REPAIRS PAGE 7
RESTORATION TOPICS - Part 2 - A and B posts, SILLS
Just to remind members, this is my continuing attempt to record my DIY restoration
efforts on my NA.
I am also delighted to say that some members are beginning to submit articles on this
subject - thank you - they will be published asap! They are highly appreciated
and will add considerably to the Club knowledge 'database'.
INTRODUCTION - Terminology for this article.
As to this issues topics, whilst I am well aware that those technically inclined
members know exactly what A, B, C posts, sills etc are, - but equally they might
be confusing to many others.
To explain,, these 'posts' are vertical body sections that connect the 'floor'
section to the 'roof'. As such, they are extremely important structural members
- and not just for rollover protection - but for chassis rigidity and handling.
These posts are conventionally designated from front to rear ie.-
a) The A-posts are the ones that hold the door hinges and the windscreen.
b) The B-posts hold the front door lock catches and extend up to the roof. They usually also hold
the upper seat belt mountings.
c) The C-posts are usually just for 4 door cars – ie. those at the back of the rear doors.
d) Hatchbacks often have D-posts - at the back of that little triangular rear side window.
The MK1 has just the A and B posts - ie. at the front and rear of the door respectively.
(The hefty rear pillar at the back of the fixed 3/4 glass is not really a C post
- as there is no lower structure to it.
As such, both the A and B posts take the chassis loads up to the roof. (The roof in
itself is fairly important in this equation - but that’s for a later article.)
OK, so that's that’s the A and B posts -so now the sills. These are, as most people
know 'that bit below the doors what you put your foot over to get in in'.
However, the sills are actually amongst the most important structural members of the bodyshell.
All the above areas are MOT check items - so they cannot just be ignored!
Taking each item in turn, and considering their foibles and repair-
1) B-POSTS - These tend to rust internally -which weakens both them and the sills below.
Inspection - the quick and easy check is to remove
the black plastic aeroflow intake grille - halfway up the B-post. It’s only held by one
self-tapper, so nothing could be easier. Then the inner sill membrane and lower
B-post can be seen - a pencil torch obviously helps to peer down. The chances
are it won't look good - but hastily screwing the grille back on does not
constitute a repair - such miracles just don't happen!
Repair - Although this part focuses on the B-post, the base of this and the rear sill are so
connected that there will be some overlap Problem areas seem (predictably) to be
on the lowest 6 inch section. Unfortunately, if you take just one look down
there (just open the door!) you will see there are some very complicated skin
surface profiles, with very sharp and complex 3-D curves on the outer skin.
This complexity would be be very much minimised if repair sections were available - but alas not so.
So, without repair section availability, this is a bit of a tricky area - but it can
be done of course by a good body shop. In my case I did it myself as a challenge -and it was!
If the middle membrane of the B-post is bad - then it has to be the 'cut-in, weld out'
technique. This means cutting the outer skin off to access and weld repair the
membrane. Access is limited, and I just managed with MIG. Oxy or TIG would be
very difficult - too little space
for getting both torch and filler rod in. Arc would do - but needs a good low amp welder, and
slag chipping would be laborious.
As for the outer skin - this is where the 'door open' switches reside beneath the
rubber gaiters- - a real tight 3-D contour. To form such tight curves I had to
hot-work the metal on a selection of dollies -I used oxy-acetylene, but a good
propane torch might just suffice. Please bear in mind that it is only possible
to make relatively small sections at a time by this technique, and that the
sections then have to be welded/blended together.
If you haven't got hot-working facilities, then it can still be done, but even more
sections are needed.
Of course, you could just go to Toyota, but you'd have to buy a whole rear 3/4 panel (ca £350 + VAT)!
All in all, its a decidedly tricky area - can be done, but needs a lot of patience and
time - probably best left to a good body-shop.
2) A-POSTS
Inspection - These
usually go at the bottom bit. On my NA the rot was relatively slight - which was
lucky as the door itself hinders welding access round this area. If the rot is
bad the door will have to come off - if neglected the door will eventually start
to fall off of its own accord - (bear in mind that the door hinges hang on this post!)
Repair - The curves are thankfully simpler than the B-post - but still tight radii, which also
really need hot-working. Welding access is a bit limited with the door on, but I
found MIG access was reasonable.
3) SILLS
Plastic sill skirts cover the whole length of the outer sills, so any rot tends to
progress unnoticed until it's too late.
Outer sill inspection - The first step is to remove the sill skirts, each side is held on by about 10
self-tappers with hex heads - which are on the flat undersurface.
It is most likely that any corrosion has taken place at the rear sill area, but don't
neglect the front though - remember they are both jacking points. Also check the
inner sill - only accessible from under the car - again out of sight and easily neglected.
Repair - Fortunately the rear sill sections are relatively easy to replicate (simple 2-D curves) - a
competent amateur or reasonable body shop job. Bear in mind though that all rot
(and a bit more for good measure) should be cut out - including the internal
membranes - before any weld-up commences. To omit this will just let the 'rust bug' restart anew.
SUMMARY
1) All the above areas of the car are important - structural MOT items.
2) Rear outer sill repairs are relatively easy, but A and B post repairs need tight
curvature metal forming - best left to body shops or well-worn masochists such
as those who write these articles!
ALAN JONES