Full Length Infloor Subframe Install (oh the agony!!!) DUW

[Moving_Target]

Hi folks, I have been doing some thinking about modifications to my '86 notchback and I have decided to add to the chassis strengthening of the car. This last summer I did the (expensive) 351W swap to the car and seeing as how I like to autocross (damn addicting) I may as well do something to improve body stiffness. Swapping an engine that did not originally come with the car already puts me in to a (D/MOD) modified class, I may as well add in floor subframes and really go modified. I figured there wasn't any point dicking around with the add-on subframes so the decision was obvious. I will be adding to this thread with my fabrication of the subframes using the plans from Mustang Performance Handbook 2 by William Mathis. After the fabrication, I will detail the installation of the subframes.

Just a warning: There will be a LOT OF PICTURES!!! Mathis says it's a lot work, he's not kidding. It's not for the faint of heart.

Wish me luck!

[TL TTop Coupe]

Just a warning: There will be a LOT OF PICTURES!!! Mathis says it's a lot work, he's not kidding. It's not for the faint of heart.

Look foward to them. Good Luck!! TL

[Mike Croke]

I did the through-the-floor connectors on my Capri in 1993. It is amazing how stiff the car is. Definitely a pain to put in but well worth it. Biggest hassle is welding the rectangular tubing to the thin sheet metal of the floorpan.

[Moving_Target]

Ok, here is the first picture: I figured it wasn't necessary to take any pictures of me cutting the 2"x3" tubing to size(and it was dark out too )and make the 40 degree cuts for the tips.

sorry about the panel covering the other subframe, trust me they look the same.This picture is before I welded the caps onto the tips. To layout the 40 degree cuts, I used a cheap protractor head from a local tool place. To make the cuts I used my Delta chopsaw. Indispensable tool.

[Moving_Target]

Some pictures of my ehm welding of the tips...



2"by 4.7ish" 0.125 flat bar for the caps.
I didn't have any 0.125 flat bar at the time so i cut up some 2.5"x2.5"x0.125 angle iron and used it. Having a cutting torch is handy sometimes...
Before I did the welding, I beveled the edges to get a bit more penetration.

[Moving_Target]

Mathis calls for a 6.5" x1/2" bolt. The closest I could find was 7" so that's what I bought. Grade 5 by the way...

The bushing material that he suggests is 0.75ODx.120 4130n tubing. This gives you a hair over 0.500" so the bolt will fit. Chrome-moly tubing is a special order item around here as no-one (and I mean no-one) carries it in stock. I called up a hydraulic equipment supplier and asked if i could order in some mild steel with the required dimensions. The counter guy said yes but... only in 20ft length min. Damn. Oh well, I ordered it anyway. I have an aversion to going to machine shops for something so dinky. Yep, I'm stupid. Before anyone chimes in, I know about Aircraft Spruce now.

I just marked where I wanted to make the cuts and used my chopsaw. I will never use a hacksaw again if I don't have to.

[Moving_Target]

I didn't feel like buying any layout dye so I used a trick that I'd seen on the 'net. Black felt pen. As long as the steel is relatively clean, it works great.

I'll admit to a small mistake I made while I was laying out the hole for the bushing. That pilot hole should have been over to the right. It worked out ok though since that hole was where I had to later cut the tubing. It alllowed me to eyeball my cut with better accuracy.

[Moving_Target]

After I had layed out both sides, it was a simple matter of drilling the pilot holes and then using the holesaw. I used my cordless 3/8 drill and a liberal amount of cutting fluid. You don't need much pressure just let the saw do the work.


After I made the holes, I just wanted to make sure the holes actually lined up. I've made that mistake before.
Looks good to me.

[Moving_Target]

After I made the cut with the chopsaw I employed the BFH approach to bending the tubing to my will. Here I am checking it with a protractor. Sorry for the blurry Image. After I was satisfied with the angle, I welded some steel temporarily to the tubing to keep the angle from changing as I welded the cut closed. I couldn't weld the gap closed in one pass as it was way too big to try and fill so instead I just built up the edges with 1-2 sec bursts and moved up and down the sides until it was almost closed. Then I was able to weld both sides together without any trouble. After I had the weld done, I knocked my jig off the tubing.

[Moving_Target]

A couple more pictures of how I did it:
Before

After

[Travis T]

That's an ambitious project, good luck with it. Doesn't that bolt go through the rear control arm? If so, you may want to look around and find a grade 8 bolt when you assemble it.

[Moving_Target]

I did the through-the-floor connectors on my Capri in 1993. It is amazing how stiff the car is. Definitely a pain to put in but well worth it. Biggest hassle is welding the rectangular tubing to the thin sheet metal of the floorpan.

Yea, I believe you on that count. Welding thin sheet metal to thick = headache. I haven't gotten that far yet, just the fabricating so far. But I've done similar work so I'm not worried about my abilities. This will just take a boatload of time to put in. It really is something Ford should have done to these cars before turning them into quasi-performance cars.

Cheapskates.

[Moving_Target]

That's an ambitious project, good luck with it. Doesn't that bolt go through the rear control arm? If so, you may want to look around and find a grade 8 bolt when you assemble it.

You are correct sir, that bolt does go through the lower control arm. What grade did Ford use for that application? I haven't stuck my head under there yet to see if I can make out the head markings.

[Moving_Target]

Ok, last couple of pictures.
The opposite side was basically the same just bent to a different angle so I'll spare you the gory details. The subframe on the left is for the right side and vice versa for the other subframe.


I may add caps to close off the ends of the subframes.

Stay tuned...

[85 Notchback]

That's an ambitious project, good luck with it. Doesn't that bolt go through the rear control arm? If so, you may want to look around and find a grade 8 bolt when you assemble it.

You are correct sir, that bolt does go through the lower control arm. What grade did Ford use for that application? I haven't stuck my head under there yet to see if I can make out the head markings.

You can telljust by looking that it's a Grade 5 bolt. Grade 8 are he goldish ones. I would DEFINETLY recommend using grade 8 on something like this.

One other thing I would recommend with you weldin (not that it's bad or anything), is that you do a wider weave pattern on the thicker steel. That way, you would hopefully get better penetration, as well as widen the surface area of the weld, which in turn will alow it to handle more stress.

[Moving_Target]

Well I'm a little ways away from really hacking up the floor so I may swing by the bolt supply place and get some grade 8 hardware instead. I'm not worried about the weld penetration, I had problems with the weld sagging out because it was so hot. The weather here is finally like winter so before I really get going on the car part of things, I need to put some insulation in the garage walls. Throwing money away on cars is one thing, heating bills has no fun factor attached to it.

[fede85gt]

Moving Target: Very nice work, but be carefull on fabbing against the dimensions in the book, heres a post from William Mathis made on corner-carvers:


I have watched these forums for years without participation. Even when topics were discussed that affected me, I have remained silent. However, I would like to clarify a few things. When I wrote the Mustang Performance Handbooks, I foolishly thought that what I wrote would actually make it to print. Ten years ago, when I wrote those books, I was unaware that HPBooks had a publishing restriction on the size of the book that could be published. At that time, Price, Stern and Sloan (then publishers of HPBooks) required that all their “how-to” books could not be physically thicker than would permit 3 books to fit in a standard bookrack with ease of insertion and removal. Most bookracks then and now are typically limited to approximately 1.5 inches in depth. You may have noticed this in places like Lowes where the do-it-yourself books are displayed. In my case, what this meant was that my manuscripts were hacked to meet this criteria. Unfortunately, this resulted in publications that barely resembled what I had written. Some of the sections, particularly in the second book (this was actually published as the first book on powertrains), were so modified that the sections were confusing at best, and blatantly wrong at worst. Most of the chassis drawings, including the double-wishbone suspension and tubular crossmembers, were not even included in the book. Actually, I am still puzzled why they chose the drawings they included. I submitted all my drawings in AutoCAD format only to be told they were “too complex” for the eight-grade reader they assumed their market was. To make matters worst, the publisher did not have the ability to read AutoCAD drawings into their print system; so each drawing was run through some sort of graphic program for conversion. The results were drawings that had strange tolerances and looks. This was most evident in the weight and balance drawing in the back of the chassis book where the formulas were improperly converted leaving half the variables out. When I received the published copies, I was livid and demanded the books be withdrawn and corrected. However, I was informed that the contract I had signed gave them final editorial control and basically I should F.O. For those of you that have relied on some of this misinformation I apologize to you and thank for purchasing the books in spite of it.

William R. Mathis
Graduate Mechanical Engineer

[fede85gt]

Moving Target: Very nice work, but be carefull on fabbing against the dimensions in the book, heres a post from William Mathis made on corner-carvers:


I have watched these forums for years without participation. Even when topics were discussed that affected me, I have remained silent. However, I would like to clarify a few things. When I wrote the Mustang Performance Handbooks, I foolishly thought that what I wrote would actually make it to print. Ten years ago, when I wrote those books, I was unaware that HPBooks had a publishing restriction on the size of the book that could be published. At that time, Price, Stern and Sloan (then publishers of HPBooks) required that all their “how-to” books could not be physically thicker than would permit 3 books to fit in a standard bookrack with ease of insertion and removal. Most bookracks then and now are typically limited to approximately 1.5 inches in depth. You may have noticed this in places like Lowes where the do-it-yourself books are displayed. In my case, what this meant was that my manuscripts were hacked to meet this criteria. Unfortunately, this resulted in publications that barely resembled what I had written. Some of the sections, particularly in the second book (this was actually published as the first book on powertrains), were so modified that the sections were confusing at best, and blatantly wrong at worst. Most of the chassis drawings, including the double-wishbone suspension and tubular crossmembers, were not even included in the book. Actually, I am still puzzled why they chose the drawings they included. I submitted all my drawings in AutoCAD format only to be told they were “too complex” for the eight-grade reader they assumed their market was. To make matters worst, the publisher did not have the ability to read AutoCAD drawings into their print system; so each drawing was run through some sort of graphic program for conversion. The results were drawings that had strange tolerances and looks. This was most evident in the weight and balance drawing in the back of the chassis book where the formulas were improperly converted leaving half the variables out. When I received the published copies, I was livid and demanded the books be withdrawn and corrected. However, I was informed that the contract I had signed gave them final editorial control and basically I should F.O. For those of you that have relied on some of this misinformation I apologize to you and thank for purchasing the books in spite of it.

William R. Mathis
Graduate Mechanical Engineer

[Moving_Target]

And that's why I bought enough to make two sets. I always like having extra "just in case". BTW, I am a member of c-c.com and remember reading that there.
The executives at HPBooks that came up with those choices are [insert expletive]. Of all the criteria to base the content of a book on.... bookshelf depth

PS: thanks for the compliment and I'll be careful.

[Moving_Target]

And that's why I bought enough to make two sets. I always like having extra "just in case". BTW, I am a member of c-c.com and remember reading that there.
The executives at HPBooks that came up with those choices are [insert expletive]. Of all the criteria to base the content of a book on.... bookshelf depth

PS: thanks for the compliment and I'll be careful.

[Moving_Target]

Ok on with the show. After I pulled the seats and carpet out I was greeted with this:

I will fix that after I get the subframes in.
Drilling out the spotwelds...all eightyleven bajillion of them

After using body chisel to cut throgh what was left of the spot welds:

I decided to hack off the part that I'd gotten free to make the rest easier to manage:

A little bit of rust hiding in there hm?
Picture of the cut at the front of the subframe where it turns upwards.

I'm going to have a little bit of fun getting the transmission mount off what's left of the subframe but hey it's a ford, fustration is part of the package deal.

[Moving_Target]

Ok on with the show. After I pulled the seats and carpet out I was greeted with this:

I will fix that after I get the subframes in.
Drilling out the spotwelds...all eightyleven bajillion of them

After using body chisel to cut throgh what was left of the spot welds:

I decided to hack off the part that I'd gotten free to make the rest easier to manage:

A little bit of rust hiding in there hm?
Picture of the cut at the front of the subframe where it turns upwards.

I'm going to have a little bit of fun getting the transmission mount off what's left of the subframe but hey it's a ford, fustration is part of the package deal.

[fede85gt]

Yup, they certainly did trash the book, but its still damm good reading material, and very inspiring for the do it yourselfer, Im almost half way with my torque arm build, and I got a lot of good ideas from it also.

Keep up the excellent fab work!!!!!!!! And if you need/are interested in some dimesions on the torque arm or pics let me know. I have a bunch of pics and templates already made.

[fede85gt]

Yup, they certainly did trash the book, but its still damm good reading material, and very inspiring for the do it yourselfer, Im almost half way with my torque arm build, and I got a lot of good ideas from it also.

Keep up the excellent fab work!!!!!!!! And if you need/are interested in some dimesions on the torque arm or pics let me know. I have a bunch of pics and templates already made.

[Moving_Target]

Exactly, that's what I am partly using the book for, inspiration. As for the torque arm, I am all ears. Just give me some time to finish this part of the project and I will be hitting you up. That's what you get for volunteering information.