Torque setting for yokes on 750 SF2

Important: - Never use stainless steel screws (V2A) in important areas such as the fork or housing cover!

1. they can get stuck in aluminium
2. less tensile strength = screws loosen faster (and lids leak)

I would choose the torque according to the quality of the screw (min. 8.8) and the diameter of the thread.
Or see: LAVERDA torque 1.jpg and LAVERDA torque 2.jpg

Thomas aus LAU
 
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Thomas aus LAU said:
Important: - Never use stainless steel screws (V2A) in important areas such as the fork or housing cover!

1. they can get stuck in aluminium
2. less tensile strength = screws loosen faster (and lids leak)

I would choose the torque according to the quality of the screw (min. 8.8) and the diameter of the thread.
Or see: View attachment 61754 and View attachment 61755

Thomas aus LAU
Click to expand...
Thank you, and thanks for the advice on stainless.
 
Thomas aus LAU said:
Important: - Never use stainless steel screws (V2A) in important areas such as the fork or housing cover!

1. they can get stuck in aluminium

Thomas aus LAU
Click to expand...
I hear this but from my experience it's never been a problem - I've had stainless holding the two halves of my 08 Goldlines for years - pulled them out to check them and they are still perfect - the zinc plated originals had already started to show corrosion when I replaced them. Ditto in many other parts on the bike. Maybe in Europe where they salt the roads it's a bigger issue?
 
piranha-bro2 said:
I hear this but from my experience it's never been a problem -......
Click to expand...
I am not an official stainless steel specialist, you could read >30 pages about this topic.

The fact is that there is not one type of stainless steel, but different ones. Some are more problematic in combination with aluminum such as X12CrNi18-8 or 1.4301 (X5CrNi18-10), others such as 1.4401 (X5CrNiMo17-12-2) are not. Who knows exactly what type of stainless steel the screws are made of?

Some stainless steel seems to damage the oxide layer of the aluminum, which then leads to problems in connection with salt, aggressive cleaning agents or environmental influences. Why take the risk, when nowadays you can have all your screws re-galvanised or nickel-plated for very little money? They last longer than we live! And the stretched, tightened normal screws still keep the housing cover tight, even if a seal has settled a bit.

Thomas aus LAU

IMG_6968.jpg IMG_6976.JPG
 
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Important: - Never use stainless steel screws (V2A) in important areas such as the fork or housing cover!

1. they can get stuck in aluminium
Click to expand...
I've used them on the covers for decades and never had this problem.
The trick is to use a thin layer of copper paste.
I'm with you on not using them on important connections, like brakes.
If you, e.g., fasten the calipers with stainless steel bolts, you will most
likely not pass the TUEV (mot) here in Germany.
 
Re-galvanising or other plating costs a bloody fortune here. I have found electrolysis in aluminium from plated steel bolts plenty of times. Sometimes engine mounting bolts on old bikes that have been very reliable have to be cut out, an absolute bastard of a job. My habit is anti seize paste on virtually anything that can happen to.
Nolacus, make sure it is clean and dry in the triple clamp as well. I have had the fork tubes driving themselves up through the clamp when racing, they need to be well clamped, I would go with Thomas´ suggestion from the chart for bolt size and material if using a torque wrench.
 
While stainless steel certainly isn't suitable for high tensile or high safety-margin applications as in aviation, or racing, and not reccommended for use in aluminium alloy, it rarely poses a problem on our bikes if measures are taken to avoid/prevent corrosion. Screwed into and tightened in alloy in a dry state, the stainless can gall and damage the alloy thread, a suitable anti-sieze lube will avoid that.

Not a bad idea to use anti-sieze with mild steel screws and bolts in alloy either! Especially zinc-plating will react with aluminium under certain circumstances and can wreak havok in the threads.

BTW, max. torque for M10 in alloy is around 40N/m, I'd use a bit less with lube, but be carefull when doing up the yoke clamps. Quite common for these to give up and crack under excessive torque, maybe time to check yours?

While not explicitly reccommending the use of stainless, I've used it all over my bikes for decades without issues. Not very many screws that I remove from bikes deserve to be restored/re-plated due to prior ham-fistedness.

piet
 
I use stainless all over the bikes I rebuild, without anything on the threads without the slightest problem if and when I need to take the screws out. That includes caliper assembly screws, caliper mounting screws and the disc carrier mounting screws on my long suffering SF2.

I don't spend my time riding on salted roads, but it does happen.

Paul
 
On other bikes I had to repair the threads for the 750 alternator cover with HeliCoil inserts again and again. Felt more often with stainless steel screws. So I looked today at it under the microscope.
The threads are rolled during manufacture. With normal steel, this results in a relatively soft edge on the outside of the thread (pic. 1), where you can see that the metal has been pressed, and sometimes you can also see the individual layers or "metal plates".
Different with stainless steel. There is a precisely defined "hard" outer edge which, due to the brittle material, sometimes has sharp-edged "saw teeth" (pic. 2-4). Frequent unscrewing or screwing in of stainless steel screws thus inevitably wears out an aluminum thread.
To me, that's an understandable explanation. Unfortunately, the images are not 100% sharp when enlarged. You can see it better "live" on the monitor

Thomas aus LAU

WIN_20220201_09_10_16_Pro.jpg WIN_20220201_09_16_10_Pro.jpgWIN_20220201_09_10_56_Pro.jpgWIN_20220201_09_06_52_Pro.jpg
 
I went to remove the reservoir cap on the front brake master cylinder of my Kawasaki a couple of days ago (needed bleeding). The cap is held on by 2 x M5 countersunk Philips head screws. They're black steel and both of them were seized, probably due to corrosive action of the brake fluid. One came out with the use of an impact screwdriver, but the other refused to budge. The impact driver just stripped the guts out of the Philips slots. I had to resort to the use of a little cold chisel I have that's handy for such delicate butchery jobs.

I replaced them temporarily with non-countersunk socket head screws. But I'll buy some countersunk ones and I'll remember to use anti-seize grease when I put them in.

I was wondering whether stainless might be a better idea than black steel given the corrosive nature of brake fluid.

Edit: picture turned itself upside down when I attached it - bloody computers.

Kawasaki MC.JPG
 
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Thomas aus LAU said:
On other bikes I had to repair the threads for the 750 alternator cover with HeliCoil inserts again and again. Felt more often with stainless steel screws. So I looked today at it under the microscope.
The threads are rolled during manufacture. With normal steel, this results in a relatively soft edge on the outside of the thread (pic. 1), where you can see that the metal has been pressed, and sometimes you can also see the individual layers or "metal plates".
Different with stainless steel. There is a precisely defined "hard" outer edge which, due to the brittle material, sometimes has sharp-edged "saw teeth" (pic. 2-4). Frequent unscrewing or screwing in of stainless steel screws thus inevitably wears out an aluminum thread.
To me, that's an understandable explanation. Unfortunately, the images are not 100% sharp when enlarged. You can see it better "live" on the monitor

Thomas aus LAU

View attachment 61764 View attachment 61768View attachment 61767View attachment 61766
Click to expand...
100% correct Thomas.
S/S will strip aluminium threads in a heartbeat.
That last quarter turn to nip it up and buggar....:(
My 3c had all S/S casing bolts when I got it, didn't think anything of it.

They are all zinc plated steel now, as per original.

Cheers
Tom
 
Cam, a while back I heard that some Japanese bikes use a different head type, it looks like Philips but is NOT. Who knew, this was completely unknown to me
www.motorcycle.com

So You're Telling Me that's Not a Phillips?

After all these years of mangling screws on Japanese bikes, people still don't know the difference between Japanese and Phillips screwdrivers.
www.motorcycle.com www.motorcycle.com
 
Thanks Vince. Now that you mention it, it does ring a bell. I think I probably had that bit of info in some dark corner of my memory. But obviously buried deep enough for me not to recall it.
Not that it would have made much difference though because I don't have any JIS screwdrivers.
 
Who does, its why 100% of older bike riders own hammer hit Impact screwdriver kits, and we thought all Japanese engine case fixing were made from SOAP.
 
Those master cylinders are famous for stripping the screw heads. On any tight Philips screw my first tactic is to give the screwdriver a good whack with my plastic hammer. Next is to whack the impact screwdriver bit into it with the steel hammer before putting the impact driver on it and often I don´t need to hit the impact driver. The only #2 Philips we see her are either normal (PH) or Pozidrive (PZ) which have the little flutes between the main parts of the tip and the screws have the associated lines, as used by IKEA amongst many others. Using a normal screwdriver in PZ screws will easily wreck both the screw and the tip. With #1 or #3 Philips there seems to be all sorts of specification.
One for Cam. Why is it far more effective using a long screwdriver than a short one?
 
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