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Improving the MRSlotcar Patriot Evolution chassis

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  • Improving the MRSlotcar Patriot Evolution chassis

    In my initial review, (also posted in the review section here on HRW) , I did mention a couple of things that I felt held it back from being an "Elite" competition chassis. While it is very good out of the box, especially for the less experienced scratchbuilder (it has a wide range of wheelbase/guide lead options ) it does not have an adjustable front axle vertical adjustment, and it is torsionally a bit too stiff, which limits ultimate rear tire grip........don't get me wrong. it is quite good, but, everything can be improved

    I have not yet tackelled the adjustable front axle issue, but have done the mods. to allow for some torsional movement in the chassis...........both these mods. are being addressed on future MRSlotcar chassis releases, but, in the mean time you can incorporate these if you wish..

    Cheers
    Chris Walker

    In the first pic. you can see that on the stock chassis, that the guide mount, is part of the front axle carrier/wheelbase adjustment plate, and when bolted snug, as it has to be to secure the guide, the whole chassis becomes very (too) stiff torsionally

    Click image for larger version

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    To remedy that the guide mount plate needs to be cut from the front axle plate and mounted separately and securely

    In the next pic. you can see the guide plate has been cut and soldered to the base plate....(2 holes in the actual guide mount plate and the 2 different length guide tongue bits allow for 4 varying guide lead dimensions)

    We can now have the guide solidly mounted, with the ability to add some torsional flex to the front axle/wheelbase plate.

    Click image for larger version

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    In order to maintain perfect alignment of the front axle holes, I cross braced the front axle plate, before, cutting the guide mount section away.

    Modified front axle/wheelbase plate...

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    To achieve some torsional flex in the front axle plate, I used some silicone washers on top of the axle plate, and under the Nylok nuts....these should be adjusted to be snug, but, not tight enough to compress the washers.

    In a perfect world, it would be nice to have washers above and below the front axle plate, but, without a major re design, this is just not possible.

    It is hard to see, but the washers are there

    Click image for larger version

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    Another little thing with the out of the box chassis......if you wish to use any front tires with less than 19mm dia. there is precious little room under the guide for even thin braid......you will be OK on tracks with a bit of braid recess, but on taped/steel rail tracks it is dodgy. So a quick fix for that is to file/grind the bottom flange of the guide tube a few thou,.....if you take too much, not to worry, as it is easy to add a guide spacer.

    This pic. is upside down ........the wide flange sits on the top of the guide surface.

    Click image for larger version

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    Modified, the chassis was just over a 1/10th quicker on my track, and more progressive/easier to drive at the limit



  • #2
    Thanks Chris, appreciate the update and the tuning ideas, I suspect we might see one of these under a proxy car entry soon.

    Would it not be possible to add spacers underneath the guide tongue to lift the guide a .5mm or so?

    How does the lap time compare to a stock Slot.It group C chassis or your GT3 Corvette, and what's the total weight with a long(?) can motor fitted?....inquiring minds wanna know!

    Chris
    "I don't make mistakes. I make prophecies which immediately turn out to be wrong "
    "And that just shows you how important the car is in Formula One Racing"

    Murray Walker

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    • #3
      Originally posted by F1Fan View Post
      Thanks Chris, appreciate the update and the tuning ideas, I suspect we might see one of these under a proxy car entry soon.

      Would it not be possible to add spacers underneath the guide tongue to lift the guide a .5mm or so?

      How does the lap time compare to a stock Slot.It group C chassis or your GT3 Corvette, and what's the total weight with a long(?) can motor fitted?....inquiring minds wanna know!

      Chris
      Hi Chris, I did cover the weights/measurements in the initial review (also just re posted here in the "Product Reviews" section) but to answer you question ,with an FK180 motor you will be in the 75(ish) gram range for your rolling chassis...not light !!

      You could add spacers under the guide plate to lift it, but, it must be cut from the main plate, or you will just end up raising the whole plate, wheels and all, which will raise the Cg., and require you to use 20+ mm front tires. I did try the easy route of adding spacers to the underside of the guide tongue (after removing it from the front wheel/wheelbase plate) but, the small mating surfaces resulted in a less than a solid mount......so I soldered it !!

      Out of the Box , it is , a 1/10th or so slower on my track vs. a very mildly tuned Slo-it GroupC , due in large part to the 15+ grams of extra weight of the complete chassis. (my track does not need /favour heavy cars). Modified as above, the times are identical to the same Slot-it Group C.

      With its current weight, the need for even more front end torsional flex, and the lack of the fine tuning available with an adjustable front axle (it does not allow any form of corner weighting),....it will not compete with my GT3 (or many/most other of my cars).

      Don't get me wrong, it is a good chassis, and handles well .....the adjustable guide lead/wheelbase/body mounting options will be very attractive to the less skilled scratchbuilder, and it is on par with the mildly modified Slot-it cars, but, for the Elite racer, it (in its current form) is just not there yet.

      Cheers
      Chris Walker
      Last edited by chrisguyw; April 23, 2020, 09:38 AM.

      Comment


      • #4
        It would be easy to design and 3d print a bolt in cross support with built in axle height adjusters then cut off the steel uprights.

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        • chrisguyw
          chrisguyw commented
          Editing a comment
          Certainly a good option......!!

      • #5
        I don't have one these right now, but this is a great thread!

        Zack

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        • #6
          Have been experimenting with chassis and share Chris' observation. Please note that if you are not following Chris recommendation on guide flag adjustment you are looking at a minimum diameter of front tire at 19.25 mm which a standard Slot.it 15x8 mm front wheel you will find it difficult to find a suitable tire to use. You may choose to run a Slot.it 1140 and true down. If someone is good at CAD a 3D front suspension would be ideal. As structured now you cannot use a SCC adjustable suspension block. I am certainly not as talented as Chris Guy W of supporting and making the chassis cuts as described. The rear axle is not an issue as you can adjust tire height and pod offset, if you feel more flex is needed you can also go to a independent suspension. One note on the rear that i believe that Chris pointed is that you are limited on rear wheel width due to how chassis is cut around rear pod. For this chassis to be used in a high level proxy you are limited as the chassis is delivered today. I am not sure if there are plan for Allan and Mr. M to make any updates but feel that it would be welcome for the master builders. My ask on this forum if there is someone that is capable of designing a 3D front suspension I would definitely be interested.
          Aloha
          Dale

          Comment


          • #7
            This is the second chassis I’ve worked with. The first was in a Slot.it 962. Found it to be a bit cumbersome to drive. About 1-1.5 tenths slower than with the stock chassis. Sorry, no pics, sold the whole package. This second one I have done a bit of work on. Used Mr.M’s .5 washers everywhere that would take them for ‘suspension’. Also did some file work and fiddled with the front guide system to achieve what I thought was better. Had considered soldering like Chris did, but was satisfied with what I had.....at the time! Mounted to a Slot.it Opel Calibra by installing a new body post approx 6mm behind the front post. Had to slightly shave just a Cajun shorthair from the back edge of the rear wheel wells. Piranha motor with 10/25 gears seems to push it around the track okay. I say okay, because out of the half dozen DTM’s in my stable, its right in the middle. Handles well and predictable, and weight wise its right there with a Scalextric. Thanks again Chris W for the tips!
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            Last edited by War Eagle River; April 23, 2020, 05:29 PM.
            Scott.....War Eagle River......Tampa, Florida, USA

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            • #8
              Originally posted by War Eagle River View Post
              This is the second chassis I’ve worked with. The first was a Slot.it 962.



              ​​​​​​Scott, Both versions of this chassis (SR1001 and SR1002) are identical with the only difference being that SR1002 comes with a slightly longer guide tongue....both guide tongues (short/long) are available separately.

              To anyone interested, I would recommend the SR1001...it comes with the shorter guide tongue, but with its range of adjustability, it is more than long enough for all of the various bodies I have measured. I have one currently in a Slot-it Porsche 956 (not short), and the shortest of the guide tongues is set in its shortest position in the chassis......lots of extension possible for longer bodies

              Cheers
              Chris Walker

              Comment


              • War Eagle River
                War Eagle River commented
                Editing a comment
                I know they are identical chassis, except for the guide tongues.😁 Have had both chassis, and the extra tongues. Along with many packets of 1501, 1502, 1503’s.
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