Sub-frame connectors

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Captainkirk

Captainkirk

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A while back I had mentioned installing subframe connectors on my Duster. I asked if bolt-on was OK for street use or if they needed to be welded as well. Several replies surprised me, as more than one poster mentioned subframe connectors needed to be installed with the car in street trim (engine, trans, etc installed as it will be run on the street) and with weight on the suspension; i.e NOT on jack stands.
This is surprising to me. Right now my A-body is up on jack stands with no suspension or drive drain, including torsion bars and K-frame. Obviously the perfect opp to crawl under and do the work, but totally against what these other guys are saying. So, if true, is the body 'pre-flexed' in the street trim with motor, etc and weight on the wheels? I'm not sure why this would make a difference. Right now the chassis is in a full-relaxed position-seems this would be the ideal time to install the SF connectors. Anybody else wanna weigh in on this? And what negative results would be derived from installing them now?
 
see alot of pictures of cars on rotisseries being restored..and they install sub frame connectors...

I have done 3 cars...all were on jack stands...with no weight on the suspension....
 
this next month I am putting subframe connectors on a 72 dart ...it is a bare shell ...it makes more sense to me to do it while its a shell than in street trim...

if Chrysler would have installed sub frame connectors from the factory they would have done it as the floor sections were coming together to form the shell.

I doubt they would have had a fully assembled car and said "oh yea lets do the sub frame connectors last" ...that don't even make sense

if its assembled you may have heat transfer damage paint on the topside of the floor under the carpet ....maybe start a fire ...no thanks .....it makes more sense to weld in a major structure member to a shell and do all welding before any paint flies........IMO
 
Yeah, kinda my thoughts as well. Since I'm doing the underside now and have the interior out, it would be ideal.
 
You just need the body to be square.

For example: Having the car jacked up in one corner probably isn't the best time to install sub-frame connectors.
 
1968FormulaS340 said:
You just need the body to be square.

For example: Having the car jacked up in one corner probably isn't the best time to install sub-frame connectors.
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It's level. Four jack stands of the same make & model on the same height setting....
 
ive heard that doing it not in street trim could pose problem with the doors opening and closing correctly
 
hemitheus said:
ive heard that doing it not in street trim could pose problem with the doors opening and closing correctly
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read the old chrysler race manuals. they say to do it w/ the car jacked up level and squared up even if u have to put shims under the jack stands, it should be level. your suspension tweaking(s/s springs or what ever) any preloading ain`t right if the car is welded up twisted. if it`s done right, the engineering in the s/s springs (for instance) will be used correctly. :-k
 
Captainkirk said:
It's level. Four jack stands of the same make & model on the same height setting....
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This doesn't necessarily guarantee level or square. I would measure and double check. Floors aren't all perfect, nor are jack stands. You may already have done this, but I would hate to see anybody make a simple mistake.
 
gdrill said:
This doesn't necessarily guarantee level or square. I would measure and double check. Floors aren't all perfect, nor are jack stands. You may already have done this, but I would hate to see anybody make a simple mistake.
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yep. stick a level on the ground dead senter between the stands in the center of the car and see if its level. then set it under the exact center of every jack stand and check that too. Make sure everything is as level as can be. Its better to be anal and 100% sure. This is coming from my stand point. mr. worrisome himself. lol
 
This is an interesting point. Does anybody have experience or have had trouble welding them in either way. I have always heard as long as the jack stands are under the suspension and squared up its ok. IE jack stands not on the frame.
 
I don't think the trouble is in the insatllation on the vehicle. If the frame is not square and level when they are installed panel alignment issues can result, as has been cited.
 
I can give you an example of why we welded mine in on a drive on rack. When we lifted the car on a frame rack, the gap at the top of the fender would open up and the doors wouldn't open. There was nothing wrong with my sub-frame, no rust or rot, it was just a 40+ year old unibody car. Once we welded the connectors in place, I can lift it up and these problems disappeared.

If you can put your car up on four jack stands and everything still lines up okay and your doors work fine, then I say go for it. If they don't, I would put the jacks under the rear axle tubes, and then under the K frame to support the weight of the engine and front sub frame. This would basically be the same as a drive on lift.

The same on a rotisserie, if everything is lining up, weld them in.
 
40+ years and gravity will cause a unibody to sag.
If a car is completely apart and on a rotisserie all the body panels will be realigned eventually anyway.
If its all together and on the wheels when the connectors are welded in, where it is at this time is where it will be.
Could 4 stands properly placed allow the engine weight and differential weight to flex the unibody back to where it was OEM ? I don't think so.
It wouldn't take the sag out of the A-posts but then a rotisserie setting wouldn't either.
In the end, the purpose for installing subframe connectors is to stop the flex and continuing sag. I don't think there is a way to get each individual car back to where it was 40 years ago. We already know every one was slightly different anyway due to lack of strict tolerances and/or production methods that were used.
Chrysler did give is adjustable torsion bars instead of coil springs to compensate for suspension variations and a huge fudge area where cowl, hood, fender, and door all meet.
So what is the best way to add subframe connectors ? Who knows. Rotisserie is as close to "back to square one" as we can get. Or should I say "OEM un-square one ?"
What is the most wrong or incorrect way to weld in subframe connectors ? I think bumper jacks on 4 corners is about as wrong as we could get.
Anything in-between those 2 methods is "geter done" acceptable. Adjust body panels and suspension as needed afterwards and happy moparing.
To make rocket science of it leads to headache , not happy moparing.
 
Good thread! I haven't added connectors yet but I can see that it's very important to measure and level carefully. I had a friend that just welded his in and the doors wouldn't close. The best way would be to pay a body shop to put it on their frame machine, square it, and tack the connectors in. tmm
 
I just put stands on all four corners of the frame sections and then used a lazer level to get it flat, checked the doors for position and welded them up.

Never a problem
 
Chrysler would have done it as the floor sections were coming together to form the shell, but they would have done it in a jig to make sure everything is in alignment.

You can't guarantee that a 40 year old car hasn't sagged, twisted or warped and you don't have a jig to secure proper alignment.

It seems to be that without the weight of the engine and rear-end you would need to bolt the car down to a frame to insure that it isn’t twisted or sagging


It seems to be that without the weight of the engine and rearend you would need to bolt the car down to a frame to insure that it isnt twisted or sagging

RaniDart70 said:
this next month I am putting subframe connectors on a 72 dart ...it is a bare shell ...it makes more sense to me to do it while its a shell than in street trim...

if Chrysler would have installed sub frame connectors from the factory they would have done it as the floor sections were coming together to form the shell.

I doubt they would have had a fully assembled car and said "oh yea lets do the sub frame connectors last" ...that don't even make sense

if its assembled you may have heat transfer damage paint on the topside of the floor under the carpet ....maybe start a fire ...no thanks .....it makes more sense to weld in a major structure member to a shell and do all welding before any paint flies........IMO
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But, if all the doors, fenders align properly now, shouldn't this be an indication everything is hunky dory?
 
My. US Car Tool connectors came with instructions stating to install them with car resting with its weight on the suspension. I do not know why, but they must know better than me.
 
my doors open and shut fine if it is on the ground, If I jack the front up and put jack stands under the frame right behind the front tires, the doors still open fine but the driver will normally not shut at all. When I just had the tranny out recently, I also had the the back end up in the air (stands under the rear axle tubes) and the driver door worked fine but the passenger door opened and would not shut. I think when I weld mine in, I will go get a pair of old school car ramps and drive the front wheels up on them then put jack stands under the rear axle and make sure both doors open and shut properly.
 
gdrill said:
This doesn't necessarily guarantee level or square. I would measure and double check. Floors aren't all perfect, nor are jack stands. You may already have done this, but I would hate to see anybody make a simple mistake.
Click to expand...

Yup, I used a level on mine, side to side and fore and aft.
 
What is the purpose of sub frame connectors?...to tie the sub frames together...Does it matter if the sub frame connectors are off a few degrees or not level...will the sub frames still be tied together...???



Too much thinking...Just do it....
 
70aarcuda said:
What is the purpose of sub frame connectors?...to tie the sub frames together...Does it matter if the sub frame connectors are off a few degrees or not level...will the sub frames still be tied together...???



Too much thinking...Just do it....
Click to expand...

I meant the car. Yes if it's not level and the doors aren't opening and closing properly at that point would you weld them in, or make the adjustments and then weld them in?
 
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