VSS TBI Option? JTR not making what I need anymore.

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NikP

NikP

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I installed a 92 Chevy TBI in my 75 FJ40. I placed an order for the JTR speedo driven VSS and after 10 days they say they are going to make them.

They sell a reluctor ring version that bolts on the PTO shaft but it can't bolt on with the AA crossmember. I saw someone retrofitted a mount on the cross member but are there any easier options?

I'm not interested in Swapping out to electric speedo. Too costly.


Looking for something to bolt on.

Nothing is ever easy is it?
 
You need a 2 pulse VSS, and the hardest thing to imagine is that Stealth discontinued them, hot hot item. Did you ask them for part number #2PRS-TOY ????
 
Downey said:
You need a 2 pulse VSS, and the hardest thing to imagine is that Stealth discontinued them, hot hot item. Did you ask them for part number #2PRS-TOY ????
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Yes, ordered from their website.

Hadn't heard anything so sent email to ask. Here's the response: I'm pissed!

Sorry for the delay.
I needed to talk to Mike about your order.
He doesn't seem to think that he will make them anymore.

I will return your payment through paypal.
 
NikP said:
Yes, ordered from their website.

Hadn't heard anything so sent email to ask. Here's the response: I'm pissed!

Sorry for the delay.
I needed to talk to Mike about your order.
He doesn't seem to think that he will make them anymore.

I will return your payment through paypal.
Click to expand...
Did they tell u why? That's strange, I can't imagine they are hard to make.
 
From my understanding, If you ever decide to go with a Dakota Digital instrument cluster the computer box has an output that can be set for different pluse outputs.

I talked with their tech extensively about this and he said the output should work great for this.

Just another option....
 
I admit I haven't studied the electronics of a GM TBI speed sensor circuit but here's a thought.

What if I purchase the standard chevy VSS for less than $20. Doesn't it just need a rotating magnet to register pulses?

So then buy this collar with magnets - mount it to the driveshaft and formulate a simple bracket for the stock VSS sensor.

It should pick up pulses right?

I figure my 33 inch tire makes 630 revs per mile... X 4.1 gear ratio would put the driveshaft spinning 2583 revs in a mile.

The stock VSS needs 2000 revs per mile so I really only need on magnet located on the driveshaft and I should be in the ball park right?

I'm in for around $60-70 and some fabrication.


s-37x-ring.webp
shaft-collar-drawing.webp
 
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I'm following this closely - your idea would seem to work, as long as the pulse count is right. On the JTR website, there's a .PDF file with an image showing a reluctor ring mounted on the diff pinion flange, which is a variation of what you're suggesting.
 

Attachments

After looking at this, I assume anything mounted on the driveshaft will require something to emulate a 40-tooh reluctor ring since that's what is mounted in all transmissions it seems.

The JTR reluctor ring I'm assuming won't match the Toyota diff or drive shaft bolt pattern so the question becomes, how would it be mounted? For those of us with a stock parking brake drum, there might be a way to fabricate something to attach it to the drum but I'm not sure it would read correctly if backed by the drum. Would it need spacing?

I need to determine where the sensor was mounted on the 92 chevy. If it was on the transmission shaft with a 40 tooth reluctor then this is all feasible. If it was part of the speedo cable, then we'd have to figure out the pulse difference and see if it could be replicated somehow.
 
Do you just need this for TBI? That only requires a 2-pulse VSS. I believe there are other in-line 2-pulse VSS manufacturers/vendors than JTR. Get a 2-pulse with SAE fittings and send your speedo cable and VSS to a speedo shop to have the cable adapted for installation of the VSS a few inches away from the speedo housing. A number of speedo cable shops have been mentioned in these pages over the years.

1996 Vortec and later require the 40-pulse.
 
Yes, just for TBI. I was hoping for something to bolt on and not have to make one-off cables. It my be my best option though.
 
It's not really a big deal. How often do you replace a speedo cable? Hell, have them make two cables for you at the same time and then you're set for life.

NikP said:
Yes, just for TBI. I was hoping for something to bolt on and not have to make one-off cables. It my be my best option though.
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Greg from JTR called me because I had asked questions about other options. When I called back he and Mike were rude. They forgot they called me... anyway basically they said F%$ Off we can't or don't want to help you.
 
I didn't find them helpful years ago when I needed a 40-pulse, so I built my own.

NikP said:
Greg from JTR called me because I had asked questions about other options. When I called back he and Mike were rude. They forgot they called me... anyway basically they said F%$ Off we can't or don't want to help you.
Click to expand...
 
Not sure if this pertains to your current installation, but I have a VSS from AutoMeter connected to the speedo port. It can also be used as a pass through using the stock cable connected to the back sick of it. The AutoMeter has the wrong signal for the computer, but I was able to install a converter from Dakota Digital which the computer accepts. Seems like a bit much for your application, but an option.
 
Tools R Us said:
Will the VSS in the factory speedo work with TBI?
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Not sure. I read something about it but I'm not sure I found anyone really testing it out.

I'm not sure I'm smart enough on sine waves and all that stuff to know for sure. It would be easy to connect two wires to the speed but I don't want to screw anything up.

If someone could confirm it's DC in the proper range I'd contemplate hooking it up.
 
I found to threads discussion the internal reed switch in the speedo as a VSS.
Correct speed sensor (VSS) info for 3FE swap
Fj40 Instrument cluster HELP !

It looks like I can connect one terminal to ground, the other to the ECM VSS wire and it will supply pulses. Too many for my ECM.

Does anyone know I'd the ECM really cares or it it just cares that it's moving?

Also, is there any harm hooking it up to see? I'm not an electrical engineer so want to make sure it's generating the right signal. Smart engineers, what's your perspective?
 
I'm certainly no TBI expert, but I can see from the TBI diagrams that the VSS signal for a 7747 ECM is supplied by a permanent magnet generator. PMGs and mag-pickups (MPUs) generate a voltage/frequency/wave-form based on engine RPM and design of the PMG/gear/MPU/reluctor. I don't know what a TBI normally gets for speed input from the PMG, but a MPU typically puts out a few volts at nominal rated engine speed.

I have never looked into a speed switch on a Land Cruiser cluster, but per the posted info they appear to me to be reed switches adjacent to rotating magnetic poles. So, you could possibly use the LC speed switch if you applied voltage to it and allowed it to interrupt that voltage going to the ECM. It would be a square wave at whatever voltage you applied. 12V would be the easiest voltage to apply, certainly, but is 12V OK for the 7747 ECM? I don't know. Seems appropriate, but I also see on the TBI diagrams that they use a buffer between the PMG and the ECM. The voltage chart on the TBI diagram shows, as best I can read on the diagram that I have, that the VSS signal voltage varies from 0.6v to battery voltage. So 12v seems appropriate, but I don't know what that buffer does. Maybe it just damps the signal. Maybe it rectifies the signal. I don't know.

OK, with all that being said, for a TBI installation where there is no transmission control or ignition advance control I believe the ECM only needs to know when the vehicle is coming to a stop so that it can idle-down appropriately. I've read a lot of complaints from people with TBI and no VSS that their engines stumble or race when coming to a stop. It may not matter significantly whether the signal is from a 2-pulse, 4-pulse, or 6-pulse sender, as long as the ECM can sense that the vehicle is slowing to a stop. Perhaps you can do some testing and report back.
 
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I think the wire from the ECM would actually supply the necessary power since on a two wire VSS one wire is connected to ground and the other to the ECM VSS wire.

If the reed switch just interrupts the ECM supplied signal I think it should work. I sure feel better if some would say yes they do it that way.
 
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