Rear wheel bolt replacement

[BamBam]

Still nobody on here has confirmed what the tensile strength they should be . . . . . .
. . . anyone ???

Hope this helps
These Bolts were supplied with my 5mm wheel spacer kit HPN

Heavy duty washers and the socket sizeis 19mm not 17mm

Right or wrong I have always used copper slip on all wheel nuts and bolts and mounting surface,which includes 350bhp off road race, performace cars, and all my BM bikes. No wheels have fallen off, and have always been able to undo them at the side of the road

 

[SJRoome]

Stainless steel whel bolts

Hi Martin

I am afraid I am going to take a completely different view to everybody else who has replied so far. The purpose of the 4 wheel bolts is to hold the wheel on the bike and to transfer the torque from the bevel drive to the wheel hub.

Like you I also get annoyed that the heads of these bolts rust and I would be happy to replace them with stainless steel bolts if I happened to have any.

The tensile strength of the bolts is a measure of the force required to pull the bolt to pieces. If your replacement bolt has a higher tensile strength than the standard bolt it will be fine.

I have seen lots of discussion about whether bolts should be lubricated when torquing them up, and whether copperslip etc should be added. You need to remember that these bolts will be doing their job provided they stay on the bike and are moderately tight. They are torqued to a high value ( from memory130nm) not because the bolt needs to be under a particularly high tension or is under particularly high stress but because of the rather unfortunate consequences of it coming unscrewed and falling out.

I would therefore recommend you get 4 stainless steel bolts of the correct length and at least as high tensile strengths as the standard bolt, ensure that the threads of both bolts and holes are clean and dry, torque to the recommended values and enjoy the improved appearance.

Steve

P.S. I cant offer any warranty with my advice but send me 4 suitable bolts and I will put them on my bike and send you my old bolts.

 

[Beemerboff]

The Touratech bolts are 8.8 grade, so any Stainless bolts you find will be at least the same strength.

One thing no one seems to mention is the fact that there is a large difference in torque values between dry and lubed bolts- you need a bit lasss if you lube the the threads.

At one time the Honda Common Service Manual had a excellent chapter on fasteners and torque values but in the manual I can find now has been shortened a bit.

It is still worth a read , as there is information in there I havent seen anywhere else - like how to read the code on bolt heads where there are no numbers, and the variation in torque values between dry and oiled bolts.

Things have changed a bit with "stainless" bolts over the past few years, and if you have a specific strength requirement you only have to ask for it.

The strength has been marked on the head of every OEM BMW bolt I have seen , and some are higher than than 8.8 and should be replaced with bolts the same strength.

And remember to order matching nuts, they come in different strengths too.

 

[Colt]

you could cover the old bolt heads with those plastic cap covers.
they are bmw cap covers stocked by motorworks etc

 

[Redboots]

I just found an item that says, in a nutshell:
A2 stainless has about 12% lower tensile strength and about 30% lower strength than 8.8 steel.
A4 stainless has the same tensile strength and only 6% lower yield strength.

Info here.

Well, I learned something today

John

 

[Deleted Member MS]

Mmm, interesting to see differing views on the subject. (esp the last 3 or 4)
The original bolts are apparently HT 11.5, BUT seem impossible to come by in Stainless. As ive said above though, I can get them in higher and lower tensile strengths but not exactly 11.5.
As one of the above comments says, stainless has come a very long way in recent years. It is now readily available with tensile strengths way beyond the normal A2/A4 most of use.
BMW and all the other bike/car makers and other engineers will be very conservative with what we should and shouldnt use I suspect. (thats why the picture above of 8.8 bolts is interesting, especially as they were supplied to you Bambam. It may go some way also to prove my point about "going" over the top)
The OE wheelbolts are stamped with some figure "BB" although i cant recall what the figure is at the mo.

I will endeavour to find the required bolts, in stainless, and post on here when I find them (local stockist or some internet site I presume)

FAO SJRoome, Thanks for the off re bolts. My current ones are being powdered at present, to see what they look like really BUT I will replace them with S/S when I can source 'em.

 

[Redboots]

The OE wheelbolts are stamped with some figure "BB" although i cant recall what the figure is at the mo.

My wheel bolts are stamped with 60. The hub is stamped with 60 as well. My book says this is the length of the bolt.

On the threaded end there is a stamp that looks like 10.9
So that makes it a fairly strong lump and you would need A5 stainless bolts to replace them.

Like hens teeth I would imagine

John