adding more trunk space - using a Boyd's Welding Gas Tank

[toadster]

Looking for some ideas as to whether this will be worth the effort but I have the Boyd's Fuel Tank which fills in the 'under trunk' space pretty well...
I have about 2" of clearance between the tank and the top of the rails that form the trunk

pic for reference
145067

The idea is to create a few prism shaped boxes that will be 2" deep, it's not much - will equate to about FOUR (4) sq.ft. of added space
it's not a ton of room, but would be beneficial to put 'stuff' in those areas that won't really roll all around, and give an extra 2" of depth in that space...

Here's a quick diagram showing the setup:
I need to create 2 access holes, 1 for the fuel sender (driver side rear), and 1 for the fuel pump (front of lower trunk)
145066
the triangular shapes are ~16"x26"x18" and the passenger side is 18"x14.5x23.5"
both triangles would be 2" deep, example sheet metal triangle

145068
is it worth the effort for 4sq ft. more?

[CraigS]

Mine in my Old MkII was more like 4-5 inches deep but even your 2" will help. I'd build them in and decide after a year of driving whether to build cover doors or not. It may be that you favorite cooler is 12 inches tall but the stock trunk clearance to door is just 10.5 (too pull a # out of the air). Cooler wouldn't fit the stock trunk but will fit in your modded trunk. Or you may find there are a lot of items that do fit in the 2" and, as you already noted, your mod will keep them from moving around. My door was was double hinged.
https://live.staticflickr.com/65535/49321524961_429b147650_z.jpg (https://flic.kr/p/2i9nH32)Trunk2 (https://flic.kr/p/2i9nH32) by craig stuard (https://www.flickr.com/photos/152454123@N04/), on Flickr
When there was other stuff on top of my door I could still lift the rearmost edge 3 inches or so to pop small items in. Otherwise it opened like this.
https://live.staticflickr.com/65535/49321027863_687c2f0575_z.jpg (https://flic.kr/p/2i9kagn)Trunk 1 (https://flic.kr/p/2i9kagn) by craig stuard (https://www.flickr.com/photos/152454123@N04/), on Flickr

[toadster]

Mine in my Old MkII was more like 4-5 inches deep but even your 2" will help. I'd build them in and decide after a year of driving whether to build cover doors or not. It may be that you favorite cooler is 12 inches tall but the stock trunk clearance to door is just 10.5 (too pull a # out of the air). Cooler wouldn't fit the stock trunk but will fit in your modded trunk. Or you may find there are a lot of items that do fit in the 2" and, as you already noted, your mod will keep them from moving around. My door was was double hinged.
https://live.staticflickr.com/65535/49321524961_429b147650_z.jpg (https://flic.kr/p/2i9nH32)Trunk2 (https://flic.kr/p/2i9nH32) by craig stuard (https://www.flickr.com/photos/152454123@N04/), on Flickr
When there was other stuff on top of my door I could still lift the rearmost edge 3 inches or so to pop small items in. Otherwise it opened like this.
https://live.staticflickr.com/65535/49321027863_687c2f0575_z.jpg (https://flic.kr/p/2i9kagn)Trunk 1 (https://flic.kr/p/2i9kagn) by craig stuard (https://www.flickr.com/photos/152454123@N04/), on Flickr

very nice! love that double hinge!!

[GTBradley]

Looking for some ideas as to whether this will be worth the effort but I have the Boyd's Fuel Tank which fills in the 'under trunk' space pretty well...
I have about 2" of clearance between the tank and the top of the rails that form the trunk

pic for reference
145067

The idea is to create a few prism shaped boxes that will be 2" deep, it's not much - will equate to about FOUR (4) sq.ft. of added space
it's not a ton of room, but would be beneficial to put 'stuff' in those areas that won't really roll all around, and give an extra 2" of depth in that space...

Here's a quick diagram showing the setup:
I need to create 2 access holes, 1 for the fuel sender (driver side rear), and 1 for the fuel pump (front of lower trunk)
145066
the triangular shapes are ~16"x26"x18" and the passenger side is 18"x14.5x23.5"
both triangles would be 2" deep, example sheet metal triangle

145068
is it worth the effort for 4sq ft. more?
As you well know, it's not referred to as "effort" or "work" when it comes to these cars, it's called "fun". So, yes, I say it's totally worth it. I can envision right off a blanket, tonneau, jackets, tool kit, etc going in there. I would suggest not dividing those two locations though.

[toadster]

As you well know, it's not referred to as "effort" or "work" when it comes to these cars, it's called "fun". So, yes, I say it's totally worth it. I can envision right off a blanket, tonneau, jackets, tool kit, etc going in there. I would suggest not dividing those two locations though.

well, it's divided by that 3/4" square tube :)

[CDXXVII]

Drop the trunk. One of my best mods. No cover on mine and it's just fine that way.

You can see that I am using the ffmetal battery box and I also used a variation of the Kleiner body/bumper mount.

https://thefactoryfiveforum.com/attachment.php?attachmentid=119917&d=1578061097

https://thefactoryfiveforum.com/attachment.php?attachmentid=119918&d=1578061135

https://thefactoryfiveforum.com/attachment.php?attachmentid=119935&d=1578077900

https://thefactoryfiveforum.com/attachment.php?attachmentid=145089&d=1616617445

[toadster]

Drop the trunk. One of my best mods. No cover on mine and it's just fine that way.

You can see that I am using the ffmetal battery box and I also used a variation of the Kleiner body/bumper mount.



see my first post, I'm not using the standard mustang gas tank :)

[David Hodgkins]

OK since we're adding lids to the mix...

https://thefactoryfiveforum.com/attachment.php?attachmentid=57741&d=1471886251

https://thefactoryfiveforum.com/attachment.php?attachmentid=57742&d=1471886252

I think a uniform 2" shallow box would be worth the effort to create. Bending metal is fun! :D

And I'd leave the bars. I added some stick-on insulation foam that holds the lid off the trunk floor by a 1/16" or so. If you look closely you can see it in the (poor) pic with the lid open.

:)

[CDXXVII]

see my first post, I'm not using the standard mustang gas tank :)

That’s a nice tank. The only way I would bother is if you delete the diagonal bracing and drop as much as you can the 2”.

The original Mk4’s did not have the diagonal bracing. They were added to keep everything square during frame fabrication. Still, probably not worth it.

[Avalanche325]

I think it would be worth it even for 2". Mine looks like the FFMetals one but a DIY. No lid for me. That would get in the way for me.
I put carpet on the 3/4" tubes. It makes it look finished, the tubes won't get scratched, and the tubes won't scratch my helmet.

[toadster]

That’s a nice tank. The only way I would bother is if you delete the diagonal bracing and drop as much as you can the 2”.

The original Mk4’s did not have the diagonal bracing. They were added to keep everything square during frame fabrication. Still, probably not worth it.


interesting - the bracing has no function other than keeping the chassis square?

[CDXXVII]

interesting - the bracing has no function other than keeping the chassis square?

Here is the original Mk4 frame from the Factory Five web page. They had several frames delivered that were out of square in the trunk area and guys were having issues with the sheet metal. They "fixed" it and we lost the added trunk space.

https://www.factoryfive.com/wp-content/uploads/2017/01/detail-9.jpg

https://www.factoryfive.com/wp-content/uploads/2017/01/detail-1.jpg

[Jeff Kleiner]

Here is the original Mk4 frame from the Factory Five web page. They had several frames delivered that were out of square in the trunk area and guys were having issues with the sheet metal. They "fixed" it and we lost the added trunk space.



Correct. I built a very early Mk4 with that configuration for a customer. There was a reason the diagonal tubing was in the Mk1-3 and there was a reason why they put the tubing back soon after taking it out of the Mk4. I’ve done dropped trunks in several cars I’ve built and always leave the tubing in place.

Jeff

[GTBradley]

well, it's divided by that 3/4" square tube :)
Correct, but I meant below that so that flexible things could slide under the square tubes for more room as is shown in CDXXVII's picture.

[toadster]

Correct, but I meant below that so that flexible things could slide under the square tubes for more room as is shown in CDXXVII's picture.

ahh i see, so I'd have about 1" of clearance below the tubes... good idea, now I need to find someone with a sheet metal brake that can handle 40" sheet... my harbor freight 18" one just won't do the long bends

[Norm B]

The trunk space is very limited unless the portion of the floor that can be is lowered. I chose to take out the diagonals and weld them back lower. If you want more room you could remove them completely and use heavier gauge aluminum for the floor. Make sure to cross brace the trunk area and take lots of measurements before you remove the diagonals. I did this and was a little surprised at how much force was being contained by the them and how much they deflected when cut. Here are a few pictures taken during the build.

HTH

Norm

[Cutter 54]

First off, beautiful workmanship going on in these mods. I'd like to jump in with 2 questions. I just started the build on my Mk 4 with IRS and ordered the FFR gas struts for the trunk lid, Breeze cockpit cubby storage and RT drop trunk kit.
1) I see the gas struts interfere with the rear aluminum partition in the cubby kit and take up space there. Is this why few guys use the gas struts? What are favored alternatives for a trunk lid prop other than a simple rod?
2) I understand there is controversy about removing the diagonal frame bars in the trunk floor to maximize access to the drop trunk space. If those bars are not structural, what is the main objection? I have not found a good thread on the subject.
Thanks in advance.

[rich grsc]

The diagonal tubes may be there to help keep the trunk area square, but they are also part of the 'crumple zone'. If you should ever get rear ended, they will certainly help protect you and help prevent intrusion of the fuel tank. Have the battery in the rear? Fuel and battery in the same space with no extra protection? I would never remove them on any car I own.

[GTBradley]

Here’s my solution to adding trunk space:
145151
I’ve been working on this for some time now and I’m almost done. It’s a spare boot lid, so I can switch back to the regular lid when I’m done with my overnight trips. Looking forward to traveling again - I’m getting my vaccination today:cool:

[Hacksaw84]

I cut mine out and re-framed it. I am not sure I would do it to gain the little space you have available.

I take it back... I would do it but that's just me and I liked doing stuff like that.

145161

145163

For the Trunk prop I used the Breeze rod. It does not hold it ALL the way open but enough and I like the simplicity of it. Some guys have had issues with the gas strut being too strong and tweaking the trunk lid.

145167

[AC Bill]

I figured the diagonal bracing, besides making the frame stiffer, and stronger, was also supporting the trunk floor. Does the MK4 with a standard trunk configuration, (not dropped), have the trunk floor aluminum panels resting on the diagonals?

[Avalanche325]

HF has a 36" metal brake. That is what I did mime with. I made two of everything and made a "kit" for my friends car.

You can get a lot of stuff behind the seats in these cars. I always have sunscreen, hand sanitizer (these days), a hand towel, paper towels, Longacre tire gauge, and two hats. I have stuffed a jacket back there too.

A friend has a waterproof "boot bag" the he used on his for long trips. https://trunkluggagerack.com/boot-bag-original/ if you need extra space.

[toadster]

I figured the diagonal bracing, besides making the frame stiffer, and stronger, was also supporting the trunk floor. Does the MK4 with a standard trunk configuration, (not dropped), have the trunk floor aluminum panels resting on the diagonals?

yep on top of the bracing

[Cobradavid]

To answer the OP question: yes it's worth it!

10 years ago I added a sub-floor storage space to my Mk 3.1. It has a hinged door like CraigS's. You'll find out that you have to have a hinged door if the box goes as far as possible towards the driver's side wall. Otherwise, one piece lid will hit the inside/underside of the trunk/left rear fender and you could only get it less than half open.

I left the 3/4" square tubes in place and put carpet on top of them just so the door wouldn't rattle. I probably could have used a rubber bumper or something. But, hey! I had the carpet laying around, so why not??? :cool:

The box is as long (front to back) as it can be between the 3/4" tubes, and it's as wide side to side as it can be and not hit the passenger side hump on top of the Mustang fuel tank.

The trunk box contains a tool kit, air pump, a scissor jack, some other tools, bungees, ratchet strap, a couple of bath towels, and a windbreaker.

https://thefactoryfiveforum.com/attachment.php?attachmentid=145177&d=1616796633

https://thefactoryfiveforum.com/attachment.php?attachmentid=145174&d=1616795525

https://thefactoryfiveforum.com/attachment.php?attachmentid=145175&d=1616795619

https://thefactoryfiveforum.com/attachment.php?attachmentid=145176&d=1616795661

[Jim Wehr]

Here’s my solution to adding trunk space:
145151
I’ve been working on this for some time now and I’m almost done. It’s a spare boot lid, so I can switch back to the regular lid when I’m done with my overnight trips. Looking forward to traveling again - I’m getting my vaccination today:cool:

Do you have any pictures of this on the car?

[David Hodgkins]

Here’s my solution to adding trunk space:
145151
I’ve been working on this for some time now and I’m almost done. It’s a spare boot lid, so I can switch back to the regular lid when I’m done with my overnight trips. Looking forward to traveling again - I’m getting my vaccination today:cool:

That's Rad!
:)

[GTBradley]

Do you have any pictures of this on the car?
Not yet, I'll put it on soon and get some pictures posted.

[GTBradley]

That's Rad!
:)
That's what all the kids are gonna say! And I think I'll be attracting a lot of enamored women too...my wife doesn't think so though.

[P100DHG]

OK since we're adding lids to the mix...

https://thefactoryfiveforum.com/attachment.php?attachmentid=57741&d=1471886251

https://thefactoryfiveforum.com/attachment.php?attachmentid=57742&d=1471886252

I think a uniform 2" shallow box would be worth the effort to create. Bending metal is fun! :D

And I'd leave the bars. I added some stick-on insulation foam that holds the lid off the trunk floor by a 1/16" or so. If you look closely you can see it in the (poor) pic with the lid open.

:)

Just so it’s on the record this is my favorite. So awesome all the polished metal!

[GTBradley]

Do you have any pictures of this on the car?
Hey Jim, I got that rack lid mounted so here’s a couple pictures for you.

https://thefactoryfiveforum.com/attachment.php?attachmentid=146054&d=1618108799 https://thefactoryfiveforum.com/attachment.php?attachmentid=146053&d=1618108630