Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 999 / 749 > mono subframes ? made of cheese

[Wave]

Bromley, south London

[andyb]

I think it was colin chapman who spoke about car parts saying if they didnt last a race, they were too weak, and if they lasted longer they were too heavy/strong.

its a mono seat frame, designed as such.........extra weight over the rear of the frame (inc the leverage effect from the mounting points) it wasnt designed for!

[iang]

Surely the subframe should still take the weight of a pannier bag, I mean I am less than 11st but I know others that are up to 16st so this is a vast difference in weight.

[Wave]

i thought that, but looking at the thickness of the metal, i wouldnt even trust it to hold its own weight. let alone the exhaust and 10kg panniers, granted getting the bike airbourne isnt a good idea, but please its less than a mm thick.

[Wave]

heres a pic
its the same the other side too

[posiden]

Wave, looks like where its broken is caused by the weight of the exhaust as your weight is applied to the sub frame at the other side of that weld. The exhaust is bolted onto the subframe with one very big bolt at the back and two smaller bolts closer to your bum.
It was a common fault on 03/04 bikes that the alloy around the big bolt would snap at the weld to the subframe.My mate nearly crashed his 03 749S when the exhaust fell onto his rear tyre at high speed. Ducati did a superb repair under warranty.
How olds the bike can you get it sorted under warranty?
If your getting it welded I would get some extra strengthening added as some alloys become soft as cheese when theyve been welded up.

[barneychubble]

I had exactly the same issue, managed to get ducati to change it out of good will........

[mileypau]

Originally Posted by barneychubble

I had exactly the same issue, managed to get ducati to change it out of good will........

Was that recently?

I didnt get any joy....bought one from the USA. Better design of bracing. Also set up the exhaust so it isnt 'hanging' off the frame. So far no more breaks. But i do have the bits of the old one...wouldnt mind getting it replaced as back up.

Who / where did you write to?

ta

[Gizmo]

As Pete points out the seat load is supported in front of the crack so its weight from behind, adding a set of panniers at 10 - 20 kg would load it quite a lot. From the ones i've seen its not just load related, its a flexed stress area and it looks like crack comes from the end of the weld, thats a fairly common one on mountain bike frames so we try and avoid welds ending like that. alloy tubing is thin, 1.2mm - 2mm being the norm.

[Wave]

Okay basically i wrote a big letter to ducati saying even though my bike is out of warrenty its unacceptable for the subframe to snap on a 2 year old bike etc etc

They got intouch with ProTwins in godstone who currently have the subframe, they told me today the subframe cannot be fixed and ducati are going to pay for a new one.

Good news