Taking Important Measurements

[cobolman]

I may be about to embark upon some welding on my car and have been researching and reading as much as I can to save myself from making obvious mistakes. I keep reading about people taking 'crucial measurements' and talk of 'It was 4 mm out and that would be catastrophic' and so on.

The advice I keep reading is to take accurate measurements and I got to thinking: How? I can't imagine that just using a tape measure would be enough?

For example: I'm thinking of replacing the part of the heel board to which the rear subframe connects. Positioning this correctly would be vital. How do you measure to ensure correct placement of the replacement panel? I've heard of people measuring (but not saying how), others using jigs and yet others that use an old subframe.

What do you do? How do you do it?

[mini_surfari]

Tape measure, vernier’s etc all useful. (I’m sure some people on the forum have very sophisticated measuring devices, but I even used a plumb line doing our van). Make a note of reference points, and mark areas that aren’t being disturbed.

Also, if the heel boards being replaced, you’ll be wanting to dry fit the rear subframe back in before you weld it anyway to check. So you’ll be in the right area.

There’s certainly tolerance in a mini, just got to see how they beat them around on the production lines.

[Peter Laidler]

I asked the same question before I started on my Mk2 S body shell. This is what I did. Get out the trusty old tape measure and make yourself a pair of dividers. An enlarged set of the ones you used at school. Just like clever Mini-Surfari says above

Then I fitted two cheap old 6' ex WD treestle tables together using wood beams between the two as necessary and accurately marked on them the EXACT drop marks as shown in the workshop manual. If you ain't got the workshop manual, then read no further.........

I bolted a couple of sub frames onto the table exactly to the spec above. Old rusty ones will do so long as they are straight of course and correct for the height, relative to each other. It was as simple as that. Based on that, the car had to be perfectly aligned. Trestle tables were about 4" off the garage floor so easy to access.

For other measurements etc etc, my wife also had a Mk3 mini that I could use. I'm a simple soul and didn't complicate anything.

Oooooooops..... I said 4 INCHES off the garage floor above. I meant to say 4 FEET

[MiNiKiN]

For the rear subframe mounts: I made a jig from a few old 14mm tubes and pieces of flat iron. I connected the tubes longitudinally and diagonally. This enabled me to exctly position the repair panels on the heel board and the rear mounting areas before welding them in.
Provided the chassis dimensions were correct in the first place.

As yours has had some patching done in the heelboard area I would first reasure the dimensions are correct.
Measuring diagonally from each mounting point to the other and comparing the figures will give you a first indication. A good tape measure, or better a quality yard stick. Well even a piece of string can be used, without even asking yourself how long it is

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