Section : Chassis

Main rail repairs 

Posted By : Simon Belt, 18-Jan-2005, 12:47pm

Right then, as many heralds before it mine has rust issues around the diff area on the main chassis rails. The result of being jacked up several hundred times no doubt over its life time without too much care being taken. These sections, particularly the bottom of the rails have been patched and repaired before at various stages in the past and now look somewhat rusty again. My question is does anyone make repair sections for the main rails or is it a case of making them myself?

I do not have the luxury of a garage or even a drive way so a chassis change is out of the question for a few years yet. I had considered cutting up another chassis and using the relatively small sections I need as repair panels but that seems a bit of a waste. I could probably make the bits myself but the shape is never going to match exactly.

Any help to save an old friend much appreciated.

• Main rail repairs 

  Posted By : Chris Taylor, 18-Jan-2005, 02:39pm

  Not sure if he still does, but Chic Doig used to sell sections of the main rails around the diff. BUT I would not like to try and use such a section except on a bare chassis, properly supported and able to check measurements frequently.
  However, and it is difficult to pass comment without seeing the actual damage, if the damage does not extend too far up the rails, a repair in situ is quite feasible. The trick is NOT to cut too much metal out at any one time.
  From preference, the outer vertical face should be replaced first, then the inner vertical, and finally the floor of the box. If the damage does not go too far up the main rail, then it is possible to replace the lower outer face and floor in one folded piece, but of course while that metal is cut out, the only beam strength left in the main rail is that provided by the inner face etc.
  Of course you need to be confident that you have achieved good quality welds, and pay special attention to the corner attaching to the rear crossmember and boot outrigger. Ideally you should replicate the inner strengthening for the diff mounts, but with 1147cc power that should not make a huge difference. (The internal diaphragms in the main rail probably ceased to have much strength some years ago..............).
  I replaced the floor of the main rails some years ago, and advise this caution if using gas welding: I welded the repair section in one go, so as a result the floor of the box got quite warm before welding was complete. As the metal cooled, it contracted and the end result was the rear of the chassis warped down a bit. (Fortunately I did the same on both rails so at the end there was no twist!) The end result was I needed aboout half an inch packing under the rearmost body mountings, but it would have been much better to take the job slower and/or tack it at both ends etc first.
  When the job is finished you should drill drain holes at the lowest point, and if possible, seal off the ends of the boot outriggers. That should reduce the chances of water getting in, and allow out any water that does collect at the lowest point.
  Good luck!

  • Main rail repairs 

    Posted By : Alistair Banks, 18-Jan-2005, 05:52pm

    If possible take the car apart and bring the chassis to me and I will repair it for very reasonable cost.
    Chassis are what I do best
    Alistair
    
    South Yorkshire TSSC

  • Main rail repairs 

    Posted By : Nick Bracey, 20-Jan-2005, 10:48am

    excellent advise from Chris IMO - just one addition.
    
    waxoyl or similar the inside of the chassis after fixing!
    
    

    • Main rail repairs 

      Posted By : Simon Belt, 20-Jan-2005, 08:56pm

      
      Thanks guys, I was expecting doom and gloom answers but its all been quite encouraging! Time to break out the welder me thinks. Well when it stops raining maybe!
      
      Cheers