The question we have been hearing most since Gavin’s Estate first appeared on these pages is, how has he got it so low? Here’s how...
Cortina is now at home in Gavin’s lock-up, but it will be going back to Rayvern soon.
Before I go anywhere I thought I’d better describe what’s been done to my estate to get it sitting so low. It seems that my brief to Ray was asking quite a lot as I wanted it low, but I still wanted to retain the rear seats in as near standard form as possible. Riding low and carrying passengers seems to be quite challenging!
In May’s issue you will have seen Jon Hill describe the problems he’s having installing a back seat in his estate. Well Jon’s car may be low, but on full drop my sills will be just 35 mm off the ground so you can imagine that my brief got Ray scratching his head!
At the rear fitting air bags meant the original leaf springs were made redundant, but throwing them out meant that the axle needed some other form of location. The obvious choice, as has been fitted to Jon’s estate, is to four-link the axle, but doing this would cause a couple of problems with the axle movement.
Firstly, the link boxes protruding into the cabin would foul the seat, but the movement of the axle would also cause problems. A four-link set-up keeps the axle in an upright position at all times which is ideal for suspension geometry, but the extreme movement of my axle would mean that the travel of the propshaft would conflict with the back seat. So Ray has designed a hairpin set-up instead. This joins each pair of links together at the front so there is only one fixing point, mounted in the original leaf spring mounting.
This means that the axle movement describes an arch around this fixing point, thereby pointing the diff downwards slightly on full drop. This wouldn’t be ideal if the car was to be driven at this height, but full drop is parking mode — running 35 mm off the Tarmac wouldn’t be a good idea! This all kept the suspension install below the seat, although it did require some mods to the seat tray.
With this in place and on full drop the diff casing was going to be knocking on the boot floor, so mounting the airbags below the boot floor was never going to work. A section of the boot floor was cut out above the axle and a subframe installed mounted on the top of the (notched) chassis rails. The airbags are mounted to this subframe.
To do all this work and retain the original steering box seemed silly so I was intent on a rack conversion. We looked at a few ways of doing this but in the end based the front suspension around an Old Ford Auto Services conversion kit.
This kit uses an Escort crossmember which Old Ford modify to bolt straight to the Cortina chassis. Rather than use a standard crossmember I asked Old Ford to modify a World Cup crossmember, and Ray then modified the engine mounts to suit the V6. The kit also uses Escort geometry, which necessitates moving the strut tops inwards slightly (the angle between spindle and shock shaft is bigger on the Escort that the Cortina). This isn’t a problem when using coil springs, but airbags are a lot bigger and they fouled the inner wings. So out came the cutter again and the inner wings and strut tops were relieved of a bit of metal to provide the required clearance.
Mounting the engine as we did meant a large part of the bulkhead had been removed with the heater bubble all but gone. In re-forming this and the strut towers Ray tidied the whole bay up, making it look a lot cleaner and modern.
The front suspension isn’t quite complete, with drop links still to be added to the anti-roll bar to achieve full drop, but before this is done exhaust manifolds are being fabricated and the steering column connected to the rack to ensure there is enough space for everything. More on that next time!
What’s been done this month:
Run through how to make a Cortina sit 35 mm off the ground
Next on the to-do list:
Fabricate exhaust manifolds, finish the front suspension
Old Ford Auto Services