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 Post subject: Flywheel bolt thread tap
PostPosted: Tue Sep 19, 2017 2:35 pm 
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998cc
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Joined: Mon Jul 07, 2014 12:36 pm
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Location: Bentleigh, Melbourne
I've a damaged thread in the crankshaft that needs cleaning up. The flywheel bolt is not cross threading but the threads are being damaged. Does anyone in Melbourne (I'm in the S.E. suburbs) have a tap I could borrow for a few hours? It's a weird one, sort of 5/8 16 TPI Whitworth but not quite. It seems to be a one off thread that only the English could dream up...

Thanks

Michael

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67 Deluxe
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1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
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PostPosted: Tue Sep 19, 2017 2:44 pm 
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848cc
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It's a 5/8 UNS thread, very uncommon thread...I can't help you with a tap but just giving you the thread.


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PostPosted: Tue Sep 19, 2017 3:22 pm 
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1360cc
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Location: Sthrn HiLoLands, NSW, Australia
this (from Wiki) may help as well...

Taps and dies are tools used to create screw threads, which is called threading. Many are cutting tools; others are forming tools. A tap is used to cut or form the female portion of the mating pair (e.g., a nut). A die is used to cut or form the male portion of the mating pair (e.g., a bolt). The process of cutting or forming threads using a tap is called tapping, whereas the process using a die is called threading.

Both tools can be used to clean up a thread, which is called chasing. However, using an ordinary tap or die to clean threads will generally result in the removal of some material, which will result in looser and weaker threads. Because of this, threads are typically cleaned using special taps and dies made for this purpose, which are known as "chasers". Chasers are made of softer materials and are not capable of cutting new threads, however they are still tighter fitting than actual fasteners and are fluted like regular taps and dies (to provide a means for debris like dirt and rust to escape). One particularly common use is for automotive spark plug threads, which often suffer from corrosion and a buildup of carbon.

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PostPosted: Tue Sep 19, 2017 3:51 pm 
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Location: Wodonga - Vic/NSW border
find another bolt and make it into a chaser?

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PostPosted: Tue Sep 19, 2017 4:13 pm 
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998cc
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Location: Bentleigh, Melbourne
Hi Simon,

Tried that, works as in you can thread it in all the way ok but damages the threads. So it will still damage a good bolt. The one (damaged) that came out held the flywheel on ok. Took a bit of effort to remove the flywheel.
I could reuse it with locktite but that would be a bit of a bodge and would prefer not to go there...

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..


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PostPosted: Tue Sep 19, 2017 5:19 pm 
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Joined: Fri Mar 19, 2004 6:19 pm
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Location: near Baulkham Hills, NSW
Someone out here had these taps for sale.
Might have been Minis plus?

I made a chaser from an old flywheel bolt, it's fine for getting wasps nests or Loctite out but won't clean a damaged thread up.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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PostPosted: Tue Sep 19, 2017 5:37 pm 
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1275cc
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Location: Wollongong, NSW
drmini in aust wrote:
Someone out here had these taps for sale.
Might have been Minis plus?

I made a chaser from an old flywheel bolt, it's fine for getting wasps nests or Loctite out but won't clean a damaged thread up.


https://www.minisplus.com.au/classic-mi ... es-18g1128
https://minikingdomonline.com.au/produc ... shaft-tap/

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PostPosted: Tue Sep 19, 2017 5:46 pm 
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998cc
998cc

Joined: Mon Jul 07, 2014 12:36 pm
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Location: Bentleigh, Melbourne
Yikes! Big bucks for something that'll only ever be used once... :-(

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..


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PostPosted: Tue Sep 19, 2017 7:01 pm 
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848cc
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Big $$$ yes but cheaper than another crank and engine rebuild...


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PostPosted: Tue Sep 19, 2017 7:06 pm 
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Location: near Baulkham Hills, NSW
How did the crank get damaged?
I always sit a short 5/8 bolt with the threads turned off in there when using the flywheel puller. To protect the crank.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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PostPosted: Tue Sep 19, 2017 8:35 pm 
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998cc
998cc

Joined: Mon Jul 07, 2014 12:36 pm
Posts: 608
Location: Bentleigh, Melbourne
Because the last time the flywheel was removed some dick in a rush (me) forgot to put the fitting in the the crank to protect the threads. Realized halfway into the process but have obviously chewed up the first couple of threads in the crank. Contemplating using the existing bolt with locktite because it held up ok before. Seems like a dicky thing to do though...?

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..


Top
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PostPosted: Tue Sep 19, 2017 8:47 pm 
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Joined: Fri Mar 19, 2004 6:19 pm
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Location: near Baulkham Hills, NSW
You could put the crank in a lathe and bore the first couple of threads out that are damaged. Cheaper than buying that tap!
There is plenty of thread engagement length without them.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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PostPosted: Tue Sep 19, 2017 9:46 pm 
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848cc
848cc

Joined: Sun Apr 17, 2016 9:33 pm
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Location: Melburn
Try Bryan at Link?


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PostPosted: Wed Sep 20, 2017 7:30 am 
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998cc
998cc

Joined: Mon Jul 07, 2014 12:36 pm
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Location: Bentleigh, Melbourne
I've known Bryan for 35 years! First met at Link when I was an 18 year old with my Mini K, how time flies...
He would have lent it to me yesterday but he can't find the bloody thing! He's looked for it several times..
Doc, the engine is in the car, it was meant to be a simple primary gear seal replacement exercise.
Removing the engine and stripping it down is the last thing I want to do!

What do people think of the idea of reusing the existing bolt with locktite? As I said before, it was tightening up ok and the flywheel took the usual amount of effort to remove. Would it be madness to go that route?

Thanks

Michael

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..


Top
 Profile  
 
PostPosted: Wed Sep 20, 2017 7:34 am 
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Location: near Baulkham Hills, NSW
Loctite 262 will hold it. I and others have used this for years rather than the current too soft locktab.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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