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Thread: Speedo signal from PCM

  1. #1
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    Speedo signal from PCM

    Our LT1 swap into the 79 Malibu needs a solution for speedometer. We have the 4L60E with the swap so there is an electronic signal to and from the PCM that will be available. We dont want to hack up the original horizontal sweep speedo in the Malibu but since it normally works off a mechanical cable, I guess it wont be reading for us since the 4L60E has no cable drive. We were thinking of installing a stand alone GPS speedo and calling it a day.

    I know we can buy expensive electronic cluster for the Malibu we're not loving that idea.

    Do any of you have any other ideas or suggestions on speedo arrangement in a swap like this?

    The GPS idea would probably be a 2" A pillar pod mount like this from AEM. > AEM GPS Speedometer

    Thanks

  2. #2
    Super Moderator dave w's Avatar
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    Have you checked with JTR for the 4L60E cable driven speedometer options they offer? Rumor has it that some 700R4 tail housings that use cable speedometers will fit some 4L60E.

    https://jagsthatrun.com/products/rel...99275fa3&_ss=r

    dave w

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    Quote Originally Posted by dave w View Post
    Have you checked with JTR for the 4L60E cable driven speedometer options they offer? Rumor has it that some 700R4 tail housings that use cable speedometers will fit some 4L60E.

    https://jagsthatrun.com/products/rel...99275fa3&_ss=r

    dave w
    Won't I loose the electronic speed sensor from that location if I install a cable drive gear? I think that sensor is needed for transmission shifting control of the 4l60E via PCM. Is it not?

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    Super Moderator dave w's Avatar
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    I recommend checking with JTR, they have a cake and icing solution! (Both cable drive for the mechanical speedometer and the computer signal for shifting)

    Not sure the solution is in the budget, but good cake and icing are rarely wallet friendly.

    dave w

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    Quote Originally Posted by dave w View Post
    I recommend checking with JTR, they have a cake and icing solution! (Both cable drive for the mechanical speedometer and the computer signal for shifting)

    Not sure the solution is in the budget, but good cake and icing are rarely wallet friendly.

    dave w
    Understood

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    You talkin like this part is all I need?

    https://jagsthatrun.com/collections/...edometer-cable

    No wait...I bet I'd need a 700r4 tail housing and drive gear too.

    Then there's this option, if I could splice into the VSS wiring for the signal without affecting its signal delivery to the PCM >

    https://www.dakotadigital.com/index....rod/prd886.htm
    Last edited by JD1964; 07-10-2020 at 05:11 AM.

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    10-07-2020 12-00-35 PM.jpg
    One of these or similar may be an option. Goes inline gives electronic pulse and mech cable attaches to end
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    Super Moderator dave w's Avatar
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    I was thinking something like this for cake and icing: https://www.word-works.com/shiftworks/tailhousing.htm

    The kit will convert your 1993-97 4L60E transmission to a factory mechanical speedometer while retaining a functional VSS capability. This is a simple 30 minute bolt-on installation.

    The conversion kit includes the tail housing, new speedometer sleeve with new gear, new VSS sensor, new reluctor/drive gear bushing, and bolts.

    $500

    4L60E-1993-97-Tailhousing.jpg

    Maybe DIY conversion would be less money?

    dave w

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    Chew on this but I can't seem to find any on Ebay or the wreckers...idk if it uses same reluctor/tone wheel though either.

    http://www.montecarloss.com/communit...Number=1039065

    Edit: Oops! I missed the part you said you have the long sweeping speedo! Move along, nothing to see here...



    Last edited by stew86MCSS396; 07-11-2020 at 02:18 AM.

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    a standard 700r4 tailshaft will bolt providing the 4l60e has is pre 98. you can then swap a 700r4 output shaft or carefully measure and drill the hole for the speedo clip. then you can run a speedo cable. either run an inline vss or drill/tap or weld on a magnetic sensor and press on a 40 tooth reluctor behind in front of the speedo drive gear. the shift works is a nice piece but expensive. if you don't have the skill set to mod one probably worth it.

    not my "thing" but pretty sure Dakota makes a digital dash for that era a-body....

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    A 79 Malibu is not an "A-Body". That would be a 68-72 Chevelle, El Camino, Monte Carlo, etc. But yes, a Dakota Digital HDX cluster is my thing and it works well on my 70 El Camino using the VSS / speedometer signal from the PCM. And it is very accurate once calibrated along a precisely measured one mile length of road.

    Rick
    1970 Chevy El Camino, LM7 Engine, 4L60E - Two 896 and two 0411 PCM's

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    I was under the impression 78-80 was considered an a-body then in 81 they renamed to g-body and a-body turned into FWD.

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    g-body was from 78-87

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    I'd say you're looking for one or more of these products. Top row of the search mostly.

    https://jagsthatrun.com/search?type=product&q=4L60

    I personally wouldn't run the PCM from an inline sensor. Any instability of the sensor signal will mess with the transmission operation. The sensor that plugs into the tailshaft and gives both is 4000 pules per mile. The 40 tooth reluctor ring is typically something like 50,000 or more pulses per mile. I don't know if the lower pulse signal would mess with the transmission operation or not.

    Dakota Digital has a dash for $800. Their dashes give some really nice features and work well. I tried to figure out what you're trying to do for a 65 Impala, but finally just did the DD dash. They didn't have a dash for the car at the time so I modified the dash insert and made a universal cluster work . It ended up being a much, much cleaner installation. The advantages were well worth the extra cost vs trying to add both a cable and pulse output to the transmission.

    I couldn't see the point at all of using one of those $500 cable driver boxes compared to what the DD dash at $800 gives. For me, that was not even worth a second though.
    Last edited by lionelhutz; 07-13-2020 at 04:00 AM.

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