Manuals smoking in reverse

[mjoekingz28]

I have noticed on more than one occasion that a stick shifted car will visibly smoke only in reverse.

Now, i just read on Redline's site that reverse use sliding gears while forward gears need friction in a MTF to engage gears.....so that could be part of the reason but I just dont know how the engine could 'know' what direction the tires are spinning unless it is a computer, BCM or PCM type of programming.

 

[eljefino]

May be something stupid like a PCV baffle. You could also smoke under hard braking but the vacuum is different.

 

[exranger06]

You sure it's not just exhaust smoke/steam coming out the back of the car, and the car "drives through" it in reverse, making it look like it's coming from the front?

 

[Rand]

also most cars reverse just after being started.

 

[CT8]

I doubt that manuals smoke in reverse. Most trans I have been into do not have bearings in reverse but I don't think people drive in reverse enough to get a trans to smoke.

 

[kschachn]

Originally Posted By: CT8
I doubt that manuals smoke in reverse. Most trans I have been into do not have bearings in reverse but I don't think people drive in reverse enough to get a trans to smoke.


I don't know any manuals either that have a bearing for the reverse gear. But even if it was smoking, how's that smoke going to get out of the transmission?

 

[mjoekingz28]

I mean out of the tailpipe.

 

[spasm3]

 

[HerrStig]

Somebody's into the Christmas spirits.

 

[exranger06]

Originally Posted By: mjoekingz28
I mean out of the tailpipe.

You're imagining things. There is no reason a car would smoke only in reverse. The car has no way of knowing it's in reverse, and there is no different programming in the computer for reverse. Furthermore, even if there are different types of bearings in the transmission for reverse, that would not make the engine more likely to smoke in reverse. An engine may be more likely to smoke when under a certain amount of load, and perhaps a different type of bearing can put more load on the engine, but a load is a load; regardless of the vehicle's direction. You could put the same amount of load on the engine going forward by modulating the throttle, or driving up a hill, or adding more weight to the vehicle, or any other variable you can think of.

 

[CR94]

Going forward, you may not see the smoke cloud behind you, or you can ignore it. In reverse, you're breathing it, or seeing it in front of the car, so it's harder to overlook. If the car's also smoking under the hood, in reverse you'll see smoke after it comes out through the grill and radiator.

 

[Bamaro]

As others have said, it's not smoking more, you're just noticing it more.

 

[Quattro Pete]

Originally Posted By: mjoekingz28
I have noticed on more than one occasion that a stick shifted car will visibly smoke only in reverse.

I think you are the one who is smoking something, and I want some, too.

 

[IndyIan]

Skidoo powered cars? Skidoo implemented reverse on some 2 stroke sleds by just running the motor backwards, and they seem to puff out a little more smoke then.

 

[rectifier]

Automatics run differently in reverse, I know this for a fact from my [censored] work truck. Traction control/stabilitrak etc. is disabled so that you can spin the tires and try to back out of the mud that it got you stuck in. So the timing gets un-retarded, and the gearing is low, too, so you can blow a big exhaust plume at high RPM while you spin the tires. The truck is not moving to dissipate it, so if the air is cold and there's no wind, there is "smoke" everywhere. And mud.

I don't have a standard vehicle with that safety B.S. but the switch that turns the reverse lights on could be used to trigger such a mode. I guess.

Niche case though, and I suspect this is not what you're talking about.

 

[Surestick]

I suspect the O.P. is confused by the same effect you can see accelerating through the gears from a stop on a cold morning.
First gear produces a much bigger cloud of water vapour (not "smoke") than second and the cloud gets less and less as you go up through the gears.
The effect is due to revs per unit distance travelled (or combustion events per unit distance travelled (same thing)). In first gear each revolution takes you less distance down the road than in higher gears so the cloud of vapour from the exhaust is released over a shorter distance making it look like there's more "smoke".