Service Bay – Common MoT fails BMC 1100/1300
One of the only BMC models to keep arch rival Ford off the top spot in the UK sales charts, the BMC 1100 was a very advanced car for its time and that’s one of the reasons survivors should be professionally tested every year
Before putting your ADO16 in for its annual test, check out these common MoT fails to save time, money and effort.
In a way this should be an article rooted in the ‘Seventies when the BMC 1100/1300 range – by then getting on for well over 10 years old – would be filling up the average breakers yard following a catastrophic MoT fail. As brilliant as it was, and these cars were light years ahead of models like the Viva and Anglia, the ADO16 range in BMC parlance was known for body rot that was harder to repair than just welding a plate onto a rusty Anglia’s chassis rail.
Because there were literally millions on the road and old ADO16s weren’t worth a lot, most owners elected to take the twenty quid from the scrapyard rather than have their cars repaired, which is why so few exist. There are very few cars now that are still original and haven’t been welded and the standard of repairs varies considerably. This is why the annual MoT test really is essential on this top selling model, as they had minimal crash protection when new and a rusty example could quite literally be a death trap on today’s ultra congested roads.
1 OUTER SILLS/FLOOR:
1100 sills are quite a complex structure with a curved outer sill that curved down in cross section and is spot-welded onto another downward curved section. The trouble here is that the shape makes a perfect moisture trap and there’s no escape for it. To make a good repair in this area the best way was to cut the outer panel off, repair the inner membrane and weld a new sill on, but that just wasn’t happening back in 1975!
3 REAR SUBFRAME MOUNTS:
The Bete Noir of 1100 owners and welders of the period – many turned 1100’s away, as they could be such a nightmare. Rear door open, rear seat cushion pulled up and there is the serious rot in the rear seat base/heelboard corners. This box section is complex and hard to repair, but the rear boot floor mounting areas for the subframe weren’t quite so bad.
5 INNER SILLS:
Outer sills were one thing and the inners were another. Due to the design, – it was such a bad rust trap that Pressed Steel engineers advised Issigonis to redesign it (he didn’t) – moisture collects here and causes havoc. Had the shell been properly rust protected it would have been fine. Repairing rotten inner sills will be a serious task, as the rest will need doing as well.
2 REAR SUBFRAME:
These aren’t quite as rot prone as on the Mini but they still rust out in the lower sections beneath the displacer. New subframes are available and the same rules as the Mini apply. Getting the old one out can be a pain of broken bolts and you’ll definitely find that welding will needed around the mounts. But do it now to a good standard, rustproof it thoroughly and the repair will be permanent.
4 FRONT SUBFRAME MOUNTS:
Even the ADO16’s oil leaking A-Series engine often wasn’t enough to protect this area. The rear mounts for the front subframe (on the front toeboard) rust away and are not easy to repair, as there is the main floor section and the reinforcing plates in the way. Moisture gets in between the two and results in a mess but to make a good repair you need to drop the subframe slightly (not too difficult) and replace both bits.
6 HYDROLASTIC SUSPENSION:
The most complex and Avant Garde bit of the 1100/1300 was ironically the most reliable. However, the oldest 1100 is now 56 years old and the pipes can rust and burst but that’s not so common. That’s just as well, as you’d need to drop the subframes out to make a repair if that happens. New pipes are available but check for leaks where the displacer hoses fit – they can be rebuilt.
There won’t be many 1100/1300’s left on the road today that haven’t been welded up somewhere during their lifetime.