i used the search function and didn't find what i was looking for. my car like many has gotten floppy over the years. i have outer connectors and they did help out but i want to add inners for the stiffest "frame" i can get. i thought i would need to have a body shop put it on a frame table to make sure it was level and then weld the connectors in. i contacted one and they said that isnt needed to install subframe connectors. i know i need a good level surface. whats the agreed upon method to make sure this junk is sitting flat?

 

You want to weld them on as the car sits on its own weight. If you try and "square and or level" you will put the car in a position that it won't naturally be once on its wheels, which will put all kinds of stresses on the car and subframe welds.

 

Just install on a 4 post lift.
you can rent they out for fairly cheap in most areas.

https://m.youtube.com/watch?v=avr6HdKlU30

 

[QUOTE=Evilokc;6481425]... i have outer connectors and they did help out /QUOTE]

While the replies above will do the job (I had my outers done with the vehicle sitting on the suspension as on a four post lift), I'm more interested in how your outer SFC didn't help. The Spohns I installed a dozen years ago have provided plenty of chassis stiffness. So much so that jacking up the car at any one corner (at the jacking points) will raise the entire side.

 

Outer SFC are typically less effective than inner SFC due to the length.(for the most part)
what's stronger?
A 50in tube being twisted? Or a 36in tube being twisted?

That's why welding the pinch welds to the SFC makes a insane difference in rigidity.
50in becomes basically 0 inches.
I removed 2 sets of SFC and went with DSE. The difference is measurable.
But this is all basically irrelevant for street driven 3rd gens. Just throw on a set of SFC and forget about it.

 

I have Spohn outers and alston inners installed at the same time right after I bought my car in '15. The thing is great for chassis stiffness and has No squeaks or rattles which AFAIK is rare for these cars. Mine was done on a drive on lift at the time.

 

I can't imagine installing them without welding them in along the rocker. As stated, that's where the strength comes from.

 

I originally installed these (or any Sub-Frame Connectors) on a Drive-On (4 Post) Lift...

I realized early on that many (if Not most) of these Cars are not straight anymore.
I changed to using a Frame-Machine to do the installation after any needed Frame Correction...

I'll never go back to doing this any other way.

 

My Spohns were done by my good friend at Altered Image. Chassis building specialist and all round excellent fabricator.
We used his level shop floor as a reference for relative flatness and preloaded/unloaded each corner via the lift and jack stands.
Otherwise this stuff gets done on frame jig but my heap was already a fully decked out street car so no jig for me.

 

Should the car not be off its wheels so the chassis can be squared before permanently fixing it in place? Then suspension should be adjusted accordingly.

 

Install them with the weight of the car on the wheels. Use a lift or cut 2x4's and make blocks

 

...and for the love of god...

DO NOT USE BRICKS, CINDER-BLOCKS, OR ANYTHING BRITTLE enough to crumble and KILL YOU!

 

Definitely!

 

Obviously this is the best route, but it is pretty difficult to source someone with a frame machine willing to do the work, even in a massive city the size of Houston. All the shops want simple jobs these days.

 

I have yet to travel to a big City where Body Shops are NOT pulling Frames during Collision Repair...

 

I've seen this too. Production body shops, resto shops...anyone with money tied up in this equipment keeps it busy and profitable with collision work. They are generally not interested in small jobs on vintage vehicles.

Keep looking...hopefully you'll find a local shop that will take this job on.

 

Frame shops notwithstanding, if your unibody is bent like a trapezoid from a collision, it may be that subframe connectors are the least of your concerns.
However, with a nice level floor, and a chassis that isn't mangled, you should be able to determine the measurements in the bottom graphic of the image posted below.
Once you've established that the chassis is "level" to the ground, the SFC's can follow with whatever means you have to get the car sufficiently high enough to work on.

 

Additional data for referring to the picture above.