Baffled By Txt-1 Cantilever Setup

[Saito]

This little experiment started when I began to look at ways to minimize the torque twist on my 14.4v titan Txt-1. I understand that cantilevers increase the amount of travel and "suppleness" via a lever ratio. Just for the heck of it, I removed the shocks and installed them in the normal position vertically from axle to frame. I removed the rubber travel limtier tubing as well. To my surprise, the truck still has the same, if not more travel then the cantilever setup. In fact, all I noticed was an increase in suspension firmness because the shocks were no longer actuated through the amplified lever ratio. So here's my question: why run the cantilevers at all? The new direct mount shock approach sets the shocks towards the outside of the chassis giving them a wider "footprint" to stabilize the chassis twist. Other than firming up the suspension (which can be softened with softer springs) I see no ill affects on articulation. I'd love to keep the cantilevers as the look great but if the new method eliminates most of the twist, I'd be hard pressed to keep them. I suppose some testing will be in order once its daylight.

[mobias]

I was going to do that mod last year and posted a question about it here and over at rccrawler.com. Everybody warned me that it significantly hardens the suspension and makes it less subtle for crawling. If it doesn't make that much difference i'm tempted to do it now as torque twist is a real problem for my extended chassis TXT.

[mymonsterbeetleisbroken]

When the txt-1 was designed canter lever shocks on rc trucks were the "big thing" i think. Think back to the thundertech tremor and various other clod buster chassis.

Its design had some input from Kevin Hetmanski from Radio Control Car Action magazine. He made a project tamiya juggernaut which had canter levered shocks and Tamiya decided to take his idea and make it a production truck. (thats what i've read on RCCA anyway ) so thats probably why the txt-1 has the canter lever setup.

I've not tried the shocks vertically, but it sounds like it should be good!

The width of the txt-1 chassis lends itself to those in bound canter lever links and arms nicely though, and they are kept out of the dirt and mud at the top of the chassis, plus they look cool, so i dont think they are totally wasted

[ryanbored]

In this hobby i've often found cars to have "quirks" to set them apart from the crowd. There is so much choice nowadays innovation isnt always the driving force behind modification.

Just my 2 pence

They do look cool though eh?!

[Saito]

Well, I got a little transmitter time with the new set-up. I only changed the front to vertical shocks. I went through my spring collection until the front end was as soft as the rear. Lunch Box springs seemed to do the trick. The good news is that twist and sway are greatly reduced. My main goal was to get some more steering input back since the cantilever setup allowed one of the front tires to ride up higher than the other (my locked rear diff wasn't helping either). To my delight, steering was indeed improved. Just powering around off road, the truck seemed great, now with a much more "flatter" stance. Ah, but there is bad news. When slowly crawling over obsticles, the front was clearly not articulating like the rear. While this wasn't an issue crawling over single objects (its just as not cool and "flowing" as the canti setup), I have a feeling more aggressive rock crawling may not work out so well. Instead of slipping over objects, the whole chassis would pitch to and fro. Not good for subtle crawling.

I gave it some thought. The reason the cantilevers give such better articulation despite near identcal spring rates and overall travel is their axle mounting location. When the lower mounts are inboard like the canti setup, there is greater distance from that mount point to the tire centerline. This increases the leverage on the mount point which is what allows the cantilevers to subtlely adjust to varying terrain. With the wider "foot print" of the outboard mounted vertical shocks, there's no way to get this effect so the whole chassis is pitched up. You can use softer springs, but then the chassis won't be supported and will sag the shocks.

In the end, you can't have both. Use vertical front shocks if you mainly just high speed bash off road. Use cantis if you do a good balance of slow speed crawling as well. I'm going to return to cantis but add another sway bar like the New Era setup to keep the chassis more level. I'll make it quick disconect if the need to crawl comes up. This seems quicker than constantly switching shock locations. After all, my full size Jeep buddies always disconect their sway bars when its time to hit the trail.

[Saito]

Update: In a further effort to level out the front end to gain more steering input, I began toying with using tire foams in the front tires only. The results were unexpected and dramatic. I cut some foams out of upholstery foam which was soft enough to allow the tire to still have a little "give". My thinking was that the one front wheel would be less likely to ride up in the air if the opposing tire offered more resistance. It seems I was mistaken. The one front tire still sails up high from the torque of the twin Titans. What DID change was I got back a ton of steering. The front end hooked much harder. On loose dirt and gravel, the front would plant hard and the rear would swing around nicely. Great tight turning with two wheel steering and a locked rear diff. On higher bite surfaces, like grass, the effect was less pronouned, but still greatly improved from before. I was leerly about adding foams. The squishy tires absorb alot of shock and adding unsprung weight isn't normally a good idea but in this case it worked out well. The only down side is I have to be a little more gentle with the wheel. The truck rolls easier now that it can actually turn respectably.