73 bonnet questions

[scr8p]

Hey guys!

I'm currently converting a 71 bonnet to a 73. I have all of the correct parts to do it, but i have a question about the bumper braces / impact bars. They have the flange that goes between the center section and fender, and the lower nose section. Should there be a relief made to the center section and fender to allow the flange to lay flush with the edge of said panels? The flange is pretty thick and I wouldn't think they would have been left with that kind of gap from the factory. But this is my first Jag resto so I could be wrong. Any info or pics would be great. Thanks in advance.

[MarekH]

Yes, the later bonnet is totally different. By 1974, aside from the two ~2" holes in the front to take the crash bar through the bonnet, the gap between the centre section and the underpan is wider by a few mm to accommodate this flange where it bolts in between the two. Beyond that, there is no gap, just as with your bonnet.

You'll also find the ducts along the wings went down both sides for the fresh air pull vents into the cabin. That means several other panels on the car will also be different.

The Parts Manual ought to show these changes.

kind regards
Marek

[scr8p]

OK, thanks.

So the brace just gets bolted between the upper and lower pieces. No notching of the upper panels were done to allow the parts to fit together nicely? Just left with that wide gap?

[MarekH]

No, the exact opposite. The six inches or so (to about halfway along the indicators) of the bonnet centre section nearest the radiator opening are rebated upwards by about 3mm so the flanges of bd42130 and bd42131 fit into the gap. Only the underpan is unchanged, exactly as you surmised.

The later bonnet has a totally different bonnet centre section which wouldn't join up vertically in the middle without a shim where this flange is supposed to be sandwiched between the centre section and the underpan. The edges towards the wheel arch remain the same on both bonnet types and do bolt up against the underpan in each case, but there has to be a gap for the flange, from about half way along the front turn indicator along and inwards to the mouth opening.

The front and rear bumpers are totally different on Euro spec and US spec cars also.

I might have some pictures on another computer.

kind regards
Marek

[MarekH]

Here's a picture of the left side of the bonnet, from the inside, looking forwards.

On the left is the fender and on the right is the centre section. You can see through the headlight opening. At the bottom is the left hand indicator.

If you trace the line along the underpan to topside join, the fender is rebated upwards a few mm close to the leaded bonnet seam/join to the centre section (A to B). The centre section is rebated upwards by the same amount (B to C). Between A and the left hand edge of the car, the two bonnet types are identical.

kind regards
Marek