My wife always worries that this heavy sunroof might collapse one day and fall on my head (the black steel tubes alone weigh 7kg (14lbs) due to faillure of the U-bolts to the ROPS - and off course it lifts the centre of gravity increasing the risk of rollover under critical circumstances.
I was thinking of replacing the steel tubes with aluminium ones. Any comments would be appreciated.
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I don't think the benefit of weight savings between the aluminum and steel tubes would justify the trouble. The aluminum will need to be thicker than the steel to have same strength. If the fear is the ubolts failing, replace them with higher grade units (grade 8 or better). As far as center of gravity issue, it may be worth looking into. I have seen canopies weight 20 lbs, I have seen them weight 200 lbs. 20 lbs on a 4000lb tractor won't shift the COG anything worth mentioning. 200 could make a difference in marginal situations.