25 replies to this topic

[Ruts]

Ok so the last thread was fitting an A9X scoop to an LH/LX Torana bonnet, in this thread we will cut a hole in the bonnet under the scoop as per A9X specs. Now let me get something straight the measurements that I am using to replicate the hole in the bonnet was obtained from an original A9X race car. I am not saying that the measurements are correct as the race car may have had a new bonnet fitted at some stage and the size of the hole in the bonnet may have been altered away from factory specs. No matter what size you want the hole in the bonnet you can enlarge it according to your own needs. In this thread I wanted to replicate as close as possible an A9X hole so that if someone (like me) is building a replica they can go by these specs. I have received a lot of emails about this one so I thought now was a good time throw this together.

 

So while I was at the Muscle Car Masters a few back a mate of mine allowed me to trace the outline of the hole in the bonnet of his race car along with the position of the hole in the bonnet. These are the measurements I came up with and I made a drawing to record the measurements. Please note that the drawing isn't drawn correctly but if you follow the measurements all will work out.

 

Here is the drawing.

 

when finished it should look something like this.

 

 

So to start we need to measure how far the rear of the hole is from the rear edge of the bonnet as per the drawing which shows 285mm

 

 

 

 

From that mark I then measure a further 220mm which will be the front edge of the hole.

 

 

To get the rear edge of the hole square I set up a straight edge to help measure from the rear of the bonnet.

 

 

By the time it was square I had to make sure I had 305mm on each side from the straight edge straight back to the rear edge of the bonnet in line with the rear bonnet scoop mounting holes. Once the square was level I marked the rear edge of the hole.

 

 

 

Once I had the rear edge square I was able to mark the front edge of the hole and the sides. Remember, get the rear edge square and the rest will fall into place, and always measure twice cut once. follow the measurements and should end up with a rectangle measuring 355mm wide and 220mm deep.

 

 

 

 

 

 

 

[Ruts]

Once we have the rectangle marked on the bonnet I used a lid from a large pressure pack can to trace the corners. This is because the corners of the hole are rounded as per A9X specs.

 

 

 

 

I cleaned up all the markings once the hole was traced and this is what you should end up with.

 

 

Now there are a number of ways you can cut the hole but I like to use my trusty angle grinder with a cutting wheel AND A GUARD.

 

When you cut through the bonnet skin leave the frame work in place for the time being. TAKE YOUR TIME.

 

 

 

Once the skin is cut away then you can cut the frame away. Cut it along the same edge as the hole.

 

 

 

View of hole from underneath.

 

 

Now the hole is cut we want to trim the inner frame as per the A9X style. The rear frame is cut back 55mm from the edge of the hole.

 

The front of the frame is cut back 95mm from the edge of the hole.

 

Ok what I like to do before I cut the frame is put tape in the grooves between the bonnet skin and the frame and a rag near where the frame is going to be cut. The reason for this is to stop as much as the grinding sparks and filings from being thrown under the frame which may help cause rust to form at a later date if you don't clean it out properly. 

 

 

 

[Ruts]

Once all the framework is cut this is what it should look like.

 

 

Once the frame was cut I used these tools to clean up the edge of the hole.

 

 

 

 

Now what some people might not know is that the A9X had the inner frame popped riveted to the outer skin. I placed the pop rivets in the same spot (well close enough) as per the A9X.

 

 

 

 

 

 

 

And this is the finished product.

 

 

So there you have it, a hole cut in the bonnet as per A9X specs (I hope). If anyone has any questions or needs things clarified then feel free to ask. If anyone has a better idea that what I have done then please let me know as I am always willing to learn more. I want to thank all those for supplying me with the pictures and specs to help piece this thread together including MYSS427 and REDA9X. If my measurements are incorrect then I apologise but this gives you an idea on how's it done.

 

Ruts 

[Ice]

Great work dennis but those pop rivets look woeful there has to be a better way surely

[warrenm]

Great work dennis but those pop rivets look woeful there has to be a better way surely

 

You could use "Sikaflex" or similar instead of the rivet, but may not look "genuine".

[a9x868]

Great work dennis but those pop rivets look woeful there has to be a better way surely

gene pop rivets were originally used on a9x's
as dennis is doing the thread as per original
that's what you get!
there may well be a better way available now
but i wouldn't have it any other way

[Stinga]

good write up Ruts, makes me want to cut a hole in the uc's bonnet   you would be doing well to see the tail end of the rivet with the scoop on anyway? 

[Ruts]

Thanks for all positive comments. I know the pop rivets looks very ordinary but as stated I wanted to do this one as per A9X specs....GENE!!!. I will be doing a bonnet hole in the future which will look a lot better when I do the one for the hatch which will have the blower poking through. 

 

More threads to follow soon.

 

Ruts.

[Ruts]

Your spot on Pete, mine was the same. The bonnet skin was sitting off the frame about 10mm so what I did was get a hacksaw blade and slice the old glue away. It came out as one large piece about as round as a 50 cent piece and about 10mm thick. Once it was gone (2 pieces) the bonnet skin sat against the frame with no gaps. When it was riveted there was NO distortion on the skin.

 

Ruts

[Ruts]

Dennis.....Mum is gonna be really pissed at you,that was her good bonnet you just destroyed






good job m8

LOL, don't worry Ian there are another 8 in the shed.

[Clearshield]

Good job, the only thing I would do is maybee use Stainless Rivets . They look ally in the pics .

[350mick]

Very good stuff
Now how do we make it seal so the scoop works as it should

[a9x868]

Very good stuff
Now how do we make it seal so the scoop works as it should

mick one option here
a honda thermo fan shroud inside an original aircleaner base
did i say honda?
centre cut out correct diameter to fit inside orig aircleaner base
some cut outs for snorkel entry and left rear rocker cover breather
correct angle for forward sloping bonnet on an LX
does not interfere with any of the original anti pollution bullshite in my case
aluminium frame around the outside to retain the high density foam seal
easily changed over to factory aircleaner element and top cover
sucks through the top of the carby like a bitch
awesome sound on the induction with the secondaries open
i run a taller K&N filter top and bottem
and carry the factory aircleaner and top with me if i need it
as i must keep up appearances being an A9Xhatch
changed over to stock in 2 mins
everyone who has seen mine has been amazed by it's simplicity!
my design and i love it!
cheers
davemc

Edited by a9x868, 27 February 2014 - 12:45 AM.

[a9x868]

 Photo0045.jpg   212.77K   33 downloadspic

since this pic is old!

right hand rocker cover corrected
not a commodore one

washer bottle cap correct now

new pcv valve to carby hose fitted

but!
still a work in progress

cheers
davemc

Edited by a9x868, 27 February 2014 - 12:54 AM.

[a9x868]

That's a bloody awesome idea Dave - thanks for sharing! 

your welcome jase