Rotiserie, The rear mount Options

[cwpeden]

So I've finished my rotiserie and after mounting the rear bar to the bumper holes, the whole rear looks a little 'flexy'! I can grab the bar and move it up and down easily.

Did those of you who used the bumper holes reinforce anything?

I built it according to drawings and advice on this forum.

Conrad.

[Richard Casto]

A few quick random thoughts...

The plans that were on Roadglue were mine. As Roadglue is down for good and the wiki is eventually going to be back up here, those plans should show up here in the future. I may host the plans again on my site if that conversion takes a long time.

Everyone may not build exactly to my plans (and that is OK). The tubes I used to offset were pretty thick. I also offset them as much as I did so that work (including media blasting, etc.) could be easily done. I have no doubt that the design is fine with respect to the strength of those tubes at the length I have them. I am sure they are stronger than the box section they are welded to.

I like the idea of putting fender washers on both sides of the sheet metal (or plate on outside and fender washers on inside, but I think fender washers on both is easier). It should increase the "clamping area" and would reduce the risk of damage. Especially to the top holes (see comments below). Also I don't think the smaller bolt diameter is an issue as in my opinion the bolts are not used to "position" but rather "clamp". It is the clamping force that keeps the entire bar positioned on the car. The bolts just need to be large enough to safely provide enough clamping force.

The structure on the car for the rear bumper mounts is a joke compared to the front bumper mounts. On the rear you have a small angle reinforcement that ties to the trunk floor, but only for the lower mount. The top mount is just a hole in the thin sheet metal with no other support. The front bumper has a significant angle piece that supports both top and bottom mount locations. I don't know what early 1970's crash testing was like, but I assume the front had to meet some level of crash tests while the rear on the other hand must have had much less severe requirements.

My trunk has way more "swiss cheese" going on than yours. Mine has been on the rotisserie for a long time. So I can't remember exactly how much flex it had when unmounted. When on the frame, I can't seem to get it to flex at all. Maybe as it is fixed along a rotational axis now it can't easily flex as much as it might have when not on the rotisserie frame. If there is any flex, I would guess it would be around the unsupported (see comment above) top mounting holes.

Good luck and I hope it works out for you!

Richard