Y Register Technical Advisor Neil Cairns was recently asked this question :
“Regarding the sun roof sliding panel, can you explain where and how the rubber strip is fitted. I cant say I remember one ever being fitted to my car. I have a major problem with the internal rear gutter trough almost rusted away so even with a home made fabrication I need to stop as much water as possible reaching this area.”
On my YB I have a strip of soft rubber sponge stuck on the leading edge of the roof itself, not on the sliding bit. The sliding roof butts up against this well (the ends need slight tapering) and water simply runs over it. At the rear (and this is important) you need a similar seal right across the sliding roof itself, so it lives just under the rear roof edge and down in the ‘lip’ and so is hidden from sight. This seal stops lots of water from the windscreen and front portion of the sliding roof from going under this rear edge.
I know there is a ‘drain channel’ in the sliding roof but this is for leakage, NOT massive downpours. Nowhere could I find a suitable seal for this (the front one came from NTG) so I raided a car in a scrap yard that gave me a 1/2″ deep, hollow, very soft rubber seal. This folds up against the rear roof edge nicely when trapped as the roof is ‘locked’. This way the vast majority of rain water simply glides right over the sliding roof and off the back of the car. The drain tubes only have to deal with the little that gets into the edge slots of the roof. Another gain by fitting this rear seal is you massively reduce the ‘wind-roar’ above your head as the air passes over this rear edge.