Need speedo help after trans swap

[kickdeez]

This forum has been very helpful to me so far. I am hoping you guys can point me in the right direction again.

1990 R2500 Suburban with 454 tbi. The previous owner swapped in a SM465 in place of the original automatic transmission. Not sure what the original was, maybe a 700R4? He also converted to 4wd and installed a NP205 transfer case. This is how I bought the truck (speedo not hooked up to a speed sensor).

I have been told I can just get a pulse generator from Dakota Digital, install it in the NP205, and hook it straight up to the existing wire connector on the inside of the frame rail next to the transmission. Some of the reading and research I have done leads me to believe that this type of device doesn't really work as well as it is proclaimed to (not specifically Dakota Digital's products - just pulse generators in general) and there is some calibration and potential re-wiring that needs to be done.

Is this my only other option for getting the speedometer operating correctly (and maintaining cruise control)? http://www.northwestfab.com/NP205-40-Pulse-VSS-Speedo-Housing-Kit_p_1903.html

I don't really have the desire to take apart the dash and install a mechanical guage, and I would lose cruise control in that scenario. What have you guys done?

 

[yevgenievich]

mechanical spedo is not hard to install, and mechanical spedo has a sensor on it to output pulse signal to cruise control.

 

[HotRodPC]

Being a 90 truck, it is equipped with an electronic speedo. Chances are the Trans is equipped with a manual speedo. @RetroC10Sport will have to confirm or deny, but I think you can get one of the manual speedo clusters that have the electrnoic conveter for the cruise control. Not positive on what years models that is, but pretty certain my 86 is that way. You'll know one when you see it because it will have the wire pigtail hanging off the cluster with a small thin pale green box about the size of a cig pack on the end of it.

 

[RetroC10Sport]

1983-89 should have the cruise control VSS.

 

[kickdeez]

Correct, truck has an electronic speedo and original transmission had an electronic VSS. The swapped in NP205 has a gear driven speedo cable. I have heard (could be complete BS) that the computer uses readings from the VSS to adjust fuel and air mixtures, and that these trucks run more efficiently when a proper VSS is installed and hooked up. Can anyone confirm or deny this information? If this is true, I think I would want to find a way to install a proper VSS and hook it up to my current speedo. If the VSS has no tangible benefit, I think I could probably just install a mechanical speedo guage. Thoughts???

 

[marks86]

my advice would be find a np241 out of a 90-91 suburban or k5 with the VSS in it

unless the truck has 40" tall tires 4.56 gears or does extreme off roading a np205 is an overkill IMO

 

[kickdeez]

Thanks for the reply. You are right, I probably don't NEED a 205, but when it comes to towing 10k+ lbs, having that piece of mind and reliability goes a long way. To me, buying a new (or junkyard) tcase just to hook up a speed sensor doesn't seem like a cost effective route. Especially if it's a downgrade from what I already have.

Anybody have experience with the kit I pasted a link to in my original post?

 

[kickdeez]

The kit I pasted the link to uses the tail housing, reluctor ring, and VSS from a NP241.