[bob_oz]

Hi Guys,

Over the Easter weekend I fabricated two plates to replace the standard plastic ones on my 2012/13 GV. Easily done in around 6h but had to stop to buy bolts (12 HT M8x1.25 plated bolts used total + springs)

I tapped all the plastic pin clip holes in the subframe with an M8x1.25 tap which gave me a few good threads to anchor onto – definitely not bomb proof but given the shear forces on the plate it will be more than fine. 6 on the rear plate and 6 on the front plate.

I used 6mm cold roll hardened aluminium. I’ve used it a lot before for bash plates on Pajero io’s etc with great success. It’s tougher and has a decent spring to it over normal soft aluminium while still being able to form up by hand tools. I’ve lifted light 4wd’s off the ground at speed after hitting large rocks and jacked off the middle of plates without permanent distortion. The Aluminium is light enough that you can offer each plate up with a knee or a strong arm while bolting in with your spare hand – far easier than the weight of the 4mm steel plates you purchase from TJM etc. I purchased a specific aluminium thick sheet circular saw blade ($30ish) that made it very quick.

Rear plate was 500mmx700mm and needed a recess hammered to clear the front diff. Easiest method was to bolt it up flat and go for a drive – this showed the main rub points and hammer from there. A 15mm ply template supported the sheet as I peened the plate down on the anvil with a standard extra-large engineer’s hammer.

Easiest way to align the bolt holes was to fit bolts into the subframe holes then lightly clamp plate into place. Once I was happy with its position a sharp hammer blow on the plate beneath the bolts marked their heads into the aluminium – punch and drill for a perfect fit.

Front plate was another 500mmx700mm sheet with two rebates at 290mm to clear between the front tow eyes. A gentle fold at the tow eyes gives a nice angle of attack without over stressing the Aluminium. I marked the bolt holes the same way as above making sure there was 1-2mm clearance between the front and rear plates.

Putting the fold in the sheet was easier than expected – directly peening the sheet along the fold line caused it to bend along the impact line. I kept hitting the sheet until it had folded the correct amount and peened sections harder to ensure the fold was square. I chamfered the front edge to fit snugly under the bumper by 10mm at the corners but this wasn’t needed in the end.

Once I’ve fitted the behind-bumper winch bracket I’ll likely brace down and bolt up the front leading edges to stiffen.

A run up to bribie at night with some deep drifts and stumps buffed it to a nice shine, it took some heavy hits (60kmh to 10kmh driving into very deep sand) and no scalloping or bending occurred.

I’ll run it for a few more months before I drill drain holes, if at all. Preference would be to keep it solid and avoid any holes as they are great at passing large sticks up into the engine bay or acting as a weak point for a rock to snag upon.

EDIT -

front plate is 700mm wide and 500mm long.
fold is 300m from the rear (200mm from the front)
cut outs are 200mm deep x 85mm wide (they go from the front lip to the fold)

rear plate is 700mm wide 500mm long

Cheers

[bob_oz]

So after almost a year with quite a few good trips (Belthorpe, Bribie, Border Rages State Forests) i thought i'd post an update.

Lots of good hits and a hang-up at Ormeau Hills - it's been off twice now, once by the mechanic and he was happy it was so light and reconned it's far better than the 4mm steel ones.

You can see some gouges and scrape marks and the black marks mid-way between the first two bolts back from the passengers eye is the impact point where it hung up and got the front passenger wheel off the ground.

All in all great success and shows that cold-rolled 6mm aluminium plate is capable of

Attachment:

Capture.JPG

[NGV13]

Very good protection. Did you do anything for the transfer? It's very exposed in the model too, being the lowest point.

[bob_oz]

NGV13 wrote:

Very good protection. Did you do anything for the transfer? It's very exposed in the model too, being the lowest point.

Hi - YES I am currently (as in right now) building a brace off the floor, sill and chassis bolt points to support the back of a transfer case plate - will run on a slight angle towards the drivers side from the front gearbox shield bolt holes all the way to around 2-3" behind the transfer box maintaining the level angle from front cross member over gearbox cross member so no clearance is lost .

I've made a post with load spreading washer that bolts through just in front of the drivers seat rear floor mount near the tunnel. It pinches the floor pan to chassis seam and hopefully will be solid enough. also tying into the bolt holes on the sill and the one just behind on the floor stiffener. Post is made from 40mm x 40mm x 4mm steel square tube with 50mm x 50mm (queenslander cyclone tie down) washers.

It will be based on a 500mm wide sheet of 6mm cold-rolled aluminium as the shield to match the front set. I'll likely fold up the outside 1" at an angle to stiffen it and profile the ends so the key into the gearbox cross member.
I'll update once complete with photos - is a tad difficult due to quarantine etc. Main focus was on a solid steel cross member from near the exhaust over to the sill that is on the same plane as the gearbox cross member and front cross member so the plate sits level.

I'll also likely drop the gearbox cross member off and weld up some shielding for the outside circular bolt holes - these get thumped and bent easily.

I'll upload a measurement diagram so it can be a DIY for others - so far the main measurement of interest is 190mm vertically down from the floor as the brace level - gives 10mm for transfer case which will be fine once I dome the plate a bit near the bottom of the TC.

[NGV13]

That sounds great! thanks for your answer.

I have seen few protections that get a good clearance in the transfer area because they use only a straight plate from the crossbar that holds the gearbox. This makes it take a certain angle off and leaves the central area worse than standard.

Good luck with your design.

[vespamike]

Hi, have you made any progress with the measurement diagrams?
I’m looking at attempting to construct my own underbody protection plates.

Many thanks in advance