1441 replies to this topic

[Ron Hershman]

This is a interesting question/statement. If the motor has to clear by .050" and the front end by .015" what does the middle of the chassis have to clear by?? Is it .040", .035", etc., etc.

If it has to clear by a certain amount in a certain area, then if weight (lead or brass strips) is attached to the bottom of the car then it probably is not legal.

[Noose]

It's from the motor bracket to the rear of the car that has to clear .050" and from the front axle to the front for the .015". It has to be a flat plane. The lead strips you have seen on some East Coast cars is the type used for golf clubs. It is very thin actually. For those cars that I have tech'd, none of them failed to pass the stated clearance. Most applications have only been one layer I admit. I would think that if someone added mutiple layers then it would surely not be in compliance with the IRRA rule which is as follows:

The rule states:

• No part of the chassis, motor, gear, or other component may hang below the main chassis rail(s), which may not be bent or bowed vertically for the purpose of lowering the midsection of the frame below the level dictated by the clearance specifications.

[gascarnut]

The rules do not allow anything to hang below the level of the main rails as they slope downward from the rear to the front without any bowing to lower the middle of the frame below the flat plane between the .050" at the rear and the .015" at the front.

So, if lead tape is added to the underside of a frame that was built with the pans level with the main rails, it would be illegal.

[Ron Hershman]

When I read component... I generally think of a part. Not weight (brass or lead).

The rule should also read no weight may be added or attached below the frame rails.

I guess if there wasn't an advantage, then guys would be putting the weight on top of their pans instead of the bottom.

[Noose]

The lead can be construed as a component as it is a part once it becomes attached. Same as a body is a component of the car.

[gascarnut]

I don't see how a piece of lead or a length of lead tape could not be considered as part of the frame, or a component of the entire car. Maybe we just need to say "nothing can hang below the main rails" and be done with it?

Whatever, most of this is semantics - the intent of the rule is clear and I'm sure the IRRA Tech Inspectors will clear this up before the race if it looks like it will be a problem.

[Ron Hershman]

I don't see how a piece of lead or a length of lead tape could not be considered as part of the frame, or a component of the entire car. Maybe we just need to say "nothing can hang below the main rails" and be done with it?

That would pretty much clear things up and stop the practice of weight on the bottom of the cars.

[gascarnut]

Oh, you could still put the weight on the bottom, the pans would just have to be attached higher up so that the lead is level with the rails, that's all.

[MSwiss]

I got the impression that the lead being used is only .006" thick and still makes clearance.

[Noose]

It is and does. Tape thickness of 0.0068" and consists of 0.0047" thick lead foil with 0.0021" rubber adhesive.

[Phil Smith]

I've been wondering about the lead on the bottom of the chassis myself. Regardless of clearance, it seems the lead would be below the plane of the chassis, and break the "flat plane" rule.

[Cheater]

Phil,

The "plane" being referred to in the rules is an imaginary one, connecting the front and rear clearances. It is not the bottom of the chassis.

If the car passes the clearance checks, and the bottom of the chassis is flat, I can't see the benefit of being concerned about lead tape on the bottom on a chassis.

[MSwiss]

Having a chassis that's tall enough where you can tape lead on the bottom seems counterproductive
unless you do do it the whole length of the chassis. Otherwise you have lead mounted down low
but piano wire and brass too high.

I guess what I'm saying is if you have an extra .006" clearance in the back where you can tape lead,
you're better served grinding your tires down .012" in diameter.

[Cheater]

Mike,

That's how I see it as well.

[Mark Wampler]

Wheelbase is always the distance measured between the centers of the front and rear axles.

I'm going to disagree on this one far as slot cars relate. Basic handling characteristics are more determined by the distance between the guide and the rear axle. Guide to front axle is a matter of much finer tuning. Wheel base is more identified IMO with vehicles other than slot cars.

[Ron Hershman]

Basic handling characteristics are more determined by the distance between the guide and the rear axle.

And that is called "Guide Length", the distance between the center of the guide post/hole to the center of the rear axle/bearings/bushings.

NOT to be confused with "wheelbase".

Wheelbase IS the distance between axle centerlines.

[Phil Smith]

If the car passes the clearance checks, and the bottom of the chassis is flat, I can't see the benefit of being concerned about lead tape on the bottom on a chassis.

Greg,

Do you include the lead tape when you say, "the bottom of the chassis is flat" ? Or are you saying as long as the chassis itself is flat, the lead tape can be below the flat plane of the chassis, as long as it meets clearance requirements?

[Cheater]

Do you include the lead tape when you say, "the bottom of the chassis is flat" ? Or are you saying as long as the chassis itself is flat, the lead tape can be below the flat plane of the chassis, as long as it meets clearance requirements?

Phil,

I think you're still missing that the "plane" referred to is NOT the "flat plane of the chassis", but I'll just answer your question.

Yes, the lead tape can be below the flat bottom of the chassis, as long as the chassis meets the clearance requirements

[Phil Smith]

Greg,

I think you're right. I did misunderstand. I went back and reread the rules and previous posts. It seems the "plane" is determined by the main rails, "No part of the chassis, motor, gear, or other component may hang below the main chassis rail(s), which may not be bent or bowed vertically for the purpose of lowering the midsection of the frame below the level dictated by the clearance specifications." I take it this rule is to keep people from building stair-stepped chassis that drop down to .015" in front of the motor bracket.

As I read the rules, the rails are the plane. The rails can't be bent to lower the midsection, so the rails, and thus the plane, are flat. Nothing is allowed to hang below this flat plane, regardless if it clears or not.

So if the lead is below the main rails, it shouldn't be legal, at least as I read it. Dennis has pretty much already pointed this out. It seems pretty clear to me that the lead wouldn't be legal unless your pans are really screwed up and ride above the bottom of the main rails.

[gascarnut]

Phil,

You've got it right.

I will deal with Greg and his semantics at the R4 in Columbus.

With the 20/20 of hindsight, we would have had a lot less interpretational issues if we had simply specified a single clearance under the whole car.

[Noose]

With the 20/20 of hindsight, we would have had a lot less interpretational issues if we had simply specified a single clearance under the whole car.

Yeah... Dennis and Tony want to go back to 1/16" all the way around like the "old" days.

[Cheater]

Hmmm... and I think I actually wrote most of that verbiage.

I dunno if I will come to Columbus now... knowing that there's this African-American guy waiting to "deal" with me... LOL!!

Phil, I think the main problem we were trying to resolve was to prevent chassis from being bowed down in the middle between the axles. We know from Flexi racing that such a warp is an advantage.

[Larry Mattingly]

With the 20/20 of hindsight, we would have had a lot less interpretational issues if we had simply specified a single clearance under the whole car.

Can we have an AMEN!

LM

[Ron Hershman]

.050" front to rear with the car/braid/guide sitting on/in the tech block would be very simple to check and and would be an easy change to make.

[Larry Mattingly]

Hey Joe,

1/16" like the 'old' days. Now that is in the s..... Naw, I won't go there...

LM