04 LM7 into 87 K5

Vbb199 said:

there might be something major im missing here, but if you use the VSS adapters in place of the cable "box" , you cant run a speedo cable also, unless maybe you do like what that guy above did. It appears he can have his speedo cable for his instrument panel as well as VSS for the PCM

Because if you use solely VSS, then you have no speedometer, which puts you needing a 90-91 instrument cluster from a burb k5 or 1 ton

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Right but i *believe* if i use the adapter, i can get my vss signal at the adapter (between transmission and transfer case) - this leaves the speedo cable in the transfer case untouched. So i *think* that is the best of both worlds unless it changes driveshaft length or the pcm needs to see vss specifically at the transfer case for some reason ? <— Which I dont think that it does but I can’t confirm. Both would kind of be a deal breaker

(Duplicate)

K5Rob said:

or the pcm needs to see vss specifically at the transfer case for some reason ? <— Which I dont think that it does but I can’t confirm. Both would kind of be a deal breaker

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I dont think it matters where it gets the vss signal from, you should be ok

Theres people running mega trucks with aftermarket drop transfer cases behind their 4L80e, and they just weld a reluctor on the output shaft of the drop box and put a magnetic pick up there to count the teeth.



Sounds like youve about got all the bugs worked out

Thanks vbb. Could anyone touch on the high/low range switch? I know ppl are using a switch that they either epoxy or screw to the shift gate so it is actuated when put in low. What pins on the pcm do I wire this switch to?

If you have the speed sensor before the transfer case there will have to be some way to tell the speedo it’s in low vs high range to correct the reading. If the speed sensor is reading from the output of the transfer case it will read correctly regardless of high or low, as it’s reflecting the true output speed.

legopnuematic said:

If you have the speed sensor before the transfer case there will have to be some way to tell the speedo it’s in low vs high range to correct the reading. If the speed sensor is reading from the output of the transfer case it will read correctly regardless of high or low, as it’s reflecting the true output speed.

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What i meant was, with a switch wired up, will the pcm shift the transmission correctly?

My speedometer is going to be cable driven off the transfer case in its stock location

K5Rob said:

What i meant was, with a switch wired up, will the pcm shift the transmission correctly?

My speedometer is going to be cable driven off the transfer case in its stock location

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I gotcha, I missed that part about using a mechanical speedo still.

legopnuematic said:

I gotcha, I missed that part about using a mechanical speedo still.

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No worries. My main question is will the pcm shift the 4l60e correctly if i use a switch to tell it that it’s in low. And second, how is the switch wired. Hopefully someone thats done this can chime in

I did a LS swap on my 1973 K5 Blazer with a 4L60E and a NP208 transfer case. I have a terminator max ECU. I am using a walter engineering VSS. I would not say it's a perfect solution. The VSS issue caused me a lot of time and money. Initially the speed would not registerer until 20-25 mph. The VSS sensor was too far from the reluctor wheel to read voltage at lower speeds. I ended up sanding down the plastic sensor holder to get the transmission to shift at lower speeds. Now speed registers at 4-5 mph. I figured that might be good enough. Currently, the Blazer is at a rear end shop getting lower gears installed. The Blazer originally had 3.07s, way too tall for 33" tires and the 4L60E. I am having 4.56 gear ratio installed. I am also using a Dakota Digital gauge set that gets all its readings from the terminator max including vehicle speed. Your concerns with the VSS are very valid because the vehicle will not run correctly without an accurate vehicle speed.

I believe what you'll need to do in order for this to all work out is, you will need the speedo cable off the back of the trans with that ORD adapter or what have you so your speedo will at least work when in high range. (The instrument panel)

You want the VSS coming from the back of the transfer case, so the PCM can shift the transmission if youre in high or low range on the T case.

Thats what lego was concerned about and i believe there was a misunderstanding

Here you go.

Has anyone not looked at this adapter? It goes between the 4l60e and 208. And the speedo cable stays in its original location in the 208. I will be using the factory pcm. I do not see myself using 4 low but would be nice id everything worked. I absolutely do need 4 high and 2 high. Both my tuner and tech support didnt see any issues but they were brief as stated before i’d like to avoid any headaches. Would this not work and why? Has anyone gone this route with a stock pcm?

K5Rob said:

Has anyone not looked at this adapter? It goes between the 4l60e and 208. And the speedo cable stays in its original location in the 208. I will be using the factory pcm. I do not see myself using 4 low but would be nice id everything worked. I absolutely do need 4 high and 2 high. Both my tuner and tech support didnt see any issues but they were brief as stated before i’d like to avoid any headaches. Would this not work and why? Has anyone gone this route with a stock pcm?

4L60E HEX PATTERN/4L60E SHAFT 50-0405E

6 bolt to 4 bolt adapter with VSS for the 1997-Current GM 4L60E/4L65/4L70 4 speed automatic transmission.adapter kit.

www.advanceadapters.com

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If you are picking the VSS signal off before the T-case, then it won't matter if you are in 4-lo or 4-hi. The shift schedule is based on vehicle speed and throttle position, and that won't change if you are in 4-hi or 4-lo based on that signal location. You can still adjust your shift points and things like engine braking with the 4-lo signal, but the shift strategy will be almost identical in the 4-lo table to start with.

Bextreme04 said:

If you are picking the VSS signal off before the T-case, then it won't matter if you are in 4-lo or 4-hi. The shift schedule is based on vehicle speed and throttle position, and that won't change if you are in 4-hi or 4-lo based on that signal location. You can still adjust your shift points and things like engine braking with the 4-lo signal, but the shift strategy will be almost identical in the 4-lo table to start with.

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Can you dumb this down for me? Are you saying 4 high (and 2 high) will behave like 4 low? Or are you saying 4 low will not shift correctly? I thought with the use of a switch, i could tell the pcm “hey i am in 4 low” and it would use 4 low shift tables?

The VSS in the trans (before the Tcase) will read the same speed regardless of the T-case being in high or low. The ECM(PCM) uses VSS for shift tables. I don't think you can use a switch to adjust that.