1200 gsa torque arm

[ghost-rider]

Could some one please explain what the purpose of the rear paralever / torque arm is??? I know it has a purpose and needs to be there, the reason i ask is, ive got a stainless steel bolt kit and it gives you the two torque arm bolts, now i cant make my mind up whether its a good idea to swap them or not?? Is a4 stainless strong enough for these points? Are the bolts under a lot of stress etc???

Probably worryin over nothin, but just thought id get sum input b4 i swap em!
Andy

 

[TLSgazza]

I thought it was designed to stop the rear lifting and falling due to the torque reaction from the shaft drive.
Pogo stick without it I should think.

 

[Pukmeister]

Unbolt it and you'll soon find out why it's there and wish you hadn't.

It stops the torque reaction from winding the final drive back and forth, it also keeps the rear suspension geometry correct and it runs as a parallelogram hence "para lever".

Not sure of the compressive or tensile forces going through it but why do you feel the need to replace the correctly graded and engineered fasteners for something else?

 

[ghost-rider]

i dont want to remove the torque arm, all i want to do is slowly replace the fastners with good quality allen head stainless ones, i started off with the timing cover and then slowly worked round, they look much nicer than the mixture off galvenized and stainless torx heads bmw give u, but when it came to the torque arm, i just cant make my mind up whether stainless is strong enuf for that position

 

[Delboy777]

Far stronger than normal bolts, but they must not be used in place of anything that requires high tensile bolts ie brake caliper mounting points etc.

 

[ghost-rider]

But why not the caliper mounting points??? Ive dun them alredy, i would of thought theyd be ok, but i wouldnt wanna do the actual caliper bolts that hold em togetheer

 

[(RIP) Miff]

But why not the caliper mounting points???

They need to be high tensile. Stainless is not necessarily high tensile...

 

[Delboy777]

AFAIK they dont have the tensile strength of "high tensile" bolts. Ive always been told NEVER to fit stainless bolts to anything that requires tensile properties.Most websites that sell stainless bolts will tell you exactly the same.

 

[Pukmeister]

I personally avoid stainless fasteners. Very pretty until you need to undo them. The risk of galling, shear or tensile failure is a good enough reason not to use them, otherwise your bike would probably have them fitted as standard.

 

[(RIP) Miff]

I personally avoid stainless fasteners. Very pretty until you need to undo them. The risk of galling, shear or tensile failure is a good enough reason not to use them, otherwise your bike would probably have them fitted as standard.

I suspect COST is the main factor in why they aren't fitted as standard.

 

[ghost-rider]

I suspect COST is the main factor in why they aren't fitted as standard.

Id agree with that!

 

[Greenman14]

Bolted joints work in two ways: the bolts are designed to be in shear, so tensile loading is not particularly critical; or the joint relies on friction between the bolted faces and bolt tension is critical, the bolts are not in shear. I don't know what the design is for the caliper fixing but it looks like the bolts are in shear as the surface area of the mating faces is quite small. If this is the case then the bolt tensile strength is not particularly critical.

The tensile strength of a bolt will vary considerably depending on the exact grade of material. "High tensile" can mean a range of strengths and for critical applications unless you know the exact grade of the bolt you are replacing, and the exact grade of the replacement you could be in trouble.

That said, the caliper bolts, with a torque setting of circa 30Nm, don't seem to be highly stressed in tension, which suggests the joint is designed for the bolts to be in shear.

After all that, I would not fit stainless bolts to the calipers as the risk, although small, does exist, and the benefit is negligible.