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I have done my best to avoid front engined cars, but being too impatient to wait till Racer bring out their version, I decided to "have a crack Nig" at the Revell offering.

On my track it was struggling to get 6.1 after first development stage, before I ran it at club member Mac's track last Thursday for a best time of 7.75 for 95 feet.

In the pics below, I have replaced the stock Rubber with slot.it F1 tyres, F22 compound, and turned them down on the truer to 19.7mm O.D. Trued the fronts, and raised the front axle about 0.5mm to drop the front end.
I replaced the tiny Revell guide with a Slot.it guide and soft braid . Now it sits full depth in the slot.
Shaved off the cups in the chassis so the body posts can move around with loose screws.
Removed all the chokes off the motor - about 5 altogether, crazy.

Added about 10gms lead in the centre and 3 at back.




That was still 6/10ths a second slower than a Fly Racing Capri, same track same night. Worst handling characteristic is that it would erratically front deslot and body roll, so you couldn't push it, because you never knew how it would take the same corner from lap to lap.

So today I have had another crack at it today.

As the Revell motor revved like crazy, but lacked torque and thus lacked brakes (almost none); I swapped it for a Slot.it yellow bell that I had cut off the bell end of the motor shaft so it doesn't foul the front axle. It is actually slightly slower now in a straight line if anything, but has more punch, and medium brakes. I may go back and fit an 8 tooth pinion to gear it down more, and make the type of acceleration and braking closer to the Fly Racing Capris.
Ran the super-glue collar trick on the axle bushes, and driveshaft bush.



Dremelled away some body material on the side wings, under the central pan, and around and cut 1mm off the front body posts to drop it a bit.
Needs the body screws replaced, but that requires filling the body post holes and re-drilling, and also adapting the chassis so smaller thread and head screws can be used, which have a smooth shaft to stop fouling on the body.
Also added another 3gms lead at back, total 6 grams, and 3 grams blu-tak at front as an experiment in removable weight
(I find Blutak great for experimentation. I replace it later with the same weight of lead or tungsten.)

On my track which is tighter and more windy than Macs, the Capri has a natural advantage, even though it is slower than the BMW in a straight line, because the Capris with their 14mm (5/8th") wide feet, which feel like magnet cars on plastic.

The BMW is now easier to push hard, but still not as easy to drive as the Capris,

I got the Capri to about 5.70 today, and the Revell is still 0.2 slower, but getting closer.
Finally I got a 5.76 last adjust before supper.

A bit more weight adjustment, better body float and freeing up the rear axle bushes which are creating a little friction at present after the "collar", should get it into the 5.6s.

I should be able to get a 7.4 - 7.5 on Mac's now.

If anyone has tips on tuning these - I am all ears. I'd love to get it good enough to play against the Fly Racing Capris (we run the Capris with NSR Vanquish hubs and 14mm wide supergrips or ultragrips.)

Here's a quick clip, last complete lap is 5.88. Track is 65 feet, 8 turns.

 

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Nobby Berkshire
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That track looks like art.

So, basically you've completely gutted and replaced everything and rebuilt the car in the hope it will run exactly like your Capri? Why not simply buy another Capri?
 

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QUOTE (Screwneck @ 27 May 2012, 03:42) <{POST_SNAPBACK}>That track looks like art.

So, basically you've completely gutted and replaced everything and rebuilt the car in the hope it will run exactly like your Capri? Why not simply buy another Capri?

Not exactly like the Capri, but similar lap times. The Capri are low powered, but setup with the fat rear ends we give them, and properly set-up, they are very stable.
Actually, I haven't replaced much at all. Tyres, guide, and finally the motor. That is not very radical. I could have put in a shallow interior, and switched it to mid-engine boxer, or put an HRS chassis under it.
But the motor change is to gain 1/10th a lap. Ignore that, and very little has been spent in cash - half a package of Slot.it F22 tyres, and a guide.
So a car which was diabolical for wood, can be made to run very well with a couple of hours tuning.

Someone reading this could copy to acheive the same result in about 1 hour......

And DJ is correct - I want more Group 5 models to race.

Next up is a Fly Porsche 935 - but I think that I might need to remove the motor which is currently behind the rear wheels, put in a shallow pan and make it mid-engined. I would use a Fly EVO-2 racing boxer, - which are rated at 22K at 14 volts from memory, and not much torque, maybe a 10 watt motor, so it would have the same power as a Capri. The chassis on thesee is just a flimsy sheet of plastic with no longitudinal or cross bracing or ribs at all. It is so flexible you could wrap it around a rolling pin.

Then a BMW 3.5 CSL Group 5.

That will give me 4 different group 5.

Then the Racer ones will start to arrive, and I will need to bring them all to similar lap times..... so I will need more power for these, or de-power some Racer ones to match. (The least powerful Flat 6 motor is still a little too powerful, but I can fix that with a couple of diodes to drop the effective voltage to the motor about 10%.)

Group 5 is my 2nd favourite ever racing class, after CanAm....I like "brutal" cars which represent when motor racing was more mad, less refined....
 

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that was a really good informative article slotcrazy. i,ve just aquired one and you,ve done all the work for me. thanks. john by the way group 5 is my favourite, ive got 6 different group 5s and i,m after the old ninco ones, panterra, opel. ect, and the mrrc one. anyone got any off these to sell, swap?
 

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I use an orange slot it motor in my 320i and Slot it gears (9/29). I switched the rear axle and wheels with a set from a Fly 3.5 CSL, as I have crooked the stock wheels. Traction is not a problem on the Ninco track that I race on, but the car has a heavy body and that slows it down. I too have a slot it guide. I think I have a bit less weight, and no weight at all in front of the motor. If the car deslots unexpectedly, it doesn't need more in front, it already has plenty. Maybe it needs some work in the front setup.
From the video it seems that the car has good rear traction.
 

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The old Scalextric BMW CSL can be made to go well for little cost, basically change the guide (you'll need to add a front body post to do this), replacement motor and back axle and limit the travel of the front axle with a 3mm tube.
 

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I have a Revell BMW that competes with the Capri's and it is also not as competitive as it could be, I used the stock motor and replaced the rear axle assembly with BWA wheels and a Slot It 30 tooth crown gear. It was better but it would also have the random deslots, so I changed the guide widened out the front end with a new axle and 2mm spacers on each side. It was better again but not up to the speed of a racing Capri or the nemesis of the MRRC Celica so it set in the box. This question brought it out of the box and made me think. The space between the motor mount and the driveshaft mount was the same as the length of a FK180 motor, the Capri has the 180 motor. Out comes the stock driveline, Dremel and the carving knives. Twenty minutes later the FK 180 motor fits but the chassis is weak, so I made some bracing out of 1/8th by 3/16ths Plastastruct to go around the motor, tie in with the rear axle mounts and stiffen the rear end back up. With the use of some hot glue the motor was attached to the chassis and let cool. The 30 tooth gear was change out to a 27, a set of rear Maxxtrac tires got trued up and installed on the BWA wheels. Since the Capri has a vac form interior, I used a photo of the stock Capri interior printed on a piece of regular paper that was glued to a piece of .010 Plastastruct sheet for the interior with a Fly Viper driver mounted to it to get the clearance needed to be able to mount the body with the motor moved back.
The car is still heavy at just under 100 grams without any extra ballast but it does run a bit faster than the racing Capri with it's flimsy chassis. With just a little time and some parts from the spares box I took a shelf queen and made it a decent runner that can keep up with the hot rods.





More photos here http://s225.photobucket.com/albums/dd308/m...0BMW%20upgrade/

Ken
 

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Hiyas,

thanks for the emailed pics Ken - STILL only one came through later, but gave me the detal nicely.
I'll probably do one by that method as well. I found an uncommon livery at a European dealer which I have coming, plus the other ltd edtion #13 car.
And I have a blue "Loom" like Ken's and a Warsteiner lying about.
I just wish I had a Jagermeister one, they're getting expensive to but now.

QUOTE (timkoul @ 29 May 2012, 22:08) <{POST_SNAPBACK}>I use an orange slot it motor in my 320i and Slot it gears (9/29). I switched the rear axle and wheels with a set from a Fly 3.5 CSL, as I have crooked the stock wheels. Traction is not a problem on the Ninco track that I race on, but the car has a heavy body and that slows it down. I too have a slot it guide. I think I have a bit less weight, and no weight at all in front of the motor. If the car deslots unexpectedly, it doesn't need more in front, it already has plenty. Maybe it needs some work in the front setup.
From the video it seems that the car has good rear traction.

The front end is pretty flat and stable Tim, but the rear grip is so high that it won't let go at all to slide, so the thing was bagging out on the front end and body rolling. More weight to swing te back was counter productive to fast laps, so the 3gms front weight just planted it that much more. It seemed wierd to me too . . . but there is so much body and interior weight, and the blu-tak addition just brought it into nice balance.

Imagine those same video laps, but 0.2 faster - which you'd probably notice on a video.

I haven't de-tractioned the front tyres yet, need to get out the nail varnish I pilfered from daughter No.2 a while back. - I made sure I got the top quality, clear hard stuff . . . hey, she has another 30 or 40 bottles, she'll never even notice.
 

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QUOTE (slotcrazy @ 30 May 2012, 07:39) <{POST_SNAPBACK}>I just wish I had a Jagermeister one, they're getting expensive to but now.

You can get a Jagermeister for under NZ$70 incl shipping. Not too bad.
 

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Plafit also did one of those BMW group 5s, I believe it was actually a Revell (Jaegermeister) body with a Plafit chassis underneath.
A bit more expensive than a regular Revell one. And pretty much all sold out I think, but you could try to look for one.
 

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QUOTE (slotcrazy @ 29 May 2012, 21:39) <{POST_SNAPBACK}>The front end is pretty flat and stable Tim, but the rear grip is so high that it won't let go at all to slide, so the thing was bagging out on the front end and body rolling. More weight to swing te back was counter productive to fast laps, so the 3gms front weight just planted it that much more. It seemed wierd to me too . . . but there is so much body and interior weight, and the blu-tak addition just brought it into nice balance.

Imagine those same video laps, but 0.2 faster - which you'd probably notice on a video.

I haven't de-tractioned the front tyres yet, need to get out the nail varnish I pilfered from daughter No.2 a while back. - I made sure I got the top quality, clear hard stuff . . . hey, she has another 30 or 40 bottles, she'll never even notice.


Yes I see, it seems that you need to lower the GC a bit more. You can acheive that by either adding weight down low, or removing weight that sits high, ie some of the interior. Personally, I don't mess with interiors when it's not a club racing car (and now I've quit club racing, so I don't mess at all...). Sometimes you can find time elsewhere though, for example brakes! Strong brakes may result in lower entry speeds and possibly less deslots.
Do the thing with the front tires, it will help too!
 

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QUOTE (timkoul @ 31 May 2012, 00:10) <{POST_SNAPBACK}>Yes I see, it seems that you need to lower the GC a bit more. You can acheive that by either adding weight down low, or removing weight that sits high, ie some of the interior. Personally, I don't mess with interiors when it's not a club racing car (and now I've quit club racing, so I don't mess at all...). Sometimes you can find time elsewhere though, for example brakes! Strong brakes may result in lower entry speeds and possibly less deslots.
Do the thing with the front tires, it will help too!

Precisely what I have done - added weight low in differing places till I found the unusual optimum, and didn't want to remove the interior both for aesthetic purposes, and because part of the idea of this build was to try and replace as little as possible, while getting what was really a "magnet car" to run well on wood.

The motor change was precisely to provide halfway decent braking as noted above.

But i have it about 1/10th off the Capri and stable now, so I probably won't take it any further, the lap times of consistent 5.8 on my track and good top speed indicate it will also be a decent car on more open tracks around our club circuit. - Mine at 65 feet is the smallest track we race on.
 

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I put a complete scaleauto a/w plastic chassis under my jagermeister version with a falcon motor in it. mainly because I couldn,t wait for the side ways version, the original front motored version handled badly and I had a spare car and chassis ect in my projects box. its a pavement scraper and handles very nicely and quick as well. John
 
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