Bad frame rail

[ScoopMan]

With the weather finally warming up, I was in the process of disconnecting components so I could remove the head on the 1971 Spider I picked up late last October. The compression was on the low side and I know I have a blown head gasket at the minimum, but I wanted to see if I might get 'lucky' and get the engine in a decent running state without pulling it for a total rebuild. I was hoping to just get away with a basic head job and bolt it back together with new gaskets. I did not get that far in my evaluation because of what I found next....

To my dismay I discovered that the passenger side frame rail is massively cracked and corroded on both sides of the crossmember. I somehow completely missed this when I bought the car, doing a driveway inspection on a chilly October evening in fading daylight. I am still kicking myself. However, considering the engine needs work, the engine mounts need replacing and I am sure to need to do front end work anyway, I might as well pull the engine out and take care of this. I found that VAS sells replacement frame rail sections, so it cannot be TOO uncommon an occurance.

Has anyone here done this job or had it done? I was OK with doing the mechanical work myself, but as far as the frame cutting and welding I would not attempt it myself. At the moment it seems kind of daunting. How specialized is this kind of work? I am not so sure the average body shop is set up to do this kind of work. If the measuring is not spot on the car will be screwed ever after. Help....

[kmoses]

I've repaired mine, one side was cracked and broken on the bottom around both bolts. Ended up cutting and modifying both sides just to keep everything balanced strength wise. Making reference marks and taking good measurements is a must. I found that the swaybar studs were the same distance to the crossmember mounting bolts on each side of the car. You need to be very handy with a Mig or Tig welder and have good metal fabrication skills (cutting, drilling, grinding) or know someone who is. There are some links to photos showing what is inside the rails and how others went about their repair (search for frame rail repair). I decided to repair my rails so that bolts would go through the rail from top to bottom with steel tubes between the two surfaces.



I with the tubes inserted, the top was welded first.

Then bolts were inserted, everything was tightened and the bottom welded.

Removed bolts and grind flat and level.

Then a plate was added to the top, bolts inserted, tightened and welded.

While I was in there, I decided to paint the engine bay. This is how the repair looks when finished.

[djape1977]

big job if you want it done right.
i've done it on a customer's car.
new frame rails are available, i have a few left

[ScoopMan]

I've repaired mine, one side was cracked and broken on the bottom around both bolts. Ended up cutting and modifying both sides just to keep everything balanced strength wise. Making reference marks and taking good measurements is a must. I found that the swaybar studs were the same distance to the crossmember mounting bolts on each side of the car. You need to be very handy with a Mig or Tig welder and have good metal fabrication skills (cutting, drilling, grinding) or know someone who is. There are some links to photos showing what is inside the rails and how others went about their repair (search for fraim rail repair). I have some on my home computer that I will post tonight.

Cool. I have done welding but that was over 30 years ago when I welded in a new floor into my Alfa Romeo. Fun times. I would still probably not attempt it myself. I would be willing to yank the motor out myself but leave it a roller that can be towed or flatbedded over to someone who can do the rest. Probably flatbedded as towing might end up pulling the car in two.

Problem is there is still a lot of work to do unless the guy can just unbolt the crossmember and leave it dangling by wire. I need to check what the crossmember looks like, for all I know it is part of the problem. I was surprised that it had cracked in two places.

[djape1977]

usually the crossmember cracks because of rotten chasis legs. once the chasis leg can't take the loads it's meant to, forces transfer to crosmember and other chasis leg

[ScoopMan]

I think the curving shape of the crossmember puts some lateral thrust into the rails, which probably does not help. I am a structural engineer so I am on top of this! There is so much crud on the piece I really need to clean it to see what kind of shape it is in.

[kmoses]

The repair insert used 1/8" x1"x1" angle, 1/8" flat stock and 7/8" round stock. The bolts are Spider head bolts.

[ScoopMan]

You did a beautiful job kmoses. It looks like show car quality to me.

I guess I will pull the engine and clean up the area. The sides of the box section are fully cracked vertically on either side of the crossmember, and the bottom of the box is rotted out between the crossmember and the sway bar attachment. I will need to make a judgement on whether to weld in new pieces as you have done, or completely replace the section from the firewall forward, which is what the replacement piece would seem to require.