VSS & speedometer gear ratios

[bikersmurf]

I recently purchased a TPI setup with a Painless wining harness. It came with all the sensors including a VSS that mounts inline in the speedometer cable. It’s an early Chevy style. I know that with 33s and 3.70 gears, the speed wouldn’t be super accurate... but aside from it not screwing in, would it give me a useable signal?

Perhaps the simpler way to ask the question is does a Turbo 350 speedometer cable turn at a similar speed to a stock Toyota speedometer drive?

I’m sure it could be regeared to work... but getting the right VSS would likely be easier than trying to do that.

How do those running Chevy transmissions make a stock speedometer work?

@Downey
@65swb45
@Poser

 

[Downey]

GM Auto tranny should turn about same rpm as L.C. tranny, they are both 1 to 1 in high gear. Spedo drive gear versus tire diameter will come into play, BUT not enough to hinder the VSS signal enough, your VSS will still work. BTW, don't listen to the Mud guys that tell you they didn't need a VSS, their rigs probably run ok (because they don't know any better), but they don't run with the best drivability.

 

[archie73]

Is there something like this to make vss work from back of an Orion and talk to a las ECM?

Speedometer Adapter, Mechanical to Electrical, VSS

Mechanical to Electrical Speedometer Adapter Looking to put a gear-driven transfer case underneath your Tacoma, but having issues adapting your electrical speedometer to the transfer case? Trail-Gear is now offering a Mechanical to Electrical Speedo Adapter to remedy this issue. This...

trail-gear.com

 

[bikersmurf]

GM Auto tranny should turn about same rpm as L.C. tranny, they are both 1 to 1 in high gear. Spedo drive gear versus tire diameter will come into play, BUT not enough to hinder the VSS signal enough, your VSS will still work. BTW, don't listen to the Mud guys that tell you they didn't need a VSS, their rigs probably run ok (because they don't know any better), but they don't run with the best drivability.

Thanks Jim, that’s what I wanted to know. I’ve got enough spare cables around I should be able to make the VSS work with some carefully designed adapters. Always appreciate the input from those who have been there... TPI on a 350 is hardly blazing a new trail. It seems proven and well suited to a slower moving rig.

Since it has square fittings I’ll first look at hiding it behind the dash and out of harms way... but that may change once I layout the wiring harness.

 

[Dynosoar]

JTR (Jags that run) makes a very cool simple vss adapter. for the Lan Cruiser.

Speed Sensors

Why You Might Want One. Without a Vehicle Speed Sensor (VSS) and the reluctor ring that feeds it signals, many engines including the Chevrolet TPI fuel-injected engines we specialize in will not run correctly and will not pass a smog test.Background on Our VSS Products. JTR Stealth Conversions...

jagsthatrun.com

 

[archie73]

JTR (Jags that run) makes a very cool simple vss adapter. for the Lan Cruiser.

Speed Sensors

Why You Might Want One. Without a Vehicle Speed Sensor (VSS) and the reluctor ring that feeds it signals, many engines including the Chevrolet TPI fuel-injected engines we specialize in will not run correctly and will not pass a smog test.Background on Our VSS Products. JTR Stealth Conversions...

jagsthatrun.com

Maybe I’m missing something, but all I see are ones that bolt to the back of tcase when I click on their “Toyota” button. I was hoping to find one that slips into the speedo cable like the Dakota Digital. The JTR ones I see are $270 and the LS swap potential list is growing...

 

[Dynosoar]

Call them they have everything you need.

 

[65swb45]

Call them they have everything you need.

/this\

I trust a recommendation from @Dynosoar on this. If you see his sig line, you’d know he’s been down this rabbit hole.

I have never done this swap. But if I was to do one, I’d be bribing him for tech.

 

[archie73]

/this\ I trust a recommendation from @Dynosoar on this. If you see his sig line, you’d know he’s been down this rabbit hole.

I have never done this swap. But if I was to do one, I’d be bribing him for tech.

I’ll try on Monday. If I do use their vss adapter I’ll have to figure a way to bring a shaft off the SM465 output shaft. My plate adapter/tapped output shaft doesn’t stick out the back of the transfer case like stock or spud shaft applications. Also, my AA crossmember causes another dilemma.

My thought on the speedo adapter(Marlin/Trailgear) was something that didn’t require as much head scratching. It looks like it simply plugs into the speedo cable housing and potentially talks to the ls ecm.

 

[bikersmurf]

Is there something like this to make vss work from back of an Orion and talk to a las ECM?

Speedometer Adapter, Mechanical to Electrical, VSS

Mechanical to Electrical Speedometer Adapter Looking to put a gear-driven transfer case underneath your Tacoma, but having issues adapting your electrical speedometer to the transfer case? Trail-Gear is now offering a Mechanical to Electrical Speedo Adapter to remedy this issue. This...

trail-gear.com

That’s an interesting option... but wouldn’t still drive the mechanical speedometer. Could work for an aftermarket speedometer.

 

[bikersmurf]

I’ve already got an in-line VSS so I think I’ll make adaptors to splice it in-line.

It is already the correct one to use with the computer. The square drive will likely match the speedometer drive... a couple custom fittings and I should be set. $270 usd is more than the painless harness, manifold, tubes, computer, plenum, sensors, and all the bits and pieces cost me. I’m sure the Delron ‘pucks’ in my scrap pile will provide me the material I need to adapt it to cruiser parts.

 

[archie73]

No you’re right about driving the mech speedo, perhaps the Dakota Digital speedometer cable adapter would help with the mechanical gauge. Only problem is it will need an adapter before and after the adapter. It’s sae threads.

I’ve already got an in-line VSS so I think I’ll make adaptors to splice it in-line.

I’d be interested in how you have one set up. I’m sorry if I hijacked your thread.

 

[bikersmurf]

No you’re right about driving the mech speedo, perhaps the Dakota Digital speedometer cable adapter would help with the mechanical gauge. Only problem is it will need an adapter before and after the adapter. It’s sae threads.



I’d be interested in how you have one set up. I’m sorry if I hijacked your thread.

No worries. I’m all about getting the information out.

 

[65swb45]

I do know that people occasionally ask me for the factory inline speedmarker relays that Toyota put in the FJ40 around 1970. I guess they provide a pulse the people use for a vss trigger. And they don’t give up the speedometer function.

 

[Downey]

The point that has not been brought up yet in this discussion is that TBI requires a 2 pulse square wave DC signal, and you guys are probably discussing 4 pulse sine wave AC and/or 40 pulse options. I'm thinking Dakota Digital #GPS-50-2 and #600041 might be the way to go.

 

[bikersmurf]

The point that has not been brought up yet in this discussion is that TBI requires a 2 pulse square wave DC signal, and you guys are probably discussing 4 pulse sine wave AC and/or 40 pulse options. I'm thinking Dakota Digital #GPS-50-2 and #600041 might be the way to go.

For TBI and TPI 85-89 the two pulse module is needed (per Jags that run). Four pulse are used with electric speedometers, and not as useful for a 40.

I’m new to this, so please correct me if I’m wrong.

 

[Downey]

You are correct that the 4 pulses are generally used with electronic speeds, but there could possibly be some fuel injections that also use the 4 pulse. 40 pulses are used on the newer LT1 and Vortec engines.

 

[bikersmurf]

Here are a couple pictures of mine.
A google search leads me to believe it’s:

"Masstech" and TR8-2525-2

From: SD tune - Page 4

 

[terrx]

How do those running Chevy transmissions make a stock speedometer work?

Assuming it's mated to a stock LC transfer case, BTB sells an adapter cable from LC metric threads to VSS:

FJ40 Speedometer Cable Adapter to Electric SPEEDO Generator 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984 - BTB Products - Land Cruiser

THIS SHORT SPEEDO CABLE ADAPTER ATTACHES TO THE TRANSFER CASE AND EXTENDS OUT 6-INCHES ALLOWING SPACE FOR A VSS, RATIO ADAPTER, OR OTHER SPEED TYPE GENERATOR. THEY ARE OFTEN USED FOR FJ40 DASH CONVERSIONS WITH ELECTRIC SPEEDOMETERS.

btbprod.com

They might have a longer version to connect VSS to stock speedo. If it's not listed on the website maybe give them a call.

 

[bikersmurf]

Assuming it's mated to a stock LC transfer case, BTB sells an adapter cable from LC metric threads to VSS:

FJ40 Speedometer Cable Adapter to Electric SPEEDO Generator 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984 - BTB Products - Land Cruiser

THIS SHORT SPEEDO CABLE ADAPTER ATTACHES TO THE TRANSFER CASE AND EXTENDS OUT 6-INCHES ALLOWING SPACE FOR A VSS, RATIO ADAPTER, OR OTHER SPEED TYPE GENERATOR. THEY ARE OFTEN USED FOR FJ40 DASH CONVERSIONS WITH ELECTRIC SPEEDOMETERS.

btbprod.com

They might have a longer version to connect VSS to stock speedo. If it's not listed on the website maybe give them a call.

That's an interesting option. I bet a new end could be put on the stock cable to match it to the other side. I'll keep it in mind, but my first thought is to mount it at the back of the speedometer.

Any thoughts about it putting too much strain to run at the far end of the cable? Most seem to be mounted at the transfer case.