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#46 Nightrain

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Posted 29 March 2009 - 10:30 AM

READ THE ABOVE posts, I'm Not getting into it again. I have told you all what it is, shown you the *melonsing* tap and the evidence from the Original BMC Manual..............some people you just can't teach.

#47 bigmotherwhale

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Posted 29 March 2009 - 10:42 AM

mra minis, please read the thread from the begining, its not unf its UNS, weve been through this and its getting old ;)

sorry jn1702 bet you didnt think youd start ww3!

just use a flywheel bolt and a dremel, cut a notch all the way down on both sides, at least this way you will know your putting the right thing down the hole, tho if i were going to tap a crank i would use a whitworth form that is finer than usual hope i worded that ok

Edited by bigmotherwhale, 29 March 2009 - 10:48 AM.


#48 MRA

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Posted 29 March 2009 - 10:57 AM

A 'respected engine builder' in Leicester told me to use 5/8 UNF BUT 16 tpi ........ thats what he told me it was.... 5/8th unf is normally 18TPI

Rob



I was simply referring to the above post !

#49 MRA

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Posted 29 March 2009 - 11:07 AM

Ok, the book says Whitworth, how old is this information ? how up to date is this information ? and how many of you out there are working with crankshafts that are actually that old ?

After all how many of you would have thought that CV joints have been metric M22 for quite some time and not as supposed to be 7/8" UNF ???

#50 Nightrain

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Posted 29 March 2009 - 11:14 AM

Ok, the book says Whitworth, how old is this information ? how up to date is this information ? and how many of you out there are working with crankshafts that are actually that old ?

After all how many of you would have thought that CV joints have been metric M22 for quite some time and not as supposed to be 7/8" UNF ???


How many times did rover change there tooling to alter the crankshaft then ? They didn't even change it to metric........
Ball joints made in china could well be M22, but Im still using my old stock of original's.

#51 Ethel

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Posted 29 March 2009 - 11:55 AM

There's no basis for an argument here. The thread in a crank can only be to one specification - though that specification may have changed at some point in history. Also, like any good historian, we shouldn't rely on any written on oral evidence when he have the hard evidence still available. A shadow graph or 3 sounds like irrefutable evidence - whatever the dimensions are shown to be is what they are, any argument over whether you want to call it Whitworth fine or UNS becomes just semantics other than asking for a tap to produce the same profile.

Any thoughts on why BMC chose such an odd thread, could it have been to stop punters using anything other than a bolt of proper specifications in such a critical high load area?


Next discussion: KPI of Metro swivel hubs, my opening bid is 11.5 degrees ;)

#52 monkey

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Posted 29 March 2009 - 12:03 PM

Heya, im a bit of a simpleton when it comes to "Whitworth" and "UNF" etc, im the kinda guy who if it fits, i screw it in... so going from that, ot settle the argument, can you not get a bolt that goes into the hole in question, and then figure out what thread that is, and make a tap to suite.. or is that to simple? Like i say, i dont really pretend to know about different threads, just throwing my tuppance in.

#53 Ethel

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Posted 29 March 2009 - 12:24 PM

Monkey,

The problem would be the same as me putting my size 7 feet in size 8 shoes, sure they'll fit on but they'd be more likely to fall off 'n give me blisters.

#54 MRA

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Posted 29 March 2009 - 01:45 PM

Ok, the book says Whitworth, how old is this information ? how up to date is this information ? and how many of you out there are working with crankshafts that are actually that old ?

After all how many of you would have thought that CV joints have been metric M22 for quite some time and not as supposed to be 7/8" UNF ???


How many times did rover change there tooling to alter the crankshaft then ? They didn't even change it to metric........
Ball joints made in china could well be M22, but Im still using my old stock of original's.



I didn't mention Ball joints......... where did that come from ?

CV joints made by the factory and several OEM's that supplied the factory where and still are made with an M22 Metric thread, and I would be interested in checking yours ? I was quite amazed to find this out myself........ as most of you I always believed that CV's where Imperial, however I can show you one that is over 20 years old and Metric ??? Oh and NOT made in China, Italy or Spain but in the UK, by GKN

Ok I know that this is off post, however what I am trying to say here is check don't assume that which is written in a book is correct.

#55 monkey

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Posted 29 March 2009 - 01:58 PM

Monkey,

The problem would be the same as me putting my size 7 feet in size 8 shoes, sure they'll fit on but they'd be more likely to fall off 'n give me blisters.



Fair play make sense ;)

#56 1984mini25

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Posted 29 March 2009 - 02:20 PM

mra minis, please read the thread from the begining, its not unf its UNS, weve been through this and its getting old :wacko:

sorry jn1702 bet you didnt think youd start ww3!

just use a flywheel bolt and a dremel, cut a notch all the way down on both sides, at least this way you will know your putting the right thing down the hole, tho if i were going to tap a crank i would use a whitworth form that is finer than usual hope i worded that ok


That’s fine to do if you just want to clean good treads, but completely useless you want to clean up and remove damaged threads.

I tried that method of cutting a few slots down a perfectly good flywheel bolt so I could bolt on a flywheel/clutch assembly to an engine to make dismantling it a little easier. Unfortunately that was when I had found whoever had had removed the old flywheel (I bought just the short block and head as I already had a suitable gearbox, clutch etc I could use) had used the puller, but without the cone to protect the tread in the end of the crank. ;)

Yes the bolt did go in, with some force, but certainly didn’t help matters, as all it did was to further damage the tread in the crank and completely mash the bolt it’s self.
Even more annoyingly after stripping the engine down a bit more the rest of the crank seamed fine and would of got away without a re-grind (I’m on a tight budget), unlike the other spare cranks with good threads I had.

I had been meaning to get in contact with guesswork as to whether or not it could be saved with the cost of the tap from a mini specialist compared to a re-grind, etc… but like most things minis I got distracted…

#57 Dan

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Posted 29 March 2009 - 03:46 PM

I just read back and noticed what Nightrain was alluding to before, something that escaped my attention. Yes I accidentally transposed the angles for Whit and Unified in an earlier post, that was just a typo and I'm sorry. If I've done it more than once then I'm sorry for that too. It occurs to me that since I've been looking back at that I may have also transposed which tap would destroy which thread and which would clear. Again I apologise. And Nightrain I'm not saying you're 'talking *poop poop*'. I'm just questioning what you've said is all, not attacking you. You however are accusing pretty much every respected engine builder, many good engineers and many members of the forum of being bodgers and I think that deserves a little investigation before it is accepted.

As I said above I thought I had a flywheel bolt in the garage that I could check but it turned out I had none so today I got a couple at Brooklands. I don't have the specific special pitch taps in question but I have others of both Whit and Unified that run 16 tpi (3/8 Whit and 3/4 UNF) and while neither will be exactly right because the major diameter is wrong (throwing the maths off for the rest of the calculation) they both sem to fit the bolt thread as badly as each other. Neither is obviously wrong. This has just confused me further so I won't bother again.

As mentioned above it would be a good idea to ask some manufacturers of cranks and the various uprated crank bolts that are available what thread they use and this was my intention. I'll get on with it tomorrow. I really want to know the answer to this now and if GW is going to order us a batch of taps we need to make sure it's the right one.

As for the use of Metric threads on CV joints, as I think I mentioned above metric and Unified are actually the same thread designed to the same form and calculation. If the major diameter for any pair of metric and imperial threads (if specified to the same pitch) falls within the tollerance of the thread you will never be able to tell the difference between the two. 7/8" is 22.225mm so there's very little in it. This must be a special pitch Metric thread though if it is the case because metric course specifies 10.16 TPi and metric fine specifies 16.93 TPi for 22mm, while 7.8 UNF specifies 14. All large CV joint nuts are interchangeable so the pitch must be the same on all of them.

#58 Nightrain

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Posted 29 March 2009 - 04:48 PM

LOL no idea where balljoints came from sorry about that mra, must have been reading another thread........

Seeing as I have provided documented and photographic evidence, to confirm it's a Whitworth thread. Can anybody provided any evidence to show that (a) it's a UNS thread or (b) It's not a Whitworth fine thread. And Im not talking about word of mouth or internet references.
Until such proof is provided I ain't got anything else to say on this subject.

#59 widerim_pickup

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Posted 29 March 2009 - 05:06 PM

http://www.engineeri...bcat.asp?id=281

This is where i got one from, 67.50plus vat and delivery. Right near the bottom. 5/8 16tpi

Edited by widerim_pickup, 29 March 2009 - 05:07 PM.


#60 MRA

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Posted 29 March 2009 - 05:15 PM

LOL no idea where balljoints came from sorry about that mra, must have been reading another thread........

Seeing as I have provided documented and photographic evidence, to confirm it's a Whitworth thread. Can anybody provided any evidence to show that (a) it's a UNS thread or (b) It's not a Whitworth fine thread. And Im not talking about word of mouth or internet references.
Until such proof is provided I ain't got anything else to say on this subject.



This thread (no Pun intended) has raised one big question mark, the older mini manuals do indeed show that a Whitworth form tap should be used, this is not contrary to what I have said above, as I have previously had shadowgraph analysis performed on a crankshaft, I think that one of the following applies,

a) The company I sent it out to made a mistake.
b) Possibly someone had already used a UNS tap to "rectify" a fault.
c) It has in the past been changed to UNS, may be this coincides with the A+ changeover.

So because there is an element of doubt, I have been busy preparing some more samples to resend out for analysis, I will confirm either way what the analysis says........ Rest assured I have two companies in mind that can do ISO9002 quality and dimensional checks.

Either way Taps can be made available for either cleaning or recutting the correct thread form wether that be Whitworth 16tpi or UNS 16tpi .... 5 to 10 working days should be sufficient.

Edited by mra-minis.co.uk, 29 March 2009 - 05:50 PM.





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