld 2x tabs on,,, one on the lower pipe & one onto the uper piece & then use a spring like on a go-kart pipe to make sure that even if the bot falls out then at least the pipe can`t fall off

insurance is such a good thing in the long run
Author:  Wombat [ Fri Mar 21, 2008 12:24 pm ]
Post subject: 
I've got a doggy sump drain hole - original UNC thread has had a UNF thread forced into it and it's missing some bits on the edge. What should I do with it? Here is a picture of the hole and the two plugs I've got.

Image

Image
Author:  drmini in aust [ Fri Mar 21, 2008 12:48 pm ]
Post subject: 
Wombat wrote:
I've got a doggy sump drain hole - original UNC thread has had a UNF thread forced into it and it's missing some bits on the edge. What should I do with it? Here is a picture of the hole and the two plugs I've got.

Image

Image
I would get a 5/8-11 UNC tap and clean it back out.
If there are not enough threads left to hold the plug then, I would get it helicoiled.

<edit> that other plug looks like a 3/8 BSPT to me, they are about .010" smaller than 5/8. :wink:
Author:  Timbo [ Fri Mar 21, 2008 7:33 pm ]
Post subject: 
I had one that was stripped, I went to an engineering place and they tapped it for the next size up. They had a rack of sump plugs for that exact job. Cheaper than a helicoil.

Tim
Author:  drmini in aust [ Fri Mar 21, 2008 9:27 pm ]
Post subject: 
We bought one once (in a $20 van) with the casing broken away that had a lump of hardwood bashed in there, it never leaked a drop. :lol:
It's an engine stand now.... 8)

Tapping it out to take a standard plug is good, but I'd drill a hole and press or araldite a magnet in there. :wink:
Author:  Wombat [ Fri Mar 21, 2008 9:43 pm ]
Post subject: 
drmini in aust wrote:
Tapping it out to take a standard plug is good, but I'd drill a hole and press or araldite a magnet in there. :wink:


I think that is what someone has done with the plug on the left as the magnet can be pulled out of it.
Author:  drmini in aust [ Fri Mar 21, 2008 9:53 pm ]
Post subject: 
Gentle press fit better lasting than araldite, sitting in hot oilz.... :wink:
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