Trailing Arms Vs Duel A-arms?

[Kaptain Krunch]

Whatsup everyone, just joined the forum. I'm hoping to build a small buggy in the near future, and I'm starting to do some designing and gathering of parts.

I recently finished cramming a kz400 engine into a small yard kart frame, and once i was done i realized even just 50mph off road without suspension sucks! So I'mplanning on transplanting that engine and some other parts into a small buggy.

Anyways, I'm wondering what the advantages/disadvantages of A-arms and Trailing arms are for rear suspension? The only thing i can thing of is that trailing arms will be easier, and more compact, but I'm only 16 and no master, so I'm sure i've overlooked some things.

I'm also wondering if i could possibly use the front forks off the motorcycle (kz400) as rear shocks? I would assume i would have to add some extra oil, and maybe makes some special mounts, but thats no problem.

Thanks in advance for any help!

[bdkw1]

Trailing arms are simpler and easier to make. The downside is you have axle plunge.

A-arms are more complex and expensive to build and maintain, but there is little to no axle plunge and you can get away with using off the shelf FWD parts.

[yoshi]

Originally Posted by bdkw1

A-arms are more complex and expensive to build and maintain, but there is little to no axle plunge and you can get away with using off the shelf FWD parts.

If they are designed correct. I've seen a ton of rear end setups where the center of the cv is way way far ahead of the center lines of the hub mounts, which will cause a lot of plunge, just like incorrect mounts on a control arm will cause the front end to have bumpsteer.......

[standfast]

In general, I would have to say that a trailing arm would last longer when subjected to heavy abuse. The handling characteristics of a a-arm rear is appealing to me. Especially the control over the camber curve. I just think for desert stuff like I do, it's too many parts to worry about so I K.I.S.S.

Now a 5-link is the ultimate in control of the rear suspension but I have not seen one deal with some serious abuse in the desert but that is even more working parts. I am anxious to see how BDKW's car works out. His results may be a factor on how I build my next car. Although it will probably be a couple cars down the line unless he gets a wild hair to finish that thing already!

[Kaptain Krunch]

I think i'll go for trailing arms then. I have started to draw up my plans, right now I'm starting to design my trailing arms, what should i consider geometrically when I'm drawing them?

And this is probably a very dumb question, but when you say axle plunge what do you mean? Is that just how far the CV joints move in/out?

[bdkw1]

Originally Posted by standfast

I am anxious to see how BDKW's car works out. His results may be a factor on how I build my next car. Although it will probably be a couple cars down the line unless he gets a wild hair to finish that thing already!

Wild hair, check.
Time, check.
Shop space, check.
Money, aw crap.........

If your on a budget, 5 link is not for you.

[bdkw1]

Originally Posted by Kaptain Krunch

I think i'll go for trailing arms then. I have started to draw up my plans, right now I'm starting to design my trailing arms, what should i consider geometrically when I'm drawing them?

And this is probably a very dumb question, but when you say axle plunge what do you mean? Is that just how far the CV joints move in/out?

Build a little camber gain into the arms. About 3* gain at full bump is good. should have about 1* at ride height.

Yes on the plunge and the CV's moving in and out....

[Kaptain Krunch]

Ok, so then plunge would just wear out CVs quicker?

Now How will mounting affect the trailing arms(like the angle at which there mounted to the frame)?

I know it must affect something but I'm a visual person and i cant quite picture it in my head, would it be camber change?

[standfast]

Yes it will give you camber change, slight toe change. Better handling. Regular 930's are designed to plunge. Don't worry about that.

[Kaptain Krunch]

Thanks for all the quick answers, and sorry for all the questions haha.

Just a few more,

First, is there a recommended angle to mount the arms at, or is it something i that has to be calculated specifically the aplication?

lastly, would the motorcycle forks work? i have no problem machining special mounts for them, but im not sure how much abuse they will take.