Gearchange noise

[roger mcnab]

hi
to get an approx size for the drill using a vernier measure from the bottom of the tap threadfrom side to side the should give a close drill size with coarse threads works fine should be fine with sump plug
cheers roger

[Skywatcher]

I’ve got the Minisport helicoil kit made by Vcoil, but no drill bit in box just tap? No instructions either?

You should find that the required drill bit size is written on the tap, off the top of my head it's 16.5mm but I'm away from home at the moment so can't confirm. I've actually done this a few times with the power unit in place, this is how I do it.
Jack the car up and bias it so it's higher on the near side and drain the oil.
Remove the offside tie bar as this gives you more room to manoeuvre.
Using blacksmith type drill bits, drill the hole to the right size, you will notice I have said drill bits, I use drills in .5mm increments, this tends to stop the bit from grabbing and wrecking the whole operation, also coat every drill bit with grease as the stops ingress of swarf into the box.
Next cut the helicoil down to the required thread count, if you have 1D coils then 1 coil off should work, do not take the coil off the tang side obviously.
The tapping part is pretty easy as the tap should be ground with a taper, so will follow the drilled hole.
Next screw the helicoil in using the pronged tool supplied, you won't need a lot of force, screw it in so the coil is below the face of the drain hole.
Once in place you need to remove the tang, do this with needle point pliers, so you don't loose it in the box
Job complete.
One thing I do is give the helicoil a dab of loctite before fitting it and let it go off
I use a dremel type tool to cut the coil off


Skywatcher

[Jasonking]

Thanks for that, yes will be doing repairs with engine in situ, sorry for my ignorance but using drill bits incrementally? Not quite sure how you mean?

[Exminiman]

Here you go from above post from Skywatcher
“ Using blacksmith type drill bits, drill the hole to the right size, you will notice I have said drill bits, I use drills in .5mm increments, ”

[Skywatcher]

Thanks for that, yes will be doing repairs with engine in situ, sorry for my ignorance but using drill bits incrementally? Not quite sure how you mean?

I apologise for not being more expansive, the reason for using incremental drill bits ie say starting at 14mm then 14.5mm etc is that you will find if going straight to the correct size the drill bit will grab/ jam and try to rotate the drill instead of the drill bit rotating, this can lead to the hole not being drilled straight. I have found using the incremental drill bits so only increasing the hole by .5mm at a time the grabbing scenario is greatly reduced. Also try not to hold the drill too tightly and dont use a lot of pressure, you will find a sharp drill bit will just glide through.
You can buy cheap blacksmith drill bits off ebay ( drills UK) so keeping the cost down.

Skywatcher

[Ronnie]

Going from a stripped 5/8" dia to 16.5mm is an increase of 0.026". The correct tool to use is a multi flute core drill https://smet.org.uk/news/2023/core-drills/ especially if you are not removing much material, a standard drill bit will grab and try to screw itself into the soft material unless you hold it back (virtually impossible unless using a drill press).

[Peter Laidler]

That was interesting Ronnie, for a couple of reasons. First, about multi flute drills. Seen them but never actually used one in anger. I'm an end mill man - or was until read this.

Next is that I see that it was written by a Scottish Model Engineering group. These model engineers are GOOD people to know if you have any living near. They're ALWAYS willing to lend a hand and offer engineering advice and make small parts for a bit of beer money. When you see some of their model engines and locomotoves, you see why. My friend Terry Mitchell, the Chief Engineer at the MG works was a pure master at the art. He designed the complicated (?) oil pump cover and remote filter system for the MGB GT V8

[Skywatcher]

Going from a stripped 5/8" dia to 16.5mm is an increase of 0.026". The correct tool to use is a multi flute core drill https://smet.org.uk/news/2023/core-drills/ especially if you are not removing much material, a standard drill bit will grab and try to screw itself into the soft material unless you hold it back (virtually impossible unless using a drill press).

May I kindly ask where you bought yours from as all the ones I have are MT , and also where did you manage to find one in the correct size or did you have it specially ground?

Skywatcher

[Ronnie]

Going from a stripped 5/8" dia to 16.5mm is an increase of 0.026". The correct tool to use is a multi flute core drill https://smet.org.uk/news/2023/core-drills/ especially if you are not removing much material, a standard drill bit will grab and try to screw itself into the soft material unless you hold it back (virtually impossible unless using a drill press).

May I kindly ask where you bought yours from as all the ones I have are MT , and also where did you manage to find one in the correct size or did you have it specially ground?

Skywatcher

I have had my core drill for years it was purchased to repair a Linde forklift hydraulic pipe that kept getting damaged (cheaper than buying a new makers part), I don't remember where I bought it, I used to attend a lot of liquidation auction sales, or second hand machine tool suppliers, it wasn't bought new. Keep your eye on the likes of https://www.ebay.co.uk/sch/i.html?_from ... l&_sacat=0 ask around local machine shops they may be able to help. As has been mentioned earlier in this thread some of these items are non standard parts, and therefor expensive new, compare the price of a 3/8" UNF tap against a left hand thread same amount of material
https://www.ebay.co.uk/itm/274412716549 ... CZA&edge=0 about 0.007" over size

[Peter Laidler]

Just a minute chaps....... Surely there's something wrong happening here. Unless I am sadly mistaken in my engineering inexperience that I freely admit....... By pulling out - or stripping - the 5/8" threads in the gearbox, you have effectively made the hole the o/d which in this case is 5/8".

All Jason needs to do now is to tap THAT hole which is the new CORE diameter - or tapping size - for the 5/8" UNC helicoil tap and thread.

The HELICOIL tapping size is TWICE the depth of the thread that you've just pulled out. Tap that stripped hole, insert helicoil and outer half diameter of helicoil insert threads into newly cut thread.
INNER half of the helicoil insert now acts as the new steel and stronger 5/8" UNC thread.

No need to drill anything unless you simply want to ream out or clean any residual thread left at the inner end of the stripped drain plug hole.

My helicoil experience is limited to helicoiling and re-helicoiling rotating Dillon minigun casings and mountings that vibrate themselves to bits!

Got my steel helmet and flack jacket on, awaiting the incoming mortars

[Stopped-again]

I had to repair the sump plug thread, admittedly with the gearbox out of the car which made the job easier, I got an M20 bolt, (that’s a bolt with a bit of thread and a bit of plain shank, not a set screw that’s threaded all the way down) about 100 mm long, cut the hex head off and hold the plain shank in a lathe chuck (or find someone who’s got a lathe to do it for you) drill the centre of the bolt out to the correct diameter to tap 5/8-11 unc. (13.5mm) and then cut the thread. Cut off a length of the now M20 outside and 5/8 inside threaded bush (just over the length of the threads on your drain plug) Now drill the damaged drain plug hole 18.5mm and tap M20. Your newly made threaded bush can now be put onto the drain plug (put some grease on the threads) then the outside can be treated to a few drops of the strongest Loctite you’ve got. Screw the plug and newly made insert into the gearbox and leave for a while to let the Loctite go off and then the drain plug can be tightened to the usual torque, job done (and cheaper than the Wurth insert but similar idea) If you want to borrow the taps pm me with your name and address and I’ll post them to you.

[Polarsilver]

My problem with an in situ sump plug thread repair..i had some excess gearbox internal casting that bottomed out any attempt to restore the sump plug thread with a conventional thread Tap.. solution with the gearbox off the engine useing a Dremel & Burr this excess internal gearbox casting was easy cleared away . next the Magnetic Pin question .. my solution purchased from MS their part no DP1 extra long Magnetic sump plug took out the extension magnetic rod part & fitted into the now drilled blind hole in the center of my oversize thread sump plug.. worked out ok & does the job.

[Skywatcher]

I had to repair the sump plug thread, admittedly with the gearbox out of the car which made the job easier, I got an M20 bolt, (that’s a bolt with a bit of thread and a bit of plain shank, not a set screw that’s threaded all the way down) about 100 mm long, cut the hex head off and hold the plain shank in a lathe chuck (or find someone who’s got a lathe to do it for you) drill the centre of the bolt out to the correct diameter to tap 5/8-11 unc. (13.5mm) and then cut the thread. Cut off a length of the now M20 outside and 5/8 inside threaded bush (just over the length of the threads on your drain plug) Now drill the damaged drain plug hole 18.5mm and tap M20. Your newly made threaded bush can now be put onto the drain plug (put some grease on the threads) then the outside can be treated to a few drops of the strongest Loctite you’ve got. Screw the plug and newly made insert into the gearbox and leave for a while to let the Loctite go off and then the drain plug can be tightened to the usual torque, job done (and cheaper than the Wurth insert but similar idea) If you want to borrow the taps pm me with your name and address and I’ll post them to you.

Just asking, but are you sure you drilled out the hole to 18.5mm? Normally a M20 bolt is on a 2.5 pitch, and in metric to find the correct tapping drill or something very close you just subtract the pitch from the diameter ie 20-2.5=17.5.
Spider from these parts has what I believe is an excellent way of repairing sump plugs, but you do need machinery to make it which is no good to a guy with just hand tools.

Skywatcher

[Stopped-again]

Sorry could’ve been17.5mm was doing it from memory while sat on the sofa.just looked it up and yes should’ve said 17.5mm, 18.5 for metric fine 1.5 pitch.

[Peter Laidler]

Skywatcher, tell us where you are in the world. Cllearly not anywhere near us.........!!

[Skywatcher]

Skywatcher, tell us where you are in the world. Cllearly not anywhere near us.........!!

Go on then

Skywatcher