Trailing arms question

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Devastator
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Trailing arms question

Postby Devastator » Sun Jun 13, 2010 7:43 pm

New poster here.
I'm building a set of trailing arme for my sandrail and was wondering if I'd get better, (less), CV angle from 4" wider X 3" longer trailing arms, or 4" wider X 4" longer trailing arms, or even 3" wider X 4" longer trailing arms. I read that you have to move the tranny back for 5X5's, and I don't wanna do that.
Thanks,
Dev
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Crash
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Re: Trailing arms question

Postby Crash » Sun Jun 13, 2010 9:30 pm

We have never had to move the tranny back for 5x5's or 6x6's. I would think it would be necessary for 3x4's

Let the flaming begin (again)

Mark
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Re: Trailing arms question

Postby drmiller101 » Sun Jun 13, 2010 9:35 pm

I've been reading some.

I'm guessing a 3x4 is 3 inches wider, and 4 inches longer?

If i want more travel, but not a wider car, do I do 3x3's, and get less offset in the wheels?
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Re: Trailing arms question

Postby Devastator » Sun Jun 13, 2010 9:48 pm

Devastator wrote:We have never had to move the tranny back for 5x5's or 6x6's. I would think it would be necessary for 3x4's

Thanks Mark.
Which would give me a better CV angle? 3X3, 3X4, 4X3, or 4X4?
I can go up to 4" wider without a problem getting it on the trailer.
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Re: Trailing arms question

Postby Leatherneck » Sun Jun 13, 2010 9:51 pm

Crash wrote:We have never had to move the tranny back for 5x5's or 6x6's. I would think it would be necessary for 3x4's

Let the flaming begin (again)

Mark



Well Mark why don't you explain why it is that you have not had to move the tranny on those arms. And what flamming do you speak of?

Devastator, Good to have you on here. Would like to hear more about your project. The longer your axle the less angle is put on the CV's but you have to figure in what kind of riding am I going to be doing, what kind of terrain etc how much do I need?

drmiller101, yes it is width then length on the measurement. Yes you could do that but getting into the longer arms you will also be looking at going coilovers as the longer arms makes it hard for the torrsions to handle that kind of stress. Yes the less wheel offset you have the better on the bearings and other componets.
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Re: Trailing arms question

Postby fusername » Sun Jun 13, 2010 10:44 pm

the longer the arm, the more cv angle you loose cause it has to sweep back as well. teh wider the more CV angle you recover for the same amount of travel as it is spaced further from the tranny. if you draw the triangles it is fairly clear. as for actual numbers and stuff, don't look at me! I could use a set of 0x3s tho...
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Re: Trailing arms question

Postby drmiller101 » Sun Jun 13, 2010 11:46 pm

fusername wrote:the longer the arm, the more cv angle you loose cause it has to sweep back as well. teh wider the more CV angle you recover for the same amount of travel as it is spaced further from the tranny. if you draw the triangles it is fairly clear. as for actual numbers and stuff, don't look at me! I could use a set of 0x3s tho...


so a 3x0 will give no more travel, but make the angles "better" for the CV?

a 0x3 will give more travel, but run into angle issues the quickest????

again, I don't want any wider of a car, but am thinking about more travel. If I go 3x3, and 3 inches less offset, I could end up with same track, but more travel?
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Re: Trailing arms question

Postby fusername » Mon Jun 14, 2010 12:07 am

uhhh, a lot varies from car to car. 0x3 would give you some more travel without increaseing track, but 3x3 would give you even more travel, with a slightly larger track. If you move the tranny back, you get even more travel. When I say travel, I mean given a certain max CV angle, how much travel down you can get.
give a man a watch and he'll allways know what time it is. give him two and he can never be sure again.

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Re: Trailing arms question

Postby Getrdone » Mon Jun 14, 2010 10:47 pm

I have some clicking with 3x5 and 1/2" motor setback. I have smaller balls now so I am hoping that will quiet her down a bit! :shock:
The CV's roll with no problems and dont have any binding, but if aint da CV's it's the trans. :?
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Re: Trailing arms question

Postby Crash » Mon Jun 14, 2010 11:03 pm

Leatherneck wrote:
Crash wrote:We have never had to move the tranny back for 5x5's or 6x6's. I would think it would be necessary for 3x4's

Let the flaming begin (again)

Mark



Well Mark why don't you explain why it is that you have not had to move the tranny on those arms. And what flamming do you speak of?




It is a subject that has been beat to death and I rarely comment any more but to say you "have" to move your tranny back with 5x5 arms is an overstatement.

When I came up with the 4x5 and 5x5 sizes of arms the requirement was to be able to use wrecking yard parts and bolt in place. Those sizes and the 6x6 arms can use vanagon axles of differing models and they fit with no suspension mods.

Moving the transmission comes into play when you try and relieve the compound angles on the CV's. That is the angle created by adding the vertical angle of the axle and the horizontal angle caused by the misalignment of the wheel to the transmission. The problem is alleviated somewhat by the wheel rotating around the tranny flange rather than moving straight up and down. The offset is that when you move the tranny back to relieve that the axle plunge becomes more of a problem and requires a shorter axle to keep it from bottoming out. In installing a couple dozen of these in cars the most extra travel we ever gained was 1/2". Some have claimed a couple inches but we have not seen that.

Even if you only get 18" of travel instead of 19" is it really worth the hassle of moving everything back? If you really want to get more travel go to extreme axles and stop stressing about the small stuff. It is only money after all.

We currently have seven cars with either 4x5 or 5x5 arms with the transmission in the stock location that have run for years and would have from 18" to 20" of rear wheel travel if you could keep the engine from hitting the ground.

Mark
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Re: Trailing arms question

Postby Big Dave » Mon Jun 14, 2010 11:34 pm

That is the best explanation for this I have ever seen. It makes total sense that the travel gained by setting the trans back would be negated by too much axle plunge.
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Re: Trailing arms question

Postby drmiller101 » Tue Jun 15, 2010 9:37 am

the way you described it, it DOES make sense.

I was also thinking you have angle issues at the top and bottom of the swing, not in the middle.

Because of the geometry, at the top and bottom of the swing, the stub actually comes FORWARD in the car compared to where it sits in the middle of the swing. so I can totally see where the stub could come forward to be closer to stock location.

Thank you!
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Re: Trailing arms question

Postby Leatherneck » Tue Jun 15, 2010 6:22 pm

Crash wrote:
Leatherneck wrote:
Crash wrote:We have never had to move the tranny back for 5x5's or 6x6's. I would think it would be necessary for 3x4's

Let the flaming begin (again)

Mark



Well Mark why don't you explain why it is that you have not had to move the tranny on those arms. And what flamming do you speak of?




It is a subject that has been beat to death and I rarely comment any more but to say you "have" to move your tranny back with 5x5 arms is an overstatement.

When I came up with the 4x5 and 5x5 sizes of arms the requirement was to be able to use wrecking yard parts and bolt in place. Those sizes and the 6x6 arms can use vanagon axles of differing models and they fit with no suspension mods.

Moving the transmission comes into play when you try and relieve the compound angles on the CV's. That is the angle created by adding the vertical angle of the axle and the horizontal angle caused by the misalignment of the wheel to the transmission. The problem is alleviated somewhat by the wheel rotating around the tranny flange rather than moving straight up and down. The offset is that when you move the tranny back to relieve that the axle plunge becomes more of a problem and requires a shorter axle to keep it from bottoming out. In installing a couple dozen of these in cars the most extra travel we ever gained was 1/2". Some have claimed a couple inches but we have not seen that.

Even if you only get 18" of travel instead of 19" is it really worth the hassle of moving everything back? If you really want to get more travel go to extreme axles and stop stressing about the small stuff. It is only money after all.

We currently have seven cars with either 4x5 or 5x5 arms with the transmission in the stock location that have run for years and would have from 18" to 20" of rear wheel travel if you could keep the engine from hitting the ground.

Mark


Thanks Mark. Great explanation. Nothing can be beat to death to much! :wink:
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Re: Trailing arms question

Postby Ol'fogasaurus » Tue Jun 15, 2010 6:43 pm

Bump it to a sticky???? :D
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Re: Trailing arms question

Postby Devastator » Sun Jun 27, 2010 11:10 pm

I'm baaaack.
For some reason I never gat an email stating that there were any more posts to my original question.
Devastator wrote:Devastator, Good to have you on here. Would like to hear more about your project.

Thanks. Been a lurker for quite some time, but have been distracted with my fuel injection system. Now, that works great. So good in fact, I blew most of the teeth off of the ring gear in my tranny, (again).
My obsession:
1990 Chenowth 2LB frame. 2276 turbocharged, fuel injected engine, running on E85. Transform sandpro, type 1, tranny, (missing the aforementioned teeth). HD torsion bars, boxed tye 1 trailing arms, standard CV's, (only blown 3 of those so far). 1300plus STU paddle tires.
I have set the R/P gears in the sedan type 1 tranny very tight in order to keep it together this long, so I didn't drive it on the dirt very often. This sandrail sees 99% sand.
I busted open the piggy bank and bought a fully build Sand Pro 091, 6rib, bus tranny. I have 930 CV's and the matching stub axles. Now, I'm going to build 4x4 trailing arms and switch over to coilover shocks. Next, I'm going to cut the beam front end off and fab my own spindles and a-arms to bolt resevior emulsion shocks on the front.
Me: CNC programmer and journeyman machinist. Built first sandrail when I was 15 and still tinkering with them, (I'm now 42).
Well, that was ehxausting. Stay tuned....
Dev

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