Rear frame rail replacement

[standupjskiguy]

This is my wife's 85 T-Type. It has 143,000 miles and is unmolested. We've kept it in good repair over the years, I even replaced the doors due to rust. Most of the car is very solid. We had a hitch on it as we used the car to tow our small boat to the launch ramp at out cottage. I think that hitch caused the rear frame areas to rust faster for some reason. The mounts for the body bushings were also rusted away.
Back in 2005, I got the idea to just replace the frame rails behind the axle housing instead of trying to replace the whole car onto another frame. I ordered some rust free frame rails from an Arizona junk yard but I never got around to this project. The problem with this approach is that if you cut off the frame rails with a Sawsall, the saw cuts won't match each other and if you try and weld that together, you will have gaps. Sure you can overlay steel and patch it but I have at my disposal a duplicating machine. My former job was to run this machine for years machining molds for plastic injection. But now that is mostly done by CNC machines. I had my own home based business so I have the machines just sitting around. My idea was to use the old frame rail as a pattern to duplicate the saw cut shape from the old to the new allowing it to match to the frame and be straight once welded with minimum gaps to fill with weld. Also I could control the length more precisely. I took a different job when my business died out and after seven years, I was laid off that job. I finally had the time to tackle this project.
The series of pics that are attached show the car and how it's condition is very good. Next there are pictures of the rusty frame rails. Then the frame rails I got from Arizonia. Condition of the sheet metal behind the frame rails was like with the holes in the areas of the bushings and the frame with the rusty rails cut off. Then there are pictures of the old and new rails on the duplicating machine being cut to match. I made some sheet metal "cups" to weld over the sheet metal to form a base for the body bushings. Then you see the duplicated frame section in position ready to be welded. Then there is my not so perfect weld.
We then go over to the other side of the car and see that same thing over there. I should mention, while the frame rails were off, I used both Rust Bullet and Por-15 after wire brushing the heck out of the sheet metal. I don't know how well this stuff does with rust but we don't drive this car in wet weather anymore anyway. You finally see the frame sections painted with Por-15 and the gas tank back on etc. Yes I pulled the tank, I didn't like the idea of welding near a tank of gas. By the way the last photo is one of the metal fuel lines between the tank outlet and main lines going to the engine. The high pressure line started leaking as I removed it. As you can see rust had eaten all the way through. Check you cars lines back there and look for rust
around the lines where all three go through a rubber block.

 

[standupjskiguy]

continuing with the photos

 

[standupjskiguy]

the last few pictures and one of the fuel line rusted through.

 

[RUDE DOG]

Looks like youve got everything under control.

 

[BIGPSI]

looks good! when sectioning frame rails,especially full frame i like to always beveled the edges on both pieces, it gets a little better penetration when welding. and if you are really worried about strength, you can make sleeves to put inside frame rail. just my 2 cents. i have been doing body and frame repair for 20 yrs.

 

[standupjskiguy]

You have the advantage of 20 years experience doing this type of work. I'm just a hobbyist.
I considered chamfering the edges but the metal is only 1/8 thick. Me and my wire welder are not of the highest quality. When I tried some
welding on 1/16 metal, it was too easy to burn through so I decided not to chamfer the edges.
On the 1/16 metal I experimented with, I was able to bend the metal all the way over without breaking the weld so I thought this would be
strong enough. In researching welds, they say the weld develops cracks from having too large of gaps in the joint. This is where I got the idea
to use my old machining equipment to minimize the gaps. I also welded around a little at a time going from one side to the other to
help control stress.

 

[BIGPSI]

You have the advantage of 20 years experience doing this type of work. I'm just a hobbyist.
I considered chamfering the edges but the metal is only 1/8 thick. Me and my wire welder are not of the highest quality. When I tried some
welding on 1/16 metal, it was too easy to burn through so I decided not to chamfer the edges.
On the 1/16 metal I experimented with, I was able to bend the metal all the way over without breaking the weld so I thought this would be
strong enough. In researching welds, they say the weld develops cracks from having too large of gaps in the joint. This is where I got the idea
to use my old machining equipment to minimize the gaps. I also welded around a little at a time going from one side to the other to
help control stress.

i understand,wasn't trying to dog it,just offering some advice. by the way your cuts and joints looked great, couldn't get that with just a tape measure. that machine works great!