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DiSCA GT3 Chat
#11

I will take the one step forward and learn from the set backs. 

The pod is the one that came with the chassis, I will search out what kit is available to convert it to tripod. 

I used the existing 'raised' hole in the chassis for the remote LED... I was quite pleased with that as it keeps the bottom of the bulb flush with the underside of the chassis. It's 18mm from rear edge of guide. I thought I would get a tick for that!

I'm gaining soldering confidence with every mod, so feel a bit more comfortable to shorten leads and take better control of cable routes...and seeing the picture, I will add some insulation to the FM legs.

I will reinforce the antenna base

And finally... 

I will go back through posts to check if I am going in the right direction!
[+] 1 member Likes BourneAgainRacer's post
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#12

Step 3: analog track testing. 
We used an analog throttle in the club plug point and held it open on full throttle.
We then powered the SCP by a 9v battery to drive the car.

Note: Depending on the club/track controller plug system a good tip is to modify your own plug and hard wire the connection between power supply + and track +
If the track voltage does not exceed 12v you could even use the plug to power up your SCP

Step 4. : How To ? 
We have not worked out how we can test:
- the emitter LEDs for lane changing (incorrectly polarity stops it working) 
During assembly: Almost all LED's have a polarity mark, when in doubt for the IR LED, do a quick test on the lead wires with a normal LED with visible light.
LC Failure check: Place car on XLC track, move the car over the LC sensor with one of the LC change buttons pressed, repeat process with other LC button pressed.
Repeat procedure on other lane.

- the hall effect sensor for lap counting. (Installed upside down stops it working)
O2 system has a fail safe feature that prevents cars stopping on top of a finish/pitlane magnet. 
If the hall sensor detects a magnet and brake is applied it will send a short power pulse to the motor to move the hall sensor past the magnet.

This feature can also be used as a simple stand alone test of the (mounted) hall sensor with an external magnet:
Power the car and SCP, take an external magnet and hold in under the hal sensor, if mounted correctly wheels should be given a short spin.
If it doesn't work the first time, flip the magnet and repeat. 
If it doesn't work the second time, flip the hall sensor and repeat test.

- set up an oxigen dongle to update firmware on the chip and SCP. 
To do so you would need the download the Slot.it boot loader program and install on your PC. 
As O2 RMS and Bootloader software is windows only and I don't run Windows...no experience  Banghead
Check Slot.it info on its new app based Chip update firmware.

Hope this helps

with kind regards
Tamar
[+] 1 member Likes Tamar's post
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#13

Back again.

Have been spending my time on a couple of other slot car project, but returned to my GT3 chassis this evening having re-re-read the advice and hopefully made some steps forward this time.

So here it is...
   

Jobs done
1. Shortened the wiring to the motor and tidied up the routing back to the chip [should now avoid clashing with body fitment]
2. Fitted a SureChange guide to give an out-front remote IR LED [new to me, but maybe others have tried them before]
3. Fitted some shrink wrap to the base of the antenna [!]

Jobs not yet done
1. Looked everywhere for an alternative, single point, front fixing bracket for the motor pod. Think I found the item for 1/24 scale but nothing for 1/32. Looking at all I could find on RT3 mounts, the double fixing at the front seems to be intended for two suspensions springs.
2. Fitted suspension springs to the front motor pod fixing points. Cannot find any in stock anywhere, but will fit them when they become available again.
3. Fitted the Hall sensor yet [it's safely stored in my spares box]
4. Painted the exposed silver rim of the rear wheels, and the hub centres, black.

Did some weighing. The chassis is currently at 69g, and the proposed body with lexan interior that I am preparing for my WEC car, and which will be repeated on this chassis, is currently sitting at 17g. So a combined weight of 88g against the class minimum of 85g. The body is 2g under the minimum weight limit, but once the lighting kit gets fitted, I think that will take it up to the minimum, and the overall car to around 90g. So 5g heavy, with half of that being the SA motor pod compared with the SI one. Will probably run it in the current configuration for testing purposes and see how I get on with it first before putting it on a diet!

I love gears 
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#14

Lying in bed this morning reliving my previous evenings work, something clicked in my head that I got my arithmetic wrong. Now it's too late to edit! 

So current chassis & planned body = 86g. Add a couple of g for the lighting kit and I will be at 88g, not 90g. So swapping to a slot.it pod would bring it down to 85.5g, and if I change from blutac to a sticky foam pad to fix the chip in place, I should be right on the button!

I love gears 
[+] 1 member Likes BourneAgainRacer's post
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#15

I miss Racing, can't wait to get back to some 

Anyway, other weight tips, reduce as much weight as possible in the wrong place you can add it in the right place ie lower down.

Thinner wires (not sure what the two wires to the front of the chip are) all round and when you install the light kit ensure the connector uses fine flexible wires so they have min chance of interfering with body float
Carbon front axle and front wheels that are no more than the min allowed diameter.  Lightest ones you can find.  Delrin ones seem the lightest and strongest although we drill out standard ones.
Alan uses carbon rear axles, I use titanium ones for disca. Not convinced with carbon for the rear as they twist under torsional load.  Might help though?

Then if you have to add weight to get to the min standards you can add it low in the chassi to aid stability.
Breathable tape over the motor holes. The sponge dust created is ultra fine and you don't want it in your motor.

Heat shrink all wire soldering joints.

Then suspension.  Tripod is proving popular but that requires altering the chassis which is not permitted. I can't remember if the SA chassis allows that config as standard.  If it does find a way to use it. 
Use the sidearms suspension, and play with the set up, this is where you will get the difference between a car that is good to a car you feel you can push and it won't come out.Worth experimenting with firm up from and back and medium on side, or none at back and loose at front with lots of up and down movement possible.

Do SA release the Porsche with a chassis with the cut outs as they do for the viper and corvette? If they do buy one and use that as it introduce flex in to the chassis which helps produce mechanical grip.
[+] 1 member Likes Mtucker666's post
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#16

Matt

Thanks for your comments. I'm beginning to realise that in GT3, you need to think about every component, however minor.

So the wires coming out from the front of the chip are to the remote IR LED in the SureChange guide. Not sure if these have been raced with any success, but it helps me with tidying up the chip zone in the middle of the chassis.

With regards the motor pod, I have used the one from the donor car that did not come with outriggers. You cant seem to buy these separately so it looks like a new pod is needed to open up suspension tweaks. What offset do people generally go for?

With regards a 3D printed chassis with cut outs, yes, SA do sell one for the Porsche, but it was not clear to me reading the DiSCA regs that they were permitted...

2.1. Chassis may be any from the list of homologated chassis in section 7, including those supplied as original equipment with a model from the list of approved models. 
2.1.1. Non-specified aftermarket option chassis, e.g. soft versions, are illegal. 

Is it the case that they are specified aftermarket options. Do others race with these types of chassis? 

Is there a collection of GT3 race results somewhere that I can look through to see what cars others are using?

Hoping to test/race at Rockingham when it is possible again!

I love gears 
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#17

(6th-Jun-20, 01:27 PM)Mtucker666 Wrote:  Alan uses carbon rear axles, I use titanium ones for disca. Not convinced with carbon for the rear as they twist under torsional load. 

We gave up on carbon rear axle after the first DiSCA car (kesselrun corvette) for the reason you state. 
SlotingPlus titanium for the rear every time Thumbup
Carbon for the front but be sure to use rounded end set screws to lift the axle. Sharp ended set screws will cut into the axle)
Alan
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#18

SA Porsche chassis change - that will be fine
Motor pod, the SA rt4 pod uses sidearms, but so do the slot it evo pods.
Offset. Either no offset or 0.5mm.  The spec sponge tyre is 21.5mm when new, and I think you still have the required motor clearance of 1.8mm if the tyre goes to 21mm with 0.5mm and 20.75mm with no offset.  You need to have have the motor clearance when  you go through tech inspection
[+] 1 member Likes Mtucker666's post
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#19

Thanks, that's really helpful.

I love gears 
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#20

In terms of results look at slotforum.  Number of events held at Rockingham, north staffs and Eindhoven using the disca gt3 specs.

A further thing is the wing. Try and fashion, if not avail separately, rubber wing struts. You need the wing to be able to withstand impacts without coming off and that is best met with flexibility. Wings need to be replaced, and loosing one most of the time through min fault of your own, means a pit stop and loss of laps. That will put pay to any hope of a podium and loose you a good few places that were otherwise deserved.
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