In Friday practice for The Canadian race, Jarno Trulli had similar failures of the upright, this failure was where the upright meets the lower wishbone pivot. I heard that Toyota have switched from MMC to Titanium for their uprights in Indianapolis.
What are the material benefits of switching material?
One assumes the design remained the same and that they are fully machined parts. Surely the Ti uprights would have needed to be manufacturered specially for the race.
Wouldn't a design change and retaining MMC as the material not have been a better route to take?
I believe Toyota just went on the safe side, running uprights and suspension with "standard geometry", and which have been already used and tested at Indy.
They are running a quite high rake lower wishbone ( more than others teams ) with tight uprights. This has been used since a long time but obviously some extreme setup with change in caster & cambers angles, installation stiffness, and a certain angle of lock have cause failure of the uprights.
It did appears that on a specific corner ( turn 8 if I remember well ), you have full steering lock as the car is hitting the inside kerb, causing with the setup used on the car, a major interference between the upright and the wishbone, and failure.
Obviously with a good simulator you can anticipated these problems.
If you just change from MMC to Ti-6Al4V with the same design, you have:
1) Same stiffness
2) More weight (more or less 50%)
3) Higher UTS, YTS and fatigue resistance; so higher reliability
You can just do this if you have no time to re-design the part . Otherwise it is really better to design again the part, solving the existing problem and keeping the MMC material.
Well, I agree that is quite singular that a F1 Team famous and so important as Toyota could have these problems. What I don't know is if the parts were machined following the right and very complex route for MMC material without any mistakes and, much more important, with all the necessary inspections (i.e. NDT as FPI at highest level, but not only) during the machinings and obviously at the end.
I hope so, but CRP Technology is not producing Uprights for Toyota and so I don't know which production cycle they use.
Toyota change in upright material 
. Otherwise it is really better to design again the part, solving the existing problem and keeping the MMC material.
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