Replace a Front Frame Rail - How Much Trouble?

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KCBones

KCBones

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Hi,
I've posted recently about some rust damage in the driver's side front frame rail of my 1968 Dart GT. I've been going back and forth about trying to repair the frame rail or replace it. Now I'm back to considering just replacing it but I've never done anything that invasive on a unibody car. I've posted two pictures, one showing a nice clean A-body driver's frame rail and one showing my wasted, rusted out frame rail. That hole is where I put a red circle on the clean rail. The damage goes right up to where the k-frame mounts to the rail so it's a difficult place to patch to say the least. I think it's a pretty poor design because the frame rail sort of forms a pool right below the upper shock mount so that dirt, leaves, and water can sit there and rust out the top of the rail. Mine obviously rusted the top of the rail and then finally rusted through the side and bottom of the rail. In the process of rotting out, the rust also took out the lower control arm bumper bracket, there's nothing left of that but rusty scraps.

The question is, based on this picture, should I consider trying to patch that area or bite the bullet and figure out how to replace the whole rail. One of the guys on this forum is a few hours from where I live and has a Barracuda shell with a good frame rail with the shock tower that he offered to sell me. My HOA would **** if I started cutting it up in my yard so I've found a place I can take the shell and remove the good rail. I'm just wondering if I'll be able to get the rotten one out of my car and put the good one back in place so that everything lines up so that I can move forward with my project. I was wondering if I could make some sort of jig to line up the tops of the shock towers before I remove the old one that I could use to help line up the new one. I think the K-frame will also be helpful to line things back up before final welding. I value any thoughts, opinions, and advice from some of you A-body experts. Just for reference, I've also uploaded a picture of the car. It's not great but it's not a piece of crap either, very worth fixing in my opinion.
I know I can't say it enough, this is a great place for people wanting to get their old Mopar A-bodies back on the road, thanks in advance for any input you might have.
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@67Dart440GT is a professional paint and body man. He can tell you exactly what it takes. I tagged him so maybe he'll chime in.
 
@Lee Robinson

This man breaks cars for fun (Living?) and can probably tell you first hand what it takes to replace than member. These cars dont have any sheet metal thicker than frame rails and they are pretty thin themselves, the strength is in the forming of the channels. If you can remove the spot welds, the whole thing will come right off and then you can weld on the new one right over the old spot weld scars. That rust in that place looks structural so a cap wont fit nor work in my opinion. When welding it back up make sure the car is level on multiple jack stands to preserve the dimensions, ie. no crooked unibody after your done.
 
The inner fenderwells are under tension. When I cut the last spot weld the thing went BANG and popped 1/4 inch off the rail. Not sure if that is from the placement of the jack stands or what but it was a loud surprise.
 
Rule #1: The damage is going to be worse than you think.
By the time you cut that back far enough to get to solid metal to work with, you'll basically be putting in a new frame rail anyway.
Get a copy of the body/frame section of the FSM, so you will have all the dimensions for squaring up the new section- a car that has been gradually rusting out has also settled over the years and likely will not be square any more.
2.) Be prepared to replace more panels than you thought. An adjoining panel may seem solid, but the lap seams have rusted along with the rail, leaving you no way to reattach the panel. See rule #1.
It's not for the faint of heart, but don't be intimidated- and be honest about your own abilities. It's just a large jigsaw puzzle that gets welded up when you're done.
Take it for what it's worth- from a poor Wisconsin rust belt guy who has seen WAY too much of this ...
 
I may be off base, but my thought was to level the car as level as I could get it using some leveling screws like shown in the picture (used for scaffolding), maybe with a steel tubing framework that would let me get the car level but leave space to remove the rail. I also thought I'd make some sort of locating jig that would allow me to get the new shock tower back in the same place as the original one. I expect that the front sheet metal will have to come off, the engine will have to come out, the complete front suspension will have to come out and the K-frame will have to be removed. The driver's side inner fender will also have to be removed. This all came about because I wanted to rebuild the front suspension.

Removing and replacing a frame rail was not on the agenda and actually it's very intimidating to me. I planned on learning a lot with this project but didn't really plan on going that deep into it. On the bright side, I intended to remove the front suspension anyway so I could rebuild it and make it look nice. This will also give me a chance to blast the K-frame and repaint it as well as make a minor repair to the driver side inner fender. An engine refresh would probably also be smart at this point.

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K-frame and engine out the bottom, spot welds at the radiator support; bay side of the frame rail and shock tower, lower firewall splash, floor pan(if not rotted our already) and finally at the trans cross member. Disassembly is probably more work than the actual frame removal. You will have to backfill the cut out spot welds to do it correctly. Essentially removing the long side of a large rectangle.
 
If that side is rusted tha bad the other side s interior will be bad also. It is easier to replace the complete unitized front. It one time before my son took over the shop to do Engines we would replace the complete front in a week end. The easiest and the best way to do the job. When we were done you could not tell any welding was done on cars. There is a trick to doing them. And if they need a torsion bar cross member That is done separate from the font clip for a reason.

Nothing worse then Having a rail installed on a car and then having the other side done later. The hard part is finding fronts which I have here. The last one we did was mikes 72 Duster. drive it in on friday drive it out on monday. $800 labor. $400 for the front. No paint work. Just put one on for state inspection.

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Oldmanmopar,
If you were in Florida, I'd be on the phone to you right now. To the best of my knowledge, the torsion bar cross member is solid and actually, the passenger side frame rail seems solid as well, I poked around on it with a screw driver after I saw the driver's side. I'd prefer to do the whole front clip for sure but I don't have the greatest work space and definitely don't have access to a lift. If I found a complete front clip with nice inner fenders and a K-member, I'd probably consider going that route.
 
I used the k member as a guide, and welded a piece of 2x2 box tubing to the torsion bar x-member where the frame connects, the rails slide over the tube and makes it easier to play with not a super bad project. I got my rails from Lee Robinson. Good luck!
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Oldmanmopar said:
If that side is rusted tha bad the other side s interior will be bad also. It is easier to replace the complete unitized front. It one time before my son took over the shop to do Engines we would replace the complete front in a week end. The easiest and the best way to do the job. When we were done you could not tell any welding was done on cars. There is a trick to doing them. And if they need a torsion bar cross member That is done separate from the font clip for a reason.

Nothing worse then Having a rail installed on a car and then having the other side done later. The hard part is finding fronts which I have here. The last one we did was mikes 72 Duster. drive it in on friday drive it out on monday. $800 labor. $400 for the front. No paint work. Just put one on for state inspection.

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Wow! For those prices I had to double check to make sure this wasn't an old thread. Lol. :thumbsup:
If I were KCBones I'd be planning a little vacation to Pennsylvania.
 
KCBones said:
Oldmanmopar,
If you were in Florida, I'd be on the phone to you right now. To the best of my knowledge, the torsion bar cross member is solid and actually, the passenger side frame rail seems solid as well, I poked around on it with a screw driver after I saw the driver's side. I'd prefer to do the whole front clip for sure but I don't have the greatest work space and definitely don't have access to a lift. If I found a complete front clip with nice inner fenders and a K-member, I'd probably consider going that route.
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Road trip Brother........No bullshit involved. Get R' done!
 
I'd recommend getting them from Lee too... he shipped from Cali to NY for me to pick up from Ontario.

Was my first and only time replacing the front frame rails. Wasn't a horrible job getting them in and lined up right. It took me awhile as I didn't have a lift but I did a complete suspension rebuild along with engine and driveline swap.
 
CFD244 said:
Road trip Brother........No bullshit involved. Get R' done!
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Yeah, sometimes easier said than done. I have a pretty full plate at the moment and diesel fuel is pushing $6 per gallon where I'm at. That'll add nearly $1000. Still, everything is on the table right now. I just want to move forward with my car.

Edit - That all being said, I've always wanted to visit Pennsylvania. Another of my hobbies is flintlock longrifles and Lancaster was pretty much ground zero for that whole thing back in the 18th century.
 
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KCBones said:
Yeah, sometimes easier said than done. I have a pretty full plate at the moment and diesel fuel is pushing $6 per gallon where I'm at. That'll add nearly $1000. Still, everything is on the table right now. I just want to move forward with my car.

Edit - That all being said, I've always wanted to visit Pennsylvania. Another of my hobbies is flintlock longrifles and Lancaster was pretty much ground zero for that whole thing back in the 18th century.
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I did a front clip on my Demon as I restore this car. After everything was said and done, if someone offered to do it for a couple of grand...parts included I would jump at it. Unless of course you want the satisfaction of doing it yourself. Well, that's a different ball game.:)

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I'm a complete amateur, but I was able to replace a torsion bar crossmember, a section of a front rail, firewall, cowl, uca mounts, with zero experience or brains.

Took detailed measurements, making sure everything was square and straight to start.
Welded in a few pieces of square tubing to keep it all honest.
Started cutting away to see where the rust really ended.
Measured again before/during welding it all back together.

When I sectioned in a piece of frame, I drilled holes in both ends, spot welded plates in the rail, slid them together, spot and seam welded it all up.
I would bet it's stronger now than ever.
But, once again, I'm an amateur.
 
RustyRatRod said:
@67Dart440GT is a professional paint and body man. He can tell you exactly what it takes. I tagged him so maybe he'll chime in.
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You really need to consider some bracing or clamping before you start. You also need to establish a measuring point under the car called a datum plane. This is a point that you can measure height from. Lots of measuring before you start. This is how I do it at home.

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67Dart440GT said:
You really need to consider some bracing or clamping before you start. You also need to establish a measuring point under the car called a datum plane. This is a point that you can measure height from. Lots of measuring before you start. This is how I do it at home.

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Invasion of the caulk filled frame rail. lol
 
To add to my previous post, I take two pieces of 2x2 from door side rear wheel to door side of front wheel and tack them to the rockers, then two more under those perpendicular, then level everything out once its all square.
 
Thanks to everyone for all the input, it's greatly appreciated. All the pictures are very helpful too.

67Dart440GT , Thanks for the tips on the rear frame rails. I'm hoping I don't have to do that but if I do, I can see what's involved. I also hadn't seen a body cart like you use and looked that up. Now I'm wondering if I should try to get one like it, I do have another car to do, non-Mopar, but it'll need tons of work too.
 
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