01-08-2021, 10:37 PM
I had an interesting seat failure. I am still waiting to hear if I am even allowed to try VINing my special so the other day I was driving it round and round the garden to fiddle with the tune and test the brakes. I did a hard stop on the driveway and the brakes worked great but my seat suffered. I am using a Ruby seat modified to fit in the special using the original seat mounting rails so I had some adjustment. The rails themselves were unmodified I just welded some 3mm strap across them so I could bolt the seat to the floor through holes in the strap. The strap had bent on the hard braking (but not broken) so I beefed that up and tried again but as soon as I sat in the seat it went PING! and felt very wobbly.
It turns out the failure was on the seat rail itself. The left hand side rail attached to the base of the seat has split all along where it folds to form the lip that fits into a matching folded lip on the base to allow it to slide. It has fractured nearly it's entire length. Looking at the crack the first inch or so looks like it was cracked some time in the past as the metal there isn't shiny. The rest of it split from there. I imagine that is quite a stress point as the steel if folded through quite an angle to provide the lip.
That rail is riveted to the seat as well as spot welded through. Replacing it would be tricky and my only replacement would be the other seats rails which are likely to be the same age.
In the end I ground off the folded over lips and made a new frame from 5mm steel strap. The seat base is welded to this in many places so it should be secure. The frame has mounting holes drilled in it to bolt it directly to the floor of the special. There is a series of holes so I can get 3 inches or so adjustment if needed. It's much more solid now and also has the advantage of making the seat sit slightly lower.
Was an interesting failure though and I wonder how many others cars suffer it.
![[Image: 20210801153555-d3282e02.jpg]](http://www.asciimation.co.nz/photos/upload/2021/08/01/20210801153555-d3282e02.jpg)
Simon
It turns out the failure was on the seat rail itself. The left hand side rail attached to the base of the seat has split all along where it folds to form the lip that fits into a matching folded lip on the base to allow it to slide. It has fractured nearly it's entire length. Looking at the crack the first inch or so looks like it was cracked some time in the past as the metal there isn't shiny. The rest of it split from there. I imagine that is quite a stress point as the steel if folded through quite an angle to provide the lip.
That rail is riveted to the seat as well as spot welded through. Replacing it would be tricky and my only replacement would be the other seats rails which are likely to be the same age.
In the end I ground off the folded over lips and made a new frame from 5mm steel strap. The seat base is welded to this in many places so it should be secure. The frame has mounting holes drilled in it to bolt it directly to the floor of the special. There is a series of holes so I can get 3 inches or so adjustment if needed. It's much more solid now and also has the advantage of making the seat sit slightly lower.
Was an interesting failure though and I wonder how many others cars suffer it.
Simon