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Thread: Random questions...

  1. #1
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    Random questions...

    1- Why do some cars have a rear diffuser that's tucked up to the body, and others have one that's spaced way down?

    2- What do people do for door mechanisms that aren't running outside handles?

    3- Is cruise control setup to work with the kit, or do you need to add something to make it work? For reference, I am using a stock ECM and I have no speed sensor on my trans (running GPS for the speedo).

    4- Painting body on the chassis or off?

    5- Does a rear view mirror do anything in a GTM?

    That's it for now. I'm just looking at random GTMs online for motivation.
    Sal Mennella
    Unfinished GTM #30 FFR - in progress!
    Roadster 5132 - sold

  2. #2
    VRaptor SpeedWorks, LLC's Avatar
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    1. That was a change that FFR made between the Gen I and Gen II. The diffuser profile of the body is the same on Gen I and Gen II cars, but FFR shipped a different shaped diffuser with the later Gen II cars that was designed to be spaced away from the body.....rumored to be because the sharp transition/angle of the Gen I diffuser was too sharp to make the diffuser usable for creating downforce and the shallower angle of the Gen II diffuser was better in that regard. Again, the body is shaped the same on both generations, so you could use a Gen I diffuser on a Gen II car or vice-versa if you wanted to.

    2. Electric door solenoids. 50#. We normally install a small momentary push button in the body right behind the door under that lip of the scoop area of the body, which acts as the "door handle" to activate the solenoid and open the door. Even when using door solenoids, I always still use a mechanical rod linkage and hook up the inside door handles like normal.

    3. Not sure if anyone has successfully done cruise control or not? I know we tried to use a Dakota Digital cruise module years ago when they first came out....and it didn't work. You'd be driving down the highway and suddenly the accelerator would just "disconnect" and you'd have no control over the throttle and the engine would go to idle and you'd have to coast to a stop along side the road, shut the car off and restart it to get throttle back again.

    4. Always off the chassis on a body buck.

    5. It does take up a ton of your "mail slot" view of out the windshield. Yes, it is useful to see behind you, but IMO, is hugely outweighed by restricting the view out the front. We normally just don't install one. The car I'm working on now has a rear view mirror that is really just a screen with a rear camera that projects to the "mirror". This way, you can mount the "mirror' way up high on the halo instead of the windshield and not restrict your front view.
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
    Turn-key GTM, SL-C & Ultima GTR Built to Your Specs!
    Offering a full line of GTM Upgrades and Custom Parts

  3. #3
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    Thanks Shane. What do you do for emergency door opening in case of power failure?
    Sal Mennella
    Unfinished GTM #30 FFR - in progress!
    Roadster 5132 - sold

  4. #4
    VRaptor SpeedWorks, LLC's Avatar
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    Run a cable forward from the door latch into the front wheel well area on one door. Honestly, you can look right down thru the slot the window comes up thru and see the whole door latch.....on most GTM's you could probably open the door with a paint stick or almost anything that would reach down to the latch and push down on the release lever.
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
    Turn-key GTM, SL-C & Ultima GTR Built to Your Specs!
    Offering a full line of GTM Upgrades and Custom Parts

  5. #5
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    3 - I'm not sure about all the ins and outs of cruise control in the stock ECM, but I'd imagine you have to have at least the transmission speed sensor and the wheel speed sensors hooked up. Beyond that, and how the stock system communicates, I'm not fully sure.

    I have elected to run a MoTeC M170 aftermarket ECU that can handle this task for me easily, but that would be a hugely cost prohibitive step just to get cruise control.

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  7. #6
    Senior Member beeman's Avatar
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    The main components of the cruise control system include the Throttle Actuator Control (TAC)
    module, Powertrain Control Module (PCM), cruise control functional switches, cruise control
    release switch (A/T), cruise control brake switch (M/T), brakelight switch and clutch switch
    (M/T).

    https://www.tuningconcepts.com/Cars/...%20CONTROL.pdf
    MK3.1 2004 Mach 1 donor. ABS, PS, TC.
    GTM #304 LPE 525hp LS3
    2000 C5 Lingenfelter LS1@489hp
    1999 Corvette FRC/Z06 track car

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  9. #7
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    As far as the diffuser thing...not really sure why the diffuser mounting changed on the Gen II. Anything over about 10 degrees makes the diffuser non functional. I think the addition of the spacers may have had more to do with getting more hot air out of the engine compartment than helping with activating the diffuser as the spacer difference really did very little in that regard...IMHO.
    www.myraceshop.com

    GTM solution kits
    Corvette and Race parts

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  11. #8
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    Shane... can you post info on the door poppers that you use?

    Thanks to everyone so far for the great feedback and info.
    Sal Mennella
    Unfinished GTM #30 FFR - in progress!
    Roadster 5132 - sold

  12. #9
    VRaptor SpeedWorks, LLC's Avatar
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    Ok....Autoloc seems to be the "gold standard" for door solenoids. With that said....here are a couple of links. Look at the solenoids. Look at the hardware....the bolts, the brackets, the button, the cable. I've used both. I can't tell the difference. The fact that all of the hardware that come with is 100% identical, tells me that the solenoids are also all from the same manufacturer.....just re-branded and packaged differently.

    https://pitstopusa.com/products/auto...xoCmCgQAvD_BwE

    https://www.ebay.com/itm/403969040221

    I bought the ebay set (x2) and just installed them in both doors yesterday. Where the 3 small holes are in the stud for the solenoid for the cable to route thru, I opened the center hole up to accommodate a plastic linkage clip and used a chunk of the donor door linkage rod to attach to the door latch. I already had the mounting plates drawn up as I've used this set-up multiple times in the past. I did have to grind a bit off the top edge of the factory solenoid bracket to get the solenoid positioned where I wanted it.....and yes, it's TIGHT......as you can see, the bottom of the solenoid is tight against the door fiberglass. 50# solenoids will seem pretty violent and severe.....until you get your door weatherstripping in place....which puts a great deal of outward pressure on the door when it's closed......and that outward pressure on the latch makes it much, much, much harder for the solenoid to release the latch with the door closed than just bench testing it with no pressure on the latch. I don't have the mounting plates advertised on my website (along with probably 90% of the other stuff I have designed that I use repeatedly for my own uses on the builds I do in house here.....but could be persuaded to offer them if anyone wants to use them.


    Popper1.jpgPopper2.jpgPopper3.jpg

    Edit to add.....if you look at the bottom photos of the ebay unit, is shows a rectangular hole in the solenoid stud to attach the linkage to. The ones I received (yes, that is the actual seller/auction that I just purchased them from last week) are like shown in the very first photo...and the same as shown for the Autoloc in the first link.
    Last edited by VRaptor SpeedWorks, LLC; 11-01-2024 at 11:39 AM.
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
    Turn-key GTM, SL-C & Ultima GTR Built to Your Specs!
    Offering a full line of GTM Upgrades and Custom Parts

  13. #10
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    So I'm assuming when those solenoids are fired they pull in and then pop back out?
    Sal Mennella
    Unfinished GTM #30 FFR - in progress!
    Roadster 5132 - sold

  14. #11
    VRaptor SpeedWorks, LLC's Avatar
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    Yes.....the solenoids do have a spring in them that pushes the plunger back out when voltage is removed. Some of the other cheap solenoids don't have that. Yes, they pull in when activated.....violently.....
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
    Turn-key GTM, SL-C & Ultima GTR Built to Your Specs!
    Offering a full line of GTM Upgrades and Custom Parts

  15. #12
    VRaptor SpeedWorks, LLC's Avatar
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    Oh.....and depending on how the whole system acts together, most of the time I end up pushing the pivot pin out of the inner door handles, removing the clock springs and put them back together, as that spring in the inner door handle is fighting against the door popper. If I feel those springs are necessary to pull the latch back to the "closed" position, I'll leave them in.....just sort of depends on how well everything seems to work together on each car.
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
    Turn-key GTM, SL-C & Ultima GTR Built to Your Specs!
    Offering a full line of GTM Upgrades and Custom Parts

  16. #13
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    Anyone recognize what this is? I've got a pack of 15 or 16 of these that came with my car.

    20241117_153142.jpg
    Sal Mennella
    Unfinished GTM #30 FFR - in progress!
    Roadster 5132 - sold

  17. #14
    VRaptor SpeedWorks, LLC's Avatar
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    That is not a GTM part....and the part number doesn't look like a FFR number.....so I'm guessing totally unrelated to the GTM?
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
    Turn-key GTM, SL-C & Ultima GTR Built to Your Specs!
    Offering a full line of GTM Upgrades and Custom Parts

  18. #15
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    Quote Originally Posted by VRaptor SpeedWorks, LLC View Post
    That is not a GTM part....and the part number doesn't look like a FFR number.....so I'm guessing totally unrelated to the GTM?
    Okay, I wasn't sure. My car came with a lot of early custom parts that were made by individuals back in the day like Russ Thompson and David Borden, so I wasn't sure if this was something I had not seen before.
    Sal Mennella
    Unfinished GTM #30 FFR - in progress!
    Roadster 5132 - sold

  19. #16
    VRaptor SpeedWorks, LLC's Avatar
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    I'm not saying they aren't for the car....but they aren't something that FFR shipped with the kits and not anything I've ever seen before.
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
    Turn-key GTM, SL-C & Ultima GTR Built to Your Specs!
    Offering a full line of GTM Upgrades and Custom Parts

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