View Full Version : Reversing a starter motor?

02-20-2005, 11:50 PM
Other than the PM types is there a way a starter motor can be reversed? Extra brushes?Change internal connections? I seem to remember someone had a way,but don't recall who it was,Winchman maybe?

02-21-2005, 12:11 AM
Are you talking about an automotive type starter? If so, just reverse the magnets. (coils)

[This message has been edited by CCWKen (edited 02-21-2005).]

02-21-2005, 01:07 AM
Check with a marine engine parts company they should be able to supply the information and parts. Think you would have to change the bendix drive.


02-21-2005, 04:19 AM
Reverse either the brushes connections or the field connections, but not both. Might be easier to reverse the field wires. If there's four wires to the field, reverse each pair, if there's two wires only, that's easier. Maybe. I bet there's internal connections that will make it a pita to do this. And yeah, the bendix won't work in reverse, but I think you must have a different application in mind. Either that or you want your engine to run backwards, that would be interesting.

[This message has been edited by darryl (edited 02-21-2005).]

Ted Coffey
02-21-2005, 06:28 AM
You should be able to just reverse the voltage polarity but you may find excessive brush sparking. It may be possible to shift the brushes to correct this depending on the starter design. Also the original brush position will probably not give you the maximum torque.

J Tiers
02-21-2005, 08:50 AM
Starters are series motors, optimized for high current draw and high resulting torque.

You MAY be able to reverse it, and have it work as it did before, or not.

Reversing coils as noted will reverse rotation. Also as noted the brushes are likely in the optimum place for the existing rotation. There may be other features, like interpoles, that cannot be moved....or not. Starters are fairly simple motors.

The Bendix engagement screw will be the wrong "hand".

[This message has been edited by J Tiers (edited 02-21-2005).]

02-21-2005, 10:54 PM
Thanks for the replies,no I'm not using it for the original app.

I want a cheap option for 12vdc boat winch motors.

J Tiers
02-21-2005, 11:46 PM
Might work fine..."series motor" and "winch" go together.

They do tend to suck current though, more than it seems like they should, when more lightly loaded.

And, they are made for short duty cycles. The whole principle is a motor which can be severely overloaded for a short time. That was the classic Kettering principle, and it still works. Efficiency is of no interest to the designers unless it relates to torque.

Boat winch, as in haul it up on the trailer, probably fine.

Boat winch as in deck equipment, maybe not.

3 Phase Lightbulb
02-22-2005, 12:35 AM
<font face="Verdana, Arial" size="2">Originally posted by wierdscience:
Thanks for the replies,no I'm not using it for the original app.

I want a cheap option for 12vdc boat winch motors.</font>

If your just building a pulling winch, why not just change the motor from a left side drive to a right side drive, or vise versa?

Is you winch drive shaft drivable from either side?


02-22-2005, 10:06 PM
I have built trawl winches using a worm gear reducer with a flywheel and two starter motors,one facing forward the other aft.You hit one switch is huals up the other lets out,but that's too clumsy for a simple boat winch.

I also had a pregnant Idea today,thinking of taking a starter motor and a power steering pump and coupling them together.Should make a cheap liftgate pump.Checked out a pump today,typical Ford for a ball box is 2.1gpm at 1400psi.Got to try it.

02-23-2005, 08:43 PM
You can also nearly double the psi by changing the valve spring. (Ford pump) http://bbs.homeshopmachinist.net//biggrin.gif
I've got a Mitsi pump that's about 1/3 the size that I need to make a new valve for. I don't think I'll try to boost it though. It's cast aluminum. http://bbs.homeshopmachinist.net//frown.gif

02-23-2005, 08:51 PM
Ken,I am assuming the heavier the spring the higher the pressure right?