Hi everybody. I finally installed UMI subframe connectors on my '89 Formula, and I thought I'd detail it here for other people who might be looking to do the same thing.

Please don't respond to this thread until I'm done posting all of the pictures; there's about 15 of them. After that, feel free to ask any questions you might have.

These are the subframe connectors as I received them. Disregard the ring & pinion gears and the limited slip differential, those went on a different car.


Here are the same subframe connectors after they have been modified by me. You can see the pathetically small passenger side brace next to my welded-in custom brace on the left, and you can see where I added to the bracket on the right.

When I test-fit these connectors, I knew that there would be a lot of custom work required. Right here, you're looking at the front-left SFC mount. It's made out of really thin steel, and this is what the SFC is supposed to be welded onto. Note the oval-shaped hole; this is where one of the welds SHOULD be.
I could have just welded the SFC bracket on one side, but it wouldn't be as strong, and it would probably crack. I had a better solution...


I welded in a plate to spread the load out. Those pock marks you see in the middle of the plate are rosette welds; I drilled holes in the plate and welded them up.
Keep your eye on the bottom of that oval hole.

 

Here's the right-front SFC welded in. The circled area is where the oval hole was. I wouldn't have been able to use any of that area if I hadn't welded in that plate.
Also, note that I ground some material off of the side of the tab; this was to clear my exhaust system (a muffler-shop job, 2.5" into a single 3").


As you may have seen before, the front of the subframe connector kit I got wasn't up to par, in my opinion. On the driver's side, it would be "connecting" to another really thin piece of stamped steel. In my opinion, that was not strong enough, so I reinforced it. I cut and bent some 1/8" steel, drilled some holes in it, and welded that in.


Here's the steel plate I welded in. The holes drilled in it are for rosette welds.


Even with that plate welded in, there is another problem: The subframe connectors only connect to the car with this one little tab!
I know why the manufacturers did this: To allow for manufacturing variances, and for body-flex (after all, these cars are over 20 years old.).
But that's not good enough for me...

EDIT: You can also see the 7/16" round stock pieces that I welded onto the bottom of the SFC; this is to keep the jack in place when I lift the car and keep it from sliding off.

 

Here's another view of the contact area with the subframe connectors in factory form.
There's a huge gap that could be filled... so I filled it.


I welded some tabs of 3/16 steel to fill in that gap. I welded it for 3/4 of the way. I'll provide better pictures of the installed product later.


This is the passenger side subframe connector, with my added on connector/arm. The added on piece is 2"X2" 3/16" square tubing that I had laying around my shop.


Here is a different view; that section on the left is cut out to clear a dip in the floor-pan.

 

Here is that same 2"X2" piece of steel installed, after all of the trimming for exhaust and floor-pan clearance! Looks kind of flimsy, doesn't it?
Wait until you see what I did with it next.


I had to cut out sections of the 2"X2" tubing to allow for floor-pan clearance, and for exhaust clearance. But I gusseted the inside with 3/16" steel tabs. Then I welded a plate over it.


Additional view of the gusseting I welded in; this is the top side.


Here's what the finished product looks like, with the patches welded in and painted.
Bottom:

 

Here's what the finished product looks like, with the patches welded in and painted.
Top:


Here's what the passenger side brace looks like from behind:


For the rear, there wasn't much to it, although I trimmed a little bit of material off of the tops of the tabs, to allow me to weld them up (I wouldn't have been able to get the tip of the welder in tight enough otherwise).
The driver's side mount was a damn-near perfect fit, but there was a slight gap between the "cross bar" and the control-arm mount on the passenger side, and that required a shim to be welded in, seen here (I dressed up those welds with a grinder before I installed the control arm):


After driving the car for a couple of weeks with the SFCs welded in, here's my overall impression:
One of the main reasons I even got SFCs was to quiet the car down; 3rd generation F-bodies have a well-earned reputation for being squeaky and rattly.
There is still a very noticeable squeak from the front-end, but I'm not sure if that's the chassis or the polyurethane control-arm bushings (urethane bushings will squeak when they run out of lube, and mine haven't been lubed since I installed them in '09).
The ride seems improved; as soon as I got done with the job, I drove the car down the bumpiest road I could find. You still feel the bumps (these cars are never going to ride like Cadillacs), but they don't seem to jar the car around as much now.
Before the SFC installation, my car would sometimes exhibit this weird behavior when braking: It felt like the back end of the car was moving around. I would be holding the steering wheel straight, but it felt like the rear wheels were wobbling/moving the back end. I could never figure out what it was.
(And YES, the rear control arms/bushings/panhard rod were all in good shape.)
It doesn't do that now, so I guess the problem must have been some kind of flexing in the chassis.
Having an easy/ secure place to jack the car from is a godsend.
The best part is the peace of mind knowing that I'm not twisting the hell out of my car's undercarriage when I hit bumps/potholes.

Last of all, I used a Hobart 140 MIG welder with .030" flux-core wire for all the welding on the body, and a Lincoln 225 "Crackerbox/Tombstone" arc welder with 6011 rods for the heavy material on the SFCs themselves.

Thanks for reading. You may now commence with the questions.

Edit: One last thing I forgot to mention: I'm pretty sure that the exhaust Y-pipe is hitting the passenger side connector, even after the grinding; on some bumpy roads, I hear a clunking/banging coming from that area.
Even with the material I removed on the mount, it was still a VERY tight fit.
I plan on making a new y-pipe as soon as I get some more money and time.
Here's what I'm running right now, shown off the car:

 

Nice job.

 

I admire ALL the extra work you needed to do with this Brand, but I bought the ALSTON SFC and ONLY needed to have them welded in (where they slid over the front and rear body rails). Lots of HD metal and fit like a glove. Their "U" shaped mounting allows you to either bolt them in or weld them on. Just make sure you remove all the galvinized coating first to get to the actual metal if being welding on. There was no difference in ground clearance and like everybody says, no matter what brand you go with, these SFC are an absolute must do on these models.

 

Thanks for the kind words, guys.
edpontiac91, I actually want to install some Alston-style SFCs as well; when I was under the car prepping it to be welded, I prepped the mounting points that the Alstons would use at the same time.
So you say that there aren't any ground clearance issues with the Alstons?
I was actually thinking of making my own out of the 2"X2" square tubing, cut down the middle and gusseted as shown earlier. That way I could get it tucked really close to the floor pan.
It would be cheaper (because I already have the materials), but it would be a lot more work.

 

What's the plan for the car?

My first reaction is that you braced the heck out of those things, but I don't think the increase in stiffness over most of the way those connectors came is worth the extra weight. Any idea what the total weight of the connectors was by the time you installed them?

I've wondered if anyone has actually tested how much stiffer the Alston + perimeter connectors is vs just alston or just perimeter connectors.

Back in the day I had a set of GW SFC connectors on my autox 83 TA, and they were just some 1-5/8" chrome moly with simple 3/16" plates on the back to weld to the sides of the rear CA mounts, similar plate to mount the front driver's side, and the end of the tube just got welded in in between the floor and the back of the rocker, then they got welded along the pinch seam on both sides. NOWHERE near as beefy as most of these parameter style SFC's, and they made a world of difference without adding much weight. That car got t-boned by a guy that ran a stop sign and was going 55 before he entered the intersection (don't know how fast he was going when he hit me). Crumpled the door, fender and rocker face, pushed the hinge mounting surface in a bit, but the area with the SFC connector wasn't moved/bent at all, a couple of the pinch weld seams cracked but they were still tight after that. I couldn't open that door, but the car still drove straight, and the alignment was still in the acceptable range after that. I was pretty impressed by that also.

 

That is all these cars are, thin pieces of stamped steel. It was a real eye opener when I began tearing into my 91 convertible as to how flimsy these cars are and just removing one connecting piece will make it even flimsier. You did well adding in support where you saw it necessary. But why did you use Flux core on everything? Was your tank empty?

 

I have the dual cats (from the factory) and the ground clearance is 3 1/2" from the cats down. When I measured the ALSTON setup after installation, it was 3 1/2" from the bar down. I think a system, such as UMI, is really overkill for a street car. If your going to do autocross or such, then there MIGHT be a small advantage, but that would require driving the car at its limit (which is crazy to try on the street).

 

Hi, guys.

83 Crossfire TA - It just completely slipped my mind to weigh them until after I'd welded them on. I'm going to weigh the car next chance I get; it weighed 3,300 and some change with a mostly full tank when I bought it.
If I had to guess, I say that the extra stuff I added on is about 10 pounds over the factory weight of unmodified UMIs.

And the intended use of this car is just a daily driver; no racing. Overkill? Yeah, probably. But I wanted to do this right.

Tibo - I was borrowing the welder from a friend, and he didn't have a tank. Also, it was almost all over-head welding, so the argon wouldn't have done much good, anyway.
I know that the flux-core welds look pretty ugly, but I had to work with it.