Re: sub-framing

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Posted ByJacin on March 03, 2002 at 09:15:43:

In Reply to: sub-framing posted bylenny on February 26, 2002 at 11:32:10:

: planing on doing a 49'chevy pick-up,with a camaro sub,any body got any plans on it,as i have never done one,thanks

I've done this to my 1937 Chevy Truck and it works GREAT!
1. Determine ride height of subframe on origional vehicle.
2. Determine desired ride height and rake of truck (by placing on 4 jack stands)
3. Set in place - marking floor for wheel base and centerlines may be helpful as well.
4. On my truck the core support located all the front sheet metal so I needed to make a fixture to locate this point that could be used later - I used light wall tubing - but as long as it's sturdy you could use almost anything as long as it's stiff enough. Set aside - don't damage it!!
5. Determine the point of "grafting" on truck and subframe cut perpendicular to floor. Carpenter's square is good for this. Remember subframe should be set at ride height/rake already. Cut the frames so that you have taken an extra 1/4 out. This will make more sense later.
6. Roll subframe up to truck frame. The frames should now butt up to one another, but will likely be "off" in other alignments, that's OK. Double check for square by measureing diagonals.
Note that if you haev chosen a serious rake the frames will not be flat to one another - that's OK!
7. Once you are sure it is positioned correctly look over the point of intersection and note the overall shape of the two boxes (truck and subframe) you will now cut that shape out of 1/4" mild steel plate and place in between the two frames. This will allow you to fully weld each section to the other. I suggest further guesseting that will overlap preventing this from being a total "butt" joint. Keep in ming this area is one of the most stressed areas of a chassis and as such must be reinforced accordingly.
8. Locate and install your core support fixture. Build up a cross member to mimick the old surface for the core support to rest on.
9. Graft in your steering and whalah. Modern conviences at last!

By doing this method you will ensure the factory geometry is obtainable - specifically caster. I did mine and have yet to need an alignment.
If you have any doubt to you welding skills - seek professional help.
If you have any doubt to your chassis joint reinforcement - seek professional help.
If you have any doubt to your ability to measure accurately - seek professional help.
If you have any doubt about your professional - seek other opinions.
Make it safe make it fun!

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