Power Pop Top Lift

I have been using JackBombay's Poptop Shocks for many years with great success. They made lifting the pop top much easier, but in the back of my mind I have always had the desire to have an electrically powered pop top. Part of that may just be the desire to engineer it!

Several vehicles have such a system, including the Mazda Bongo, and the new VW T6 California which is available only in Europe.

Several threads on theSamba have mentioned commercially available linear actuator kits for the VW Westfalia. However it seems those who purchased the kits were less than satisfied with the product. So after a lot of measuring, drafting and modelling this is my home-made powered Westfalia Pop Top Lift System.

This modification will not suit every one. Those who use the upper bunk will not be able to mount the actuators inside the van, as done here. There will probably be those skillful people who can figure out how to mount them outside, preserving the use of the upper bed.

Cost for this project: $283 for 2 actuators
$20 for a DPDT switch for the up/down function and wire
$11 for 4 stainless steel bolts and 4 acorn nuts. (Acorn nuts alone were $2.30 each!)
all other bits such as hardwood for the pivot mounts, stainless steel reinforcing plate, 4 clevis pins, 4 wood screws and microswitch came from junk bins around my garage.

Unless there is some major improvement needed - the project is complete.

Click on images to see full size.

The Measuring Stage

Finding the critical measurements.

By measuring the critical dimensions of the roof when up and when down, I determined a 300 mm linear actuator would be sufficient. A longer actuator could be used, however the longer unit decreases the angle between the actuator and the roof when the top is down. This reduced angle means the actuator will need more force to lift the top through the first portion of its arc.

The lift point on the roof is in the reinforced rib about halfway along the roof top length.

We have removed the upper bed folding base and mattress, so with the top down, there is still plenty of space for a real actuator - though only the mockup is shown here.

The Modelling Stage

A simple model of the linear actuator made of aluminum tube and piece of dowel could be extended and contracted easily without power to determine angles and pivot bracket locations. Simple pivot brackets were milled out of scrap hardwood.

The actuator is shown on the outside of the van only to get an idea of location, and to compare it with the pop top struts already installed.

The actuators will be mounted inside the canvas pop top for several reasons:

  • If a battery should die, or a motor or electric circuit should fail with the roof down, it will be easy to reach the pivot brackets, pull out the clevis pin and raise the top manually,
  • Due to the limited space between the fibreglass top and the metal van top outside the canvas, it is impossible without removing the canvas to determine if the actuators will fit,
  • The curved surface of the metal van top would make mounting the pivot brackets very difficult,
  • We do not use the upper bunk as a bed so have removed the folding bed base, leaving plenty of room for actuators. If a future owner wished to return the van to original, it would be easy to remove the actuators and reinstall the folding bed base and mattress.

There is plenty of space between the fixed bed base and the fibreglass top for the actuators.

Because the actuators sit at an angle of about 12 degrees from horizontal, they will have sufficient leverage to lift the top. To aid this leverage, the top will raise a small amount when the latch lock is released, and as well, the roof actually moves about 45 mm forward due to the scissor hinges at the rear.

The Equipment

The actuators are Concentric International brand, model LACT12-P. The 12 signifies 12" (nominal) travel, which actually is exactly 300 mm. The -P means there is a built in linear position rheostat for use with an electronic controller. I won't be needing this feature, but that is how they came. Dymanic lift load is 110 lbs and static load is 500 lbs. Power requirements are 12V DC at 3.5 A, although tests show it can operate well on several hundred milliamps. Travel time is rated as 1/2" (12.5 mm) per second, maximum (meaning no-load).

Actual lifting time is about 33 seconds. I can live with that.

Lowering time is somewhat less, due to gravity!

The only option missing are internal adjustable limit switches, as found on some brands of actuators. These may not be the best and certainly were not
the cheapest actuators around, but what were available to me at the time.

The brackets are machined out of hard maple wood. They should be plenty strong enough, but if not, the same design can be milled from billet aluminum.

The right hand brackets are for the piston end and fit upside down against the top. The stainless steel plate fits on top of the fibreglass roof, all held together with stainless steel bolts and acorn nuts. The clevis pin holds the piston rod into the bracket.

The left hand brackets are for the motor end and fasten to the upper bed platform with the large wood screws.

This is the final wiring diagram.

There is already a fused 12V supply in a cabinet from a previous modification.

All wires are run almost out of sight - along the aluminum track that holds the canvas to the roof; inside the front support for the upper bed; and behind the spice rack behind the curtains from the upper bed down into the electrial cabinet beside the water tank.

An aluminum bracket was made to mount behind the pop top latch/lock and a microswitch screwed to it. The bracket is slotted to allow the microswitch to be adjusted up or down to ensure the roof portion activates the switch.

When the roof is locked down the switch prevents power from going to the actuators.

The hand-held UP/DN switch housing was milled out of solid maple. It hangs freely on a cord so it can be used while tucking in canvas, locking or unlocking the lifting bar, etc.

It can be stored in the spice rack above the sink.


After very nervously drilling the 4 holes in the fibreglass top, the upper pivot brackets were bolted in place, with the stainless steel plate on the outside. Sealant was used under the plates.

Then the lower brackets were temporarily clamped in place on the upper bed base. The actuators were wired in parallel, as per the wiring diagram, and the testing began. The actuators could lift the roof with the aid of the pop top struts, despite some binding of the pistons.

However, they could not pull the roof back down against the struts. So, the pop top struts were disconnected and testing continued. I had forgotten how hard the roof was to lift before installing those struts quite some years ago!

Without the aid of the struts, the actuators could lift the roof quite easily, and of course, lower it even more easily.


After bolting the pivot brackets to the roof and clamping the lower brackets to the bed base, I discovered that the actuators would bind between fully retracted and fully extended.

The reason was the bow in the roof. Across the 1.2 m (48") width of the roof there is a bow of 20 mm (3/4") at the centre. The pivot brackets were bolted flat to the roof, so this meant that when fully extended the actuators tried to pull inwards, narrower at the motor end.

When fully retracted, the piston end could rotate in the cylinder to compensate for the angle of the clevis pin.

The cure was to mill just under 1 mm off the outer edge of the two upper pivot brackets. This put the clevis pins truly horizontal and perpendicular to the lift direction.

With the actuators and their upper pivot brackets bolted to the roof, the actuators were retracted and the top was lowered to determine the location for the motor end brackets.

Because the roof brackets were mounted in the reinforced ridge, the actuators could not be used through their full range of travel - limit stop to limit stop. This meant determining where to screw the motor end brackets to the bed base when fully retracted.

After marking, raising the pop top again (whew it's getting heavier!) and drilling screw holes the brackets coud be screwed down.

IF, IF I had chosen to mount the upper bracket forward of that reinforced ridge, the actuators would have been able to operate limit stop to limit stop. However, I felt that the strongest point would be in that ridge, so went with it.

Both actuators are mounted and working!

The two units do not operate at quite the same speed, so one reaches the top first, by about 10mm (3/8"). However due to flex and the overall length of the fibreglass top this does not seem critical. When the top is lowered again, both actuators self-correct when they reach their lower limit switches.

Method of Operation

To raise the top:
The latch/lock is released and the roof allowed to raise about 25mm (1") on its own. Flexing and play in actuators and mounts allows this.
The UP button is held for about 30 seconds. When the actuators begin to labour when the roof is almost fully raised, the button is released.
The lifting bar is pushed into locked position manually. Again the small amount of further lift in the roof is taken up in play.

To lower the top:
The lifting bar is pulled back manually.
The DN button is held until the top is nearly in the down position, then released.
The canvas is tucked in and checked for pinch points.
The DN button is held again until the actuators stop due to hitting their limit switches.
The latch/lock is pulled down manually to lock the roof down.

I felt this project deserved bit of advertising so made up this logo using Inkscape. The .SVG file was then transferred to my wife's Brother ScanNCut cutter. The logo was then cut from outdoor black vinyl and stuck on the fibreglass pop top.

It may raise a question or two from some other Westfalia enthusiasts.

Improvement Needed for These Actuators

The only improvement I can see needed is to cause these actuators to reach a limit switch when extended as far as the roof needs to go. This would ensure that the left and right have lifted an equal amount. It could be done by wiring two external limit switches on the roof, but that would entail a lot of exposed wiring and bracket making.

As mentioned these actuators do not have built-in adjustable limit-stop switches so they need to be modified internally to make the extended-stop adjustable.

By making the left hand limit switch (mounted on the white plastic strip) moveable within the aluminum cover tube (bottom), the extended limit could be adjustable shorter than full travel. A small screw mounted in the black plastic end cap could move the portion of the plastic strip and left hand microswitch inwards or outwards.

The parts laid out Left to Right

  • 4-40 X 1 1/4" screw to adjust the extended limit stop
  • Actuator end cap
  • Brass nut. Machined to fit the 4-40 screw, small enough to fit into the end cap. This will be thread-locked to prevent the screw from backing out.
  • Brass post. Threaded to fit the 4-40 screw. The small end fits into a hole drilled in the plastic strip
  • Plastic strip holding the limit switches
  • Actuator tube

The parts assembled

The white plastic strip has been cut at 75 mm from the end, and 15 mm removed.
When the adjusting screw is screwed CW (fully in), the plastic strip will butt against the end cap.
When the screw is screwed CCW the two pieces of the plastic strip will butt against each other, preventing the screw from disengaging from the brass post.

The effect will be to move the extended limit switch from fully extended to some point up to 15 mm less.

The right hand portion of the plastic strip holding the retracted limit switch is locked in position in the actuator tube by a small screw.

The end result was successful, decreasing the fully extended travel of the actuator by 15 mm. Unfortunately the whole modification was not successful. The 15 mm of shortening was not enough for the position of the actuators in this installation.

This whole improvements section could be avoided by using better actuators - ones which have fully adjustable limit stops!

The only other improvement I could suggest would be to use actuators with greater lift capacity - say 160 pounds.

The owner takes no responsibility for anyone else making these modifications.
Photos provided by owner. Contact the postmaster for permission for use.

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F. Griffiths

Last updated September 07, 2018

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