NP208 to NP241 speedometer questions

[AR_K5]

I'm doing a driveway build on an '83 K5, I have to swap my transfer case from passenger side to the drivers side to run the front. I'm trading my NP208 for an NP241 with a mechanical shift lever. As far as I know the adapters should be the same, and bolt right up so long as I get a 27 spline input shaft (I'm running a TH350).

My question this time is about the speedometer. Is there a simple solution to converting the truck to an electric speedometer or converting the Tcase to run a mechanical speedometer (cable). I have read (for what that is worth) that you can remove the plug in on the case and just screw in the cable. But I've never tied and don't yet have the case to look at, other than this one picture.

If that's not possible and turns out to be your typical internet mechanic advise, is there an electric speedometer that will fit my cluster? Or should I just forget about having a speedo with that TCase?

 

[dyeager535]

I *assume* the passenger and driver drop 241 with VSS is the same sensor. So no, you can't just remove the VSS, there is no drive gear in there, it's a reluctor. Yes, you probably COULD make it cable drive, but who wants that? (lol) I suppose if the 208 parts fit it would be simpler in terms of time right now to accomplish.

Your solution is to run the DRAC and '90/91 cluster. They are pretty much better in every regard to cable IMO. There should be plenty of info here about wiring the DRAC and cluster up, if not, there are a few of us that can help.

I'm running the '90/91 cluster and DRAC. You'll just have to do some learning and wiring, but it's not tough.

 

[AR_K5]

Thanks for the tip. I will do some more looking into it. I'm good with wiring so that's no big deal I was just looking for either the answer you just provided or an easier cable driven solution.

With everything else I am having to do to get these axles swapped in I was hoping for at least one thing to be easy.

This busted rear end has quickly become a complete custom build project. Unfortunately it's too tall to fit in my garage and it won't stop snowing long enough for me to get anything done.

 

[dyeager535]

Not much you can do about weather!

Since you are talking about having a speedometer, one very positive benefit of converting to the later VSS speedo setup for some is that speedometer corrections (such as after gear or tire changes) are simply a matter of some soldering, or if you go all out, DIP switch changes.

 

[AR_K5]

That was going to be my next question. How do you adjust for gears and tires?
And since I'm running a QJet I won't need an ECM just for the speedometer will I?
I've done a lot of wrenching and customizing on these old trucks but I guess this is one conversion I haven't done. Actually this particular whole build consists of various conversions I've never had to do before. It's going to be a Super Frankentruck when it's done. I guess the only original parts will be the body, frame, and motor.

 

[454Sub]

They offered them t-cases with mechanical speedos if you want. It would be a simple conversion.

And btw, you can keep all that snow down there, I had 15in last month and I really dont need anymore of it. I hear we are going to get another 15 to 19 this time around.

And to adjust for tires and gears on a mechanical unit you must change the gears around, they go by colors. Electric if you go that way you must mess around with the drac, and IMO its a pain in the a$$. I wish my Suburban had a mechanical speedo, because I cant get the drac to function correctly and it irritates me.

 

[dyeager535]

Only adapting need done in your case would be if you have cruise that you want to work.
The VSS buffer is on the back of the earlier cluster, so you'd unplug it, and just feed a wire from the DRAC to the cruise module, done. Everything else would just be added.

Power, ground, 2 VSS wires from t-case, output to speedometer, output to cruise, that's it.

 

[AR_K5]

I'm guessing the cluster from a 91 Blazer is what I need, if so I think I just found one on craigslist. I hope I can get it cheap.

 

[dyeager535]

'90 or '91 K5, Suburban, or Crew cab. They are by no means rare or desirable. I think $50 for a perfect condition one is ok, $25 is a steal.