43 replies to this topic

[Marty N]

Digging around on the web the other day and I ran across references to the windings of what we call the G20 motor. I found several old articles that stated different windings for this platform that noted, depending upon the author, the following specifications in its original form:

45/27
35-45/27
38/27

Any idea what the original winding was? Who and when it became a recognized "class"? Was is always .440" long X .510" OD? Did it start as a C-can wind? How did it crystallize as a class?

Any and all information welcome.

[havlicek]

I thought the old C-can G20 was 40/27. Whatever it was, it was a fast and fun motor.

-john

[Ron Hershman]

45/27 was the "original" wind and on .500" or so long blanks. .515" or so dia.

I have no idea when exactly they went to 38/27 but when I started racing in 1982 that's what a Gr 20 arm was wound and on a .450" stack length. .513" diameter.

In 1983 they were minimum .440" stack length. .513" dia.

.510" and .500" diameter Gr 20 arms came about in the early '90s and were for C-can drag racing.

All of these specs were for C-can Gr 20 arms/motors.

[Hworth08]

The 20 goes all the way back to the NCC days of late 1969.

There was the Group 12 and 20 and the G20 arm was the only legal arm for the Formula 1 class though any other motor parts were legal.

I don't know what the 20 wind was but it was a very smooth, easy to drive wind. I would guess about 60 of 29 which was the original modern G12 wind but the 20 had a longer stack.

The NCC G20 motors were the first "fast motors" that we EXPECTED to actually finish a race! The arm usually lasted until the comm wore out.

[jimht]

As I recall, the original NCC Gp 20 was machine wound 40 turns of 27 +/- 2.

Bill Steube introduced (and got legalized) a 38 turn hand-wound arm and that was the end of that.

The original progression was quite logical for the Group arms and RTR cars:

Gp 12 50 turns of 29, car cost $12.
Gp 15 45 turns of 28, car cost $15.
Gp 20 40 turns of 27, car cost $20.

Later, Mura mistakenly produced a batch of Gp 15 arms that were 50 turns of 29 and that was the end of that.

(An aside: the 28 gauge Champion arms were priceless for a while, then Champion ran out of the .006" blanks and started reselling Mura arms and that was the end of that.)

Even later, I came up with a class I called 20-7, which turned out to be a way to go slower than an Open for the same amount of money and that was the end of that.

Even later, later, I came up with a class that used a Gp 15 arm in a 27 setup with bushings, that devolved into Cobalt 12; that also turned out to be a way to go slower than an Open for the same amount of money and that was the end of that.

If I actually find documentation regarding my memories, I might post it... then again, I might not: what if it proves my memory to be fallible, instead?

[Ron Hershman]

Bill Steube introduced (and got legalized) a 38 turn hand-wound arm and that was the end of that.

Group 22 which later became Group 27.

[jimht]

Well... actually, Ron, the Gp22 class was formed the second? year after the introduction of the wildly successful Gp20 class, as were the other Group classes.

Thorp and others were miffed about not being on the Gp20 money bandwagon (that was originally restricted to a Mura motor in a Champion chassis) so they got Gp22 as a token extra class, not to be included in the original Gp20.

Everyone naturally ignored the artificial distinction and just ran them all together.

The hand-wound arms came later as the California USRA developed after the demise of the NCC.

[Ron Hershman]

Yes. Jim, but IIRC... Group 22 was created for the "others", with a slightly different chassis and also allowed hand-wound Gr 20 arms (yes, I still have a Steube HW tagged 22 arm) and this was the reason these cars had to sell for 22 bucks or less.

The extra 2 bucks allowed for "hand winding".

Hey Jim... while we are on the subject of "history"... there is a guy in the Slot Racing History forum here that would like to know the eight guys who were in the USRA Nats Pro main at your place in 1975.

Can you help him out???

[team burrito]

Bill Steube introduced (and got legalized) a 38 turn hand wound arm and that was the end of that.

I had one of these arms and it was quickly banned from my track. We used Group 20s in Group 7 frames and called it Group 27. At least, that's what I remember back in the NCC days.

[Zippity]

Group 20
38t/27, .440" stack length, .513" diameter.
- C-can setup used in wing cars and drag racing.

Group 27
38t/27, .440" stack length.
- Hand-wound, any diameter, used in cobalt strap setups.

Source.

[Marty N]

Thanks, guys. Now that's what I call a history lesson. Keep it coming. I'm on the edge of my seat here.

[S.O. Watt]

Group 20
38t/27, .440" stack length, .513" diameter.
- C-can setup used in wing cars and drag racing.

Group 27
38t/27, .440" stack length.
- Hand-wound, any diameter, used in cobalt strap setups.

Source.

That's all the late info and specs concerning 20s. Not quite the same as when they were introduced in the '60s. Wish I still had my old NCC 20 car, it was the one Morrisey built up for the article back then.

I raced that car four times and it finished with a good record - one win, two seconds, and a fourth, plus three TQs, and I was given the Moniker "Grp 20 Ace". I believe the stacks were .500" long by .513" then and thick laminations (not remembering really well, another CRS moment). I set it up in a old Mabuchi can and it really made some HP after that. I also used the Lancer Porsche 908s and liked them on the 20 cars, not on opens.

The class was first proposed in 1968, finalized in '69. There was a Grp 20 exhibition race run in conjunction with the House of Hobbies USRA race on their red track in Oct or Nov (?) '69. Mike Morrisey gave me the car to help fill the field. Bob Bernhardt won that with me taking second. As far as I know or remember, that was the first race for the class.

The following January, 1970, the Car Model series in Los Angeles area ran a split program with the races alternating between Grp 20 one month and Open class the next. The Pros and Semi Pros were also combined for the Grp 20 class events. The first race was held at Santa Ana Raceways, a local track to me, and I was TQ and won. The next race for Grp 20s was held at the Dave Howard's home track, Bellflower Raceway. I somehow squeaked a TQ out and Dave and I had what was one of the most exciting races I ever ran (had to be tied with the two races Fred Hood and I split the wins on at the '70 Arco and NCC races held at Speed and Sport). We were nose to tail for 40 minutes with those cars! He won and I felt that he had raced probably his best as I thought mine was right up there, too.

The rest they say is history...

Edited: added some race history for the LA Grp 20s.

[jimht]

Yes. Jim, but IIRC... Group 22 was created for the "others", with a slightly different chassis and also allowed hand-wound Gr 20 arms (yes, I still have a Steube HW tagged 22 arm) and this was the reason these cars had to sell for 22 bucks or less.
The extra 2 bucks allowed for "hand winding"

Well no, not exactly, Ron. The $2 difference had nothing to do with hand winding.
In fact, the original Gp 22 price was $24.95.

The Checkpoint arm was originally priced at $9.95. I believe, and didn't arrive until well after Gp 22 was formed.

Its price made it illegal when it was first sold, but when it was found to be faster it was immediately legalized, of course.

Here's an excerpt from MRJ, Vol 1, No 24, Mar 10, 1970.

[John Streisguth]

I have two original NCC 20 arms from about 1971. Stack diameter is .515", stack length is .470".

I also have a Mura 20 arm from about 1990, measures .513" dia and .440" length.

[Hworth08]

For comparision. I got a Wing car off eBay that was mixed in with several other cars. The car had a very pretty frame the way it was bent, piano wire Box Stock chassis. The motor was probably an early '90s setup but had a NCC 20 tagged arm.

I thought the frame was pretty so I cleaned the car up and freshened the motor as I was anxious to drive a NCC-20 arm again. I did a little tuning and got the car to running the King track wide open with full width tires (not much glue) with the Wing body.

I was pretty proud of this old three-legged horse until one of my buddies got out his modern Gp12 Wing car. His car had been at Mike Swiss's (maybe 2006) a couple months earlier for the Nationals race. Handling-wise he was just a little better but his car was SO much faster on the straight! He was probably 20 feet faster on the straight. He would come to a complete stop before the deadman so I could get caught up and we could race through the infield.

Sure is hard to beat technology!

[Marty N]

The original progression was quite logical for the Group arms and RTR cars:

Gp 12 - 50 turns of 29, car cost $12.
Gp 15 - 45 turns of 28, car cost $15.
Gp 20 - 40 turns of 27, car cost $20.

Later, Mura mistakenly produced a batch of Gp 15 arms that were 50 turns of 29 and that was the end of that.

When then 15s were 45/28, was that on the .440" long stacks? (50/29 on the long stack just never made sence to me).

If so and the NCC 20s were .470" to .500" long seems there was a plan there where the wind got hotter and the stack got shorter?

[idare2bdul]

There were some 36 turn Champion machine would arms that inadvertently went out the door when the machine was set wrong to wind them. The funny thing about that was that by this time these machine wound arms didn't sell well compared to the Muras and this went unnoticed till Champion briefly hired Big Jim Greenamyer who caught the mistake and perhaps amazingly had it stopped.

[Marty N]

Guess I made the question too long.

When Group 15 was 45/28 what was the stack length?

Thanks.

[Ron Hershman]

Around .500" length. Could be .480" to .510"... they tried to keep the stack lengths pretty close to .500" in the Group 15 and 20 arms back in the day and in the beginning.

[Marty N]

Thanks, Ron.

[Dan Miller]

The hand wound 38T27 GP27 wind may well have been a byproduct of when Bob Green had a new Mura armature lamination die made. Bob and Bill Steube found out that 38 turns of 27 fit the blank well, thus dropping the last 2 turns going from 40 to 38.

This info came my way when Bob gave me a walk through tour of Mura back in 1979.

There was a time when very few armature blanks were available. Bob Green was generous and allowed some people access to the Mura blank. This led to some interesting competition between custom armature winders. We were all using the same blank. Granted, the Champion blank came and went, but the supply was only for a while and rather variable.

The first real surge of independant blanks, other than Thorpe, who kept to himself, began in the early 1980s.

Then the insanity of many different classes of racing became the norm.

... And all the factory cheating that goes with it.

[Marty N]

I just have to ask now that the ball is rolling. The only popular wind we missed in the thread is the 12 wind. What was the original stack length for this wind?

[Chris Barnes]

In 1969, we were racing a group 20 class weekly in Atlanta at the "Bowling Alley" off Stewart Ave. We used the Champion pan chassis that had floppy pans. The track was an Engleman 220, I think. We had plenty of great racing on that track. Then one day it was gone, heard they cut it up. Probably part of the threat to bowling that was perceived by AMF.

[TSR]

Probably part of the threat to bowling that was perceived by AMF.

AMF owned NO raceways or tracks in the United States. So this bogus conspiracy is absolutely, truly baseless.
Urban legend spread by the same types who believe that Elvis is alive, ancient aliens have taken over the earth, and cars can run on water alone.

The only involvement of AMF in slot car racing is that in 1966, they purchased a license from American Model Car Racing Congress to manufacture and market tracks everywhere in the world EXCEPT the United States.

They fell on their face a year later as the London-based market ploy tanked with the rest of the hobby.

[Marty N]

I just have to ask now that the ball is rolling. The only popular wind we missed in the thread is the 12 wind. What was the original stack length for this wind?

I so don't get the last two post LOL