SlotForum banner
1 - 11 of 11 Posts

·
Al Schwartz
Joined
·
3,390 Posts
Discussion Starter · #1 ·
-As in "quick to build" - on the track? TBD

Some time ago I described the building of the BRM V-16 using Mac Pinches excellent body shell and laser cut chassis. At the time, I said that I wanted to use a high revving motor and short gearing to emulate the prototype but, alas, I could not fit my motor of choice and ended up with an SCX motor with which I have never been totally happy.

When I devised a scheme to fit the new Scalex style mini-motor to a standard drilled mount, I decided to re-fit the car with one of these and ordered one of the black 30,000 RPM variants.

I put the car on the track to make a few laps for a "before and after" comparison and decided that it was running so smoothly (perhaps benefitting from some running-in over the past several years) that I didn't want to take it apart.

I wanted to try both the mounting scheme and the motor and do it in time for the Slot Car Convention this week but with only a weeks building (and paint drying) time left, it had to be quick.

I have a box with almost all of the bodies that Mac has made and a few of the chassis as well so - let's have a look. BRM - done, Talbot Lago - done, Auto Union - did one recently, W-125 - in process with a different chassis/motor combination - I've always liked the Alfetta and 4CLT (and have Merit-bodied 1/24 versions) so.....

The Alfetta is the bigger car but has a "pinched-in" shape just aft of the front wheels and the chassis fit looks problematical so - the 4CLT it is.

Cut apart the chassis parts with an abrasive disc and solder up the rear end with standard 3/32 bronze bushings fitted - now let's look to the 6 possible positions for the front axle. The wheelbase of the 4CLT is 2500mm (exactly matching the cut-outs on the body) but the closest two positions are either 1.75 mm to long or 1.82 mm too short for the scale 78.125 mm model wheelbase. Solution: I used the "longer" set-up and ground (the chassis material laughs at files!) 1.75 mm off the rear of the tabs that slot into the base plate. This meant using a chassis jig to solder up the front because the precision of the original tab and slot fit was lost. At the same time I soldered in the guide tab in reverse with the smaller hole over the base plate hole - the larger hole is exactly the right size for the sleeve of the TSRF guide that I planned to use.

The motor adaptor plate was made from a bit of 0.0625" brass the width of the chassis and the height of the motor. A clearance hole for the bearing was drilled in the center, two more holes, drilled and tapped 2-56 on the horizontal center 12.4 mm apart and two holes, on a 5 mm radius 30 degrees from the horizontal were drilled for clearance for the 2mm motor mounting screws and countersunk.

The adaptor plate was mounted to the motor with 2mm FH machine screws.

end of the first evening

The gear collection yielded a 46 tooth aluminum "drag" gear and a 10 tooth Wizzard brass pinion (HO stuff so it has the needed 1.5 mm bore). The big gear just clears the gear cut out in the chassis and the pinion is soldered to the shortened motor shaft.

Now about wheels, tires and weight - The 4CLT mounted 5.25 X 17 tires in front and 6.50 X 16 tires at the rear. These scale to 0.8750" (F) and 0.903" ® with section widths of 0.21" and 0.26" respectively. These are relatively small tires for the era and may reflect the fact that the design of the 4CLT has more in common (except wheelbase) with the "voiturette" class of the 30's than with its 8CTF forebear and the Talbots and Alfettas of the day. In any event, this wheel and tire size means that using a typical "rattle pan" slung under the chassis would reduce the ground clearance below the 2 mm often stipulated in vintage races. The solution I came up with was this: A piece of 0.0625" brass was cut to fit the chassis cut-out with 0.010" clearance all around. This was sweat soldered to a piece of 0.016" brass the same length but the full width of the chassis. The chassis material is about 0.040" thick so, with a pair of wire "L's" soldered to the rear and cross member of 0.016 brass screwed to the front from the top, it "hangs" in place with 0.010" movement in all 3 directions. (There is adequate clearance under the motor to allow this movement)



The wheels are BWA and the tires are Ortmanns - rear and Scalex Maserati 250F front (the rib on the BWA wheels was narrowed to accomodate the front tires and then the outer edge of the rim turned down as well.

While this was going on, body mount post were fitted and the body primed. Before I primed the body, I used an idea I gleaned from another thread (MAF's Mercedes collection?) and ground out the dash and thinned the edge of the cockpit. This would also allow me to fit the curious "half-dash" that these cars carried:



end of the second evening

Today I painted the body (Dupli-Color red lacquer - great stuff - 5 coats in less than an hour, painted the (already primed) metal bits, reshaped the driver under hot water and primed him and made up the wheel inserts. The BWA 0.45" inserts will fit right in but the cupboard was bare so I made some up from Ninco "Classic" wheels. These require that the wheel be bored out slightly to fit so, making advantage from neccessity, I bored the fronts to 0.500" and the rears to 0.480" to give the impression of the two different size wheels.

Will he make it for the 0:400 departure Thursday? - to be continued.

EM
 

·
Premium Member
Joined
·
1,780 Posts
Thanks for a very informative post EM, the detail of the construction really helps people like me with my builds. The chassis looks really nice, let's see some more please
.
 

·
Alan Tadd
Joined
·
4,030 Posts
Excellent Work Alan....Looking forward to seeing the finished article.

I just finished one of these chassis, using a Fox motor. The only problem with it seems to be the guide tongue, which would be much better if it was adjustible. Very neat solution to the problem you have come up with. For us lesser mortals a Slot.it wood guide seems a good choice, due to it's short overhang.

I used the "Howmet" method of assembly, i.e. fixing the individual peices with Superglue to hold them in place prior to soldering which did work very well.

Now I just need to sort out some suitable wheels/tyres for the ERA !.

Regards

Alan
 

·
mac pinches
Joined
·
2,154 Posts
Nice job Al, on that chassis the 4clt handles quite well, i drove Mark Gussin,s 2 4clt,s they had fox type motors with a added plate of brass under the chassis
iv run the moto gp motor in the ERA, my god they have some punch for a small unit but i had Ortmann,s on the rear and found they had too much grip for such a high car, it had a habit of rolling instead of sliding,

Alan[beejay] i used turned back slot-it small hubs on the rear as you know the wheels are a little smaller than the normal GP tyres. cheers Mac P
 

·
John Roche
Joined
·
4,176 Posts
QUOTE The only problem with it seems to be the guide tongue,

Hi Alan,

I've replaced it with one of Chas' SCD guide tongues on a couple of mine. I've also ground an arc our of the main chassis to allow a trailing guide.




John
 

·
Al Schwartz
Joined
·
3,390 Posts
Discussion Starter · #6 ·
QUOTE (MAF @ 29 Mar 2006, 08:09)Thanks for a very informative post EM, the detail of the construction really helps people like me with my builds.
<{POST_SNAPBACK}>

and people like you point the way for me to figure out that one can do this:



QUOTE (BEEJAY7 @ 29 Mar 2006, 08:58)I just finished one of these chassis, using a Fox motor. The only problem with it seems to be the guide tongue, which would be much better if it was adjustible. Very neat solution to the problem you have come up with. For us lesser mortals a Slot.it wood guide seems a good choice, due to it's short overhang.

I used the "Howmet" method of assembly, i.e. fixing the individual peices with Superglue to hold them in place prior to soldering which did work very well.

Now I just need to sort out some suitable wheels/tyres for the ERA !.

Regards

Alan
<{POST_SNAPBACK}>

For me, the TSRF guide is easier to use than the Slot.It - the problem I have with the latter is that the shaft has a noticeable taper and I find it hard to get a smooth but non-wobbly fit.

I just tap the bits together with a small brass hammer - they seem to stick pretty well in place but the CYA is an interesting idea.

According to the BRM (unoffical site) the "B" type ERA mounted 6.50 X 16 tires at the rear and 5.25 X 1`6 at the front - essentially the same as the 4CLT - speaking of which:

03/29/2006 17:30 (GMT -5)



Made it!

EM
 

·
Registered
Joined
·
423 Posts
Wow! What a fabulous car EM! I gotta get me one of them. Thanks for sharing. Explanations like yours make it easier for ham handed folks like me figure out how these all come together.


Todd
 

·
Al Schwartz
Joined
·
3,390 Posts
Discussion Starter · #10 ·
Have some performance observations on the 4CLT: As a wrap-up to the Buena Park gathering, we had an informal match-up of "Early Bird" class GP cars - as it turns out, only Rocky Russo (Prof. Fate) and I had any that fit so we ended up with Rocky running his SCX powered W-163 (from the Maroni race of several years ago), Stan Smith had my similary powered V-16 BRM, Dennis Sampson ran Rocky's 4.5L Ferrari (power?), I had my Pittman DC-196 motivated Lancia Ferrari and I entrusted the 4CLT to Paul Sterret, one of the "locals" and quite a good driver.

Paul simply ran away with the race - certainly some of it was his driving - he made very few mistakes - but it was also quite clear that the Maser was much quicker than the other cars. The track was a short one - the longest straigt no more than 8' -10'. Had it been a longer course, the margin would have been even greater.

Conclusion: The Scalex FF type motor is very suitable for these cars.

EM
 

·
Dennis Samson
Joined
·
807 Posts
Amen to that - the 4CLT runs really well. And a very pretty car in the flesh too. Another great EM production!

BTW, Rocky's Ferrari was also a great car to drive, especially the way one could hang the tail out through the long banking. Power I believe is a Revell RP77 or similar.
 
1 - 11 of 11 Posts
Top