CJ7 speedometer and np231 transfer case

[sbrodacz]

Does anyone know if it is possible to have a CJ7 's speedometer work with a np231? My adapter for a GM Turbo 400 to np231 finally came in yesterday (after waiting a month and a half) and I'm about finished installing my sye in the np231. I need a better pair of snap ring pliers. I'm hoping to have it mounted this week. I was going to purchase the correct speedo gear, but than didn't know if the speedometer would even work. I bought the np231 used, it's missing the speedometer adapter which I was going to purchase along with the correct speedo gear. I decided to hold off and make sure everything will work correctly before wasting more money.

 

[sbrodacz]

Also, do I need to have the vacuum switch? The new rear housing that came with the sye does not have the hole for the vacuum switch. I'm not exactly sure what it is for. For what I've read it looks like it allows the 4wd indicator light to work. If I do need the vacuum switch I am assuming I was sent the wrong rear housing.

 

[BusaDave9]

Yes, the speedometer will work.

 

[BusaDave9]

Also, do I need to have the vacuum switch? The new rear housing that came with the sye does not have the hole for the vacuum switch. I'm not exactly sure what it is for. For what I've read it looks like it allows the 4wd indicator light to work. If I do need the vacuum switch I am assuming I was sent the wrong rear housing.

You don't need the vacuum switch. When a TJ or YJ would go into 4XD the vacuum was used to actuate the front axle. If you have manual locking hubs you don't need the vacuum switch.

 

[sbrodacz]

You don't need the vacuum switch. When a TJ or YJ would go into 4XD the vacuum was used to actuate the front axle. If you have manual locking hubs you don't need the vacuum switch.

Ok good.

Is there anything specific I need to do in order to get the speedometer to work correctly?

 

[BusaDave9]

I spoke too soon about the speedometer. The NP231 came in 2 styles. Some Dodges from the early '90s had NP231 used with mechanical speedometers. It may be too late now but I wonder if you could have bought a sye for use with a mechanical speedometer. Otherwise you will need an electronic speedometer.