Subframe Connector Install Question

[splinterddt]

Finally I quit screwing around and finally going to install subframe connectors. I have a question for all my fellow gear-heads out there. I remember something about jack stand placement when installing the connectors. I've been trying to keep an eye out on the T.V. shows and search on the internet, but I can't find the info. Everywhere I look it just says "place on jack stands." Where do they need to be placed to correct the "sag" while installing the connectors?

 

[snottystang]

I have heard of doing it only using the factory jack points. I have jack stands under my rear frame right at the leaf spring shackles, another set in the middle of the factory jack points and another set placed under the where the lower control arms attach to the frame. I plan to be doing both floor pans and the sub frames as well.

 

[Fast63]

You need to place the jackstands under the suspension points. So in the front, put them under the control arms in order to preload the suspension, and in the rear put it under the leaf springs at the rearend housing. This is another good time to use the 2x4's under your tires trick because you basically need to install the subframe connectors the way that the car would be sitting normally on the road.

 

[palerider94]

What's the 2 x 4 trick?

 

[68_stanger]

maybe I did mine wrong but when I welded mine in I just drove the car up onto 3 2x6's under each wheel gave me plenty of room to get under the car and weld, nothing jacked up full weight on the car's suspention, and they fit just fine.

 

[Fast63]

Review this thread about the 2x4 trick:

http://forums.stangnet.com/showthread.php?t=727972

68_Stanger, that is exactly how to do it. You can use wheel ramps under all your tires too if that makes you more comfortable. If you have your car on jackstands the wrong way, your subframe connectors will still fit, but when you lower the car back to the ground, there will be all kinds of load on the subframe connectors, but there shouldn't be. They are supposed to keep your car from flexing only. So your car will probably sit higher if you do it wrong because the frame will not want to flex back to where it normally is when the car is sitting on its tires.

I have to mention too, don't use bolt in subframe connectors, always weld them in. Most bolt in kinds you can also just weld on, but don't bother with the bolts.

 

[splinterddt]

I heard that over time the cars start to sag in the middle, especially unibody cars. So shouldn't the front jackstands be behind the engine to take the stress out of the middle, and wouldn't the 2x4 trick not help to correct this?

 

[68EFIvert]

I placed jack stands behind the engine and let the car sit there for a number of days. Then put it back on the ground and welded them in place. There was a difference in the before and after on how the panel fit. The gaps were much closer to equal throught the car. I saw this technique on Muscle Car, the show on Spike TV.

Here is a link for a how to article.
http://www.fly-ford.com/MM0105-How_To_Install_Subframe_Connectors.html

 

[Fast63]

I don't think it's really a good idea to try and fix that sag, not even the method you did 68EFIvert. You could make things a lot worse because the car will want to go back to the sag again and when it does, you will have a lot of load on your subframe connectors instead of on the suspension, and that is not what they are meant to do. They are meant to keep the car from twisting in corners and hard launches, not fixing sag and holding weight.

 

[68EFIvert]

I don't think it's really a good idea to try and fix that sag, not even the method you did 68EFIvert. You could make things a lot worse because the car will want to go back to the sag again and when it does, you will have a lot of load on your subframe connectors instead of on the suspension, and that is not what they are meant to do. They are meant to keep the car from twisting in corners and hard launches, not fixing sag and holding weight.

Isn't installing a monte carlo bar or export brace doing the same thing to correct 40 years of sag? I feel that if it puts it closer to the way the factory designed the car it must do something positive for handling, braking or predictability of the car. I don't know if the way I addressed the problem is the best but the guy on Muscle Car sure seems to know what he is talking about when it come to chassis work. I would rather do that than weld in 40 years of sag.

 

[brianj5600]

Yes he seems to know, but I don't think he knows. Did you see the one where he totally botched the front suspension on his track car. He put the inner UCA mount high than the ball joint. And when he "fixed it" he lowered it, but it seemed to still be high or level at best. Can you say understeer? If you do it his way it will be different, but if you don't measure the chassis you won't know if it is correct before or after. If you don't know where you are or where you are going, you will never know if you got there.

 

[68EFIvert]

You make some good points. I likely would still go the path I did because I am not likely to push the car to the limit and I got the benefit of better aligning body panels. I will post an update if I start having problems with welds or other complications due to additional stress. Thanks for the friendly debate brianj5600. I like to get a little deeper details on opinions.