Fitting instructions for crash bars

[De Graaf van Salland]

I've just bought the crash bars of of this bike:
link.marktplaats.nl/392129038

Does anybody have (a copy of) the fitting instructions for these crash bars ?
The most important thing is to find out which bolts I have to buy, because I assume that longer bolts are used.

GvS

[outlaw]

Did not the threaded bars come with the engine bars, if not buy some long threaded bar the same size as the engine bolts, as you slide the bolts ( rear engine bolts and the front ones on the down tube ) out slide the bar in, if you have too many problems you could allways sell them to me :-)
OUTLAW

[Buzzin (^_^)]

If you need the long rear bolt...I have one....to swap for a short one
I removed my crash bar so I don't need the long one any more and it's sticking out quite a bit...

Let me know if you want to swap (we'll find a way to support my engine in the meantime)

[De Graaf van Salland]

Hey Buzzin,

This sounds like a very good idea to me.

My bike will be in the shed this winter for some serious maintenance. I'm sure I can support my engine somehow.

But, can you supply me with some decent photo's how & where the crash bars should be attached ? (i.e. which bolts I should remove)

Thanks,

GvS

[ED-CASE]

Co-incidence! (posted in case it helps.............)
Yesterday I pulled both main engine-cross-bolts, for two reasons
1 I have just made up some "bump-mushrooms" from white nylon bar
2 I plan to replace some or all of the gear-cluster and selector mechanism this winter
2.1 due to 2nd-gear problems
2.1.1 probably buying the cluster etc. from Joost Den Otter, thanks for the recommendation

The cross-bolts were severely corroded, and partially seized to the steel spacers
I used a battery-electric "rattle-gun" to spin the bolt-heads
(After I had used ACF-50, heat, violence, and anger-energy to release the nuts!)
After cleaning them up, there showed serious thinning of diameter on both bolts
To be sure an alternative would have sufficient tensile strength, I devised a crude test
A piece of 2inch threaded-bar, two drilled and threaded steel blocks as "test-bed"
I used a slipper torque-wrench to spread the blocks against an original engine cross-bolt
(I had bought some used similar bolts from my local bike-breaker as backup)
Then compared the effect on several samples of threaded-bar
Even "thinned-down" by rust, an original NTV engine-bolt stood >60nm before failing
The bolt stretched then parted, but the thread was also severely distorted
Three pieces of threaded bar failed, the best at 25nm!
One scrapyard bolt is a bit longer than needed for the front with the nylon "mushrooms" on
Another is just right for the rear, a bit of luck, thankfully
The front "extra-long-bolt" actually has enough spare to fit brackets for.......
The lower mount-brackets of a home-made (wood, polycarbonate, and aluminium) fairing.....
(details and pix later, IF ASKED, for those with serious insomnia, guaranteed soporific stuff)
HTH
Ed

[McF]

Wonderful stuff Ed - thanks for the helpful info.

As part of your "Peer Review" I have some observations and questions:

What material and diameter was the threaded bar?
I'm presuming mild steel, the original bolts are 10mm, so presumably M10 bar?

I used Stainless Steel threaded bar on my old aNTy and have the same material to use on my current project (when I get it going again!).

For reference, the recommended torque settings for the engine mounting are:
Engine mounting bolts Front . . . . . . . . . . . . . . . . . 40 Nm
Frame cross-member to engine bolts . . . . . . . . . . 25 Nm
Rear upper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Nm
Rear lower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Nm
Rear mounting bracket bolts . . . . . . . . . . . . . . . . . 22 Nm

So clearly the original bolts failing at 65Nm have a generous (better than 50% safety margin).

I'm rather rusty (no pun intended!) on the relative material strengths, but ordinary mild steel (ASTM 36) compared to stainless steel (T304)

........................................................ASTM 36.......................T304
Ultimate Tensile Strength (psi)...58,000 - 79,800...............73,200
Yield Strength (PSI)...........................36,300......................31,200

There are tables of different strengths for the chemical compositions and method of manufacture (cold rolling, heat rolling, etc), so I think Ed's point is very good about relative strength of a rusty original bolt compared to some threaded bar.

That said, I wasn't aware of any issues with the stainless I used, it took the torque applied without grumbling and survived circa 6,000 miles of use before I sold the bike. I might just use Ed's test to destruction method on a piece of stainless bar before the next installation - you can't be too safe!

[ED-CASE]

Good thinking, yes the threaded bars were:
2 off ferrous 10mm, of which the galvanised example failed worst
1 off mid 1970s s/s 10mm en 108J threaded bar, failed at 20nm
1 off full dia. unknown spec. s/s 10mm bar, I cut 65mm run of thread with extra care
Surprisingly, part of the plain section failed at 25nm, thread also distorted
Had to be careful to guide the moving block against twisting the test-piece
All in all, a very crude test-method, with appropriate safety-margin needed as a rating system
I was glad to have the used spares to fall back upon
All the best
Ed