390 replies to this topic

[Eddie Fleming]

IMO

 The degree of angle for the guide flag is not magic. The big thing once was you don't want the guide nose down. Now most car chassis are angled nose down so a slight degree of upward tilt is needed to counteract the chassis angle. I think the 2 degree angle comes from Mike Swiss and his guides tongues Before Swiss came out with the 2 degree part we just angled the tongue up by a few thousands. 

[Jay Guard]

Using a bit of trigonometry a 4" wheelbase  IRRA car with .050" clearance under the rear axle and .015" under the front axle will yield a .5 degree downward angle toward the front.  If you use the forward most part of the chassis at .015" that actually decreases the angle a bit more, maybe down to .4 degrees for a 1" guide lead.  So a 2 degree guide angle will yield an approx. 1.5 degree upward angle with respect to the track surface.  OK so much for math.

 

My experience has shown that if the guide is pointed downwards, especially if it is significant, the car will push out of the turn early.  If it is angled too far up in the front the car seems to push out of the slot near the end of the turn.  Again just speaking from experience the 1 to 2 degree upward angle seems to be the sweet spot for guide angle with respect to the plane of the chassis and/or track.  For one thing the slight upwards angle puts additional pressure on the rear of the guide shoe/braid and that is why the braid tends to wear out near the rear first.  Note that this additional pressure may also improve electrical contact and therefore improve speed and braking.

 

Realize this is actually a bit of a simplification of a fairly complex system that also includes the speed of the car, how soft the tires are, and the drift angle of the car in various parts of the turn.

[zettler]

Considering I haven't built or raced a slot car since the late 1960's....GOOD GOD! This discussion sounds like you all have taken several leeps forward and are at NASA level.

I am sending this from the tundra that used to be Central Illinois...

PS. I use an Android Cell and am using an excellent APP called SCANNER RADIO. I am tuned in to the Sangamon County dispatchers and it's been nonstop accidents and the like all day. Great entertainment...

[Dominator]

The idea of angling the guide is to help reduce drag and in some cases the bottom of the guide from hitting the bottom of the slot.  Keeping in mind the front wheels act as a pivot point so angling the guide also affect the pressure on the rear wheels. 

 

Adding to what Jay said about front and rear clearance.  Depending on what size front and rear tires are used when setting up your guide spacing will vary the amount of spacers needed to set your guide depth.  I have been asked multiple times how many spacers I run on my cars and I have corrected racers by saying I set my cars up with zero lift at ____ guide depth using a guide depth block.  Using a guide depth block is the best way to consistently set up cars. 

[snolde]

Front wheels touching the track also reduces drag on the car and reduces tipping out in the corner.

2 degree up tilt on the guide moves the pivot point of the guide closer to the guide post as well.

[Clyde Romero]

Front wheels touching the track also reduces drag on the car and reduces tipping out in the corner.

2 degree up tilt on the guide moves the pivot point of the guide closer to the guide post as well.

Scott I am not so sure I agree with your view on drag

anything that is touching a moving surface is drag 

[Pablo]

I think what Scott means is, a rolling front wheel touching the track creates less drag than the chassis bottom touching the track.

[Clyde Romero]

Well, I want to thank all who participated in that discussion on the guide flag, I can only speak for myself, I still don't understand why the 2 degrees nose up works but does!

 

Anyway, on to a new subject which has always baffled me, tires.

When I am at a race away from home, I see what the others are using and go that way and hang on!

From my personal observation you have 2 schools of thought.

1. go with the hardest tire you can 

2, go with the softest tire you can

 

Ok for me having raced motorcycles (knee dragger) you want the softest tire possible hands down, period no question at all. Traction is paramount!

Speaking to my car friends who race, same there when racing.

 

Soo to all of you out there reading this, have at it. I am all ears on this subject that we all have to deal with when racing slot cars.

 

We down here are kicking off our Spring SERRA season next Saturday.

 

So, stay tuned this subject is going to be interesting.

Looking forward to hearing from the guys that move at the speed of heat !

 

Be safe out there, this virus thing isn't over yet by a long shot.

 

Clyde 

[Pablo]

I still don't understand why you don't understand a chassis that is sloped down towards the front needs the flag tilted upwards to compensate.

[MSwiss]

you want the brushes as flat as possible on the guide flag, to reduce inherent drag on the car
 
Clyde

No, you never want it flat or mashed against the guide.

With the car out of the slot, you want it at a slight angle, for good contact, and let the weight and downforce of the car do it's thing, when it's back in slot, racing around.

Because of the above, the hardness/temper of the braid you use is all important.

IMO
 The degree of angle for the guide flag is not magic. The big thing once was you don't want the guide nose down. Now most car chassis are angled nose down so a slight degree of upward tilt is needed to counteract the chassis angle. I think the 2 degree angle comes from Mike Swiss and his guides tongues Before Swiss came out with the 2 degree part we just angled the tongue up by a few thousands.

Master machinist, and colorful character, the late Michael "Duffy" Heinrich was the first to sell a 2 degree/raked guide tongue.

He bought flat steel tongues from me, and much to my surprise, bent the 2 degree angle in them.

After Duffy had passed, and have had spent a fair amount of time in front of the surface grinder at Koford, I came up with the idea of grinding the base of the tongue, instead of bending it, and got my machinist friend on figuring out a reasonably easy way of doing it.

As fiercely as I protect things I did come up with, and the important word popularized, I don't want credit for something I didn't.

My take on this.

The exact angle isn't important.

I'm pretty sure you don't want too much.

And dead flat is probably fine.

But if you notice any wear or black spots at anywhere other than the back section of your braid, you're screwed.

[Danny Zona]

On the subject of tires it's just not hard and soft rubber.

Hub size is also a factor.

[Jay Guard]

And to add to what Danny said, hub material.

[Alan Dodson]

I find in retro racing that you rarely want the softest or hardest tire available, but instead you want the tire that matches your car's traction requirements and the track conditions. That's why it's important to have a variety of tire/hub/rubber combinations and take durometer readings so you can fine tune your combination. That being said, some tires just seem to work better on some tracks and you should always see what the popular tire is at that track. At least its a good place to start!

[Eddie Fleming]

Clyde 

With tires I think you have hit one of the big problems with slot racing. Current tires get expensive quick when you need to have multiple compounds in multiple rim sizes, and brands to boot. On top of that they don't last long. On top of that often you wind up racing someone with a tire manufacturer connection that is running some tire combination you can't get. Not that I could probably compete with that guy anyway but it is still frustrating.

 

The closest thing I see to a solution for all that is stickier tracks where we could run wonder rubber rather than soft rubber on dry tracks. Then the tracks need to sell tires. I see that.

 

Yep I think it is a problem. 

[DavidR]

Why not glue the track more and require one tire or even hand out, wouldnt this even the racing field better. I know many might not be in favor of this being they have the knowledge and resources to achieve performance, but many new or others that race on limited budgets might be more inclined to race more.

[zettler]

Back in the 1960's, our racetrack in Champaign, Illinois was called CU Model Raceway. Ben F. Harris, Sr., had two identical tracks built, if I am not mistaken, out of fiberglass. Very clean and smooth.

My first job back then was for a BIG Mura Race and I used a squeegee like push device that was as wide as the track itself, and would put (I believe) cheesecloth around it to clean the lanes between races.

It was an extremely smooth, clean track.

The front track was for kids or anyone but the rear track was primarily for "pros", racing and the like.

NO FOREIGN MATERIAL allowed on tires. And, it wasn't a battery powered track but an electric 12 volt system.

We used the regular rubber tires but Ben had a UNIMAT that he used to coat them with a smooth outer layer of silicon - and it worked there.

We only ran into issues when we raced elsewhere, where they were battery-powered tracks and you had to place sticky crap on tires.

It worked well for us. Didn't burn up motors. And had the constant 12 volt power source that didn't vary as it did at most other tracks.

Just a little history from back then...

Oh, by the way, towards the end of my racing back then, I used Mike Tango armatures sold by a track in Nutley, NJ.

I believe that's the correct spelling.

[gc4895]

I went with 3 friends all the way from StLouis to a race at CU model Raceway in, I believe, 1967. I think at least one of the races was in-line F1 or Indy cars. We were shocked by the silicon tires since St Louis was sponge and goo the track racing. We also didn't come prepared for the power as we were battery racers. We collectively did very poorly. But, I've never forgotten those pristine white tracks. That was a stern lesson in attempting slot racing outside of your home track.

Also, I've never forgotten the new fast food place across the street from the track that we had never seen before. It was Arby's and they actually had sliced roast beef sandwich's. Not the chopped, pressed-shaped stuff Arby's evolved into.

[zettler]

https://www.autopuzz...ster-the-story/

I was replying and lost the reply so here is another attempt...

And you can see we also had troubles adapting to the other tracks with their battery power and tire goo.

In fact, in one of my pictures I posted today, I see a bottle of that tire goo...

The link above is to a story about Old Ben that might be of interest to people here. Difficult to believe he designed and built this car in 1935!

[zettler]

Here is the inside top tray of my slot box that I still have:

https://photos.app.g...Spi734YCNVA1WZ8

[zettler]

And here are some of the gear inside. A controller, chassis jig, INDY type chassis/car I built and a bunch of motor parts, etc.

https://photos.app.g...RLEFS4zJhmHDFk7

[zettler]

I airbrushed and hand-painted all my car bodies. And that's probably why my lungs are in such bad shape today!

Here is a closeup of the one car's interior with my nickname (LOL) etched on the helmet.

https://photos.app.g...XWtwdL1x5vvcVj7

I was probably 14-15 when I was doing all this. Once I discovered girls and ___, I kind of dropped out.

[Clyde Romero]

Wow this subject got racers out from behind the benches.

Interesting stuff here, hub sizes and compounds along with track conditions are players

We have all  experienced this while  racing it just seems there is no one solution for a given race or track

Its a dynamic issue, Yes?

At least that’s what I am reading here and what I have experienced.

A spec tire race might be interesting to run, we have that at our track with the box stock series and it does level the playing field so to speak.

 

But here is what I have experienced so far in my 5-6 years of retro racing.

Every racer has a secret that they will not share for fear of losing to that racer.

When you first enter the fold everyone will help you, as you get faster they tend to abandon you so to speak.

As always there are exceptions to this.

Am I lying ?

Its kind of funny actually, since at all the major races the the top 3 cars are totally exposed and you can see what and how the chassis was laid out.

 

Anyway I still enjoy it even at the 70 year plus mark.

 

my next subject 

BRAID!

 

 

 

[Clyde Romero]

Well, we had a great retro race this Saturday at our track.

Some old faces returned to our series and a couple of new ones as well!

 

lots of good racing and fun to be had by all

look for the entire race report under the Retro Forums SERRA

 

Question?

what makes a good race director? 

and who should be a race director? Track owner/ racers?

 

looking forward to the feedback on this important question we all face as racers.

 

Clyde 

[gc4895]

We have the wife of a competitor as our race director. She is focused, fair, always timely and abides no nonsense from the, sadly, typical crybaby slot car competitor. No one messes with her or questions her judgements. Races go smoothly and when the Flying Fickle Finger of Fate lands on a competitor, as often or always happens at toy car races, they "take it like a man" because the race director just don't care and abides no foolishness. Qualities demonstrated by fine race directors everywhere. As always, YMMV.

[Clyde Romero]

While I am at it with regards to race directors and such, what constitutes a valid track call?

A car on the floor?

multiple cars off in a corner?

a car off under the bridge?

what about a car that de-slots down the straight away and slides into a corner (happens all the time on a Hillclimb track)? 

some calls are obvious, like with a king track a car that falls in the bowl 

but I would like to hear from others on this important subject we all face in this hobby called slot cars.

interesting subject