Keep it coming Gents!! This is one of the most informative threads I've read in years. Pros and cons from all sides, very interesting!!! Thanks all for sharing your knowledge! JIM
Yup! Have two sets of Hoosier slicks sitting in my cousin's shop in MO, USA Along with a trailer load of parts and a Harley sidecar body. Just need the time to get down for a visit. We're running a stock GM 350 4bbl with stock exhaust , auto and ten bolt rear with unknown ratio to get a baseline before we get too crazy. This is a very low buck teaching/ learning experiment with me supplying parts and the students doing the labour. They'll then use the car in the BC high school drag race program against other schools. Once this car is done I'll take my second body out there where they'll build an old style with the I beam and hopefully a flathead v8 manual shift with a narrowed ford 9" rear with 35 spline Strange axels, etc.You don't need to be close with the internet Jim, the art is stopping the spin, and that's why you see larger rear diameter wheels on drag cars than normal, so you may want to look at this also.
Made me laugh Jim, the film grease popped straight into my mind, your not married to Sandy are you?Yup! Have two sets of Hoosier slicks sitting in my cousin's shop in MO, USA Along with a trailer load of parts and a Harley sidecar body. Just need the time to get down for a visit. We're running a stock GM 350 4bbl with stock exhaust , auto and ten bolt rear with unknown ratio to get a baseline before we get too crazy. This is a very low buck teaching/ learning experiment with me supplying parts and the students doing the labour. They'll then use the car in the BC high school drag race program against other schools. Once this car is done I'll take my second body out there where they'll build an old style with the I beam and hopefully a flathead v8 manual shift with a narrowed ford 9" rear with 35 spline Strange axels, etc.
Getting back on topic its my view bmw engineers made a mistake in the design of the boot floor. At limit of tyre adhesion the static stress in the parent metel in the boot floor cross member is around 160MPa. A bit high? Above the fatigue endurance limit for sure. Dynamic stresses higher due to soft bushes letting the heavy differential move around and its inertial effects adding more load.Deano that's not the root cause though mate that's a contributing factor to the failure of the root cause, in other words it's what exposed the root cause failure. The OEM engineers would have done the same if not more precise calculations, that lead them to the material used and welding configuration used in the design.
The root cause is actually what caused the boot floor and diff carrier to become weak, that they were then exposed to the forces of mass at the rear end, the root cause was poor execution of the welding process, and incorrectly supplied products from the supplier, even these are not the true root cause, because then you have to ask why, the process was poor,and why the supplier had an issue, this later part was my main role on working with the Gate Hold Team.
I don't fault anyone from blaming the design, and if they've made money from it well that's all good too, but if you don't have to spend the money, then it's good to understand the issue and make an informed decision, but you have to accept that the design was correct and fit for purpose, it would not have been safe otherwise, and would certainly manifested itself during homologation testing and crash testing, and the launch would have been delayed.
I watched the head of Ford at the time delay the new build of the X350 because it did not have enough rear leg room, so I am sure that a significant structural issue, would have been a cause of delay also.