Hello all.

I have a question that I hope some of you may have an answer to.

What is the most likely thing to happen if I drove my car (Chevrolet Astro) in Drive
in around 40km/h and accidentaly put the car into reverse???

The reason for asking is that I *did* this the other day... And I've discovered some
oil spil under the car after that. Not sure if the oil spill came before or after my
bummer.

Thanks
TommyE

It's certainly possible for it to cause an oil spill if you caused enough damage to the transmission. Can you reverse the car? If you can reverse the car then you probably didn't completely break the gear off. If it does reverse, does it feel lump or does it make unusual noises? If so then you might have damaged it, shorn off some teeth, etc. Do you have an automatic car? Some automatic cars protect you from this sort of thing.

Calvin

Its an automatic car. I had it in reverse for 2-4 seconds or so.

The car shifts like before, no apparent changes in behaviour.

I found about the spil when I was tidying the car up inside and had it parked on
another spot than I usually do.

TommyE

A friend did this to his honda civic @ 60mph. He did it later to verify his findings.
It puts alot of strain on it but you should be ok. He only kept the car for another 6 months but it didn't have any problems.

Most automatic transmissions are 'fluid drive'. the engine and transmission don't actually connect. The engine drives a 'propeller' (yes,like in a boat) and there's another one in extreemly close proximity that's attached to the transmission. that's why the car can idle in first gear while stopped.
Some newer transmissions have 'lockup' units in them that actually lock the tranny to the engine. With that setup I assume that it would theoretically wrench the engine right out of the car ; )

HTH

You've probably caused the gearbox to pressurise, which would either burst a gasket, or pop an overpressure valve that may have been designed into the box. Borg-Warner transmissions usually have this. If not, you may have blown the seals on the output shaft of the gearbox, which once stressed, will gradually start to wear until you have a worn out shaft seal and no gearbox oil

You may well have caused some overheating of the oil, which could affect it's properties, so a box oil change might be a good idea.

The torque convertor may well have sustained some damage to it's impeller vanes; this would manifest itself as inefficiency in drive (sounds like the "clutch is slipping"), sluggishness changing gear while accelerating, or "slamming" into gear when the change is being made. Over time, you might even get a vane failure which would be the end of your driving experience that day.

I am surprised that you were able to transit from drive into reverse; most automatics have got some kind of detent mechanism to stop you doing this without conscious choice; given the amount of energy that would have to be dispersed in effectively using your gearbox as a brake for your car from 40 mph I do not think this was such a good idea. What happened?

I would take the oil leak seriously or you could soon be driving a dry box.

Well, took the car to the dealer today.

One of the mechanics had a look at it.
He said the oil came from some hoses which goes to the oilcooler.

Nothing serious he told me, had seen it before. They ordered some new
hoses and will put them onto the car in 2weeks time.

He then topped the oil, told me I could drive in the meantime, and that I
should have an eye on my oil level.

Thanks for your thoughs.

TommyE

Here in Norway there is snowy/icey roads now.
I was driving downhill on a small forest road, normally I put the car into 2nd
when its slippery like now. I thought the car was in 2nd, but it was already
in drive, so when the road flatened out I wanted the car in Drive, so I put the lever
2 notches up, bad thing it was already in drive...

I'll be more carefull, checking which gear I'm in next time.
TommyE

You probably had it in reverse for no more than a fraction of a second. The fright must have made it seem like a full 4 seconds. Really, look at your watch and see how much time 4 seconds really is.

If it is an automatic I would not worry as much. The other guys are right, you should change your auto tranny fluid soon.

The way the auto tranny works is you have a "propeller" spinning inside a "sticky" fluid that has the interesting property that when it heats up, it solidifies. When the propeller spins, it heats up the fluid... when the fluid heats up it "locks" up the movement of the propeller to the wheels. If you toss it into reverse it would certainly impart an extremely large amount of heat into the fluid. If you really did have it in reverse for 4 seconds, that would be a problem. But I suspect you only had it for a fraction of a second, came to a sinking feeling in a fraction of a second and got out.

Calvin

Hmm, guess you are right about the time.
The car would probably almost be running backwards after 4 seconds

I'm goining to replace some oil hoses soon, I think I will ask them to change
my tranny oil too.

TommyE

Here in Norway there is snowy/icey roads now.

If you were on snowy/icey (i.e., slippery) road, then there is very little likelihood that you damaged your transmission. The tires would have just slid on the road, transferring very little load to the inner workings of the transmission.

tanstaafl.