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Gas struts for Westfalia elevating roof

Discussion in 'Body' started by Nigel, May 9, 2009.

  1. Nigel

    Nigel Member

    Canvey Island, Essex, UK


    Compiled & Written by Nigel A. Skeet

    Elevating roof gas struts (i.e. gas springs) are worth fitting to the Westfalia elevating roof (i.e.pop-top), even if one were in perfect health; being a real boon, to people of short stature. In principle, any rear-hatch (hatchback, estate, station wagon or van) gas struts with universal joints at either end (typically 500 mm, 550 mm or 600 mm fully extended length) could probably be used.

    For my 1973 VW Type 2 Westfalia Continental elevating roof, I chose to use 550 mm gas struts from a Volvo 300 hatchback, because they were readily available and satisfied the universal joint criterion (easier to ensure satisfactory alignment!). One also had the added advantage of an integral courtesy light switch, which could be used to activate a flashing warning light or buzzer, if one attempted to drive off, with the elevating roof still raised; something most motorcaravanners have done at least once and in some cases damaged the elevating roof. Additionally, one could use the switch to activate an ignition inhibitor relay.

    The gas struts' universal joints (M8 screw thread) were attached to the rearward end, of the elevating roof lower hinge bracket, on the van's steel roof and also to a custom-made duralumin bracket, fitted to the elevating roof itself, as illustrated in the photographs. The bracket, formed from 170 mm x 90 mm x 3 mm duralumin plate (a tough, stiff, corrosion resistant aluminium alloy), as shown in the sketches, was fabricated using only a bench vice, drill & drill bits, hacksaw, files, hammer, centre punch, heavy wooden mallet, waste-wood blocks, rule and tape measure.

    It is possible that a shorter bracket may have sufficed, but I wanted to ensure that the bracket itself and its method of attachment, would be sufficently strong, stiff and rigid, to withstand the considerable force, applied by the gas struts. Using the bathroom scales, I measured the force of the gas struts, which were each approximately 55 lbf (i.e. 245 N) when fully extended and 100 lbf (i.e. 445 N) when fully compressed; so fully compressed, each gas strut individually exerts a force, nearly equivalent to one hundredweight (i.e. 1 cwt). With one gas strut on either side of the roof, there is almost sufficient force available, for the roof to become self raising (what might be termed, "flour power"!).

    From the motorcaravanner's point of view, it is simply a matter of nudging the elevating roof upward, rather than consciously lifting it. At no stage does the roof spring upwards of its own accord; the gas struts' force and the weight of the roof, being nicely balanced. Once the roof has been raised to about half of full height, the roof is self supporting, merely requiring one to gently push it up to the fully raised position and lock the original hinged support struts, for safety.

    If gas struts, other than those from the Volvo 300 were used, one would need to ensure that when fitted, the gas struts were neither fully extended nor fully compressed, when the elevating roof was in the raised and lowered positions respectively. This was an issue of angles, geometry and triangles, which I needed to investigate, before attempting to fit the Volvo 300 gas struts.

    To ensure that the courtesy light switch (i.e. roof-up warning switch) was open, when the elevating roof was in the fully lowered position, I located the duralumin bracket, so that the gas strut would be compressed (achieved by means of the Spanish windlass technique – twisting a loop of cord with a tommy bar) by 25 to 30 mm, when the elevating roof was in the fully raised position.

    All of this was achieved, by progressively updating and fine tuning the measurements and calculations, as various stages of the project were completed; not knowing in advance, the exact required position of the gas struts' upper ends, until fabrication of the duralumin brackets was completed and the lower end of the gas struts, fitted to the elevating roof hinge brackets.



    For general information and advice about gas struts (i.e. gas springs), use the following links:


    Industrial Gas Springs Limited
    22 Wates Way, Mitcham, Surrey CR4 4HR
    United Kingdom

    Tel sales: 0208 646 6595 - Fax: 0208 646 6594
    International sales: 0044 208 646 6595






    I was intrigued to learn recently, that Just Kampers, in England, now market a complete gas-strut assisted, rear-hinged elevating roof & front-mounted roof rack, with a 43.5 inch x 6 foot roof-bed, of 1974~79 VW Type 2 Westfalia style, as follows:





    A similar elevating roof & roof rack, are also available for the current, Brazilian built, 1997~2009, bay-window, VW Type 2, as follows:


    Last edited: May 17, 2009

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