47 replies to this topic

[Tom Thumb Hobbies]

The Grp 15 class was divided into “A” and “ B” divisions to encourage new racers to compete in wing racing. Off the top of my head I don’t remember the details but the “ B” class had more restrictions on both parts and drivers. An entry level wing class.


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[Alan Draht]

I was not active in slot cars for most of the 70s and started again in 1980. Already at that time, Group 15 chassis used a single hinge chassis, plummer only and no floppy pans as has already been mentioned. This Yeti 510 clearly has plummer and floppy hinges, so I would guess it is from an earlier period in the 70s. I have owned 3 Yeti Group 12/15 chassis from the 80s, and these had a semi-circular cutout on the winged nose and only plummer pivots. Should be set for 13/16" (.820) rears. 1/2" fronts, and would likely have run a 3-slot Mura C-can. Information above erroneously states the arms were 29 turns 29 wire; the wind is actually 50 turns 29 which has continued to be used for Group or International 15 and also for Group 12 and C12, although the 12 arms have a shorter stack. USRA specifications for Group 15 arms stated a stack length of .440" min, but I have old Mura 15 arms (also Group 27 C-can) that have almost a .500 long stack (.485 - .495).

 

Hi Bill,

 

Thanks for this post.  The Group 15 facts presented and your advice for wheel/ tire sizes front and rear, as well as the 3-slot Mura C-can motor recommendation tells me exactly what I need to know to select period-correct components and build the car.

 

I will choose a high-downforce body from the 1970's since, as you've outlined, this Yeti frame's design predates the 1980's version of the Group 15 regulation racing frame.

 

It's good news to me that this Yeti frame can be paired with a 1970's body.  I wasn't planning to build a wing car when I acquired the frame completely ignorant of what a Group 15 car is or looks like.

 

This has been very educational for me.   

[Bill from NH]

Not only was the O/S Ferrari a wing body, it was the first body O/S produced of any kind.. I believe its part # was 001;  Ron Hershman in IN now owns O/S bodies. If anyone has the Ferrari body mold, he probably does. I used the O/S Ferrari in opens during the 70s & into the early 80s for Grp. 20/22/27.The red body of Ray Carisi's is a Parma Mohawk. That body was used in opens & Grp. 27 until the late 90s.

[NJ Racer]

An O/S Royale was originally my body of choice on top of the Box 15 in 1988 but only took laps with it on the Nuvolari at Elmsford for kicks and  to break in tires for Int 15 and GP 27.  I  actually had the Parma Mohawk mounted on an Int 15 Zap 102 chassis & Camen ceee can setup with 15 Arm (pic below) which I actually raced often at Elmsford between 88 - 90. I used a Koford Feather 15 setup as well in Int 15. 

 

[Mike Patterson]

When I was racing in the Tri-State USRA back in the late 70s-early 80s, Group 15 was divided into A & B groups. IIRC, the major difference between the two was 15A used strap style motors, while 15B ran C cans.

 

FWIW, here's a pic of my last Grp.15 chassis and bodies:

 

I still have an unmounted/uncut O/S Ferrari body.

[jimht]

Group 15 was one of the original NCC classes (introduced after the success of Group 20).

 

Group 15 started out at $15, had changed to $20 by 1968 and had gotten steadily more expensive by ~1985 when a cabal of early Bernie loving Democratic Socialists decided to fix Group 15 by restricting some of the prices of some of the other parts of the car to stop the wealthier racers from dominating the class...coming up with chassis price rules and a new name "International Group 15".

 

That worked except for those who avoided the chassis price restriction by selling over-priced "rolling chassis" and motor manufacturers that always increased prices when their costs increased.

 

Aside from that, Group 12 motors with the same wind and a shorter stack were faster and cheaper, so International Group 15 was kind of dead in the water from the start until the motor rules changed to C-can straps and chassis devolved into beer can materials as they are now. A & B classes developed to try to keep some semblance of controlling costs, and that allowed the big spenders to spend as they wished.

 

The class is still popular, somewhere, I think.

[Bill Seitz]

Jim covered most of the Group 15 points except for scratchbuilt chassis were specifically allowed with some restrictions like the rear end could not have steel parts. I still have some of the Slick 7 phosphor bronze pillow blocks (struts) from this era and remember the Slick 7 hybrid chassis with the phosphor bronze rear half coupled to a steel front half. While scratchbuilders did race their own chassis, the successful ones were also often sold to other racers for well over the chassis price restriction. Most of the winning cars featured scratchbuilt wire chassis. Wire chassis do not survive a high speed crash fest very well, which required chassis to be replaced frequently. Though Group 27 had a higher initial cost, the spring steel chassis were more rugged and could survive several races. Eventually Group 15 also moved to spring steel chassis and then to cobalt strap motors with the difference between Group 15 and 27 so small that the lower class appears to have fallen out.

[Tom Thumb Hobbies]

Grp 15 was doomed when 12 arms were legalized. I still have some PS 12’s that have ridiculous numbers on a meter. I’m sure today’s are even better.

[Alan Draht]

I finished building a complete slot car chassis based on the Yeti "Mo" Group 15 frame.

 

It's not your typical Group 15 racing slot car.

 

Some components, like the motor, are genuine Group 15 - certified (at least the "Motor Etc." brand label said it's a Group 15 "high timed" motor).  Others components are not strictly Group 15, but the chassis sits well on the test block so I know the rear wheel/ tire size is correct.

 

The front wheels don't stabilize the chassis; they just ride along for show.

 

I like the way this car turned out.  I will not be using a wing-car type body.  It will probably be a 1970's MAC Gulf Mirage or Porsche 930 body which have good air control features.

 

 

 

 

 

 

 

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[Alan Draht]

PS… His Slotblog handle is YetiSRP.

 

No response.

[HarV Wallbanger III]

So Cal USRA developed the Boxstock 15 class in 1986. It was done so Mfg's could sell a over the counter chassis and car for people to start racing in our USRA. By then a scratchbuilt chassis was all the rage in I-15 and track owners and Distributors hated that because they did not make the $$ on them.... even thought they got to sell all the parts that made a I-15 car. I won my first USRA glue race in 1984 using a chopped up Parma Mono rail chassis at Go Faster Rwy. in Lancaster CA.

 

It's funny now one of the largest racing classes is Retro Racing all using a scratchbuilt chassis and track owners love to sell all the parts and the spray glue racing!

 

Strap cans were voted in at the Nats in Seattle in 1988 making them legal for 1989 USRA.

[Mark Onofri]

Alan,if I'm not to late to this party,I have a bit more information for you(& everyone). I'll try to find the button to follow this thread.It was a support class ( maby weekly) @ Fantasy in Rochester. I bought a lot of stuff to race but,never did.

[HarV Wallbanger III]

Thanks, Mike, for posting that photo of the 1987 Nationals Int 15 and Box 15 cars.

 

Did the Box 15 car use a stock body like the O/S Ferrari Mike Swiss mentioned or was it a wing body?  The Int 15 car used a wing body, I assume.

It was winged ... all Boxstock and Int.15 cars were winged as all USRA classes were back then.

In So Cal USRA this is a GP20 chassis or as we called them 27B class. All GP20's were C can motors. No limits on movements.

[HarV Wallbanger III]

Grp 15 was doomed when 12 arms were legalized. I still have some PS 12’s that have ridiculous numbers on a meter. I’m sure today’s are even better.

Yes I think so as well.

[old & gray]

Grp 15 was doomed when 12 arms were legalized. I still have some PS 12’s that have ridiculous numbers on a meter. I’m sure today’s are even better.

 

For me (Late 1990s) 12 arms meant I could buy 1 or 2 and have a competitive motor rather than gearing on the razor edge of burning up; buying 30 arms to get one good one; or the ever popular "I know a guy who can hook you up."  

[Bill from NH]

I never got involved with I-15, but I acquired a couple arms. Were I-15 arms only factory wound or did people such as Joel & others hand-wind them too?

[Phil Smith]

I agree it was much harder to get a fast I15 arm than it was a 12.

[Mr. M]

G15 was supposed to be a builders class to gain experience for G27 and up. We all know how that went…

[Mr. M]

I15 was supposed to be machine wound.

[Mark Onofri]

I wondered why it came with (2)two sets of pans.

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[Mark Onofri]

They were thoughtful enough to give you a little roll of solder.
Have you ran one yet(ti)?

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[Mark Onofri]

Had I reread your questions,I would have taken some body & motor pix. I'll try to be a little quicker in my response this time.

[Bill from NH]

I don't have a Yeti chassis, but I got Yeti nose pieces in brass & steel, as well as .032 brass pans. Jim Bandes was very good at designing & building a number of different chassis. I don't think he is still involved with slot cars.