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  • Is there a market?

    Is there a market for a custom lowered TJet chassis? I am talking about a Tjet type chassis (screw on body) with an AF/X chassis stance. There a bunch of TJet bodies that would benefit from this.

    Why doesn't my car run like that?


  • #2
    You would probably be able to sell a fair number of those. If you are racing Fray or T-Jet SS type cars you lower those by using undersized tires and special bodies without a rear window so that there is clearance for the chassis in back.
    Several things can be done to lower the chassis while still using standard parts. The axle holes could be moved up so the car was lower even if scale diameter tires were used. A new gear plate that was more like the A/FX or Magnatraction type would also be needed.
    Coming out with a new chassis is more complicated than you would expect. If you used 3D printing you could perfect the chassis without having to modify the tooling needed for injection molded parts. If you expected to sell a lot of chassis injection molding would be the way to go however. The tooling is expensive partly because it has a number of moving parts and designing the tooling for an injection molded chassis is not as straight forward as you would expect. Plastic shrinks when it is cooled down and ejected and the parts will be somewhat smaller than the size of your molds. Different types of plastic will shrink by a different amount and the shrinkage will be different with respect to the different dimentsions. You have to select the type of plastic to use, then design the tooling to allow for shrinkage, if you get it wrong the tooling will have to be redone costing you more time and money.


    • #3
      I never thought there was much of a need Scott, and of course I was wrong. FFWD a dozen years. Notably, Jags latest chassis contribution fills the "lowered chassis for screw on" niche admirably, and as bonus it includes the rocket inline power and reliability that many crave. I did have to giggle when I saw the disclaimer that: some bodies may require mods to aid fitment. I could write a book on it. Of course what the Jag doesnt include is the classic T-jet pancake armature, and all that glorious monkey motion slinging around the intoxicating scent of hot red oil.

      Production wise, the chassis, gear plate, and pinion shaft require simple modifications, but the mods have to be accurate to keep things square and plumb. As I mentioned in the other thread, there's also some shoe voodoo involved, depending on the model and wheel/tire choice. This means I may use standard T-jet shoes, an AFX step or ski, or one of the assorted old BSRT Fray shoes (no longer in production?); and, either a standard T-jet spring or an AFX spring. The controlling factor for this aspect is which of the three front axle bore options one chooses. Because of this more advanced "set up" component, I had a hard time justifying the T-jet "drop axle" as a viable undertaking enmasse.

      I started making the pancake version about 2006, back in the old Hobby Talk days, on a one potato two potato basis. The scheme was always just about getting the "look" for the project at hand. Merely a novelty thing out of my bag of tricks. Specifically it's works for all the T-jets with the gigantic wheel arches, ones that have been brutally cut, or gum scraper customs. Naturally there was some interest at the time, but I dont know if anyone ever succeeded in replicating the trick. You might remember Mark Olwangs innovative shaved chassis' of that period. Labor intensive beyond my sanity, on a singular production basis; and no doubt astronomically costly to mass produce. Most unique, if not outright re "Mark" able. I havent seen or heard from him for years.

      The details of the mods are in one of my threads at the Slot Lodge. I'll see if I can find it.
      Last edited by Model Murdering; December 11, 2019, 02:28 PM.


      • #4
        Mark Owyang on Hobby Talk is where I got the idea from. If I only had the capital. Remember these?

        That Dino sits oh so right!
        Click image for larger version  Name:	image_3572.jpg Views:	7 Size:	33.1 KB ID:	11450Click image for larger version  Name:	Mark Owyang chassis.jpg Views:	1 Size:	9.3 KB ID:	11451
        Last edited by noddaz; December 11, 2019, 02:54 PM.
        Why doesn't my car run like that?



        • #5
          Oh man! Good times! I originally saw Mark's work when everyones stuff was still collected under one roof in the now defunct H0 World archives.


          Before Goop, I had become frustrated with the T-jet chassis. As the cottage industry continued to drop tire and wheel diameters, I was looking for something that would drop the chassis and still allow the model to use conventional wheel and tire sizes in order to fill up the wheel wells. The only way to adjust the ride height was to lower the wheel/tire diameter, which in turn whacks out the fender openings. Along the way I spotted a rare pair of photos on the "Canadian H0" website that featured a T-jet chassis slung down to AFX axle heights. I never could develop any other leads. Based off the scant pictorial evidence, and study of the Slimline and the AFX chassis; I eventually cherry picked the applicable factory design features from both and combooberated them onto the T-jet platform.

          The end result was a chassis that handled similar to a Fray car, with realistic wheels, tires, and fender well gaps.

          The finished axle height doesnt look like much until you put it into scale perspective.

          I keep the tail plate cut out fairly straight forward. This allows easy clean up of the inner frame rails with the hobby knife by providing the room to make a clean slice across the relocated axle bores later. Certainly, it could be tailored closer to the crown and axle profile for structural purposes.

          Scribing a perpendicular line through the original axle bore gives a reference line to register the new bore location. Finding square here helps ensure that there wont be any drive-ability issues due to bad axle geometry.

          Pretend the upper hole isnt there. These pix were staged on an already modified chassis. The line serves only as guide to help plot the center point of the new bore.

          The first few drop axle examples were painstakingly measured out by hand. A template with the correct spacing turned out to be right at hand. Removing the front pan of the template chassis allows it to fit the modified rear tail plate section by over lapping on one side or the other.

          To begin, the template can be installed on either side. The templates LWB bores are pinned through original rear axle bores of the project chassis. The "truck WB" bore is aligned with the vertical reference line and lightly marked by spinning the pin vise (1/16"). The template is removed to allow inspection of the mark and adjust the center mark for any final correction before drilling.

          The new bores are actually drilled with the template removed. Nylatron will fight back and wander the drill bit, if too light a pressure is used. Its important to stay square and push it right through with a minimum of fanfare. Once both sides are drilled, both bores are flute reamed simultaneously, from both sides. A standard splined axle in a drill motor are used with rubbing compound to relieve the bores to proper tolerance.


          A birds eye view gives a glimpse of the modified pinion lurking way up in the axle box. As the axle height goes up, the CG goes down; but the tire/wheel profile has to come up enough to prevent high centering. The 9 tooth pinion has always provided the crisp response that makes me giggle. Certainly a 12 or 14 tooth pinion is doable for big ovals and speedways.

          The driven gear detail is actually simple when taken one step at a time. The pinion boss underneath the gear plate is removed flush. A crown gear relief window identical to the later AFX models is cut into the gear plate. The windows inner edge should approach the removed boss' outside border. A relief pocket is cut under the driven gear using a moto-tool. Approximately half the gearplate's thickness should be removed. I like to cant the tool to make the pocket slightly conical towards the pinion shaft center. Once the plate modifications are completed, the crown gear can move up to the new axle height. Note that half of the left side rear index peg must be removed from the gear plate. This ensures clearance at the shoulder of the crown gear. The pinion shaft is pressed up through the driven gear and the excess is carefully cut away.

          Extra clearancing for gumbos is available all the way up to the gearplate clamp. Patient work with the moto tool gets you there. Once completed, virtually any wheel and tire combination is allowable except the Dragster. It also permits the rim to move all the way in to the chassis rail if required.

          To finish, some shoe voodoo is usually required. If using the SWB or LWB front axle positions with a standard profile tire, a T-jet shoe can be used, but may require a "Z" bend. For ultra slammed chassis, stock AFX or BSRT fray type shoes with AFX springs work nicely as a base set up; especially if using the truck hole for the front axle. Notably, the AFX shoes are already travel restricted by design. Typically a bobbed guide pin and recessed front screw is required to complete the transformation.

          When combined with some post shaving a whopping 5 mm is possible on Aurora's Hot Rod before the gear plate rubs underneath.

          The end to end comparo illustrates just how low you can go. This Cobra was an Ebay bait and switch that arrived with hideously gashed wheel wells. It served as great platform to flesh out the idea. Due to the Cobra's nice body weight and balance, combined with the ultra low CG; this model turned out to be almost impossible to de-slot. The bonus was that the wheels moved up into the wells, automatically removing much of the ugliness.

          Although the body work on this XKE Spyder wasnt completed for a few years, it was mocked up on one of the original drop drop axles. Note that the hanger plates are right on the rail. In this configuration, we're on narrowed hubs and shaved tires to get it all packed under the fender wells. To compensate a hot armature and magnets help provide the necessary breakaway power needed to prevent wallowing in the turns. Rather than rolling over like a dog the extra power allows it to be sling shotted at the corner exit.

          Many thanx to photobucket for further throttling picture quality, not to mention asshatting there logo right in the sweet spot. I'll try and rehost them via Imgur. Sorry guys.
          Last edited by Model Murdering; December 11, 2019, 05:58 PM.


          • #6
            Another way to beat the hosting problem is to convert the article to a PDF, upload that to Google Drive and link to it there. I still have pictures on Photobucket and I have been paying for the site to be ad free. I do not pay extra to be able to post the pictures and I do not get the "unobtrusive" watermark or blurring......yet. A recent hitch is that I can't upload any new pictures using the Chrome browser. I will have to see if Edge works. I have a database the includes the BB codes for many of my pictures, so I don't have to go to Photobucket to get those.


            • #7
              Originally posted by RichD
              Another way to beat the hosting problem is to convert the article to a PDF, upload that to Google Drive and link to it there. I still have pictures on Photobucket and I have been paying for the site to be ad free. I do not pay extra to be able to post the pictures and I do not get the "unobtrusive" watermark or blurring......yet. A recent hitch is that I can't upload any new pictures using the Chrome browser. I will have to see if Edge works. I have a database the includes the BB codes for many of my pictures, so I don't have to go to Photobucket to get those.
              Thank you Rich. I appreciate the input. Like you, I've been fairly prolific over the years, so my global footprint was seriously impacted. Reconciling the carnage is a monumental task.