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Locking engine to tighten nuts
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Alan.Moore
Leicestershire
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September 9, 2020 - 8:36 pm
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Gents

Got to the stage of putting the engine back together. I need to lock it so I can tighten the alternator nut, engine sprocket nut and gearbox sprocket nut.

I've made a tool to lock the clutch basket to the gearbox mainshaft using a plain and friction plate bolted together. The steel arm wedges against the engine stand base so everything is locked up solid. I've already tighten the clutch centre nut up.

I know I can put the conrod gudgeon pin back in and use a piece of rod through it to lock the conrod against the crankcase mouth BUT I've just fitted a new caged needle roller small end bearing and I am a bit apprehensive that it may get damaged. Do you guys use the rod through the little end method without damaging the needle little end bearing?

My thoughts are to replace the old primary chain and then assemble the engine sprocket on its taper. The clutch locking tool should then allow me to tighten the engine sprocket nut. Once this is done i can put the alternator rotor back on and tighten that. 

Same with the gearbox sprocket, if I put the gearbox into first the clutch tool should lock the mainshaft.

Just want to check that there is not a 'weak link' in my thinking. 

And for the eagle eyed I did put the engine sprocket nut on the clutch mainshaftdunno...they are the same thread. Its now got the correct one on.

Cheers

Alan

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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mikef
Chatham Kent
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September 9, 2020 - 9:25 pm
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Hi Alan.
      I have used the gudgeon pin method of locking the crank in the past, it worked and did no harm. It is actually mentioned in one of the BSA manuals to do that. I must admit that I felt a bit uneasy about doing it though.
I have now made a chain wrench using an old primary chain that fits around the engine sprocket to do the nut up.
I also made another chain wrench from a length of old rear chain to lock the gearbox sprocket.
I think there are special spanner type tools available that fit around the sprockets, maybe Rex Caunt sells them. I have seen them somewhere.
Mike.

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Alan.Moore
Leicestershire
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September 9, 2020 - 11:44 pm
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Mike...thanks for the reply

I also read it in the B175 manual where it suggests using the gudgeon pin.... but a lot of their later manuals contain what appears to be copy and paste from earlier versions and, whilst it would be OK with a pin with a solid bronze little end bush, I'm not so sure with a needle roller.

I've seen a  spanner tool that has serrations that fit over the clutch splines and locates in the slots in the basket...basically what my tool does.

SDC13938.JPG

I'm Ok with putting an old primary chain on and tightening the engine sprocket nut using the above method of locking (there is no torque setting for this nut in the list in the manual so I suspect,. being on a taper, it does not need a lot of torque.

I can make a chain wrench for the final drive sprocket nut.

However, what do you use to lock it (other than the pin) to do the alternator rotor nut up?

Cheers

Alan

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1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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Sponge
Lancashire (A chip shop somewhere near Preston)
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September 10, 2020 - 8:05 am
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I used to use a Premier drumstick through the small end eye to tighten up the alternator nut. Drumsticks are made of very hard wood but not hard enough to damage anything. Over time the drumstick got chewed up so I bought a tool from Rex Caunt - happy days - now I never have clutch locking and nut tightening problems again.  

As an aside: I have been horrified to see people putting a tommy bar through the small end eye and letting it bear directly against the crankcase faces. The end result is damage - even if you cannot see it - these crankcase faces will leak air and cause incessant problems and teh small end bearing will get crushed and need replacement.  However, all is not lost - SRM in Aberystwyth can re build and re-face your crankcase mouth - its not cheap but it is possible and fitting a new roller bearing is not too difficult.  However you need to strip the whole engine down to bare cases to get this done at SRM and you need to get your cases to West Wales. 

The Rex Caunt tool is the best way forward - especially if you plan to do a fair bit of work on the 4 speed bikes.     

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Alan.Moore
Leicestershire
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September 10, 2020 - 3:57 pm
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The deed is done. I used the old primary chain and my clutch basket locking tool and got the engine sprocket nut tightened and then the alternator nut torqued up to the correct spec.

Cheers

Alan

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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AdrianS
Harlaston Staffs
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September 12, 2020 - 6:13 pm
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Rex has a double ended locking spanner which is very useful.

i am always wary about locking the engine with a bar through the little end. If you do use that method put some wood on the crankcase face.

i have used an impact wrench to lock the alternator nut. This is the way a lot of dealers do it. Don’t sack the torque up too high!

for the gearbox sprocket, it needs to be tight to stop it chattering on the splines and wearing the sprocket teeth 

( DAMHIK). You can wedge a lump of lead between the sprocket and the casing and the teeth will lock into the lead and you can then tighten the nut.

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Stoo63
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September 12, 2020 - 6:20 pm
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That's an extremely cunning ruse, Adrian. I just happen to have 25kg of lead from a roof that someone left lying beside a bin for 2 days. Better in my boot than in the bin lorry 🙂

 '55 D3 Battery; '58 Square Four (project); '59 D1 direct lighting plunger; '59 Tiger Cub; '60 5TA;  '76 FS1-E; '91 GTR 1000;  '97 Honda Sky SGX50.

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