Sunday 29 December 2013

Hood frame

Over the Christmas break I did a little work on the roof frame but forgot to blog - its not finished - and another pause before I go further.

The pivots either side are in place, spring side is locked in place and tensions the spring, the other end is free to rotate:

The roller does spin on its spring as required:

The theory being it can be moved into place while inside the car unfurling the roof as it goes:

All well and good - just still not decided on the windscreen mounting method...  the old sheet I was using as template material was not working - far too stretchy and not really letting me work out the shape of fabric required.

Still needs some more thought.

Update - discarded this idea, it's just too complicated and not really worth it compared with a simple surrey top or a more traditional roof frame. For now I'm sticking with a surrey top fastened to the windscreen frame and over the roll bar.

Sunday 15 December 2013

California style self rolling roof

Too much reading of Slomove's Birkini, His half hood is more for the California sun than rain protection, however - looked like an interesting concept so, not having much luck with my First hood design, I thought I would try and re-create it.

The concept is to have a hood which can be opened & closed while in the car, utilising a roller spring (roller blind) as the central support to furl and unfurl the roof fabric. No idea if it will work really...

First up the roller blind mechanism, I got one with nylon/plastic ends so they are easily dismantled  & modified - but possibly also slightly weaker? One end free wheels, the other larger end is locked in place & tensions the spring. I don't need the automatic position locking so the ball bearing & associated mechanism can all go:

Paired down the locking end with my Dremel to end up with the hexagonal nut which will slide inside the struts, reduced the height of one brass bush & reduced the internal height of the cage which holds the roll tube - the last part is to expose more of the central pivot shaft:

The locking end now will slide inside the support tube but will stop the shaft rotating. Offerred up the entire end components to check, may need some adjustment but looks ok:

The other end is simpler, this just free wheels; so modified to take an M6 bolt through the centre and will be simply bolted loosely to the other tube: 

Next up I wanted to try improve on Slomove's design a little and put a dog leg bend in the support tubes, this should ensure they don't impact comfort, hitting my shoulder, when the roof is open. A little prototyping with a coat-hanger to get the right shape then on to some 16mm aluminium tubes.

A RhoCar member kindly offered use of his pipe bender, I was impatient though, bought a spring bender and had a go myself. The bends are not perfect & not strictly identical, but will do the job:

When closed the struct sits back along the roll bar & away from the passenger shoulder. When open the top point reaches exactly half way along the roof line:

Few more parts ordered from Ebay & the next task is to work out exactly where the pivot point will be avoiding the internal structure in the side panels & drill some mounting holes. I'm intending to mount with a couple of rivnuts in the side panel and a threaded knob of some sort to make everything removable.

Update - This never worked properly, so I have not used it; its much simpler to create/buy a surrey/half hood simply strung between the roll bar and top of the windscreen.

Sunday 1 December 2013

Wind deflectors V2

I Started thinking about doors, but ended up re-working the wind deflector design. The door template ended up being incredibly long so really if doors are going on the hinge point should be further back than the windscreen pillar.

I only had enough 4mm PETG left for one side so built a template and one deflector to check it out - each deflector is about 2' tall & 16" deep. I ran into problems bending the PETG, the combined factors of colder ambient temperature and large area of plastic meant it was a real struggle to get enough heat into it and bend.. I may have to invest in a cheap heat gun for the other side & give my wife her hair dryer back.


The deflector comes back roughly level with the back of the steering wheel but not so far it impedes getting in/out of the car:

I took it out for a little test run - this is certainly an improvement over my first design, now I can feel the heater air around the wheel and less need for gloves especially on the offside hand. The 4mm PETG is very stable, no movement/flutter or vibration even at speed.

The next step to think about is a secure fixing against the side of the car & a simple hinge arrangement for half/full doors off the trailing edge. I think these deflectors will effectively be permanent, possible lift off doors to be fixed to their rear edge, possible re-enforcing aluminium U channel along the trailing edge.

Update - reverted to the original simple design for a couple of years now, don't deflect the wind as much as stop the front wheels catapulting anything from the road into my face.