Author Topic: Trailing arms  (Read 944 times)

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Offline Baloo

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Trailing arms
« on: May 20, 2012, 01:58:16 PM »

hi
l am looking at building a new buggy from scratch and and have been looking at rear suspension options
Trailing arm seems to use up less space and fit easier, so a general question on the length of trailing arms,
how long is some thing like a vw when it left the factory and how much travel can you get out of it ?
to fit in neatly l could do with making mine 20" long

Offline Engineer

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Re: Trailing arms
« Reply #1 on: May 21, 2012, 12:44:16 AM »
VW's are Semi trailing arms.  By moving the inner pivot back a bit it greatly reduces the amount of plunge generated which becomes critical on long travel lengths.  Using the Semi trailing design also results in camber change as it moves.

We have discussed it in detail somewhere here in some old threads.

I am sure there is a sweet spot on the length of the arms, but I am not sure what it is.  I do know that when going for longer travel they make the arms longer and wider at the same time to maintain the sweet spot ratio.

As a side note, the transmission output flange is a certain distance ahead of the wheel at mid travel and in line at the extents of the travel.  This keeps the plunge down and the maximum angular displacement of the CV joints at a minimum.

Offline Carlriddle

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Re: Trailing arms
« Reply #2 on: May 21, 2012, 07:50:45 AM »
I read someone that you should you travel should be about half your arm length.  But that seems too high, 20" long arm with 10" travel??  There is a drawing to show sweet spot of semi trailing arms.  Arc of arm from side vs arc from back.  Have to search for that,.....................
You can keep your CHANGE, I'd like to keep my DOLLAR.

Offline fabr

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Re: Trailing arms
« Reply #3 on: May 21, 2012, 10:07:55 AM »
A arms solve all issues IMO.
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)

Offline Baloo

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Re: Trailing arms
« Reply #4 on: May 21, 2012, 03:19:50 PM »
A arms solve all issues IMO.

l would go along with that, but l might have a space issue that trailing arms would resolve, but  it might turn out not to be as tight as l imagine,   l like the way buggy handles as it is with double wishbones all round, it has what l would describe  as lift off oversteer, if l charge into a corner then lift off sharpish the back comes round and then back on the power and round l go, so different to my pilot that always pushed on when trying to corner,
the current engine and box measure 28" from end to end, the later 16 valve twin cam version with the cvt gearbox attached measures 34 ", l need to find 6"  somewhere,  its the rail that the top wishbone fixes to that is limiting the engine bay width,   l might be able to push them out 3" on both sides and have a wider buggy, l have some mocking up to do as l want to get away from the cut and sleeved driveshafts that are on it at the moment, this might add 2 or 3" to the width each side on its own so it might all work out yet,
l will get some pics of the suspension with out the wheels on and post them up and we can discuss options

heres the only pic l can find at the moment but dosent show it in great detail


Offline fabr

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Re: Trailing arms
« Reply #5 on: May 21, 2012, 03:46:47 PM »
Pics will certainly help
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)