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1/28/2017 9:23 AM  #1


Subframe Connector Buildup

Some of you may remember that in the early 70’s, I campaigned a 66 Mercury Super Cyclone SS/JA that ran consistent 11.19’s.  Body flex was expected and part of the attrition.  I always had a cracked windshield that ran from corner to corner, and my driver’s door would regularly bind closed.  At one time, I had a photo from a track photographer that showed my left front wheel 6” in the air while the rear bumper was almost parallel to the ground!  The right front wheel was just touching.  A very strong 390 built to 427 specs, a C-6 trans and 4.88 rear gears helped a bunch.

Fast forward to today.  Our long suffering 66 Coupe has the typical body flex tell-tales, there are small cracks in the window corner of the C-pillar and a slight wrinkle midway up the pillar.  There is no accident damage anywhere, verified by extensive forensics under the body.

Following Daze’s excellent tutorial (www.dazecars.com) on building your own subframe connectors, I set out to try my skills as a welder and fabricator.  The 2” X 2” X .125” tubing, about 10 feet, set me back about $40.00, plus I added in a couple of feet of 2” X 1/4” flat stock.
http://i66.tinypic.com/2uy17ye.jpg


http://i67.tinypic.com/2e30o78.jpg

The instructions are clearly written and relatively easy to follow.  There are two important angles he mentions; one is 170 degrees, the other 174 degrees.  Silly me, what can a simple 4 degree difference do?  So I built the connectors with 174 degrees across the board.  Guess what, they didn’t fit!  I took them out and recut the described joints for 170 degrees and all is well now.  It hugs the bottom of the floor just right.  When I put a floor jack under the rear of the connector it laid directly under the rear spring subframe.  I did have to trim the rear drain-holes a bit.

I made a couple of significant changes to the plan, however.  I was concerned about torsional rigidity and that the rear weld location would put the twisting moment directly on one weld joint.  As shown in the photos, I welded two tabs on the rear of the connector.  One vertical tab in the location recommended by Daze, the other slightly forward and to the outside of the connector.  There I drilled a 1/2” hole through the tab and through the floor.  On the inside of the car, I cut open a 2”X 3” opening in the floor aligned on the seam.  The photo shows the hole and the bolts protruding through the drilled holes.

http://i67.tinypic.com/bijpea.jpg


http://i68.tinypic.com/ibgsk2.jpg


http://i68.tinypic.com/2jagqpy.jpg


I also decided to drill through the front frame rails and bolt them solidly.  I used grade 8 hardware in all locations and torqued to 80 ft lbs.  For the front bolts for no particular reason, I used Moly coated nylock nuts while the rears got locking washers.  All hardware from Tractor Supply.

http://i64.tinypic.com/j8hdgh.jpg


http://i67.tinypic.com/2v336kh.jpg


When I let the car down, the C-pillar wrinkle is gone.  When I get a bit further on the build, I will be able to determine if the car handles any different.

Materials used:
Harbor Freight $15.00 angle grinder, about 8 4” cutoff wheels, a couple of 40 grit flapper wheels, and a couple of grinder wheels.  I used about two cans each of Rustoleum Self Etching Primer and Rustoleum 7777 Satin Black paint.

For a welder, I used my trusty Harbor Freight Flux Core 100 amp wire feed Mig welder I hot-rodded (of course) using a bridge rectifier to convert from AC to DC and changed the polarity to positive ground.  Lincoln or Miller .030 flux core wire worked the best.  These mods are shown on Youtube and are well worth the $30.00 investment. 

Last edited by 66 coupe (1/28/2017 1:45 PM)

 

1/28/2017 9:47 AM  #2


Re: Subframe Connector Buildup

Very nice work, thanks for the pictorial.  So, these are a purely bolt in application?  I'll have to check these out at Day's site for a winter project.  Thanks again.

BB
 


I have found the true secret of life....keep waking up!
 

1/28/2017 10:31 AM  #3


Re: Subframe Connector Buildup

Your welds look great, nice job.  4 degrees doesn't seem like much, but from doing trimwork for years I can tell you its the difference between an open and closed miter on a narrow piece of door casing or baseboard, let alone the effect on something as long as a subframe connector.  All part of the learning curve. 

I would go back and weld everything solid.  The problem with bolt in connectors is that the stress has just been shifted and over time you'll elongate those bolts holes if you use the car hard and the body flex to a degree will return. 

You also should be sure to weld that access hole closed.  Its a small area, but with the hole there the top of the box that is the famerail has been removed, and with it 50% of its shear strength in that area. 

I'd also not recommend bypassing the thermal cutout on the welder.  You are coming up against the duty cycle restriction on the welder.  It keeps cutting out to avoid overheating the components, which will lead to a failure if it happens enough.  Cheap welders are made from cheap parts and thus don't handle heat well and have a short duty cycle.  I realize its possible that the welder is cheap enough to be considered expendable, or you are skilled enough to just replace the part that fails when it does.  But because you never know who's reading this, or for how long, I always like to make sure there's the right amount of point/counterpoint so someone with no knowledge can make an informed decision.  

 

1/28/2017 1:19 PM  #4


Re: Subframe Connector Buildup

They are very nice... good job....Thats a whole lot of work...I used weld on connectors from Tin Man  very reasonable...perfect fit....jj


"Never put a question mark where God put a period "  Richard Petty
 

1/28/2017 1:42 PM  #5


Re: Subframe Connector Buildup

TKO; I might weld up later.  I dont weld very well on my side or upside down.  I followed the lead on many of the aftermarket subframe connector providers, most of them are bolt in.  I will be welding the access holes closed, I left them open to show how they fastened to the floor.

In hindsight, I would have made the front extensions a bit longer, they only protrude in the front subframe about 6".  The bolts are 4" apart which leaves little clamping radius for strength.  Note that Daze recommending plug welding here which in my opinion, would have given me a little less clamping effort on the joint, especially since the subframe is about 16ga.  I could have easily made them a good 1.5" longer.

On my welder mod, you made a very good recommendation, one I will be implementing soon.  It was cutting out every couple of seconds, while the coils on the transformer were barely warm to the touch.  They have never been hot, even after a strong 2" long weld on 1/4" thick plate which glowed red-hot when completed.  I may replace the thermal sensor, they are readily available.

Jerseyjoe; thanks.  For the amount of time plus expense, I probably would have purchased pre-made connectors but I hate to buy when I can make.  Most of, or almost all of the mods on my car I did personally, either fabricate from scratch or installed pre-made.

     Thread Starter
 

1/28/2017 7:16 PM  #6


Re: Subframe Connector Buildup

If your welder is cutting out a lot, are you using an extension cord with it?  A cord that is too light can cause really crappy welds and overheating the welder.

Those subframes look really nice, but I agree they need to be 100% welded in to actually do much good.


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

1/28/2017 8:20 PM  #7


Re: Subframe Connector Buildup

I used Day's plans as well when I built a set for my 65.  I mocked up a set using wood to check for fit and then tweeked from there.  I also added a couple of tabs inboard and rosette welded them to the underside f the floor pans.  Very solid.


Cheap, Fast, Good:  Pick Any Two
 

1/30/2017 10:28 AM  #8


Re: Subframe Connector Buildup

To weld on subframe connectors I built four wood platforms 4' tall and 2'x2'.  This allows me to set a car on its wheels on these platforms with my two post lift.  Then I block the tires fore and aft with 2x4s and screw them into the tops of the platforms.  I built the platforms perfectly level to account for my garage floor, which was not.  This gives me more than 4' of room underneath to roll around on a stool and install subframe connectors, strip the undercarridge, etc.  I've got my '89 GT sitting on them right now.  It made welding on the subframe connectors very easy compared to trying to do it with the car on jackstands and rolling around on a creeper.  Yes, I keep the lift arms under the frame in case the platforms fail, but they haven't budged, even with me inside the car.  Each platform only really has to support about 750lbs.  I figure with an 8"x8" contact patch that's about 12 lbs/ sq.in., really not all that much.  Everything is locked together, triangulated, and there's nearly 10lbs of 3" framing screws in the four platforms.  I've less than $100 in them, and about a weekend worth of build time.  Its a good option if you have a two post lift.

 

1/31/2017 5:57 PM  #9


Re: Subframe Connector Buildup

My son welded mine up I shop class from the "Daze" instructions and I welded the. In. I was shocked at how much they stiffened the body up. I had my car of four jack stands. I took one out and you almost couldn't tell because the tire remained of the ground with minimal flex. I bet it makes a huge difference. Definitely find someone with a 220v mig to burn them in.


65 mustang coupe, 351W, C6-  2800 stall, B&M blower, 9inch- trac-loc 3.70 gears
 

1/31/2017 9:47 PM  #10


Re: Subframe Connector Buildup

Once you "get-past-the-fear" of the hot weld falling in your face overhead welding is just like flat welding....only from the bottom up! Keep the angle of the gun to the connector(or whatever you're welding) straight in. 90* I guess.  try to get so you can see the weld puddle pretty clear. Sometimes shining a bright light on what you're welding makes it easier to see what you're doing. A few "sparklers" may fall on you butt the weld won't(unless your angle gets wayyy off)
Most good welders need to chew tobacco and learn creative cuss words. (it's just part of the trade!)  Sooo go buy you some Levi Garrett  start practicing!!
6sally6


"Get busy liv'in............or get busy die'n!!"
 

2/02/2017 9:12 PM  #11


Re: Subframe Connector Buildup

Anyone want to build me set? If so let me know what the price would be. I just don't have confidence in my welding abilities. 


Yeah, I know, but...
 

2/02/2017 9:20 PM  #12


Re: Subframe Connector Buildup

calistang wrote:

Anyone want to build me set? If so let me know what the price would be. I just don't have confidence in my welding abilities. 

 
You can buy a set from Tin Man Fabrication that will fit and are not that expensive. You still have to weld them in.

 

2/02/2017 10:06 PM  #13


Re: Subframe Connector Buildup

Thanks Hornman, I'll check it out. $40.00 in materials makes it temping to try on my own, maybe with a bit of adult supervision!


Yeah, I know, but...
 

2/02/2017 10:21 PM  #14


Re: Subframe Connector Buildup

calistang wrote:

Thanks Hornman, I'll check it out. $40.00 in materials makes it temping to try on my own, maybe with a bit of adult supervision!

 
$40 for steel, plus Mig wire, plus shielding gas, plus band aids, plus electricity, plus something to precision miter the steel tubing, plus refreshments for your supervision. Don't get me wrong, given a choice I would rather fabricate than buy, but I now look at the real cost of fabrication versus buying and if there isn't enough recreational value in fabrication, I buy.

 

2/02/2017 10:59 PM  #15


Re: Subframe Connector Buildup

calistang wrote:

Anyone want to build me set? If so let me know what the price would be. I just don't have confidence in my welding abilities. 

Maier Racing in Hayward has been selling them for years.  I've had mine  for over 20 years. They're pretty close to you.  I prefer to do business with people I can see face to face.  But you still have to weld them.  If you are outsourcing the welding, do it at a body shop that has a level table.  Then the welds will not put your car in a bind.
 


Original owner - 351w,T-5, 4whl disks, power R&P
 

2/03/2017 5:45 AM  #16


Re: Subframe Connector Buildup

Hornman wrote:

calistang wrote:

Thanks Hornman, I'll check it out. $40.00 in materials makes it temping to try on my own, maybe with a bit of adult supervision!

 
$40 for steel, plus Mig wire, plus shielding gas, plus band aids, plus electricity, plus something to precision miter the steel tubing, plus refreshments for your supervision. Don't get me wrong, given a choice I would rather fabricate than buy, but I now look at the real cost of fabrication versus buying and if there isn't enough recreational value in fabrication, I buy.

That's kind of how I view it too.  I also look at the opportunity cost of my time, and how long its going to take me to make something vs. buying it.  Now, when the quality of the stuff I can buy is bad I'll take the time to make it myself (like my trap door speaker setup).  With subframes, I probably would have built my own when I was in my 20s and had more time than money.  As that situation has reversed itself I elected to buy mine from Fatman.  Its great to see guys out there building their own though, because each project is a learning experience.  I learned to weld initially for a project I was doing (can't remember what now...) and its been a great skill to have over the years.
 

 

Board footera


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