hogpuke

I'm getting into an LS1 swap in a '72 Chev. 4WD. Will it require a vehicle speed sensor and how would it adapt to the truck?

psiconversion

iTrader: (5)

If you are using Han electronically controlled auto, or want speedo output from the PCM need the vss.

hogpuke

Either way, doesn't the computer need to know the truck is moving so it can control fuel mixtures, etc.? Does something adapt to the existing cable speedometer fitting or what? What's a good source for one? Thanks for the help!

Bo185

If you have the 4l60e/80e you need a VSS. If not you can tune it out. It will work with out it but might have problems with idle and such.

You can get inline VSS as well. Form "Jags that run" google it.

But would help to know what year motor, trans and transfer case you have!

Dothedew

I ran into this same thing. Depends on you're trans choice. If anything other than the stock trans (or trans type) the ENGINE came with, you'll need to find a way to supply the vss signal. Jags that run it one way, but from what I've read, it isn't enough signal to supply the ecm in stock form. The only answer I got that 'works' is a dakota digital 8000ppm unit, sold for about $35. It screws/bolts inline with the speedo cable, and still lets stock truck speedo work. The ecm has to be changed to accept this higher pulse width, but once done, will work fine.

Haven't done this myself yet, but am in the process of.

the_merv

iTrader: (88)

If budget allows I would try to adapt a never 4L60E, and tune it.

VSS is pretty important.

hogpuke

Thanks for all the help and info. The swap engine is a 2001 cable throttle 5.3. Currently have a 350 SB with a 700R4 and original NP geared transfer case. The trans is about three years since OH and upgrades and works fine so I'd like to run it if it's not going to cause too much screwing around. So if the Dakota Digital unit would work, how involved is it to reprogram the ECM to accept it?

garys 68

iTrader: (1)

You need a VSS, without it you;ll have stallong issues.
Buy the Dakota Digital pass thru VSS.
Contact LT1swap.com for the ecu programming.

LS1MCSS

iTrader: (18)

With the 700R4, you're also going to need a TV cable hookup. Your best bet is to just find a 4WD 4L60E and call it a day.

hogpuke

Jagsthatrun has a differential-mounted reluctor ring that uses the 40-pulse VSS. Any opinions on that?

the_merv

iTrader: (88)

Since you have the 700R4 already see if you can convert that to a VSS with the Reluctor Ring..I beleive with the 4x4 it's in the Transfer Case tho...given the low range.

hogpuke

I think it would have to be in the transfer case. I don't hink there's anywhere to put one on the short transmission tailshaft. Any idea who would have something like that?

k5383

iTrader: (10)

Your mechanical speedo is driven off the T-case.

You have 2 options, what they've listed above for the adapter.

OR switch to a newer case, they vss tone rings built into them.

Post up which case you have, and we can go from there.

the_merv

iTrader: (88)

Decent used Transfer Case might be cheaper..

hogpuke

This is starting to remind me of the sink drain stopper I wanted to replace and when it was all done, I had a new drain, new trap, new faucet and a hole in the wall chasing down the old drain pipe until I got to spot good enough to attach a coupling!
The transfer case is NP205.
What about the differential-mounted ring? Do you guys know anything about these? They show it on the rear driveshaft yoke but couldn't it be mounted on the front yoke at the transfer case? Does the sensor care which way the reluctor turns?

Dothedew

The diff ring is an option, and apperently works ok; not something you'll likely want on a 4 wheel drive though; get caught up on everything. I'd stick with the dakota unit, cheaper and easier, and you don't have to change any big parts.

k5383

iTrader: (10)

You could* try and find a later NP205 that has an electric speedo.

I believe the 1 ton TBI trucks had them... could have only been when behind a SM465 though.

git_sum

iTrader: (10)

Want to revive this thread.... I'm doing a similar swap in a 88 wrangler. 5.3, sm465, np205, dana 40 front, 12 bolt rear ect full size chevy stuff. I've got a good tuner but i'm unsure what i need to run for a vss. I see people talk about the vss from JTR (Stealth Conversions), specifically number 3. A 40 pulse per driveshaft revolution speed sensor used on 1993 and newer trucks with automatic transmission, 1994 and newer rear drive cars (Camaro, Corvette, and Caprice) with the automatic transmission. My question is does this just screw into the tail housing on the stock np205? Wouldn't it need a 40 tooth wheel to read or does it just convert the stock np205 unit?

garys 68

iTrader: (1)

If you have a transfer case with a reluctor and provision for a VSS, you can just add it.
The JTR differential mounted reluctor/VSS is for an S10 diff, dont know if it will work on a 10 or 12 bolt.
If you only have a mechanical speedo output, Dakota Digital makes a pass thru VSS that connects to the speedo output. It will provide the signal the ecu needs to preventing stalling issues. You can have the ecu retuned to read the DD VSS PPM count correctly but doesn't make any difference.

patooyee

iTrader: (1)

You don't need VSS to idle. I have no VSS on my buggy and it has never stalled and idles fine.

http://www.youtube.com/watch?v=QFVOcBuZfb8

With some fab skills you CAN adapt an NP241 output shaft tone ring onto an NP205:

http://www.pirate4x4.com/forum/showt...=770136&page=2

Or the Jags that Run cable to electric adapter will also work. I have a new one for sale that I never used if someone wants it.