Trailing Arm Discussion

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JK Racing
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Trailing Arm Discussion

Post by JK Racing »

Through my eBay fun, I have ended up with a spare set of trailing arms set up (Andy's/S&K) and have this question to the guys who have actually run trailing arms....

What does it do to the handling of the car? Too much rear traction, making the car push? I will still build my trailing arm runner, but am curious what these would do slapped on the back of my 4wd car? I have contemplated attempting to adapt the Losi 5 link onto my XX4 (same concept). I do have a pie-in-the-sky dream of building a whole 4wd car from the ground up, all custom, one day, and have always wondered about trailing arms.

Thoughts? Moans? Groans?
--Joey --
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wts873
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Re: Trailing Arm Discussion

Post by wts873 »

my gold pan with A&L arms handles great!!! It has alittle oversteer, but thats mostly from the soft proline ribs I have on the front.

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Re: Trailing Arm Discussion

Post by JK Racing »

Are you racing it, or running around the house? What motor/how much power? For racing, I have graduated to brushless, and hope to keep my old brushed motors for shelfers now :twisted: .
--Joey --
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bgruen
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Re: Trailing Arm Discussion

Post by bgruen »

The two things that are effected are the travel of the wheel and the progressiveness of the spring/shock (which is dependent on the shock angle with the arm through the arm's travel). The reality is that planting the tire properly as the chassis rolls into and out of a turn is what is important. Properly does not necessarily mean flat, more that it matches the setup in the front.

The truth is that trailing arms are a fad that has come and gone. The swing arm and control rod combo are much more adjustable in terms of both tire travel and shock angle / progressiveness. You can shim the pin to add or subtract starting camber, but that will dictate your wheel progression as the two are linked by a single pivot point. The compression of a trailing arm does technically push the car forward, but it will also perform the opposite dynamic as the suspension rebounds, so I never bought into that argument.

Multi-link designs are a bit different, and they usually have a trailing bar element (Tamiya Astute or the Losi JRX-2). The Losi 5 link was an attempt to get the perceived benefit of the trailing arm while still having the adjustably of the swing arm. It worked OK, but it was just more parts to maintain / break, so Losi abandoned the 5 link. I still run a 5 link JRX-2 in stock buggy, but mostly just to be different.

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Re: Trailing Arm Discussion

Post by JK Racing »

bgruen wrote: but mostly just to be different
exactly why I want to do something with trailing arms or 5 link...

I actually have been thinking about when I had an X Factory X-6, and this Andy's trailing arm kit...now THAT would definetly turn heads...I may measure up a chassis next time I am at the track. If for nothing else but to see if there would be enough clearance with the mid motor set up & the rear arm mounts.

I am just aching to build a cross breed monster that will actually be able to run decent, if not competitive. I really wish there was a dirt oval around here in SoCal somewhere. Hand crafted cars were not out of the ordinary there.
--Joey --
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Re: Trailing Arm Discussion

Post by bgruen »

I think you will find that most molded graphite tubs will lack the strength for a suspension mount of that variety. Specifically, I think you will have to grind off the edge of the tub to get the suspension block to fit, and I don't think the chassis will last long running like that.

As far as doing a custom 4WD, I'd suggest getting a Dark Impact and redoing the chassis and suspension. Do the chassis in a single CF plate and lay a big lipo across it just in front of the motor. You'll have to reposition the steering servo, but that's not a big deal. Then redo the rear suspension mount so that it bolts to the new chassis plate and not the rear gearbox.

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