Performance Improvements for the New SCX 1955 LeMans MGA - Printable Version

+- SlotRacer Forum (https://slotracer.online/community)
+-- Forum: Slot Cars (https://slotracer.online/community/forumdisplay.php?fid=3)
+--- Forum: Scratch Building (https://slotracer.online/community/forumdisplay.php?fid=35)
+--- Thread: Performance Improvements for the New SCX 1955 LeMans MGA (/showthread.php?tid=1773)

---

Performance Improvements for the New SCX 1955 LeMans MGA - 73emgee - 12th-Dec-20

This SCX version is modeled after the 1955 LeMans EX182 prototype driven by Ken Miles and Johnny Lockett.  The production MGA model would not be officially release to the public for another 3 months.  The #41 was one of four prototypes entered by the MG Competitions Department with lightweight aluminum panels, cut-down windshield, covered passenger compartment, enclosed rear view mirror, and a driving light imbedded in the grille.  The SCX version is missing the leather hood straps and the horizontal air intake in the hood (bonnet) seen on the factory car.

  



This is the first SCX car I’ve owned; I was surprised to see that there is no wiring in this model.  It has LED headlights and brake lights. The driving light imbedded in the grill is not lit.  The LED’s, guide and motor are all connected with copper strips, not wiring.  This method causes the front end to ride very high because the copper strips are sprung to maintain contact against the guide, there is not a front body mounting post only the copper strip tension holding the chassis under the lip of the body.  On my non-magnetic track car the wheels did not touch the track because of this. On a magnetic track the strength of the magnet may overcome this tension.  The wheels are independent stub axles but suffer from a sloppy fit.  The rear axle bushings were loose and of poor fit.  It uses a small FC-130 size, but has unique motor mounts, that would require modification to fit a standard FC-130 type motor. 






On my track (non-magnetic) its performance was lacking, it was an effort to get it to lap with any speed; however, I think the body is excellent and looks good on the track.
I wish there were more slot cars available of classic British sports cars, unfortunately very are few manufactured by larger the slot car companies. Thankfully; there are several small volume resin resin casters offering these cars. I applaud SCX‘s effort to release this historic car.

I wanted the car to perform as well as it looked.  I added a front body mounting post, replaced the chassis with a 1/16” brass chassis with adjustable front axle supports, Scale Auto slim can pod with .5mm offset, and a Scale Auto 8mm deep guide. The motor is Predator 18K slim can FF-050 motor  The wheels and tires were replaced with Pendle PCS classic spoke wheels and tires with 2 ear knock-offs. I started with the Pendle 14mm set on all four wheels, but the combination of the offset pod and 14mm rear wheels, did not provide enough rear track clearance. I switch the rear wheels for a 16mm set.





The car now is a pleasure to drive and can be push in the corners with confidence even with the narrow and treaded Pendle tires.  Future plans included adding the leather hold down straps, replacing the toy-like driver, and possibly adding the hood intake that was left off the SCX version.





I would like to set this car up to race in my local club’s “vintage” class which allows 8mm tires.  I tried some Slot.it 15x8 wheels and N18 compound tires, and some ball bearing independent front wheels with this same chassis/pod and was able to reduce lap times from 6.2 -  6.1 to consistent 5.8’s; however, the tires extended slightly beyond  the rear wheel wells.  I think there is enough room to get the tires under the body if I modify the pod using Chris Walker's method to eliminate the protrusions for the spherical bearings and replace them with flanged oilites mounted  the inside of the pod.  This would mean getting rid of the beautiful Pendle spoked wheels and using wire wheel inserts.   I would also need to replace the FF- 050 motor and pod with a FC-130 pod and Jack Rabbit motor.  This would probably require some modifications to the driver tray since this motor is taller.




Our club has been on lock-down since March because of the virus. Since there’s no rush to make the necessary changes now, I think I’ll just wait, and enjoy the new improved performance, and watch this cool little car zooming around the track.

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - chrisguyw - 12th-Dec-20

Hi Bob, The car looks wonderful, and the chassis replacement should make it very competitive in your club events 

I am quite confident that removing the "claws" on the Scaleauto FF050 motor pod, and installing some single flanged oilites will give you the width reduction you are after, and , I am not sure why you would need to replace the Scaleauto pod ??

I use Scaleauto RT3 pods almost exclusively these days, (they are the best on the market) and the "oilite mod." works equally as well on these as it does on the Slot-it pods,......be a shame to lose the interior.

If you wish to use the single flanged oilites with the flange on the outside,....there are some 1/24 commercial car bushings that are great for this, a narrower flange width, and reduced od on the axle bore which makes them a breeze to install in either Slot-it or Scaleauto pods.

I am currently using ones made by MRSlotcar, but, JK and Kelley make identical bushings.

If you send me your mailing address, I will send you some.

Cheers
Chris Walker......(not Chris Wright  )

The reduced dia. bushings are on the left,.....these are commercial grade precision, and require very minimal boring of the bushing holders..(a few strokes with a round file will do it).




I do not have a handy pic. of a Scaleauto pod conversion, but it works as well, and is as easy as on a Slot-it pod.........it does give a reasonable width reduction,...and it does provide improved precision over the standard spherical bushings.

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - JasonB - 12th-Dec-20

Lovely work.

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - 73emgee - 12th-Dec-20

Sorry about the name mix-up Chris I edited the post, and thanks for the tip.  The reason I was going to change the pod is because the club requires the use of the 14k Jack Rabbit FC-130 motor in the "vintage" class.  I assuming the ScaleAuto FF-050 pod would have to be replaced for the Jack Rabbit motor.  Am I missing something??? 

I'm curious of what you think about using a pod chassis for these small cars.  I was hoping to build my first torsion bar body, but after I got started it didn't seem like such a great idea when the pod is almost as big as the entire chassis.  Can a torsion type chassis make much difference on these small cars?  It seems to me the biggest advantage of the thick brass chassis, is getting the weight down low, which really seems to help these narrow track cars.

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - chrisguyw - 12th-Dec-20

Hi Bob,.......If you are mandated to run the 14K FC-130, (I must have missed this)...you will indeed have to change the pod.

Scaleauto does make an inline RT3 pod (SC-6523C), and while it accepts the longer can FK180 motors, the 14K Jack rabbit is drilled/tapped on the can end, so you can bolt this in (2mm machine screws)  with absolutely zero issues whatsoever, no adapter needed. I have done this many many times.

While a flexi-board chassis ( a chassis that flexes torsionally) provides benefits for all slot cars , the benefits are considerably less on cars with low power/skinny tyres...(your car).

You can certainly incorporate some controlled flex into your existing chassis plate/pod by using some silicone/urethane washers, both above and below the pod lugs.......this will allow for some controlled torsional pod flex, which allows the outside rear to load progressively, improving consistency, and, improving grip............so,.......this is an easy way to get most of the benefits of a wire/brass flexi-board chassis easily 

I have had both MRSlotcar and Dart hobbies produce these, and they are the 2 I would recommend..........unlike some of the others on the market, these are suitably soft (Darts are urethane, MRSlotcar are silicone).......they both provide good compression/rebound, and as they have good memory, they will not fatigue.

Again, send your mailing address (if you wish), and I will send you some.

Cheers
Chris Walker

This is the chassis of one of my 60's sports cars for our local clubs,.......very similar in concept to yours,.....14K motor, narrow, and skinny tires !!

I did a "cheater" flexi board for this one using urethane washers both above and below the pod lugs to provide some flex.......this is not the greatest example pic., but the washers are there......in this case under the single pod mounting lug at the front, and on both rear pod lugs.

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - steveaca - 13th-Dec-20

Lovely work on that MG.  Great tips as well from Chris re the flanged oilites .

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - woodcote - 13th-Dec-20

Awesome job

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - 73emgee - 13th-Dec-20

(12th-Dec-20, 11:02 PM)chrisguyw Wrote:  This is the chassis of one of my 60's sports cars for our local clubs,.......very similar in concept to yours,.....14K motor, narrow, and skinny tires !!

I did a "cheater" flexi board for this one using urethane washers both above and below the pod lugs to provide some flex.......this is not the greatest example pic., but the washers are there......in this case under the single pod mounting lug at the front, and on both rear pod lugs

Chris - Your 60"s sports car chassis is beautiful, you must include some polishing time in your builds.  A couple of questions on this chassis:

Is the only chassis flex point the front mounting lug with the washer?  If so, i assume the guide tongue, wings, and rails that appear to run the length of the chassis are all rigidly attached (soldered).

Do you have any pics of the rear of the chassis?  What are the rear pod mounts attached to, the body mount?  Are there flex washers back there also?

It doesn't look like you used your skinny pod method on this build.  If space for the rear wheel/tire combo was limited would you bring the rail in closer to the pod to gain as much room as possible or use another chassis design method?  On my chassis, if I used your method of eliminating the bushing fingers and reversing the flanged bearing I still would be losing some tire/wheel space because of the chassis rail running between the pod and wheel.  Is possible to eliminate the rail and separate the chassis between the front and rear pod mounting points and make an adaptor to attach the rear pod mounts to a body post? 

Thanks for your time,
Bob

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - chrisguyw - 13th-Dec-20

Hi Bob, .....some answers to you questions.....hopefully I answered them all.

Cheers
Chris Walker

 The picture in my first post is a bit deceiving,......the main chassis rails are actually very close to the outer edges of the bushing faces (see below pic.), and the rear pod lugs are attached to the main chassis plate via a cross brace....(note the urethane washers both above and below the pod lugs). I take a sliver off of the bottom of the pod lugs, equal to the thickness of the washers used.

The below pic. is a slightly different chassis, but it will illustrate the points made above......this one is for a Sprite, which is very very narrow....(our rules allow 7mm rear tires, and there is room for perhaps a 9mm rear tyre)



The full rolling chassis.....................



And a very similar (identical in fact) to the chassis in my prior post, this one with a FF050 pod.

I also use urethane/silicone washers between the chassis and body posts.......this just quietens things down a bit .






If you really need to go narrow, the best way to go is to eliminate the pod, and fabricate a motor bracket.

These are a couple of F1 flexi-board chassis that I have built,.......obviously very narrow., and being flex-boards do not need pod washers.

This one is for a FC-1390.....a Lotus 16.



And a couple for FF050 motors........

---

RE: Performance Improvements for the New SCX 1955 LeMans MGA - KensRedZed - 14th-Dec-20

Bob. Great looking upgrades to the chassis on your MGA!

Chris. Stunning chassis jewelry. Always nice to see and study.

---