07 February 2023
The original bulkhead is back from the galvanising shop, but there is work to do before it can be fitted to the chassis. Trevor Cuthbert details what’s involved
THE STORY SO FAR: After a customer bought the battered body sections from this 110 Td5 hardtop, Trevor ended up with the remains including the wrecked engine and gearbox, rolling chassis, bulkhead and one wing. The mechanical parts have now been built up onto a new galvanised chassis with an ex-Discovery 2 engine installed and the bulkhead is rebuilt and about to be fitted. You can read the previous features in our 'How to' section here.
Need to know
Time: 8 hours.
Difficulty: 3 out of 5
Models: Defender 90, 110, 130.
Tools needed: Side cutters, thread tap set, files, power file, drill, blowtorch, air line, services of a professional paint shop.
Parts & costs: Everbuild Puraflex 40 Sealant, £9.50 each; to galvanise the bulkhead, £50, Sperrin Galvanisers Ltd; painting process, £250, The Paint shop, Ballynure,
• Wear protective gloves and safety boots when handling heavy objects.
• Wear eye protection when drilling and using power tools.
• Wear suitable protection including gloves when working with a blowtorch and air line.
Contacts: Anthony O’Neill, chassisseal.com, tel: 07843 182307
It was a very satisfying exercise to strip down the Defender’s original bulkhead and carry out the extensive repairs, as shown in last month’s feature. Saving a major component, rather that scrapping it, is certainly the best option from an environmental point of view, but I also have the knowledge that this original Land Rover part will fit perfectly as the rebuild of the Defender 110 Td5 progresses.
Following the repairs, the bulkhead was completely sandblasted and then sent to Sperrin Galvanisers in Co. Derry to be hot-dip galvanised in order to prevent rust recurring in the future, or at the very least slow it right down. However, after parts are galvanised, there is nearly always rectification work to be carried out.
Preparing the galvanised bulkhead
During the galvanisation process, as galvanised steel parts are lifted from the tank of molten zinc, inevitably drips of zinc will form and harden into rather sharp spikes. While the galvanisers do their best to knock these drips off before they harden, there are always a few remaining. These, as well as other build-ups of excess zinc, need to be removed, both from a safety point of view and to ensure that the bulkhead will fit correctly with other associated parts.
Original threaded holes in the bulkhead will also have become filled or clogged with zinc, so this needs to be dealt with. Finally, all of the factory sealant – which I spent a few hours softening with a blowtorch and scraping off – needs to be replaced with new material to keep the Defender reasonably watertight and to keep down draughts.
Shining brightly: The original factory-fitted bulkhead has been comprehensively repaired, sandblasted and then hot-dip galvanised. It is now ready for preparation, prior to the painting process.
Cutting off the excess: The larger sharp pieces of zinc that have formed are snipped off with side-cutters. All excess zinc is then filed off using the electric power file.
More zinc removal: The vent hinges have mostly filled with zinc and need to be drilled out, using a 5mm drill bit on a flexible drill extension.
Making sure: An old vent hinge pin is used to test that each of the four hinges are clear, as we would not want to be drilling these after the paint is applied.
Effective technique: Zinc is cleared from the steel vent meshes using heat to soften the zinc in a small area and then blowing it out with the compressed air line.
Restore threads: There are numerous threaded holes in the bulkhead on both sides which are cleaned out using a thread tap of the appropriate size on each of them.
Keeping water out: All seams on both sides of the bulkhead are sealed up using a polyurethane sealant that remains permanently flexible and is capable of being painted over.
Excess is fine: Sealant is applied generously to ensure every seam is properly watertight. Later Defenders had much more sealant applied at the factory than earlier models did.
Pieced together again: The cabin side of the bulkhead is similarly treated with the sealant. The old brittle sound-deadening material has been fixed with sealant, rather than with rivets.
The paint process
Paint does not stick to galvanised steel. If I were to apply standard primer and a finish coat to the freshly galvanised bulkhead, the paint would begin peeling off in great chunks within a few short months. I have seen this many times on galvanised chassis and other galvanised parts that have not been correctly prepared.
The correct paint process for galvanised steel involves a quality etch primer and is a more expensive process, but well worth the effort to achieve a good and lasting job. The paint shop that I use for all of my Land Rover work has carried out the process on umpteen new galvanised chassis and bulkheads that I have brought over the years. We have never received any complaints of peeling paint.
One of three paint stages: After a rub down with fine grit paper and a wipe down with degreasing solution, the bulkhead has been sprayed with a light coat of etch primer.
Both sides now: The cabin side of the bulkhead is etch-primed too, but none of the paint was wasted on the sound-deadening at this stage, as it only acts on metal.
Paint here, too: It is important to spray the vent meshes because the zinc had been purposely melted and blown off, leaving the steel meshes prone to rust.
Second step: After a short drying period for the etch primer, a high-build 2K (two-pack) primer is applied to the whole bulkhead and allowed to dry for two hours.
Resplendent: The final coat of 2K paint, sprayed onto the bulkhead is Rutland Red (LRC607), which is a factory solid colour used from around 1998 to 2005.
Dashboard will also hold it: This time, the sound-deadening material was coated with paint in an attempt to arrest the deterioration and seal it up, as it is now very brittle and fractured.
Starting to fit out the bulkhead
The safest place for a freshly painted bulkhead to be kept is on the Defender rolling chassis with the two bulkhead outrigger bolts holding it in place. So, as soon as I got the bulkhead back to the workshop, after the paint was sufficiently dried, I lifted it into position on the rolling chassis.
A blank resplendent Rutland Red bulkhead on a rolling chassis is a very inviting sight and I immediately made a start on re-fitting parts to the bulkhead. There are certain parts that simply must be fitted first, in the early stages of a bulkhead rebuild. Later jobs do not need to be carried out in strict order but I have found, through experience, that it is definitely best to fit things such as the bulkhead wiring loom and wiper mechanism first.
Set in place on the frame: With the assistance of a second pair of hands, the painted bulkhead is lifted onto the rolling chassis; the bulkhead outrigger bolt on the left is fitted, though.
Blank canvas: Before anything is fitted to the bulkhead, the cabin side looks (and is) totally bare – but it will soon become a clutter of wiring harness and inner dash components.
A little force: In order to get the bulkhead outrigger bolt through on the right side, a bottle jack is used to ease the bulkhead foot out just a little.
A happy accident: The galvanised bulkhead support brackets became coated with paint at the paint shop and the effect against the galvanised chassis is very pleasing.
Preparation work pays: Two of the threaded holes in the bulkhead, which were cleaned out earlier, are for the M8 bolts fixing this steering column bracket in place.
Fine tuning: This lower bracket for the steering column is left loose for now, so that fine adjustment of the steering column angle can be made to suit the dashboard fitting.
Proper job: The steering column has been fitted with a new seal between the outer bracket and the bulkhead – one of many new seals required.
Completed in order: The window wiper wheel boxes with tubes assembly is one of those things that really needs to be fitted early to the repaired bulkhead.
Bring the electrics: The bulkhead wiring harness is fed through the bulkhead from the cabin side to the engine bay side on the right, and the sealing boot pulled into position.
Easy to install: On the left side, the thick harness that runs underneath the driver’s seat is fed through, along with the harness to the left front lights, etc.
A certain logic: The Defender Td5 loom is one of the easiest to make sense of due to the use of multi-plugs throughout, rather than umpteen bullet connectors in earlier models.
Firmly in place: The main fuse and relay panel is fixed with a pair of screws into threaded holes already in the bulkhead, and tightened with a Pozidrive #3 screwdriver.
A mystery to solve: The green security box and the red relay practically fell into the right position, but where should the lower black box be fitted?
Coming next in part 8: Before the transmission (R380 gearbox and LT230 transfer ’box) becomes concealed behind the seatbox and transmission tunnel and floor panels, there is some important work to be carried out. The R380 is from a Discovery 2, which means the gear shifter is in the wrong location for a Defender. In addition, there is no linkage present for high-low selection and CDL (Centre Differential Lock) selection. This linkage on a Discovery 2 is via a flexible cable mechanism, whereas on a Defender there is a pair of linkages between the two gearboxes. The linkages for the transfer gearbox will be achieved using original Defender parts. However, sorting out the main gear shifter location involves some very clever aftermarket engineering – which will be carried out before any further body panels are fitted.
LIKE TO READ MORE? Try our Budget Digital Subscription. You'll get access to over 7 years of Land Rover Monthly – that’s more than 100 issues plus the latest digital issue. The issues are fully searchable so you can easily find what you are looking for and what’s more it’s less than 10p a day to subscribe. Click here to find out more details and start enjoying all the benefits now.