Subframe connector installation tips - FLSFC

[rattle_snake]

Just in case someone uses the search tool for subframe connector installation info, I will list a few tips that I think are useful that were not in the MM FLSFC instructions or on the net;

-Check ALL the door gaps BEFORE lifting the car if using jack stands. After supporting the car 'properly' open and close the doors to make sure everything is the same.

-Disconnect the battery. all of the welding current should go back to the welder but having all active circuitry un-biased/off can't hurt. move the driver seat all the way forward before disconnecting the battery to access the rear seat bolts.

-Wear f'in safety glasses when grinding.....

-Make sure everything fits right before welding. plan in grinding, bending and ob-longing holes to get suitable fitment. don't use clamps or jacks to get things to fit on the car. The connector should fit properly by itself.

-It is not necessary but recommended to pull the exhaust off (at least from the cats back) for the best welds especially to get the rear inboard vertical subframe welded to the FLSFC.

-The MM instructions say to jack up the connector or press down on the floor pan and tack the seat brace first. on the right side of my car, jacking it up to fit prevented the door from closing, the window drug on the roof pillar. Check the doors as you go. grinding an 1/8" off the seat brace allowed it to fit properly and the door to remain in it's original location.

-Make sure you do no run out of Beer or MIG wire.

-don't forget to turn on the gas. no amount of cussing or adjusting feed speed will get the machine to weld.

 

[Posi]

I'd only put subframbe connectors on a car with it sitting on the wheels and tires themselves. Never any other way imo. Not saying it can't be done but it's better for the car to be on its own weight exactly like it will be driven.

 

[BBCOBRA]

That's what I've always heard too. Most reputable shops use the drive on lifts, like a front end alignment setup or use a drive over pit for this very reason.

I've yet to do this to mine, but it's on my to do list.

 

[rattle_snake]

I 100% agree that a drive on lift is the best way. I don't have one so I decided to research until I felt confident that the job could be done satisfactory with jack stands.

I feel it is worth pointing out that a car with high power and decent traction (or even a stock mustang with slicks) can and will bend/tweak the frame/unibody. One could argue that a careful FLSFC install done with jack stands is better than a set installed on a lift, after the car is damaged/bent.....

Here is what I think is a 'decent' jack stand method
- Measure & record all 4 fender ride heights with tires inflated to known pressure.
- Lift and remove all 4 wheels.
- Place jack stands at the outer ends (safely) of the control arms OR under the lug studs if jack stands are big enough (again must be safe).
Note:
Because the frame only connects to the k member and IRS at set positions, one could argue that jack stands properly positioned under those positions would be equally effective. the MM directions mention this for the k member.

- Measure the height from the floor to the fenders. the difference between this and the original measurement should be constant offset. One could argue that there is no significant twist on the frame.

Most importantly if you don't feel comfortable, don't do it yourself, take it to a reputable shop with a lift. installing FLSFC is one of the most permanent modifications you can do.

 

[rattle_snake]

One more tip:

IF you ever want to remove the IRS.... make sure the rear end of the SFC doesn't hang over the outboard side of the rear frame rail. This will block access to the forward IRS bushing that need to be removed/installed VERTICALLY due to the angle of the IRS subframe's front 'arms'

A solid axle/lower control arm car will not have this problem as the control arms are separate pieces and can be installed from the rear.

I had to grind a little on the SFC and welds to get the IRS back in after installing FTBR 'semi-solid' subframe bushing that are wider than the factor rubber ones.