Stopping distortion on car sills.

[steve202]

Hello there. Long time no post.

Any tips on fitting long sills. Limo jobs. How to stop them possibly distorting?

Done regular sills before but nothing as long as this hence the somewhat daunting apprehension.

I will take a guess at tacking the ends and working inwards with tacks at every foot or so then making the tacks longer to say a couple of inches?

Do the joins have to be completely welded or can i use stitch welding?

cheers!

 

[Highway_Star]

Try searching around the forum, you'll find the answers you seek have been covered to death in previous posts.

Maybe it's time someone wrote the 'replacing car sills 101' article! (No I'm not volunteering)

 

[malcolm]

Like this one?

I don't think the length of the sill should make much difference apart from to the bracing. Just a little twist on a long vehicle will put the alignment out more than the same on a short vehicle, so I'd be inclined to go for at least a straight brace along the bottom of the doors and a diagonal one.

 

[runnach]

Them huge Limo sills are murder to keep straight!!!

 

[steve202]

I dont think braces are necessary or even feasable on something as long as a limo what with all the extra strength the extended chassis gives. Surely the outer sills are just cosmetic?

So just clamp the bugger in place and short welds one end then the other to keep the heat down then?

 

[malcolm]

Good point - sills aren't structural on those things. I'd go with a whole load of tacks first to hold everything in place, then keep the heat down with short welds darting about from one end of the sill to the other to let the welds cool properly. That sounds like a good plan to me.

 

[steve202]

cheers Malc!

 

[Highway_Star]

Does it really sit on a separate chassis?

If not, then the sills are most definitely structural.

Even on some chassis'd vehicles (Range Rover/Discovery springs to mind), the sills are very much structural, you can think of them as a monocoque sat on a chassis.

 

[malcolm]

It's a point - they will still close up the door gaps even if they aren't structural. Can we compromise with a bar across the bottom of the door gap to maintain the shape?

 

[bd500]

Hi. Body sills are structural. And you start in the middle and work out each way to the back and the front. Just tack it on first and check your gaps on the doors all the time you are welding

 

[malcolm]

Not if it has a separate chassis.

Thinking about it there are a lot of cars with weak separate chassis that rely on the sills for further stiffness. It was common in the 50s during the move from chassis to monocoques and called unitary construction. For a long thing like that it wouldn't be surprising if the sills are intended to add further stiffness.

 

[michael1703]

i would clamp the bottom edge together all the way along (do you have enough clamps? )

and then aim to get an even gap between the door bottoms and the sill and then worry about attacthing it last

with a limo, you can have a lot of movement over the full length

a couple of screw and scissor jacks with a block of wood on top for alignment will be a big help

 

[Justme]

Sills can also be structural if the seat belt mounts, steering, suspension or brakes are within 30cm's of it.