Roll hoops

31st March 2006

I have just been reminded that the diary is lagging behind a bit (thanks Tony!) and I am shocked and frankly embarrassed at how long it's been since the last entry. So what has been accomplished you ask since the beginning of February? Well so far I've managed to sell our house and buy another, go for several job interviews and on the side, fitted some roll hoops (and some other bits) to the cobra.

One of the jobs (aside from the door hanging) that I'd been dreading was fitting the twin hoops. Not least because it involves drilling through a large metal bar the runs across the center of the body tub with a giant 2¼" hole saw for the inner legs in exactly the right places. The new bodies now have a dog-leg in the bar so it's not a problem, but mine turned out to be one of the last with a straight bar which meant some careful marking up and some big cojones.

To mark the holes, the trick I had been told was to insert a pen into an empty tube of Sikaflex and slip this over the hoop mounts on the chassis and use this to mark the center point of the hole on the tub. Then drill a pilot hole up from inside before drilling down from the outside with the hole saw. Fortunately I still had an empty Sikaflex tube hanging around so after chopping a couple of inches off the end I made my makeshift centerpoint marker and tried it out. The tube was quite a tight fit over the hoop mounts, but not enough to eliminate all the possible movement so I had to judge by eye and with the aid of a spirit level where the exact center would be.

I offered up the drill to make the first pilot hole and hit a serious snag - it didn't fit! There wasn't enough room to fit the body of the drill between the chassis and the tub so I had to stop and make a trip to the shops. I had seen on the internet attachments that allowed the drill bit to run at 90° to the drill and fortunately I managed to track one down in the local B&Q. I relieved their shelves of one and headed back for the garage. The attachment and drill was a little unwieldy, but with some more unlikely yoga manoeuvres climbing into the boot I successfully managed to drill the first pilot hole.

In the spirit of measure twice, cut once I dropped a plumb line through the new hole and checked by eye that it dropped into the center of the hoop mount. It was nigh on perfect - fantastic! I attached the hole saw and gritted my teeth... Applying power to the drill made the hole saw grab the fibreglass like a great white shark grabs its victim and had pretty much the same outcome. Before I had time to react the saw had neatly ripped a circle in the body tub. Adrenaline pumping I offered up the roll hoop leg through the hole. It dropped perfectly onto the mount - success!!

The inner leg hole (the one through the metal bar) was centered in the same way and the pilot hole drilled. The hole saw took far longer to drill through the metal than the fibreglass, but with a good dose of WD40 it got there eventually and much more easily than I was expecting. I test mounted the hoop and stood back to admire my handiwork.

After mounting the first hoop I was given the tip that mounting the hoops perfectly straight across the car would lead to the inner escutcheon plates poking over the lip of the body and require trimming. Apparently the trick is to set the inner legs back very very slightly to avoid this. Fortunately the first hoop was positioned so the plate was perfectly on the edge but not over it (lucky!). On mounting the second hoop I decided to triple check the position of the inner leg using the pilot hole and escutcheon plate and some visual guess work. I decided that the leg needed to be mounted back a fraction, so altered the pilot hole and drilled out the full hole. Mounting the hoop was tight as it now didn't fit quite centrally over the mounting tube, but it went on ok. The inner plate sat perfectly on the edge of the body, but from the sides the hoops were quite obviously not straight - eek! I stepped back and walked around the car for a while looking at them from different angles. I came to the conclusion that unless you looked exactly across the car along the line of the hoops you couldn't tell they weren't straight and even then I doubt you'd notice unless you knew.

Satisfied with my roll hoops I moved onto the rear lamps. First job was removing yet more sodding flash lines (such a thankless task!). Once the hard graft of that was over I made up some templates on the computer that would help align the lamps and stuck them to the rear of the car. Then it was a case of drilling suitable holes and filing them out until the lamps were a good fit. Much easier to mount!

The other job I've achieved was cutting the slots for the demister vents. This required putting them in the position recommended by the build manual and simply drawing the right shaped hole and using the drill and jigsaw to cut them out. Not hard, but another thing to tick off the list.

I also started trying to make the steel straps that will tie the harness top mounts to the chassis. These are essentially 'C' shaped sections of flat bar steel and should have been easy to make. Unfortunately the limitations of DIY tools became all too apparent when trying to bend the 5mm steel bar into the right shape. No amount of blow-torching or "persuasion" in the vice with a hammer could bend the bar. Good in a way I suppose if I'm relying on it to keep me in the car in the event of an accident, but still yet another hold up. I think I will either need to borrow an acetylene torch to get the required temperature into the metal for bending or better yet find a local engineering firm who has some sort of bending press I can borrow.

I'm still waiting for the front nudge bar to arrive from Pilgrim (has been at least 6 weeks since ordering), but the postman has left notice of a parcel for me so hopefully that'll be what it is and I can collect that tomorrow morning.

Now the clocks have gone forward again and Spring is on its way I can get back into the garage after work during the week for a bit longer without turning into an icicle or having the generator running and keeping the neighborhood kids awake. I desperately want to get it on the road this summer. The Stoneleigh kit show is in a few weeks so I'm hoping to make a trip up there to get some ideas and see some more finished cars.

Marking up for
roll hoop holes

Fantastic drill gadget

Pilot hole

First hoop fitted

Both hoops fitted

Slighty wonky, but
not too noticeable

Rear lights fitted