Replacing 911 sills and Jacking Points
Posted: Mon Dec 21, 2009 8:22 pm
As a result of a couple of recent threads, I thought it may be of interest to list how I go about changing the sills on these cars, and the various extra jobs that often seem to arise as a result.
On the whole, the pictures come from one car (done a year or so ago), although I may dip into one or two other albums as the guide pans out, depending on what I'd like to show.
So, first of all, do your sills need attention? These are typical early signs that you need to look for:
a) Is the front of the kidney bowl soft or holed when examined from inside the rear wing?
b) Is the base of the B-post where is joins the outer sill 'blown' or bulging?
c) Are there pin holes on either the outer sill, or on the bottom of the middle sill (the panel that takes the base of the outer sill)?
d) Is there movement on the jacking socket (this would be bad)?
In addition, if the car feels very 'soft in the shell', with excessive creaking and general body movement, this could also point to weakness in the sill area.
Typical holing to be found after paint and filler removal:
Further investigation often reveals something like this:
Often you actually reveal something much worse:
At this point, you know that you are in for fairly heavy repairs, and the decision needs to be taken as to whether the use of a jig is appropriate, or whether careful supporting of the car is going to suffice.
Here's something I put on a recent thread regarding jigs, and the supporting of cars:
As for supporting the car, well a jig is always going to be best of course, but franky not everyone has access to one, and we are blessed that 'our' cars ar so adjustable in the wheel-alignment department. My personal feeling is that if it's your own car, and you know that the suspension alignment is good (worth getting it checked before you start work?), the gaps are good, and you are happy with the way that it drives (suspension-wise), then if you do all of the work and end up with it just as it was, then why not?
On the other hand, if you've always found that it's worn tyres out, and the suspension can't be aligned because all of the adjustments have been used, the gaps are all over the place, and it keeps breaking windscreens, then it's time for the jig.
If I'm going to do any structural repairs to any car without using a jig, then this is the way that I support it.
1) With the car on the ground, open and close each door and make a note (or mark) of exactly how it is mating up to the rear wing, and how each door latches. If appropriate, adjust latches to give the best possible door latching (e.g. a nice sound, and no graunching!).
2) Jack the car at the rear, and support it underneath the rear torsion bar end covers using conventional axle stands.
3) Jack the front of the car at the centre, using wood or a jack pad to spread the wieght if required.
4) Then , using either conventional (pinned) axle stands with thin shims (ply, sheet steel, whatever), or better, threaded axle stands (often used for siting mobile homes), set exactly the same gaps left to right. Drop the car down.
5) At the rear of the car (and especially if the engine's still in), put a screw type axle stand, or scissor jack, under the engine and gently take some weight there. Adjust this until the doors open and close exactly as they did before.
I often then use some extra threaded stands around the area that I will be working in as well, just to be sure. I also never use hydraulic jacks for support under the engine, as over a period of weeks (which these things often turn into), you find the jack sinks down a bit. If by then you've removed, say, the rear wings and the sills, you've then lost your reference as to where the rear of the car was jacked to.
These days of course, everything is done on the Celette, but before that came along I was most concerned not to build in the vagaries of by concrete floor into the shell by just dumping the car straight down onto pinned axle stands, cutting all of the strength of the thing out, and then welding it to the shape of my workshop."
I've used this method not just for 911's, but probably thirty or forty or so other big restorations that I've done over the last twenty years ( can't believe it ). I've always been absolutely paranoid about distortion, but the above method has been very reliable for me.
Finally, a jig would be best, but if you can't run to one, and the shell appears fine in tests as above, then simply support the shell very, very well in a way that at least preserves what you have got, without causing new problems. '
More to follow ....
On the whole, the pictures come from one car (done a year or so ago), although I may dip into one or two other albums as the guide pans out, depending on what I'd like to show.
So, first of all, do your sills need attention? These are typical early signs that you need to look for:
a) Is the front of the kidney bowl soft or holed when examined from inside the rear wing?
b) Is the base of the B-post where is joins the outer sill 'blown' or bulging?
c) Are there pin holes on either the outer sill, or on the bottom of the middle sill (the panel that takes the base of the outer sill)?
d) Is there movement on the jacking socket (this would be bad)?
In addition, if the car feels very 'soft in the shell', with excessive creaking and general body movement, this could also point to weakness in the sill area.
Typical holing to be found after paint and filler removal:
Further investigation often reveals something like this:
Often you actually reveal something much worse:
At this point, you know that you are in for fairly heavy repairs, and the decision needs to be taken as to whether the use of a jig is appropriate, or whether careful supporting of the car is going to suffice.
Here's something I put on a recent thread regarding jigs, and the supporting of cars:
As for supporting the car, well a jig is always going to be best of course, but franky not everyone has access to one, and we are blessed that 'our' cars ar so adjustable in the wheel-alignment department. My personal feeling is that if it's your own car, and you know that the suspension alignment is good (worth getting it checked before you start work?), the gaps are good, and you are happy with the way that it drives (suspension-wise), then if you do all of the work and end up with it just as it was, then why not?
On the other hand, if you've always found that it's worn tyres out, and the suspension can't be aligned because all of the adjustments have been used, the gaps are all over the place, and it keeps breaking windscreens, then it's time for the jig.
If I'm going to do any structural repairs to any car without using a jig, then this is the way that I support it.
1) With the car on the ground, open and close each door and make a note (or mark) of exactly how it is mating up to the rear wing, and how each door latches. If appropriate, adjust latches to give the best possible door latching (e.g. a nice sound, and no graunching!).
2) Jack the car at the rear, and support it underneath the rear torsion bar end covers using conventional axle stands.
3) Jack the front of the car at the centre, using wood or a jack pad to spread the wieght if required.
4) Then , using either conventional (pinned) axle stands with thin shims (ply, sheet steel, whatever), or better, threaded axle stands (often used for siting mobile homes), set exactly the same gaps left to right. Drop the car down.
5) At the rear of the car (and especially if the engine's still in), put a screw type axle stand, or scissor jack, under the engine and gently take some weight there. Adjust this until the doors open and close exactly as they did before.
I often then use some extra threaded stands around the area that I will be working in as well, just to be sure. I also never use hydraulic jacks for support under the engine, as over a period of weeks (which these things often turn into), you find the jack sinks down a bit. If by then you've removed, say, the rear wings and the sills, you've then lost your reference as to where the rear of the car was jacked to.
These days of course, everything is done on the Celette, but before that came along I was most concerned not to build in the vagaries of by concrete floor into the shell by just dumping the car straight down onto pinned axle stands, cutting all of the strength of the thing out, and then welding it to the shape of my workshop."
I've used this method not just for 911's, but probably thirty or forty or so other big restorations that I've done over the last twenty years ( can't believe it ). I've always been absolutely paranoid about distortion, but the above method has been very reliable for me.
Finally, a jig would be best, but if you can't run to one, and the shell appears fine in tests as above, then simply support the shell very, very well in a way that at least preserves what you have got, without causing new problems. '
More to follow ....