nuts

J

jotacole

Full member
Hi
  Does anyone know where i can get the crankcase blind nuts for my laverda 1000, from in England.
Also they must be stainless steel.

                                THANKS RUSS
 
I have found Motalia good to deal with. One of the packages of stainless steel goodies mailed to me here in Canada from Motalia in the UK broke open during shipping and most of the items fell out before the package got to me. Motalia replaced all the missing items without a fuss, and the items have always been high quality.

http://www.motalia.com/

Paul LeClair
 
Are the original nuts something special? They look to me like ordinary M8 dome nuts (also known as acorn nut or cap nut).

They are available from nut and bolt suppliers supplier in a variety of options, including class 6 steel; chrome, cadmium or nickel plate; 304 or 316 stainless.

Cam
 
OK, that's interesting. Mine are dome nuts and I'm pretty sure they're original. The cases haven't been apart before. The previous owner bought the bike new and the only disassembly he did was to bolt on Jota spec parts, which isn't a crankcase apart job. Looked like original factory gorilla snot on the case joint too.
 
If you were in Aus, I'd recommend Coventry Fasteners, I'm sure the UK has the equivalent.
 
Cam
if your bike has dome nuts then the studs must have been shortened, as the need the  length of thread, both in the case (very long) and in the nut (not so long) to withstand the required torque and stresses of running, temperature changes etc.

I believe that Motalias nuts are made in house on his CNC machine, and so are a cut thread, where as the originals (in BZP steel) may be rolled threads and hence stronger
CLEM
 
CLEMTOG said:
Cam
if your bike has dome nuts then the studs must have been shortened, as the need the  length of thread, both in the case (very long) and in the nut (not so long) to withstand the required torque and stresses of running, temperature changes etc.

I believe that Motalias nuts are made in house on his CNC machine, and so are a cut thread, where as the originals (in BZP steel) may be rolled threads and hence stronger
CLEM
Click to expand...


Could you please explain that?

                                    Dave
 
dja981 said:
Could you please explain that?
Dave
Click to expand...

Rolled cold formed threads are significantly stronger than the cut version, you can see that the grain structure is compressed, giving higher thread yield strength, smoother surface finish, hardness and wear resistance.
The world seems to be set up for cutting threads though as the process seems to be more flexible.

image-threadRolling2.jpg

 
Ralph makes the nuts himself from hexagon stainless bar, externally machined to give the required look and bevel and tapped internallyto cut a thread,  but then I could be wrong,

original steel ones (bright zinc plated) are probably made by a machine whicvh "rolls" the thread using a tool to deform the inside to a thread rather than cut it, this give a better grain struture and might be stronger, I have seem machines making externally threaded items (eg studding) by this method, but I havent seen them doing internally threaded, so again I could be wrong

Never forget stainless is actually quite soft (elasticity wise), so is not good for instalation where "stretch" might take place.
CLEM
 
According to the workshop manual, the M8 crankcase studs are torqued to 3.5 m.kg (34 Nm or 25 ft.lb). Seems a bit much for a M8 thread. If you look at fastener torque charts, M8 class 8.8 thread maxes out at about 28 Nm (dry) or 22Nm (lubed). What's the general consensus on torque for these studs among the experienced engine builders?

Cam
 
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