Looking at doing an ls swap with an existing th400 in a car that has a cable driven speedo. Want to retain the factory cable and speedometer, but supply the pcm with the correct input signal as if it were hooked to a 4L60-e still. Dakota Digital makes a vss that screws onto the speedo cable output of the trans and accepts the factory plug on my engine harness, but you lose the speedo drive. I need a sensor that attaches to the trans output but then takes the cable still, effectively pulling signal off a pass through while retaining factory speedometer operation.
i’m having a hard time wading through the bs on ls1tech of 10 year old threads with long discontinued part numbers and hoping you guys know which piece i need.
In the end a 4L60-e may be the answer because a 5.3 doesn’t need the strength of a th400, but at the same time retaining the existing transmission requires zero driveshaft work or shifter changing.
SkinnyG
UltraDork
3/31/19 10:27 a.m.
Jags That Run offered a toothed wheel that goes on the driveshaft with a magnetic pickup to give the right signal.
I Understand what you want ,don't know of one ,BUT , Will a Later 700type work, With a gear change if Nessesary, Around here a Big time 400 builder is Called Monster Trans. Call 'Em maybe in the Morn. If you have both a 400 and a 4l60 look them Over , can you make one?
stuart in mn said:
I don't know what kind of signal you need, but Dakota Digital has a pass-through version that will run the original speedometer cable and create an 8000 pulse/mile signal. https://www.summitracing.com/parts/dak-sen-01-4160?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-dakota-digital&gclid=Cj0KCQjwyoHlBRCNARIsAFjKJ6CyPjJVQcP449tAJ6sG23ACtIiWp2W1YTgsnjAW2KYNHn6IHZ_0RVgaAqsCEALw_wcB
If you look in the Q&A section in this link I posted earlier, there's mention of another Dakota Digital device that will take the 8000 pulse/mile signal and reduce it to a different value, if that's necessary for your application.
Chevy Astro vans had a vss on the dash end of the speedometer cable that just goes between the cable and speedometer. Not sure what years, but they should be cheap and it's a place to start.
Came to echo what oldopelguy said.
AFAIK, all GM to the beginning of time (except Saturn) expect the same pulses/mile. Also AFAIK, if you are not expecting to use cruise control or evap, the only other thing the VSS is for is idle strategy, and that doesn't need to know WHAT speed, just rolling or not rolling.
Contact Gear Vendors OD. They have a through-put adapter for just this thing. The GVOD needs a digital signal so they made this to put a digital VSS inline. You screw the VSS onto the trans, and the other side of it has threads and a cable output to attach your cable driven speedo.
As I recall, GVOD's VSS is proprietary, meaning it won't give the same signal to the ECM, but the ECM can be reprogrammed to accept the different signal. You might have to trick it by programming it for something like 2.37:1 gears, or 42" tires or something.
If theirs won't work, try VDO. I believe they have a similar thing for retrofitting EFI into an older car with a stock speedo.
When I did the throttle body injection swap in my El Camino I used a pass through VSS generator from Jags that run
This is what I used on my last GM swap. It sends the signal your PCM needs as well as retaining the cable.
I got it from Jags that Run.
Junkyard wise, there were lots of GM vehicles on the 80s that used a cable speedo with a vss in line. No idea how many pulses per mile.
Taxi s used to use a similar unit to drive the meter, but I bet they ate thin on the ground by now.
