Stainless bolt kit - anything to look out for?

Oh shite ! The brake lever mount bolt (m8) is for the rear brake pedal, you'll be wanting to bleed the brakes now if you removed the banjo bolt in the picture. .
 
well - I didn't remove it, but it did leak some fluid until I realised what a fuck up I'd made. The brakes appear to work but the leaver almost reaches the grip which I don't think is good. I'm going to take it for a test ride a see what they are like but I fear you're right :(
 
Try pulling the lever in and tapping (gently) the fitting and the reservoir. You may be lucky and have the air bubble that's in it travel out into the reservoir. You could also try cable tieing the lever to the grip and leaving it over night.
 
The tie back the lever trick usually works for me.
Brake fluid and paint don't mix. Clean it off ASAP unless you want a patchy bare metal look.
 
Use a chromate paste such as Duralac. It's formulated for use in marine environments with stainless fastenings into aluminium alloys.
Expensive, but a tube will last you for ever.
 
I used to work in technical sales for a company that manufactured and supplied the stainless steel wire to the nut and bolt makers. Bolts for all industries worldwide from the aircraft engine makers to the chemical industry.

The austenitic stainless steel bolts you will buy in a bolt kit will be fairly soft and low tensile. For many applications that doesnt matter - the mild steel used for most applications is pretty soft itself. However there are some applications where high tensile bolts are used and these should not be replaced by the sort of stainless that you can buy off the shelf. Yes its possisble to make higher tensile austenitic stainless bolts and nuts but these are very much specialist items made for particular applications. Indeed, one of our objectives in making the steel for the bolt makers was to produce something really soft and maleable so they could cold form it without problems.

So if the mild steel bolts you are replacing are in safety critical areas or carry head markings like 8.8 or 10.9 ( ie are high tensile) then dont use stainless to replace them. It isnt strong enough. Just stick to using stainless on applications like holding cosmetic panels on the bike.

Stainless is prone to galling ie seizing in application but this isnt a common issue with well made bolts. If you feel the bolt starting to tighten before its anything like fully home, dont tighten any further. Do the reverse and withdraw it. Run it through a die. Maybe a tap down the hole. What is a common issue is using stainless into alloy castings and then finding 2 years later that they wont come out and when you try, they shear. The problem is that electrolytic corrosion between alloy and stainless produces ally compounds that not only are more bulky than the parent metal ( and therefore make the thread a tighter fit) but they are also the sort of thing you might use as an abrasive. So they grip like a yorkshireman holding a shilling. The solution that I use is to coat the threads before assembly with Duralac, a chrome compound used in the aircraft industry for just this purpose but freely available on Ebay. There is also a Teflon compound..
 
birdseye said:
I used to work in technical sales for a company that manufactured and supplied the stainless steel wire to the nut and bolt makers. Bolts for all industries worldwide from the aircraft engine makers to the chemical industry.

The austenitic stainless steel bolts you will buy in a bolt kit will be fairly soft and low tensile. For many applications that doesnt matter - the mild steel used for most applications is pretty soft itself. However there are some applications where high tensile bolts are used and these should not be replaced by the sort of stainless that you can buy off the shelf. Yes its possisble to make higher tensile austenitic stainless bolts and nuts but these are very much specialist items made for particular applications. Indeed, one of our objectives in making the steel for the bolt makers was to produce something really soft and maleable so they could cold form it without problems.

So if the mild steel bolts you are replacing are in safety critical areas or carry head markings like 8.8 or 10.9 ( ie are high tensile) then dont use stainless to replace them. It isnt strong enough. Just stick to using stainless on applications like holding cosmetic panels on the bike.

Stainless is prone to galling ie seizing in application but this isnt a common issue with well made bolts. If you feel the bolt starting to tighten before its anything like fully home, dont tighten any further. Do the reverse and withdraw it. Run it through a die. Maybe a tap down the hole. What is a common issue is using stainless into alloy castings and then finding 2 years later that they wont come out and when you try, they shear. The problem is that electrolytic corrosion between alloy and stainless produces ally compounds that not only are more bulky than the parent metal ( and therefore make the thread a tighter fit) but they are also the sort of thing you might use as an abrasive. So they grip like a yorkshireman holding a shilling. The solution that I use is to coat the threads before assembly with Duralac, a chrome compound used in the aircraft industry for just this purpose but freely available on Ebay. There is also a Teflon compound..
Click to expand...

At last some sense!! Do not use untested stainless steel in any safety critical area such as brakes, engine mountings, suspension parts. Stainless is so generic as to mean nothing. I am told I am an arrogant git BUT would you seriously change out safety critical parts because they look good? Imagine the pilot on your aeroplane stopping off at B&Q and changing those nasty discoloured bolts for something nice and shiny? Oh my! BMW spend a relative fortune on fasteners, fully traceable and tested. Off you go buy the shiny stuff. Food industry has absolutely nothing to do with 250 kg relatively high performance motorbikes. I have never seen a high performance food mixer on the M25, two up with full luggage.
 
Apart from galling and corroding aluminium, the big issue with stainless is how the threads stop suddenly when tight. There is next to no spring so they will shake loose.

They seem ok on engine cases, maybe because the alloy itself is not especially springy, but loose brake bolts are not my idea of fun.

New bolts from BMW are not silly money.
 
Bendy toy said:
Apart from galling and corroding aluminium, the big issue with stainless is how the threads stop suddenly when tight. There is next to no spring so they will shake loose.

They seem ok on engine cases, maybe because the alloy itself is not especially springy, but loose brake bolts are not my idea of fun.

New bolts from BMW are not silly money.
Click to expand...

I did actually wonder about replacing the slightly corroded front cover bolts on my new (to me) TC with OEM zinc plated ones. My friends TC of a similar age which has been ACF'ed from new hasn't got a spot of corrosion on it...
 
MattW said:
I did actually wonder about replacing the slightly corroded front cover bolts on my new (to me) TC with OEM zinc plated ones. My friends TC of a similar age which has been ACF'ed from new hasn't got a spot of corrosion on it...
Click to expand...

Me too but I dislike the Torx socket heads so went hex head stainless. They were fine on my Yamaha.
 
I've used S/S bolts on my different bikes for years & years. Never once had a problem of any description ever with S/S bolts. I copper grease them & use anti sieze ceramic paste for bolts on the engine casings.

My 2cents worth
 
Jaws100 said:
I've used S/S bolts on my different bikes for years & years. Never once had a problem of any description ever with S/S bolts. I copper grease them & use anti sieze ceramic paste for bolts on the engine casings.

My 2cents worth
Click to expand...

I think you over value your input. Define stainless steel? Tensile, sheer, impact properties, grade testing, mechanical results, Chrome to nickel ratio,traceability, that bit between ingot and rolling/ drawing/ cold or hot reduction. Please explain why not one single motorcycle manufacturer offers a stainless option? I am an arrogant chartered engineer with many years in the super alloy business but please enlighten me.I have never fallen off a camel but hey never ridden one at full pelt. Stainless steel without full certification should never be used in safety critical applications. That is full stop. Shiny bits are not stoppy bits.
 
I'm kind of with Thornley here (I'm an engineer, although not a chartered one ;) ).

However, for non critical case screws I can't see any problem with stainless. However, I'll still probably replace them with zinc plated due to the potential for galvanic issues.

Just need to find a source of decent quality plated carbon steel screws...
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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