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  1. #1
    Join Date
    Jan 2006
    Country Flag: United States

    Just put in a 8-speed transmission into my 2nd gen..

    lol.... well not exactly. Actually I just completed my Gear Vendors install and turned my TH700R4 into an 8 speed transmission.

    Frankly this may be the best modifiication I've done to the car since converting it to EFI. Having 8 speeds available makes the car WAAAYYYY more fun to drive during spirited driving. It's a very high quality kit and it is absolutely worth every penny.

    Although I was intending to do the GV upgrade for a while, I always had just the tiniest bit of reservation, as I was curious mainly about how hard it was sometimes reported to shift.. kept hearing a mixed bag of stories. Fortunately GV was within driving distance of my house, so I ended up driving down to GV after calling them and asking about it. One of the techs had one in his LS powered hot rod Chevy truck and offered to take me for a spin in it before I committed to the purchase. Long story short, his truck drove really nicely and shifting felt firm but good (not at all too harsh).... like a good shift kit. I bought one there right on the spot.

    Any rate, after getting it installed temporarily with their controller box to validate the operation, I decided to clean everything up by having it run on my EFI ECM. Since I never plan to use the autoshift feature, I would really only be using it to keep the safety feature of preventing the unit from engaging below 20-25 mph. It's something I could get my EFI ECM to do, and then save some extra wiring and hardware being on the car.

    The fluid pressure needed to do the shifting is generated by a pump that runs basically in proportion to vehicle speed. Below 20 mph, it has trouble holding pressure and you can generate excessive clutch wear over time. People who run the unit purely manually have to bear this in mind and turn it off manually when coming to a stop. The GV controller unit (among other things) essentially locks the user out of manual control until you reach 20-25 mph.

    Because I'm running a TH700R4 with electronic VSS to run the EFI computer (which in turn runs my Sport Comp II electronic speedometer), they set me up with a unit that has electronic VSS (rather than the typical cabled driven adapter).

    The good thing for me also is that my TH700R4 torque converter lock up is not controlled by the ECM (it was installed before the EFI and only takes a 12v source to the main connector such that the converter will autonomously lock when in 4th gear).

    That left the TCC control outputs on the ECM open and free to use as a speed activated switch. So I basically installed a relay in between the manual GV switch and the GV solenoid. Then I programmed the computer to activate the TCC lock above 20mph and disengage it below 20mph. In other words, when I'm below 20 mph, the ECM will open the relay and lock me out of controlling the GV.

    Also, instead of the foot switch (which I never intended to run), I wired in a small tactile momentary switch into the stock shift handle and then from website, I put together a relay pack that converts the momentary switch to produce a toggle switch circuit. The tactile switch setup may only be temporary though as I kinda "mickey-moused" it in for now just for proof of concept. I may end up getting a factory shift knob from another car that has an overdrive control button on the knob and then try to adapt it onto my shifter.

    Any rate, the GV isn't something you'd typically use during normal "grocery getting" type driving. The car obviously has more than enough power to just use the four normal gears. But yeah, when you want to have some fun, or for instance, when you'd ordinarily be caught at a speed where you'd be lugging in 3rd to accelerate but really don't want to downshift into 2nd and blast it, having that gear in between 2nd and 3rd is just absolutely perfect.

    Also, after getting a little used to the gear splitting, I took it for a moderate blast up a freeway on-ramp. The most noticeable difference overall is the gear split between 1 and 2... That "lugging" feeling that was normally there after shifting into 2 is completely gone. With transitions from 1st to 1st-over to 2 shift, it feels like a near seamless acceleration getting finally to 3rd gear. Yeah, this thing is worth every penny.

    The icing on the cake is that the mileage readout at 65 mph went from 28-29 mpg to 31-32 mpg when the "double overdrive" is on.

    My next step is to put in (most likely) a 3.90 axle ratio. I was looking to do a 427 small block down the road, but my suspicion is after doing the 3.90's, I'll probably be satisfied. For what I'm able to do around town (w/o getting into trouble), having a set up like this and a 500+hp engine is going to be too much and probably not worth the money. If my engine ever goes out, the most I'd probably do is put in a 383 or something.

    P.S.... it's definitely true you have to cut out most of that floor brace that goes over the tunnel. That was definitely the most difficult part of the job (and the dirtiest) having to get under there with a grinding wheel while lying on my back working upside down. But it doesn't seem to have adversely affected anything.
    See me in Camaro Performers

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  2. #2
    Join Date
    Oct 2018
    San Jose, CA
    That should be a lot more reliable than the 8 speeds Chevy is shipping with the new Camaro's and Corvettes and trucks!!

    Do you have pictures of how far back you have to cut the tunnel?
    1971 Camaro - 406 / T56
    2016 Camaro SS convertible
    2018 Colorado 4x4