Straightening sub frame rails

[OldZeuski]

While attempting to prep for sub frame connectors I realized that my sub frame rails are worse than I realized. Putting a straight edge on them shows nearly 1/2" on the drivers side and 1/4" on the passenger side of gap right where the trans cross member is located. I was told the previous owner used a fork lift to move the car and I think this severely bent the already rough frame rails. Believe it or not the car drives straight, but my trans/pinion angle is clearly affected by this bend.

I am going to contact a body shop in the area to see what they might quote to pull this, but I was wondering if anyone has had any luck fixing this them selves or what they paid to get it done professionally.

I have a lift, and a welder. I am not sure I would be able to apply the kind of force necessary to pull them down though, at least not without bending something else.

 

[ttocs]

the only way I have seen anyone DIY fix something similar, they chained part of the frame to a really strong tree and threw it in reverse a few times till it was eyeball straight. This was for a junker of a car that he didn't care about and I can't say I would recommend doing it to one you like. Half of the work would be removing any body panels that might need to come off. If you talk to them and offer to deliver it with the panels off it might save a few bucks. I did this on mine, can't remember what I paid but delivering it with everything removed saved him a ton of time and me money but mine was straight on front end/heater core damage.

 

[OldZeuski]

Here are some photos with a level. The passenger side is not nearly as bad. Two photos of the drivers side show the gap. It’s 1/2” at some spots.

it’s the drivers side that has me concerned because it appears the actual cross member mount has risen.

 

[cobrajeff96]

A lot of this can be attributed to "the 90s". A lot of Fox/SN95 cars have this. Mine has it, and some of it comes from shoddy lifts at car shops that don't use rubber isolators on their lift arm pads. Usually it's the pinch welds beneath the side skirts that get bashed a lot but you also see plenty of surface level frame rail damage too.

If the car tracks straight after an alignment, it's probably just surface level damage. If what you see gives you a tough time installing SFCs, that's just life I guess. Whoever welds it will just have to put in more weld bead to get them to stick. And trust me there's more mass in the frame than what you might think - whoever welds it might have to put propane on the frame and the SFCs to preheat them. And no matter what, make sure all seats and carpet are fully removed from the car before anything.

 

[OldZeuski]

A lot of this can be attributed to "the 90s". A lot of Fox/SN95 cars have this. Mine has it, and some of it comes from shoddy lifts at car shops that don't use rubber isolators on their lift arm pads. Usually it's the pinch welds beneath the side skirts that get bashed a lot but you also see plenty of surface level frame rail damage too.

If the car tracks straight after an alignment, it's probably just surface level damage. If what you see gives you a tough time installing SFCs, that's just life I guess. Whoever welds it will just have to put in more weld bead to get them to stick. And trust me there's more mass in the frame than what you might think - whoever welds it might have to put propane on the frame and the SFCs to preheat them. And no matter what, make sure all seats and carpet are fully removed from the car before anything.

I'm able to work around the fitment issue but as it sits now the cross member (at least on the drivers side) has been shifted up because of the bend in the sub frame rail. I would like to correct this at least a little before I weld the SFC in, permanently locking things in place.

Otherwise I'm going to need to fab up a new cross member bracket and weld it below the existing one to compensate, and that seems like a lot more of a challenge than just pulling this bend out a little.

 

[cobrajeff96]

Is that separation I see within the floor pan? Or...
It's kinda difficult to tell with those pics and the lighting.

Rather than do all that fab work, you might instead try to determine the possibility of the cross-member mounting ears being reworked. Like I said, as long as the car holds an alignment and drives straight and correctly, it's much better to take the easy way out. If that mounting ear has enough 'meat' on it, you can drill a new hole in the case of a bad misalignment. In the case of only a slight misalignment, you can fill up that hole with weld, flatten it out with the flat side of an angle grinder or even a pneumatic burr, re-drill, paint, etc. etc.

The time and work and money involved with trying to attack the frame rail might still have you trying to readjust that crossmember mount all the same.

 

[ttocs]

are they welded in or bolted? I don't see the welds if they are welded.

 

[OldZeuski]

are they welded in or bolted? I don't see the welds if they are welded.

I’m not sure what you’re talking about. The stock rails are welded in place.

 

[OldZeuski]

Is that separation I see within the floor pan? Or...
It's kinda difficult to tell with those pics and the lighting.

Rather than do all that fab work, you might instead try to determine the possibility of the cross-member mounting ears being reworked. Like I said, as long as the car holds an alignment and drives straight and correctly, it's much better to take the easy way out. If that mounting ear has enough 'meat' on it, you can drill a new hole in the case of a bad misalignment. In the case of only a slight misalignment, you can fill up that hole with weld, flatten it out with the flat side of an angle grinder or even a pneumatic burr, re-drill, paint, etc. etc.

The time and work and money involved with trying to attack the frame rail might still have you trying to readjust that crossmember mount all the same.

If you're talking about the gap above the sub frame rail between the floor pan, I believe that is part of the design. I've seen it on other SN's but I could be wrong. You can see in the foreground the pinch welds which are pretty banged up as well. If you're seeing something else though let me know, I may be totally missing something.

I think you're right about focusing on the cross member ears. The car was aligned and drives straight as is, so I might just weld these sub frames in and lock everything in place so it doesn't get any worse.

 

[cobrajeff96]

Yea, right on. You always want to first do a mockup of the new SFCs. Are they just main rails and nothing more? Or are they a full matrix system with jacking rails and cross braces? Either case, have a friend or two hold them up into place and see how bad any gaps are. You can always make note of this and buy some cheap shim stock and weld those in first to fill in the gaps because trust me trying to build up filler material with only weld bead is going to look ugly and put a lot of heat into the chassis, maybe a lot more than is necessary. You will likely want to pre-heat the intended weld spots outright (something I should've done on mine looking back). And take it from me: as soon as everything cools down, spray it under over and everywhere between to keep the rust at bay.

 

[OldZeuski]

Yea, right on. You always want to first do a mockup of the new SFCs. Are they just main rails and nothing more? Or are they a full matrix system with jacking rails and cross braces? Either case, have a friend or two hold them up into place and see how bad any gaps are. You can always make note of this and buy some cheap shim stock and weld those in first to fill in the gaps because trust me trying to build up filler material with only weld bead is going to look ugly and put a lot of heat into the chassis, maybe a lot more than is necessary. You will likely want to pre-heat the intended weld spots outright (something I should've done on mine looking back). And take it from me: as soon as everything cools down, spray it under over and everywhere between to keep the rust at bay.

Just main rails all the way to the rear torque boxes. I’ll keep the pre heating in mind.

 

[ttocs]

oh crap I see now you were saying you were prepping for subframe and I thought that you were showing the subframe connectors.

Factory frame rails hell short of pounding with a hammer I am not sure what could be done. Have you tried holding the connectors up to the floor to see if they have space? Hopefully they only dented the frame rails and didn't mess up the floor. If the floor is flat enough to put the connectors on I would not sweat it.