Roelof

Some brands have indeed a shaped diff-house so it is impossible to do otherwise but with enough brands it is possible and a common thing to happen with a first time maintenance.

motoclay

iTrader: (3)

Diffs only rotate the way the input shaft tells it too...diffs at stupid...they don't work on there own...the ONLY way a diff can go backwards in direction is if you change the direction in the input shaft...that's why your real car has a transmission...moving the shifter to R puts gears in place so that the output shaft turns the opposite way...diff moves accordingly

motoclay

iTrader: (3)

I guess if you were able to somehow get the ring gear on the other side of the pinion and it mesh...which is extremely unlikely...I suppose then it would go backwards

But 99.999% of the wheels turnin backwards in rc world...engine miss fired and is running backwards

Lol I don't even know why I'm on a soapbox here....sorry guys

JoePit

iTrader: (15)

It's impossible for a Losi which is what you run. Very possible on a Hot Bodies and maybe some other makes. If after shutting down and restart with no problem the motor most definitely started backwards. I would confirm the direction of the starter box rotation.

CKmaxx

iTrader: (1)

I've seen a buggy going WOT down the straightaway, backfire and head back down the straightaway in reverse. Funniest thing I've seen that's RC related and it's always when I'm RD'ing a race. Hard to call out the race order when I'm laughing hysterically....

sschultz

iTrader: (15)

The guys laughing and saying impossible are all running losi. Maybe you can't EFF it up in losi, but I KNOW you can in a ae! Am sure you can in other brands to.

Mauve

iTrader: (3)

Some models you can put the diff in on either side, not to many these days. Some motors are more prone to be able to be started in reverse than others due to port design, crank design and port timing, most are capable of being ran in reverse, however they will usually run badly in reverse. If you run a quite low idle, and a bit rich as well, there is a chance it can bounce back on compression whilst still a little cool. Ive had it on 2 occasions, 1 when I had been changing the wiring on my starter box and accidently reversed the polarity which resulted in a difficult to start motor and when it did start, it ran in reverse obviously, on another occasion (with a Nova Plus 4C) it idled a little low, bounced off the compression and ran backwards, stopped it, started again and it was good to go. It probably has more to do with when I started it, the earthing of the glow plug ignighter caused it to not glow until I started to lift it off which happend to conicide with the bounce back of compession and glowed at the same time. To ensure this doesn't happen, make sure the glow ignighter stays on the plug for a few seconds after you take downward pressure off of the car when using the starter box.

Funniest thing I have seen was a bloke put the rear diff in the wrong way and the front diff in the right way in a Revo, he started his truck, the front and rear wheels ran in opposite directions so the car was physically trying to pull itself appart, it was hilarious, particular as for the week prior I had told him repeatedly to test run the car prior to attending the event, needless to say, he missed his practice rounds LOL

bartnz

Ive had this happen with a rb engine that was still pretty tight..starter box was fine but i think just on start up with the timing and being tight it combusted not at the end of the stroke therfore running reverse...just kill the engine and start again.

motoclay

iTrader: (3)

I don't mean to be rude by any means. I have only ran losi cars, and yea there is no way in hell you can put it in backwards, just no room around the ring gear the other way. So my bad for my ignorance of other chassis, it still seems extremely hard to do but I guess its easier than I think. At any rate, hope everyone goes the right direction at there races this weekend!! Lol, knowing my luck/karma my buggy will back off of pit lane while im walking up to the driver stand for practice!! hahha

Rsickles

iTrader: (21)

It's very possible to install a diff in reverse (though a lot of newer cars have smaller and notched gear boxes, so it's not possible).... and it will cause the outdrives/wheels to spin backwards.

Did it on an old OFNA years ago. Nothing sucks worse than realizing you put the rear diff in backwards during a rebuild because you weren't paying attention while watching TV. Should have run it and let the car have a tug-of-war with itself.

As to the point of the thread, it's mostly about the engine starting in reverse.

mtpocketsracing

iTrader: (2)

I've seen a few motorcycle engines running backward. don't know how they did it but it did.

rcfanatic573

iTrader: (10)

We had that happen on a two stroke dirtbike a few years ago. I can't remember what I did wrong but kicked the bike and it fired up, revved it up and let the clutch out and it took off backward. didn't get 5 feet before being wadded up with the bike. Would have been nice to have a hand getting out from under it but my friends were all rolling on the floor laughing too hard to get up. I wish I could have seen it from thier perspective it musta been hilarious to see me lean forward and the bike go backward.

Bud

^ Funny or not depends on your perspective I think. Was pretty funny to them.

I had an old Kawasaki 2 stroke start backwards one time. Catches you real off guard when the bike takes off backward. I was taking off easy so I didn't crash. lucky.

rcfanatic573

iTrader: (10)

I was laughing pretty hard too. It was really funny. I didn't get to see my face though and that was probably hilarious. It was a surprise to say the least. It's been a long time and we still have a laugh about it when we all get together.

Teufel Racing

iTrader: (30)

It can be done on the front diff only with the Losi's. Did that once after a quick rebuild track side. Good thing I did a little warm up in the pits to catch it.