Originally Posted by: Shearer One thing which has always puzzled me is why are VR towers an egg shape?
When VN was released, the front end was the same track as the narrower VB-VL, and the wider body of the VN caused nervous "twitchy" handling because of it. They did, however, widen the diff to increase the rear track, but this didn't help the front.
HSV solved this in the SV5000 and VN Group A by fitting a narrower VL diff, and using wider offset wheels to increase the front and rear track, and improve the handling. Holden then revised the front end with VR to achieve a number of goals, with the 2 most important improvements for handling being the wider track, and increased positive castor (adding stability, and self-centering).
To do this they needed to move the wheels out, and lean the strut back further.
To make this happen in the VR they changed to cast lower control arms, which are longer than VB-VP, and a separate hub assembly (with sealed, non replaceable bearings) that the strut bolts to. This also moved the entire geometry outwards to align with the wider track, and to maintain the camber angle, the top of the strut also needed to move outwards.
To increase castor, they had to lay the strut back, which means not only did the top pivot point have to move outwards, but also a fair way back too. If you look at the relationship between the top pivot and the wheel, you'll find contemporary Euros of similar vintage (such as BMW) also locate the top pivot points well back.
The front section of the raised part of the strut tower in a VR is the same as VB-VP, and they simply altered the tooling to extend the tower to where it needed to be. So instead of simply reloacting the round tower back & out entirely, they only altered part of the pressing, resulting in the ovoid shape, filled with a cheap, easily manufactured mounting plate for the pivot. This is most likely due to beancounters only allowing a minimum of spend on new tooling - after all, the entire front bolt-on sheetmetal, bootlid, and rear 1/4 panels were new, with additional money spent on the rear shelf, rear screen, and C pillar mods.
You can see what they really wanted to achieve with VR if you have a look at a VT - the strut tower is how VR would have been if they had more cash to spend, or the time & effort to put into it. The VT uses the same strut and top bearing as VR/VS too.