57 replies to this topic

[Steve Deiters]

Still trying to get my head around the design concept and building techniques for the "Z" rail chassis thing. I know there have been postings of builds on other strings on the blogs, but if everyone could share photos of their builds and the latest versions on this central one it would be greatly appreciated.

[MSwiss]

Here are some good pics of a recent Manta Ray Price built Z-railer that shows the basic concept pretty well.

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[Steve Deiters]

Thanks for the pics, Mike. Rail diameter?

[Jairus]

Wire-wrapping those joints would go a long way toward strengthening that chassis. Jes saying...

[Ace]

Hard to wire-wrap rail joints as IRRA™ does not allow anything below the plane of the main rails.

[MSwiss]

wire wrapping those joints would go a long way toward strengthening that chassis. Jes saying....

Wire wrapping would create clearance issues.
In the case of the car pictured above, the joints are plenty strong.
Look at the length of the down stops soldered on top.
It's a wire triangle stacked like logs.

The only time I saw a Z-rail fail was with a new builder who only had about a 1/4" long solder joint
and didn't have down stops soldered on top because he was using ultra-stiff .078 rails.

[MSwiss]

Thanks for the pics, Mike. Rail diameter?

Pictured are .062".

With using production chassis pieces, .062" works well based on the 2 extra rails per side add up to 1/8" (1/4" total), which then helps the 1" slotting in front match up nicely with the 3/4" bracket in the back.

A local racer, Graham Climpson had a nice finish at our last IRRL race using, IIRC, three .078" rails per side. That was at Mid-America on a super-fast Gerding King.

[Jairus]

I totally understand how it works. But those joints are not strong enough to withstand a "shear" shear force accident.
As far as clearance.... soldering the rails together prior to putting them in the jig is a simply solution.
or sanding the bottoms flat will still add a ton of strength from wire wrapping.

But, just my humble observations.

[Noose]

I happen to have one Manta Ray's frames and have raced it in one of our events. The joints are strong I had no ill effects form taking some hits. As with any torsion styloe car though, one must be careful that the pans aren't tweaked because that causes more problems than the joints. Minde does not have the pans lightened like the one above so that contributes to some more strength IMO.

This frame has a lot of sideways flex and on a track where a stiffer car is usually run, I was very surprised on how well this ran. The meachanical grip it generates sure made it jump down the straight but with no lift to deslot. It was also very well planted in the corners and especially flat ones.

[Rick Davis]

Steve,

Heed Mike Swiss' words - fairly sure he's the father of the Z rail.

I've run quite a few and at the R4/4 I clobbered an errant car with my F1 in practice - tore the front axle loose but the rail portion was fine.

[MSwiss]

Jairus,

If you sand your rails and use good flux, they are plenty strong enough, especially with that third wire on top.

At last years R4 race I got "ridered" into the "90" full speed from the exit of the "finger" without a solder joint failure.

The original Z-rail Retro car was an F1 that was raced by a pretty inexperienced driver. Along with a few trips over my bank, he also put the car into the metal conduit that houses my power drop to the power supplies in the infield.

Again no rail or chassis failures.

[tonyp]

The nature of the design being fairly flexible will absorb a lot more impact before breaking a rail compared to a single rail .078" design soldered solid to the bracket and nosepiece.

There is as much holding the rails together as there would be on a standard two-rail chassis.

[S.O. Watt]

Agreed.

I'm working one on right now, but of course it has my intrepretations added. Mine will be raced on a flat track mostly.

[MantaRay]

When building this type of chassis I also use Kapton tape to wrap around the rail that is not to be soldered. It allows me to use a little more heat, flux and solder...for a good joint.........It's the clear orange stuff going over the motor. Tin foil also works.....

Here's a link http://www.all-spec....CFUcCQAod5T678g

Or just Google it

[Phil Smith]

In the case of the car pictured above, the joints are plenty strong.
Look at the length of the down stops soldered on top.
It's a wire triangle stacked like logs.

That's very true. I would say it's twice as strong. I use to brace joints on wire wing car chassis' by soldering a small piece of wire on top of a joint. It was very effective.

[MantaRay]

Phil, essentially I am doing the same thing with the up/down stops

[FastG]

Here are a couple of pictures

First the short .078 wire car



and the long .078 wire car.




I had to add up-stops on both car to run on the Mid America King track, both cars were picking up track dirt on the front Z rail. The short car ran very well at Mid America, even with my lack of experience on the track it was very fast.

Graham

[Tex]

Steve,

There's times I have trouble telling what's going on with a chassis without holding it in my hands. Here's a simple explanation of a Z-rail: The inside rail is soldered solid to either the motor bracket or the front pan/axle; the outside rail is soldered to whichever of the two that the inside rail is NOT soldered to. So, you have two rails soldered solid at oppposite ends of the chassis. Now, you put a rail IN BETWEEN the inside and outside rails and solder the ends of the middle rail to the UNSOLDERED end of each of those other rails.

[Phil Smith]

Phil, essentially I am doing the same thing with the up/down stops

Ray, I figured that out when I read your first thread about Z rails. Looking at the pics, I thought to myself, "Those joints ain't breakin'."

[Mike Patterson]

Correct me if I'm wrong (and apparently I am), but I thought the main rails on an IRRA™ chassis HAD to run from the motor bracket to the nose piece. The ones pictured here don't. Can someone enlighten me?

[MSwiss]

Here's the rule:

3i. Wire or tubing rails must connect the front
and rear sections of the chassis. Using metal
strip for this purpose is not permitted. A rail is
defined as that which connects the motor
bracket to the front of the chassis.

The front is connected to the back by wire rails.

This style of car has raced at the last 2 Sano's and the last R4.

[Phil Smith]

Here's an illustration of z rails. Hopefully this helps.

[Mike Patterson]

Here's the rule:

3i. Wire or tubing rails must connect the front
and rear sections of the chassis. Using metal
strip for this purpose is not permitted. A rail is
defined as that which connects the motor
bracket to the front of the chassis.

The front is connected to the back by wire rails.

This style of car has raced at the last 2 Sano's and the last R4.

Yes, but the rail from the motor bracket DOES NOT connect to the nose piece, it connects to another rail.

As the rule is written, these chassis are illegal IMHO.

And isn't this getting awful close to the dreaded "Center Hinge" chassis design?

[Cheater]

You're funny, Phil... not!

[Noose]

Mike P.,

Nope, it is still rails. Nothing says it has to be one rail.