***LT1 Swapped car that is already running and driving***

I recently upgraded my TH350 to a 90' 700r4 out of a truck or van. i got the TV cable hooked up properly, as well as the lock up converter... for all intensive purposes the transmission seems to be shifting and driving just fine... been cruising for around 500 miles.

I have hooked the 90' 700r4 electronic VSS directly in to where the 94' LT1 VSS wire goes in at the stock harness location.

Now from what i understand (stock) the 700r4 uses an AC signal that goes to the DRAC/Buffer and then sends a DC signal to the speedo, cruise, and ECM.

the LT1's PCM has been reprogrammed to run what ever type of tranny i want but it is programmed to see a VSS signal so it can adjust the idle fuel ratios accordingly.

can i just run the LT1 with the stock 700r4 VSS in place as is or should i try and get one of these DRAC/ buffer modules so its reading a DC signal as opposed to an AC signal?

Now this is a budget swap/project car... so please DO NOT suggest i buy a 4L60E, or spend hundreds on dakota digital/ jags that run parts or some other costly solution.

I've done my research, I'm aware of these but Im also fairly certain i can get a DRAC module out of a 92-94 truck that will take the AC signal and send the PCM the correct DC signal. I like this route better because its cheap, and so am I.

I hope Im not too forward, but I've spent days scouring google and this forum for info, if i left anything out let me know.

thanks in advance for any help!

 

The DRAC wont work since the VSS uses alternating hi/lo signals. The DRAC or buffer box as most around here know it as, only outputs a single signal wire at 2,000 or 4,000ppm depending on the year and output wire. Fine and dandy for driving your speedo, but the PCM cant use it. Without a VSS input the PCM will throw a code and stall out when coming to a stop. Tweaking the tune can bandaid this but most of the time it cannot be overcome with a tune

Easier solution is to find that truck you were about to pull the drac from, yank the tailhousing off (2WD versions only) and grab the VSS and reluctor wheel. The reluctor is pressed on so a long jawed slide hammer is recommended or just buy a replacement from a trans rebuilder for <$15. The 4L60E VSS fits any large hole 700R4 tail and the reluctor presses right on the output shaft

Run the new VSS wires directly to the PCM like before. Now it will send the 40ppr (pulse per revolution) the PCM is expecting and can decode it to drive the speedo with a single 4,000ppm (pulse per mile) stream

Clear as mud yet?

 

What he said.....^^^^

 

Still kind of muddy. So I really just need to run a LT1 vss in my 700 and that will make it run 100%?

From what it looks like there is a reluctor ring already in place in my 700r4, are there different types of reluctor rings on the 700's vs the 4l60e's ?

I pulled a vss from a 94' caprice but it seems too small and like its not going to be able to line up with ring anyway. The magnets seem to be on the side of the 700 vss and in the end of the LT1 vss. Should I try and get a vss from say a 92-93 Corvette?

I haven't exprienced any stalling when I come to a stop, just occasionally having a surging idle when rolling down hill at freeway speeds.

 

What do you have in there? A plastic gear or a steel reluctor? If the magnets are even 1/3over the reluctor, it will read properly

VSS will be the same for all 2WD 4L60E's. These is no "wont fit" because there is only one part number (ok two). Only difference there is connector type

 

Steel reluctor type. But the vss in the trans has the magnet on the side pointing up. And the one I grabbed from the junk yard has brass (I think) on the inner part and the magnet is on the end.

I'll crawl under the car later today and take a closer look, try and get a few pics of what I'm dealing with.