Trailing Arms

[collinmaune]

Wanting to build a set of trailing arms,I've seen the ruff stuff kit but I think 55" seems pretty long. Also what degree are you guys bending the DOM bars to to get the shock below center line but not have the DOM stick to far down?

 

[fabricator1]

Up here in Michigan there's a lot of trailing arm rigs, but mostly long travel sand rides. They all have extremely long trailing arms and usually the shock mounting bolt is about 2" below centerline of the arm. Probably not much help but I see a lot of those setups

 

[DCXterra]

I just bought some pre bent 2" .250 DOM from ruffstuff for $55 each and cut them to the length I needed. Easier for me that way, didn't have to buy a stick of DOM for links and I didn't have to find a bender to bend it.

 

[mcutler]

Re: Re: Trailing Arms

Wanting to build a set of trailing arms,I've seen the ruff stuff kit but I think 55" seems pretty long. Also what degree are you guys bending the DOM bars to to get the shock below center line but not have the DOM stick to far down?

There's quite a few factors on that dimension; belly height, tire size, 4 link geometry, driveshaft plunge, lower link placement on axle, wheelbase, triangulation, single shock or c/o and bypass, etc, etc.

There's also a few trains of thought on what works better in the rocks. Drop them too low, rock magnet; mount them to high without consideration to combat link roll, =expensive damage to shocks.

If you have a moderate belly height (17-20") on 37-42 tires with 112-117 wheelbase, a 40-45" trailing arm can work well with proper geometry. The shock bolt must be below the imaginary line between the rod ends/bushing, and a uniball/leaf spring bushing, or some other type of mechanism must be used to combat link roll due to rocks pushing on the arms, if going below. If going above, you will need to bush the lower shock heims or use a uniball at the forward link mount to combat rolling of the links. Both methods have been proven successful if done correctly.

Is this a new build or modifying a current configuration? More info about rig and usage will help.


Edit: I'm not a pro, but I have done a lot of research to aid in doing trailng arms on my build, that hasn't seen the trail yet. There are many more experienced folks that could chime in. Just sharing info from said research.

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[CHASMAN9]

Re: Re: Trailing Arms

There's quite a few factors on that dimension; belly height, tire size, 4 link geometry, driveshaft plunge, lower link placement on axle, wheelbase, triangulation, single shock or c/o and bypass, etc, etc.

There's also a few trains of thought on what works better in the rocks. Drop them too low, rock magnet; mount them to high without consideration to combat link roll, =expensive damage to shocks.

If you have a moderate belly height (17-20") on 37-42 tires with 112-117 wheelbase, a 40-45" trailing arm can work well with proper geometry. The shock bolt must be below the imaginary line between the rod ends/bushing, and a uniball/leaf spring bushing, or some other type of mechanism must be used to combat link roll due to rocks pushing on the arms, if going below. If going above, you will need to bush the lower shock heims or use a uniball at the forward link mount to combat rolling of the links. Both methods have been proven successful if done correctly.

Is this a new build or modifying a current configuration? More info about rig and usage will help.


Edit: I'm not a pro, but I have done a lot of research to aid in doing trailng arms on my build, that hasn't seen the trail yet. There are many more experienced folks that could chime in. Just sharing info from said research.

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^^^^^This guy sees this subject clearly. Thanks, as I too do not have a grasp on how to determine trailing arm lengths. Subscribed.




ADMINISTRATOR

 

[BustedKnucklefilms]

Here are some other DIY kit options- http://bustedknuckleoffroad.com/The-Archetype-DIY-Trailing-Arm-Kit-DIY-TRAILING-ARM-KIT.htm?categoryId=-1 $799

or the beefy billy badass ones that Jake Burkey Runs- http://bustedknuckleoffroad.com/Jake-Burkey-Riot-Buggy-Signature-Series-Trailing-Arm-Kit-1836.htm?categoryId=-1

 

[collinmaune]

Its a new build the belly height is 21 inches its a bouncer. As it is right now it looks like the trailing arm setup will be 42" long and the wheel base is 118"

 

[wizzo]

I'm planning on trailing arms on my next build. I do NOT plan on running the shock eye below the center line, for exactly the reason mcutler mentioned, rock magnets. I'm not a desert racer but I can see the benefit of the design even in rock crawling/ trail digger use. My plan is to bushing the lower shock eyes. Run DOM with solid aluminum inside.

Something I am keeping an eye on is two new buggy's Todd Puckett has done recently. His own personal and a customer buggy. Both are running shock eye's above center line and NO bushings at the shock eye or on the heims on the link. Will be interesting to see what happens. We discussed it a bit at the AOP one shot qualifier race. Todd has done some very unique designs that have worked out well. He is also running is own C's and knuckles. If you see his rig out, spend some time checking it out.

The design I'm leaning toward imitating is what Randy Slawon at Bomber Fab does but with only one 3" coil over and sway bar link:

Hope some more tech comes out of this thread. It's definitely cool to see this technology incorporated into rock crawling/ trail riding/ rock racing.

 

[collinmaune]

I've talked to Todd about it and that's why I'm staying under 42". I saw the knuckles and C's in the video but haven't had a chance to see in person. I'd really like to pick his brain some more about his setup, and it seems to be working as he won the bounty hill at the outlaw race.

 

[wizzo]

mcutler - I believe you have seen the bomber fab design up close. Opinions/ thoughts? Where was the link bushinged? shock eyes, link heim ?

 

[yankster]

My next buggy is being built with the Ruff Stuff trailing arms # R1982. They measure 48" eye to eye and are bushed at the chassis end. Talking directly to Ruff Stuff about what this rig will be used for, trail riding with occasional jumping ****, these were the ones they recommended.
20"ish belly height, 118"-120" wheelbase.

 

[fabricator1]

My next buggy will probably have trailing arms. I've been following a build here in Michigan with some cnc aluminum trailing arms

 

[Rockwells607]

the ones yankster posted are their ultra4 rock bouncer arms, we beefed their bushing end bolt up a good bit to 1" they said the most common setup is 0* meaning the shock bolt is in line with the imaginary center line. Their a very nicely built unit. Id over build them if you have any doubt because they have a tremendous amount of force applied to them in the middle of the bar and if it fails itll ruin everything hooked to it and driveshafts, brakelines and shocks etc. my current buggy has 2" OD .500 wall dom links and ive bent them in standard 4 link setup so if you are going to use something like that for a trailing arm id certainly add some spines down it in more then one place

 

[collinmaune]

After looking around some people run a 14 inch coil over and a 16 inch bypass some run 16's for both tim runs 18's. Whats the better or correct setup? I understand the logic behind running a 14 and a 16 or a 16 and a 18 but just wondering if it depends if you bent the trailing arm or nit and where they mount.

 

[Rockwells607]

I think there's a few factors , a lot of people use the shocks they had , also you can get crazy amounts of travel with a trailing arm.
Depends what you want but also remember that you need to keep a driveshaft in it and control all that travel . Length of trailing arm and where they shock mounts are relative to the travel you will yield. I'm not an expert here just dabbblog with trailing arms currently . Packaging an 18" shock can be an issue also it may generate entirely to much travel to justify .

 

[wizzo]

main factor is suspension geometry and functional travel IMO.

 

[Mortalis5509]

Re: Re: Trailing Arms

My next buggy is being built with the Ruff Stuff trailing arms # R1982. They measure 48" eye to eye and are bushed at the chassis end. Talking directly to Ruff Stuff about what this rig will be used for, trail riding with occasional jumping ****, these were the ones they recommended.
20"ish belly height, 118"-120" wheelbase.

Have you seen the Campbell / ruffstuff trailing arms? They won't work on super long wheelbases but are nice and come welded already.

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[mcutler]

Re: Re: Trailing Arms

mcutler - I believe you have seen the bomber fab design up close. Opinions/ thoughts? Where was the link bushinged? shock eyes, link heim ?

Yes, I koh prepped the Redlyner Racing bomber this past January. Straight chromoly links with shock mount plates not quite the full length, (probably why I had to do a small weld repair there), and these were not slugged solid. I'm almost certain this was the same car that Randy won with, Timmy raced it, then it was bought and sold twice more, eventually to Redlyner/BAK motorsports.

Heims on both ends, probably uhmw/delrin type material used for lower shock eye bushings on both shocks, quite worn but still holding up.

For what it's worth, if you do your homework and layout your suspension mount points and links right, you won't lose much ground clearance with canoe style links, more doable if you build the links yourself. Mine are roughly 42", and compared to my straight mock up links, I only lost 1" of ground clearance at the leading edge of the tire. You must also consider lower link triangulation for shock clearance and ground clearance.


I had a long Saturday morning discussion with Dan at ruffstuff before he released the campbell links, (which he divulged with me their upcoming release, but sworn to secrecy at the time). That for ultra 4, trailing arms are a consumable item, Shannon was bending them sideways after a couple races- that's sone serious downforce and traction through the turns... Hence the reason for their joint venture on the new design. Dan is a very interesting fellow to chat with...many years of off road experience to be heard.

If I see that mine are a hindrance, I will build like Randy's our hurley on pirate.

These are mine, and the second pic is a 55" set i built for a Toyota pre runner here in NC.

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[mcutler]

Re: Trailing Arms

Other considerations:

If your running bypasses, always build your suspension to utilize the entire stroke, regardless of the coilover travel. Bypasses are position sensitive while c/o are velocity sensitive. Typically the bypass will be longer than the c/o due to its distance down the link versus the coilover...it will need more shaft for the travel.

On my 42" arms I have single mounted a 14"-2.5 shock: netting 21" of travel- likely to be strapped at about 20" due to driveshaft slip. I have 10" of uptravel.

Along with the engineering of trailing arm rear, tuning is extremely different...this I am still studying. Of course you get to use a heavier spring, I'm currently 250/300, but will likely be 3 over 3. After some talk with Wayne-zukizzy at Fox, and Ryan at Accutune, there are many ways to skin the cat. Fast desert with big whoops, lots of steel resting on the shock shaft at the piston...to control the big travel. I'm still learning on this and look forward to tearing into my shocks a number of times to fine tune the manche...but I will be doing it with the help of Fox DSC adjusters.

Frankly if your going all out with big money shocks and trailing arms, you gotta go all the way to get the full benefit. Learning to tune yourself would give everyone a better understanding of the entire system.


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[mcutler]

Re: Trailing Arms

Burkey's arm looks very good, but I would still go eye to eye on the shock mount, much like an axle truss; if your truss stops short of the backing plates or knuckles, that's where it will bend...and just like your axle, the trailing arms are carrying all the weight of the back of the car... Just my personal opinion.

Goatbuilt makes a nice kit also, shock mount below the heims but still high clearance.