NP205 4x4 Indicator Switch rebuild (Updated)

How they work, how they don't work, and how to fix them

Moderators: Greenleaf, BC847, Richie O

NP205 4x4 Indicator Switch rebuild (Updated)

Postby Michael Yankovitch » Fri Sep 26, 2014 7:26 pm

The NP205 4x4 Indicator switch is an annoying little bugger. They are often broken and are rather expensive to buy. Mine was not working so I decided, meh why not rip it apart and find out whats inside this thing. At first I reached for the hammer to begin smashing it apart... :scratch: Then I smartened up and brought it over to the lathe and machined the crimp off that is pictured, indicated by the red arrow in the picture below:

Image



The image below shows a normal switch as removed:
Image



The image below shows my switch with the crimp machined off and the detent ball spring fitted inside.
Image



Here is all the parts laid out except the spring, which i left inside the switch as it is a pain in the @$$ to remove.
Image



Here is a picture of the plastic washer used to insulate the spring from the contacts. I made mine out of a piece of plastic from packaging that usually covers the product. You know the insanely hard to remove stuff... Nevermind that black gunk on the body face, i had to tear my nicely rebuilt switch apart to get these pictures.. That's the remains of my old rubber seal.
Image



Here's another of it by itself. I cut it using a paper hole punch, it is the perfect diameter to fit! A little crude but since i took the switch apart to do this post, i will make a newer nicer one.
Image



Here is the spring inside the switch, I made one out of a piece of .045 MIG welding wire by wrapping it around a small bolt. I ground the ends of the spring flat so everything seats square. You have to play with the length a bit. I suggest making it a tad small and stretching it out to fit so there is sufficient spring memory.
Image



I sealed the switch with a piece of rubber cut out of the handle of a roto-tiller. I used a gasket hole punch and cut the inside hole with a piece of sharpened tubing. I then "glued" it on with silicone, careful not to let it ooze into the switch.
Image

When I installed the switch and tested it (set meter for continuity), i noticed it did not work, it stayed on no matter what position i had the transfer case. For some reason the problem was the plastic plunger was not lifting the copper washer off the contacts enough. So i brought the metal body to the lather and machined a tiny amount off the seating surface until the switch work properly. This is a bit tricky. If you machine too much your switch will always be off as the plastic plunger will always be pushing the copper disc off the contacts. I suggest machining 2-5 thou at a time until it works right.
Image

Since the crimp has been machined off, I just siliconed the rubber seal to the metal body and applied a little more around the exterior to seal it and hold it in pplace. Allow it to cure for 24hrs and your good to go.

I found one switch that had failed because the rubber seal cracked and allowed oil to get on the contacts causing a varnish of some sorts. I cleaned off the contacts and it worked fine. Another one had a broken spring. So if it is something simple like that, it won't take long to fix the switch. Like i said before, it took me longer to compile this then repairing the actual switch did.
Last edited by Michael Yankovitch on Wed Oct 08, 2014 12:16 pm, edited 1 time in total.
(In progress project)
1978 GMC body swap onto 1991 non-ic Dodge W250 4x4 (A727, np205, D60 & D70 with 3.07s)
Full de-computerize. Removing PCM and simplifying wiring to its most basic form.
Michael Yankovitch
fuel pin?
 
Posts: 22
Joined: Wed Aug 06, 2014 4:51 pm

Re: NP205 4x4 Indicator Switch rebuild

Postby thrashingcows » Fri Oct 03, 2014 8:49 pm

Thanks for posting this up. Seems to be a couple photo's missing?

Since the NP205 switches are no longer available, and the NOS ones that are still out there are commanding large sums...$150+. Having an alternative would be great!

Please update this thread when you can.
1984/93 Dodge Crewcab, W350, 1 Ton SRW, long box, 330K Km's, M&H spacer, 366 spring, fuel pin to deep side, 14cm housing, Piston LP, PS IC, Isspro Boost, Pyro and tach, NV4500, 29 spline NP205, 3.54's.


Check out the build....http://www.dieseltruckresource.com/dev/ ... 05923.html
thrashingcows
14mm rotor
 
Posts: 575
Joined: Wed Nov 02, 2011 12:00 am

Re: NP205 4x4 Indicator Switch rebuild (Updated)

Postby Michael Yankovitch » Wed Oct 08, 2014 12:16 pm

Here you go, I just updated it.
(In progress project)
1978 GMC body swap onto 1991 non-ic Dodge W250 4x4 (A727, np205, D60 & D70 with 3.07s)
Full de-computerize. Removing PCM and simplifying wiring to its most basic form.
Michael Yankovitch
fuel pin?
 
Posts: 22
Joined: Wed Aug 06, 2014 4:51 pm
Top

Re: NP205 4x4 Indicator Switch rebuild (Updated)

Postby thrashingcows » Fri Oct 10, 2014 5:46 pm

Michael Yankovitch wrote:Here you go, I just updated it.


And I thank you! :thumright:
1984/93 Dodge Crewcab, W350, 1 Ton SRW, long box, 330K Km's, M&H spacer, 366 spring, fuel pin to deep side, 14cm housing, Piston LP, PS IC, Isspro Boost, Pyro and tach, NV4500, 29 spline NP205, 3.54's.


Check out the build....http://www.dieseltruckresource.com/dev/ ... 05923.html
thrashingcows
14mm rotor
 
Posts: 575
Joined: Wed Nov 02, 2011 12:00 am
Top


Return to Transmission

Who is online

Users browsing this forum: No registered users and 12 guests