high tensile bolts?

[RichardM]

Looks like they lay the rear shocks down slightly more giving a lower seat height, also a softer action on the rear.
As above. If you go down the stainless route get some bolts which the unthreaded shanks will go through the mount lugs otherwise the threads will chew the mounts.

Personally I'd be more worried that the load will be transmitted through the mount in a direction it wasn't intended for and to just one side of the original mount. I'd be looking at reducing the seal height and not something which is so safety critical.

 

[winchman]

The issue I have seen only last week with stainless fasteners is poor quality. Its getting harder to buy good quality as the market is flooded with cheap fixings with no traceability as to origin quality etc

 

[Onoff]

The issue I have seen only last week with stainless fasteners is poor quality. Its getting harder to buy good quality as the market is flooded with cheap fixings with no traceability as to origin quality etc

Agreed. I bought some A2 M5 countersunk screws from the one place left near Holborn. Not only was the A2 stamp barely visible, I fitted them with aluminum anti-seize. When I went to undo them the 3mm Allen key rounded about 50% off and I had to bang a Torx bit in. Like cheese!

 

[Munkul]

Agreed. I bought some A2 M5 countersunk screws from the one place left near Holborn. Not only was the A2 stamp barely visible, I fitted them with aluminum anti-seize. When I went to undo them the 3mm Allen key rounded about 50% off and I had to bang a Torx bit in. Like cheese!

countersunk hex heads often do that, to be fair. Even the good ones. The hex size is always smaller than it should be for that size of fastener.

 

[james butler]

Rule of thumb is that stainless should not be used for such applications as they are not strong enough. I can't remember why but no doubt someone will be along to tell us.

As has been said many times before and on lots of bike/car forums stick to steel for high tensile applications because the ramifications for when it breaks doesn't bare thinking about!
lots have tried it and many have failed with either near miss or deadly consequence, not to mention complications with insurance payouts for fitting inferior non standard parts to replace important critically engineered components.
on the other hand you can always paint/plate critical high tensile steel bolts to look pretty for such applications

 

[Morrisman]

Personally I'd be more worried that the load will be transmitted through the mount in a direction it wasn't intended for and to just one side of the original mount. I'd be looking at reducing the seal height and not something which is so safety critical.

Looks to me like there’s about 5x the leverage/shear on that bolt than in the stock application.

 

[james butler]

I’ve used stainless bolts on just about every car or bike I’ve ever built, and never had one fail.

Stainless may not be as strong as a proper carbon steel high tensile equivalent bolt, but that doesn’t mean they are made of glass, or cheese.

The stock bolt is probably a minimum 3 times stronger than it would ever need to be, in a worse case scenario, so swapping it out with something marginally weaker is not a problem.

Bike Bling: When Is It Safe To Upgrade Bolts? - SnowBrains

So you want to outfit your ride with some stainless or Ti bolts? Is it safe to do? Lets dig a little deeper into bike engineering.

snowbrains.com

i have seen many failures, i have even seen someone replace caliper bolts on a car with stainless and then saw the aftermath for when they sheared
for dress up or non structural items there's little to no issue other than galling maybe with similar material or worse case stainless in alloy
but having worked in the automotive industry for years and never seeing stainless bolts used in drivetrain applications speaks volumes especially when some normal steel bolts cost more than stainless
but at the end of the day its really up to you

 

[fizzy]

What about titanium?
Used a lot in demanding applications. Corrosion resistant and as strong as 8.8 and even 10.9 in the right grades.

Titanium Hex Head Flanged Bolt M8 x 80mm

The T7Design Titanium fasteners are manufactured from the best aircraft grade Titanium Alloy; Ti-6AL-4V (Grade5), these fasteners are suitable as replacement bolts for Grade 8.8 steel fasteners with many benefits.

www.t7design.co.uk

 

[Onoff]

countersunk hex heads often do that, to be fair. Even the good ones. The hex size is always smaller than it should be for that size of fastener.

Aware of that but when I say they were like cheese I'm talking Philadelphia!

 

[Keithmac]

Looks to me like there’s about 5x the leverage/shear on that bolt than in the stock application.

View attachment 455317

I wouldn't fancy running that long term, looks like it's designed to rip the original mounting boss off!.

 

[RichardM]

be looking at reducing the seal height and not something which is so safety critical.

Should read seat not seal! . Can't even blame fat fingers.

 

[dobbslc]

I wouldn't fancy running that long term, looks like it's designed to rip the original mounting boss off!.

This is what I thought.
That bolt on 'clam' will add massive leverage on the aluminium casting of the transmission casing.

 

[MetalMonkey]

I'd only ever use stainless on non structural and cosmetic applications, body panels, trim pieces, mounting brackets, exhausts, cam covers etc.

Never anything critical like brakes, suspension, engine or drivetrain etc. Not worth the risk. For those I just clean them and paint them.

 

[dobbslc]

I've never used stainless steel on anything like that either it's just not worth it if you can easily get a good HT bolt.

 

[Pigeon_Droppings2]

If the look is important there are plenty of options with coated steel bolts I think?

I'm sure there's good quality stainless available...but most of what I've seen have been very brittle.

I usually use stainless when replacing small (M6) trim bolts as it makes disassembly easier...but that's really about it to be honest.

 

[Morrisman]

Well I must have been extremely lucky with everything I’ve built, as I always used stainless anywhere I could get the right size bolts, and I’ve never had one break, ever. I never realised how cheese-like stainless steel is.

 

[ajlelectronics]

how cheese-like stainless steel is.

Cheese like isn't so much the problem as "glass like".

 

[Morrisman]

Cheese like isn't so much the problem as "glass like".

Hmm, I’ve demonstrated this before, putting a stainless bolt in a vice and wailing on it with a hammer to see how quickly it falls into myriad pieces.

 

[Pigeon_Droppings2]

I can imagine if you carefully torque everything it might work out fine.

With stainless I find I can just keep tightening until it breaks...steel I have more of a feel for how tight it is. Different properties of the material I guess

 

[Munkul]

Cheese like isn't so much the problem as "glass like".

That is not a common property of stainless...