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Roll starting

Is it OK to roll start a manual transmission car in reverse?

I have never tried a clutch start in reverse, sounds feasible but then again sounds wrong.

NOT a good idea…The gear ratio is to low. The tires will want to skid and you could damage the transmission. When push-starting, it’s best to use 2ed or 3rd gear …

I agree with Caddyman, but for what it’s worth, I have done it before, but only because there was no alternative. It will work, but is not suggested if there is any way around it.

As long as you are also pushing the car backwards and not forward it will work if it’s a car that’s able to be “push started.” Just don’t go too fast.

The gear ratio just makes it harder to turn the engine,go for it-Kevin

While I agree with all of the above replies, I’ve done it a handful of times, but avoid it when I can. However, as I think about it, I’m not sure how anyone would be able to say “It’s bad for your car.”

It’s true that push-starting in a higher forward gear (2nd, 3rd,etc) might be easier on the drivetrain, but when you think about all the forces the drivetrain experiences, I’m not sure how one can say starting in reverse is “bad” for the drivetrain.

Back in the day I have towed vehicles in reverse and the differential would try to turn one wheel backwards and one wheel forward,not sure why-Kevin

I have done it a few times.   Usually with my old Sunbeam Imp which I could just open my driver's door on a flat area put it in neutral and use my foot to get it moving in reverse, If I was fast (I was a lot faster back in those days (1960's) ) I could get back in my car and drop it into reverse and release the clutch to get it started.  

I tended to go out to my car and listen to the radio while I ate lunch in my work parking lot, and occasionally left the radio on draining the battery when I returned to work without turning off the radio.  Funny thing that battery lasted a long time.

Reverse gearing on most cars is even lower than the 1st gear ratio. This would make a reverse start a very "herky, jerky experience but it can be done. I would recommend not “popping” the clutch as you engage reverse to spin the motor. I don’t think it would damage the car.

It’s usually easier to roll-start a car in second gear than in first gear, so it can probably be done, but it wouldn’t be as smooth as doing it in second gear.

I have done it a few times when parked on an incline. Limited engagement of the clutch, not complete. No damage apparent in the near future. This was in a RWD car. The ratios were even lower than the 1st as Uncle Turbo mentions here, so I am sure it is not great for the drivetrain.

I’ve done it too, but it is not recommended.

I remember seeing school buses started this way back in the early 1950s. Sometimes the bus would sit in the parking lot all day and something might have been left on that would run down the battery enough that the engine wouldn’t crank. The students would all be on the bus and another bus would push the first bus backward in reverse. A few feet was always enough to crank the engine so that it would start.

In most manual transmissions, if you saw how the reverse gear was supported in the transmission case, you would NEVER try a reverse bump-start…It just wasn’t designed for that nonsense…

Reverse gears arent very sturdy and some can break. Back in the days of 65 Fairlanes with 3 speed trannys, they were a bit more solid. I had the overdrive transmission and it would not roll start in forward gears. The transmission would free wheel. Strange car.

I’ve done it too, and I’ve never had a problem, but clearly it puts a lot of strain on things that are designed to handle force in a completely different direction. There are times when you chose to do something like this, and I guess the thought it to be as gentle as possible, but still get the job done.

Does anyone have any evidence that harm is done to the reverse gears when jump starting in reverse is done?

@pleasedodgevan2-- On the cars with the automatic overdrive transmissions of the late 1930s through the 1960s, you had to pull out the overdrive control lever to disengage the overdrive. The transmission then acted as a regular 3 speed transmission and you didn’t have free wheeling. You could then roll start the car.

Kmccune, the differential will do that in forward too.

I’ll try to explain using the attached differential drawing. While this one is for a FWD vehicle, it works exactly the same for a RWD vehicle except that the ring gear looks different. The tranny output shaft turns the ring gear, which normally turns the entire differential casing. That via the differential pinion shaft, causes the differential pinion gears to orbit the axle axis, dragging the differential side gears along and turning the axles. When you lift the wheels off the ground and turn one of them backward, resistance keeps the ring gear from turning and the axle turns the differential side gears, which then in turn rotate the differential gears. They in turn “roll” (if you will) around the nonturning ring gear and turn the opposing axle’s side gear in the opposite direction.

I hope this helos with your understanding of why the opposing wheel turns in the opposite direction.

http://tijil.org/Scion_Docs/05_tC_Shop_Manuals/Repair%20Info/Repair%20Manual/Manual%20Transmission-Transaxle/Differential%20Case%20Assy%20(E350)/conponen.pdf