Jackable Sills

Having had problems with the first gearbox I put in junior I decided to put in a full recon box. These are quite expensive but worth it just to preserve my hearing. It should also give me some confidence when in the middle of nowhere.


These a commercially available sills made for the defender. They look great and offer awesome protection to the doors when you drive over ridges or rocks.


After this happened to mike Wilson when he had his series 3 I thought I would start designing something for junior which would do the job.

I started with a length of 80x40mm box section steel with 5mm wall thickness. I went for something bomb proof.

I cut the ends to match the profile of the wheel arches. Capped the ends of the sills with 5mm plate and profile the welds. 


The next challenge was to make a mounting which would allow the sill to sit closely to the outrigger

By fitting closely I could use the bulkhead bolt to attach the sill and lift under the outrigger. This would be allot stronger than a mounting on its own.

Here you can see the mounting and the cut away area which allows the sill to lift under the end of the outrigger.

The mounting picks up on the bulkhead bolt.

Here you can see the front mounting. the recess into which the outrigger sits, and the second mounting which fits to the original outrigger.

At the rear I decided to use the tub outrigger but since these are only ever made from 2mm plate I decided I needed to strengthen it up. 

I cut a 4mm plate shape identical to the outrigger section and welded it all round and lug welded the center to prevent delaminating.

You can see this behind the mounting fitted to the sill.


To mount the rear of the sill I cut a shaped piece of 4mm plate which would not interfere with the tyre and look good too.

These were drilled for 4 high tensile M10 bolts and were then welded to the sills.


When we fitted the roll cage I fitted a set of dedicated outriggers, strengthened to mount the roll cage. I left the original outriggers in place to be used to fit the sills to.

I cut out a 4mm plate with the profile of the outrigger, drilled to accept 2xM10 bolts.

This I welded to the original outrigger and the main chassis rail. This is very strong and fits to the brackets on the sills you can see below.

All welding finished and tidied up, ready for test fitting and coating.

The finished article fitted on the drivers side. They sit slightly proud of the bodywork to keep rocks from damaging the panels.

And on the passenger side. the front wing was still off as the engine was being fitted when I fitted when I took the picture.

Finally fitted. Finished in black powder they look the part. 

With the jack under any point along the sill it will happily lift junior without any distortion at all.