Shearing Bolt on Touratech Frame
 

This bolt has just sheared for the third time.

I get the old one drilled out and replaced. The last one only lasted two weeks, maybe even less.

I presume the frame is twisted from me dropping the bike but this is the third frame on a KTM Adventure I've had and before the bolts only bent they didn't shear off.

Has anyone had any similar problem and fixed it?

http://www.fowb.co.uk/images/america...288" border="0

------------------
Jerome

http://www.fowb.co.uk



[This message has been edited by Jerome (edited 15 August 2004).]

Try replacing the bolt with one of a higher grade i.e. hi tensile - can't remember the grade you need? Tou could try a stainless bolt but I'm not sure it would be any better, stainless is hard but has a low shear strength.

The first one was stainless steel and the last two decent (non rusting) allen bolts.

I guess it must be misaligned.

They all shear flush with the thread.

------------------
Jerome

http://www.fowb.co.uk

Hi Jerome,

I am using a Happy-Trails rack and panniers and have had the two bolts that hold the rack and the top, stock luggage rack to the frame (the side ones, not the top) snap off. On the ultra rough roads of Japan no less... I had them drilled out and newly threaded to accept much beefier bolts, which lasted until Mongolia. I just redid them again, this time with the same size bolts, but of much lower strengh. Hopefully these will bend instead of snapping off. We'll see...

Let me know what sollution works for you.


------------------
Improvement makes strait roads, but the crooked roads without Improvement, are roads of Genius - William Blake

If using Stainless, then make sure you use A4 grade, not A2.

Hi,

thanks for the info.

I forgot to mention that I had all the bolts replaced with bigger 6mm or 8mm ones as the ooriginals are very small.

The ones I had on earlier frames did bend and never sheared.

If I look at a bolt how can i tell if its A4 or A2? - are the bolts marked with this?

is there a similar type of steel bolt i should look for (in Cusco?)

- looking forward to bendy bolts



------------------
Jerome

http://www.fowb.co.uk

You want Grade 8 or better NON - stainless bolts. IF you can get stainless A4 - which I doubt there, then they should be ok, but may still not be as strong as grade 8. Stainless is not as strong as standard steel bolts.

Grade 8 has an 8 cast into the top of the bolt. 10's would be even better but hard to get. Be sure to get matching grade 8 nuts.

BMW car dealer is a good place to get high grade bolts, pretty much all the bolts on beemers are high grade. Japanese bike bolts are generally rotten cheese.

Note I can't see anything in the picture as is, you need to lighten it a lot. I did so and can see what's happening. It looks like you just need a better grade bolt. Perhaps a bigger one if there's room to drill it out without weakening the bracketry.

------------------
Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

Here's feedback from Tom at Touratech USA:

I've seen this once on a bike with "other brand" racks they had a flexy rear crossmember, so I knew there would be bending at that bolt. I told him it would break soon and it broke in 200 miles. The problem is that there are bending forces on a bolt in the threaded area, and as soon the joint loosens a little - the bending increases at the threads and it breaks. A "hard" bolt can be more brittle in this condition.

This is the first time we have heard of any problem with the TOURATECH racks and KTM has been supplying touratech racks as OEM for a few years. So I don't know what's causing it with our racks, but pretty sure it occurs because of "loosening" then after that it's "bending".

I recommend using a bolt that has an un-threaded shank all the way thru with a NUT on the end. So you will have to drill the threads out of your frame. Grade 8 bolts are so bloody strong I recommend this method (it's tested with a 1/4-20 grade 8 american bolt but not tested with metric M6). Possibly you can use M8 I don't know if there is enough meat to drill out an M8. We don't have an LC4 to look at.

Another possibility is to use a 12.9 hardness M6 bolt ******thru with a nut on the end***** (no threads in bending). Then you only have to drill to 6mm and you can keep it all metric, but I have not heard of this tested. Probably OK though, it will be much stronger than the original.

Two important factors that affect the strength of this joint:

1) Tightening the NUT on the end is MUCH tighter than tightening it from the head.
2) Having a full diameter shank at the joint (rather than bending at the threads) is significant.

And finally.......check tightness of the rear crossmember, this is important to prevent bending at the bolt.

Tom

I will drill through as he suggests and keep my fingers crossed.

Thanks all for your help.

J


------------------
Jerome

http://www.fowb.co.uk

Hopefuly it is now fixed.

There is a strap across the back of the bike that joins the left and right frames together.

The tab on each frame was bolted to the underside of this strap on both sides.

When i looked at the alignment with the snapping bolt it was clearly too low. By moving the tab to be above the strap the alignment looks spot on.

I left the other one as it was.

my fingers are crossed.

------------------
Jerome

http://www.fowb.co.uk