cracked frame :(

[mightyDOB]

Hi all,

Its been a while since I last posted but I hoped to be popping on to say thanks again for a great resource. I have just stripped down my 4000, replaced the o- rings etc and fixing her back together, the trick of spreading the swing arm with a bolt was masterful have spent hours trying to get that dam thing back on before.

all was looking good which I noticed that I have a crack in the frame both sides near where the rear shock attaches to the frame   Its in the thinnest part of the flat metal plate.  To be honest I have no idea how long they have been there, after quite a gap I started biking again regularly towards the end of last year, and have certainly put it through it paces around Cannock Chase regularly (still handling like a dream!).

here is a pic (sorry its dark), its exactly the same on both sides

[IMG=http://img688.imageshack.us/img688/2357/img20130414231019.jpg][/IMG]

Really gutted to be honest have loved this bike since I inherited it, any of you experts think its fixable? buying a new bike is not really an option for the foreseeable future

thanks for looking

[fyrstormer]

As thin as that bit of metal is, I can't believe it was providing much support in the first place. If you held that piece of aluminum in your hands, without the reinforcement surrounding it, you could break it in half without even making your fingers sore, so it can't be contributing much to the integrity of the shock mount.

As a general rule, cracks in load-bearing components will make a ticking or creaking sound as the cracked edges rub together, and as the surrounding metal suffers under the increased strain. If you're not hearing any such noises, it's pretty unlikely this crack is actually dangerous.

The shock still has a direct and solid connection upward to the seatpost, which is where most of the weight supported by the rear shock is located (i.e. the rider), so I think I would keep riding it until something else breaks.

Alternately, Shovelon can weld aluminum, so he might be able to do something with it, but obviously I'm in no position to promise anything on his behalf.

EDIT: Ah, Cannock Chase is in England. Maybe one of our UK members can recommend an aluminum welder who can fix the crack. Or you can just keep riding it.

[Colin]

It looks to me like the upper shock mount has been "modified" at some point, i.e. it has been filed away to allow clearance for a different shock maybe an air can valve? what shock is on it at the mo' looks like it doesn't need that clearance?

That "thinnest" part should be the same thickness all the way along. Have a look at other piccies of 4000's, 5000's and EVO's to compare.

This touches on some other threads recently about fitting air can shocks onto our bikes, which I have shied away from because of the need to file the upper or lower shock mount, that is until Chris "spokes" pointed out that the RP23 shocks fit with no mods!

In the belief that PRO~FLEX would not have allowed any "fat" weight on the bikes, I have always been very wary of filing away at anything on the bikes, let alone a weight bearing point!

Not a lot to be done about that now, except as suggested a) live with it, b) get it welded and maybe beefed back up to "normal".

Good luck and maybe someone can suggest a welder in our engineering heartland of the Midlands?

Col.

[mightyDOB]

Thanks for your replies guys. 

It has a Fox float installed but I don't think it’s been modified at the upper frame mount, it all looks pretty standard to me, it’s the thin shaft of the shock up near the frame anyway so no modification required.  I bought a bush/mount kit from FT Tuning when I inherited the frame for the fox float.

Some of the aluminium on the Carbon Swing Arm mount has been filed away by my uncle who previously owned the bike; he was involved on this forum a fair amount quite a few years back.  It looks a tidy job and there are no signs of ware / movement on the aluminium shock mount on the carbon swing arm over the last 7 years (my time fly’s), and he was running a Fox Float R on it and his couple of OZ's for quite a time before that I believe.

To be honest I could be my fault due to lack of maintenance, when I stripped the bike down to service it with the kit I bought off yourself Colin (thanks btw) I noticed everything was not as tight as it should have been and there was some ware on the aluminium inserts that fit into the frame.  I am guessing there could have been some sideways play on the bike the last few months when I have certainly been a bit harder on the bike, which might have caused the damage.  On the other hand it may have been there a lot longer.

Now you have both said to live with it, I am a bit happier and I am going to keep an eye on it for the time being, it does not look like the crack has widened at all.  The bike was making some creaking but I think that was my saddle but it should be more obvious now I have completely stripped and rebuilt the bike. 

It would be good to get it welded though as long as the cost is not too much, as it might be a chance to upgrade to a new frame.  I always could have done with a Waybig version anyway being 6ft 4.

If anyone has any recommendations of a welder near me it would be appreciated.

Thanks again for your replies, the knowledge always amazes me

[shovelon]

Where are you located?

[mightyDOB]

Hi Shovelon,


I'm based in Wolverhampton, but often travel down south to my parents in Milton Keynes

Ash

[mightyDOB]

Colin I must apologies you are right the frame has been adapted i just never noticed before, as it was resprayed before I got it.  I just looked at other 4000's and it is obvious.  Must have been for a different shock in the past, certainly not needed for a fox float.

Hay ho what done is done, will keep an eye on it

Ash

[shovelon]

It is an easy fix if it gets worse. I don't think it is unridable though.

Frame is 7005 alloy, so filler will be 5356. Be sure of that. 4043 is not strong enough. Worse than not welding at all.

Ride on!

Terry

[mightyDOB]

Great thanks terry,  even better if you know aluminium and are telling to ride on :-)

I will be putting it through its paces on Wednesday :-)