Fibreglass hood scoop

[doctorpimp]

I tried a search, but didn't find the exact answer I was looking for...

Two part question:

1. What is the best way/tool to use to cut a hole in a steel hood for a hood scoop? 
     - Sawsall?  Jigsaw?  Rotary tool?

2. What is the best material to use to bond a fibreglass scoop to a steel hood?
     - Rivets?  Resin?  Filler?  Contruction adhesive?

Thanks in advance

[Silver R/T]

I would definitely rivet it onto the steel hood before you bondo it to the hood.

[Charger-Bodie]

I tried a search, but didn't find the exact answer I was looking for...

Two part question:

1. What is the best way/tool to use to cut a hole in a steel hood for a hood scoop? 
     - Sawsall?  Jigsaw?  Rotary tool?

2. What is the best material to use to bond a fibreglass scoop to a steel hood?
     - Rivets?  Resin?  Filler?  Contruction adhesive?

Thanks in advance

1 A jig saw works very well ...take youre time

2 Go to a body shop supply store and get the adhesive they reccomend for  the two substrates you are using.

[superbee383]

If you rivet it to the hood, eventually the outline of the rivet heads will show through the filler / fiberglass.  A steel hood flexes quite a bit, and bondo is the worst thing you can attach it with.  It will ALWAYS crack somewhere.  It works well as a thin filler, not an adhesive.  Fiberglass is the better material. but is still prone to cracking where the joints are.  You can rivet it to the hood to keep it in place until the fiberglass resin cures, then drill the rivets out.

One thing is for sure... eventually no matter what you do the installation WILL crack somewhere.  It's just the nature of the beast when you have one material that's stronger than the other, along with varying temperatures that cause the two materials to expand and contract at different rates.  You're better off getting a bolt-on six pack scoop or something that doesn't require being molded in, or a solid fiberglass hood with a scoop already attached. 

[evil1]

Maybe cut the hood to where the scoop would fit up threw from the bottom snugly and bond it from underneath with glass ?

[superbee383]

If you're really going to do this, the best tool to make a flat, even cut is an air hammer with the bit that's pictured here.  You drill holes at the four corners, then connect the dots.  This bit will take a nice, clean line of steel out of the path it's going, and "curl it up" as it goes along, keeping the sheet metal from getting warped.

[Silver R/T]

former member of this board 493Charger had his fiberglass hood scoop attached to steel hood and he had crack smoothed out with bondo. This was on his low 11 sec race car, I have not heard him say anything about cracks. I've seen car myself and it looked pretty good and you could not tell where the seam was at. 

[doctorpimp]

Awesome idea about the air hammer with nibbler bit...
I was actually toying with buying an air hammer - I think I may get it now!

Don't worry too much about about the hood, it's full of bondo already and it's a flat 73 hood (still looking for a bulge hood, in Ontario/Quebec Canada, Upstate NY N Vermont )

We'll see how it goes...

[Blown68Coronet]

Hey Paul
I used an air nibbler on mine. Most guys i know just rivet the scoop to the hood. How's the car coming, got any pics?

Kevin

[doctorpimp]

Hey Kev,
It's been a while
Are you staying at Uplands for another year?  How's Stace doing?
I'm posted to Montreal this summer (I.R.) so I'm working like mad to get the car done - keeping my fingers crossed - I am hoping to have the car on the road by middle June...
I'll take some new photos and post them here on the site.

I thought about just riveting it on and leaving the exposed rivets and not worrying too much about it... 
All the bondo etc is a lot of work and I also think that in the end it'll just look like crap anyway.
Like I said, it's a bondo hood with a flat black Tremclad paint job on it right now   It looks OK, but just OK - LOL

[Back N Black]

Hey Kev,
It's been a while
Are you staying at Uplands for another year?  How's Stace doing?
I'm posted to Montreal this summer (I.R.) so I'm working like mad to get the car done - keeping my fingers crossed - I am hoping to have the car on the road by middle June...
I'll take some new photos and post them here on the site.

I thought about just riveting it on and leaving the exposed rivets and not worrying too much about it... 
All the bondo etc is a lot of work and I also think that in the end it'll just look like crap anyway.
Like I said, it's a bondo hood with a flat black Tremclad paint job on it right now   It looks OK, but just OK - LOL

Posted to Montreal, i guess that french course payed off. 

[doctorpimp]

Pretty much...
I was going there with a French course or without anyway...  At least now I'll know what they're saying LOL.
The mangler told me I've been here too long and it was either there or Borden... or Wainwright 
I think I'm lucky

[doctorpimp]

Can I use resin to soften hardened fiberglass to alow a slight re-shape?

[71green go]

Hey There......I have mounted lots of scoops on steel hoods.........There are products made for bonding these in place such as "MArglass", Dyno bond" ...or even vette panel adhesive will work...its basically a Fiberglass paste  that you add hardener too and you have about 15 minutes to spread it on and mount the scoop....
Step 1....layout scoop mark where you want to cut hood...
Step 2....Use (I prefer) a Zip Cut wheel in a hand grinder,,,cutting wheel is only 1/16" of an inch thick and slices through like butter
Step 3....Place Scoop back in place and drill some screw/alignment holes that you can use sheet metal screws into while bonding hoodscoop in place...they also help it all hold together
Step 4...Remove scoop...have scoop and screws..and cordless drill ready with bit for screws to mount quickly....Grind all mating surfaces to BARE metal..and rough up bottom of scoop fiberglass area
Step 4...Mix lots of bonding material...not too much hardener...the hotter it is the less hardener u need....(might be best to have a friend to help do all quickly)...spread on roughed up surfaces and lay scoop in place and put all screws in place..(the more the better)...then after bonding material hardens you can removed screws
Step 5...Grind/sand edges of scoop so they kinda taper into hood...do not sand too much though...then you can use the remaining bonding material as filler and go over the entire outside of scoop edges filling in the screw holes....this stuff is fiberglass and is strong.......then grind as smooth as you can and finish off with Bondo...and then spot putty.....it really goes pretty quickly and I have NEVER had one crack on me...do not use rivits...looks totally cheap and hack job...OK for a race car I guess...and do not use rivits and counter sink them to bondo over...will show through eventually....and they look like hell underneath the hood..........
Good luck...hope I was a little help...post some pics when you are done!

[doctorpimp]

Thanks 71green go