Thread: Chassis Building Help

talk to your nearest Rod club, they will know where the good chassis welders are

another way is to look at what your local TAFE colleges provide in the way of car restoration courses or welding. A recent Channel 31 program had blokes going to tafe to work on their own cars hope this helps

Did the learned engineer give you anything in the way of sketch etc suggesting a layout for the chassis and pillar stiffening? If not I would be looking for another one.
Ultimately, your ability to get the car into use will depend on the engineer being totally satisfied that the design and implimentation are adequate and suitable for the purpose. This could become difficult if after you have done a load of work (or worse still paid someone to do it) only to have it rejected by the engineer.
There is also the possibility that something might impeed before completion the eng's ability to sign off the job (i.e. they may move interstate, overseas, unexpectedly meet the proverbial bus). If you are working from an accepted set of guidlines, there is a much better chance of having some other eng take over certification at the end if need be.
Re. Pillar bracing, maybe have a good look at some mid 60's Pontiac Parisiennes, same stable, similar age, 4 door "pillarless" sedan. In this case from memory, not totally pillarless but with stub pillars up to window height to hang the back doors off and lock the fromts to.

Otherwise as a basic concept, box chassis virtually in line with or just outside existing subframes, appropriate bracing side to side to tie the chassis rails together, and then an outrigger into the sill cavity each side with an upright inside the truncated pillar to the cap. Outrigger and upright would need extensive bracing within the upright base, and the outriggers would need 3D strutting back to the chassis rails.

I would be clarifying the seatbelt situation also. As I understand it, the standard FB would be exempt for compulsory seatbelt requirement as it was manufactured before the legislation became effective. However, if the chassis has previously been fitted with aftermarket front lap/sash belts, then there is generally a requirement to retain front lap/sash belts, but you are removing to top mounting points. If you were intending to close in the back doors and go to a two door configuration, the rear inner door could be reworked to provide a top attach point well behind the drivers seat so that the belt can run up and over the shoulder as per the belt equipted convertables. This obviously isn't practical for a 4 door conv.

Don't be too afraid of adding weight, virtually all convertibles are significantly heavier than the sedan or coupe versions of the same series because that have to incorporate all this stiffening into the chassis structure. I know of people who got there feet crushed thirty years ago trying to do the same thing to an FC or FE without the chassis work first. The body collapsed onto their feet as they were cutting out the B pillars. The pillars and roof structure efficiently (in terms of metal weight) supply a large amount of strength to the car.

Early toyota crown (6 cylinder) had a full chasis and are within cm of FB wheelbase to my understanding. I have seen a guy start one but don't know what happened to it. He kept the whole toyota floor and firewall and slotted the FB sans floor and firewall over it.

Best place to ask this is:

http://www.fbekholden.com/forum/index.php

Harko is the bloke who started the Crown conversion if you find him there.

Masses of info here as well:

http://fefcholden.org.au/forum/

My 2c from building rally cars is find an engineer who has mates in the game that can perform the work. Much much easier as they will tend to call each other if something doesnt make sense as opposed to you turning back up and the engineer saying "thats not how you do it, I would have done it this way" etc.

I found the changes were almost rubber stamped when they knew each other..

Hi Living in Victoria our Powers to be require a full Chassis plus any part of the main structure must be certified by the Engineer
2" x 2" Blue box is the only real way to go if you want to keep your car straight and weld as many gussets as possible and even cut and go over the back axle to the rear bar the old Holdens I found out quicksmart that once you cut the roof off it literally starts to droop and within a week mine was bent like a banana but that was 30 years ago Your best bet is to go to your local rego branch and ask for a list of qualified Engineers then the fun starts go to Hot rod shows with your list and ask the guys who they used and who not to use
But remember it is you and your friends lives at stake so please do it right as once it droops the tailshaft comes out and acts like a catapult sending the whole car flying
do not take short cuts as it is not worth it as 30 years ago we did things like that for a weekend joy ride untile she buckled under the weight and yes I put a tailshaft loop in to avoid the catapult effect more is better and weight is not a issue