Your worst mechanical screw-up - what was it?

OK, so here's mine to start this confession thread. I was 18 and had not long since bought my first car, a 1977 Fiat 126 in a fetching shade of Fluoro Green and I nicknamed it 'Kermit the Frog', even though it was Italian.

I'd been hooning around in it for a while (well, as much as you could in a 650cc car) when it began jumping out of gear and was a pig to drive around. I came to the conclusion that a new cogbox was required and I started hunting around scrapyards. I couldn't find any 126s in scrapyards but I did fond one place that had a couple of Fiat 500s.

I went along with my Dad and a tape measure and it looked like it would fit, so we bought it and I spent a full weekend swapping the gearboxes over. Everything fitted with no problems and I even had no screws or bolts left over, so I stood back and surveyed my work with pride.

I got cleaned up and prepared to take it out for a test drive. I started the car, stuck it in first gear, lifted the clutch and to my utter amazement and disbelief it went BACKWARDS into the back of my Dad's carport!!

My Dad came out and asked me WTF had happened. I explained what had just happened and my Dad's reply was something along the lines of "I find your reasoning somewhat questionable" ( I have cleaned that up a LOT). We pushed the car back up the drive and my Dad tried the car. Sure enough, first gear sent the car backwards, reverse made it go forwards. "WTF have you done to it!?" my Dad ranted. "All I did was swap the gearboxes over", I replied.

I rang the local Fiat agent and asked their Service Department a "What would happen if..?" and the mechanic said "It goes backwards, doesn't it?" before pissing himself laughing - they had obviously seen this before. "Is there anything I can do about it?" I asked. "Yeah, change it for a 126 gearbox, as they are different", came the reply.

I lost interest in the car at that point and sold it not long after, losing a chunk of money in the process.

So, confess - what was your worst screw-up?

 

Screwed up the timing on my old XS250. Somehow I got it 180 degrees out, overheated the engine badly, seized everything.
And on a customers bike, in the not too distant past, I forgot the put the retaining washer in front of the oil pump belt on the crank end, went down the road 1/2 mile after a complete rebuild, belt came off pulley, seized the top end. Again. New top end at my cost

 

working on a fiat sieciento piece of shit like the one on the inbetweeners.
for some reason (cant remember why) me and a mate were putting alloys on it.
got three on and nicely bolted on.
got distracted by another friend who rocked up on his rs125 and ofcourse we had a play on the bike.
came back to doing the car 30 mins later still with only 3 wheels on....
you can see where this is going.....
we dropped the car down on the side with 2 wheels on.....
then pulled the only jack on the left hand side out without looking at the front....
yup... poor fiat was cocking its back end whilst stationary....