1441 replies to this topic

[Justin A. Porter]

I'm a little curious about the axle tube rule.

I have an ancient brass chassis that's been hanging around at the bottom of my spare chassis box that seems to conform to the construction rules (Dad says it's probably an old Group 20 chassis, since it had the "suspension" front wheels and a motor box).

I've started disassembling it with the idea of scavenging the pans for an anglewinder car, but its rear end has a kind of soldered "box" for holding the oilites. Do I have to remove this and replace it with a tube, or could I keep my oilites.

Not that it's really a problem either way. I just want this car as a knock-about and maybe for the big race at Tom Thumb as a one off tryout.

[Ron Hershman]

Sounds like a Parma "brass-kar" chassis... Does it look like this?

[Justin A. Porter]

That's exactly the beast. Here I thought I'd done a lousy job describing it. lol

[Ron Hershman]

No, it was the only car ever mass-produced with a brass motor box. Check out a modified one HERE.

[Rick]

.820" tires and a guide spacer is all that's needed. Oh, I forgot...those bigger fronts are heavier and racers want lightweight stuff.

What tire sizes did they use in the '60's?

Are these not the same bodies?... they may look too retro, gulp!

[team burrito]

.750" dia x 1/4" wide for the fronts and 7/8" dia x 3/4" wide for the rears, per NCC rules.

[Paul Martin]

Hi Guys,

I have another question concerning the JK Spec class. I have noticed on the last two of these chassis that I built that the chassis as provided, uncut, measures 3.140" wide across the width of the pans at the rear. Since it is within the rules to run the car without cutting the pans off for hinging, is it then all right to file or sand the outer edges of the pan to satisfy the width rule of 3.125" or will this be overlooked? I did cut the pans off on the last chassis built but not until the hinges were in place. This, of course, also resulted in a 3.140" width measurement. How do I rectify this width problem and stay within the rules of not tampering with the pans to lighten them in any way?

Thank you again,
Paul

[MSwiss]

Thanks for pointing that out, Paul.

They do tend to spring/taper out a bit in the rear. By the time I shortened the pans in the rear for tire clearance, mine came to 3.120. Of course wheelbase (mine is 4") and how much tire clearance someone is comfortable with, will vary.

While this probably falls into that "trimmed at the rear to accommodate the desired wheelbase" rule, I'll suggest we rewrite the rule a tad to make it a bit more clear.

The holiday weekend might make the IRRA's usual group discussion impratical or impossible. So while not an official IRRA response, I'm 99% sure a little bit of filing in the rear around the back body mounting tab will be allowed to bring it into legal width specs.

You can also rest assure the IRRA is not the type of organization that would bounce you out of tech if you didn't hit 3.125" on the head, narrowing it down to make spec in the rear. Common sense in the interpertation of the rules will always be exercised by the IRRA.

[Paul Martin]

Hi Mike,

Your observations of the situation pretty much mirror my thoughts but I figured I would get it out in the open so the IRRA guys can address it. I would certainly agree that a racer is not going to be ousted for such a minor infraction when it isn't clear-cut.

Since all the cars are from this kit, it would seem that adjusting the width rule for just the JK Spec class is the quick and simple remedy.

Thanks again,

Paul

[Noose]

Hi Paul,

We'll tackle this after the holiday weekend and make sure we post something on it. Thanks for pointing it out.

[Hip Jones]

Greetings,

I'm new to this. The JK Spec rules say that the axle tube must pass through the motor bracket. Do I have to use axle tubes or may I place the bushings directly in the mounting holes in the bracket?

[Marty Stanley]

Hip,

Welcome aboard. While I've seen JK Chassis built without using an axle tube, I guess I have to ask why?

You still have to space the wheels out on the axle, so the tube provides a bit of both.

Just my opinion.

[Hip Jones]

Marty,

This is my first attempt at building, and to be honest with you, laziness is the reason why I want to avoid using axle tubes. None of us that hang at the local track have one of these cars and I'm anxious to see what it feels like to begin with.

Hip

[MSwiss]

The JK bracket, while it needs to opened up a hair for a 7/32" axle tube, can only be used straight with bushings if you fill it in quite a bit with solder.

[MSwiss]

I'll be adding text to the JK chassis article, hopefully later today, while Sano Dave is showing Howie Ursaner the finer tips of getting around the Flat track. Howie's been here about 15 minutes, and hasn't gotten on the track yet, but I've already heard Sandy Gross's life story.

It was great to hear they have stayed friends over the years and the super-high respect Howie has for Sandy.

[Marty Stanley]

Hip,

The article that Mike alluded to was the one he has posted right here:

IRRA JK Spec Class Chassis Build

It is an excellent article and one that shows Mike can use his fingers - correctly.

If you need or would like any more information on this, then just pose it here and I'm sure you will get all the help you can stand!

[Hip Jones]

Marty,

Thanks for your help. The IRRA rules board (Cheater) contacted me almost immediately.
I never expected such a swift response. These guys are on the ball.

My error in not reading and understanding the rules. Opening the tube mount holes to accept a 1/4" OD bearing is not permitted. It may be okay to go with a sloppy fit and a lot of solder using the 3/16" OD bearing, but that brings us back to your question of "why?"

I have a much better understanding of this part of the construction and will be using an axle tube.

Thanks again,

Hip

[Phil Irvin]

If you think about it. The wider the spacing, the less the torsional twist the bushings have to put up with in the turns. If you have a narrow spacing and the bushings get a little wear it shows up real bad at the axle ends and you might have a chatter going around a turn. AND if you back it into a wall hard the axle will bend/break lots easier and transfer it to the bracket harder.

Phil

[The Number of]

It has been stated elsewhere that full sidewinders are not legal in Retro Anglewinder class.

What is the minimum angle allowed?

[Cheater]

There is no minimum angle specified, Bill.

In a sidewinder, the armature shaft and the rear axle are parallel. Stands to reason that if the shafts are measurably not parallel, it's an anglewinder.

Perhaps if someone builds an anglewinder with a miniscule angle, IRRA would revise the rules to specify a minimum angle, but I don't see an obvious need to take that step at this time.

[Hworth08]

Bill,

The FK motors aren't well designed for a really shallow angle. Being a full can, using 15/39 gears (which may be a bit high with .790" tires), 8 or 9 degrees is about as shallow as the motor can be before the can hits the axle.

[The Number of]

Keith's pics from the 8/24 races at BP show a sidewinder with a TSR motor.

Just trying to head off a controversy when somebody shows up with a motor mounted 1/10 of 1 degree off parallel.

[Ken Bryan]

The Sano will be my first race under IRRA rules.

I am confused about the F1 bodies. I have raced D3 only, which has a narrower chassis width. I built a 1-5/8" chassis and went to look for the right bodies to fit it. I see a couple of bodies that come in "wide" and "narrow" versions. Which would best correspond to a normal IRRA chassis width?

[Ron Hershman]

The O/S 430 Cooper and O/S 431 Lotus 49 of course.

[Noose]

Ron's as well as the TrueScale bodies shown will fit nicely. Also the wide Lancers.