Author Topic: a arm rear ends vs multi link vs trailing arm.  (Read 9600 times)

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Online fabr

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #15 on: November 12, 2017, 11:21:28 AM »



well any suggestions so a better descriptive term? cannot call it anti diver really as that pertains to the geometry of a front end with brakes.
Chassis reaction due to mount locations is the only description that applies. I've never been able to find a catchy term for it though.  Actually antidive or at least braking reaction can apply to rear end brakes effect on handling. That is a whole 'nother topic though.
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Offline dsrace

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #16 on: November 12, 2017, 11:26:18 AM »
lol ok so how about irs anit lift?
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Online fabr

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #17 on: November 12, 2017, 11:49:31 AM »
All cars with non independent rear suspensions can take advantage of antisquat. On drag cars we have ladder bar or 4 link suspensions. Both can take advantage of of antisquat reaction and both can have easily adjusted "percent of rise" as coined by Chris Alston many years ago. Percent of rise can be most easily understood by looking at ladder bars first.Most cars will have 4-5 forward mount  hole positions on about 1" centers. Those 4-5 holes allow from a mild antisquat reaction to a more aggressive antisquat reaction as the front mount is raised. For the sake of discussion we will call the lowest hole 10% rise ,second hole 20% rise etc.. This can all be calculated and plotted on a graph. My old door car with 4 link actually had 60+ different percentages of rise depending on mounting hole combination used. Some even went into negatives and of course,those are not used.  rofl This refers to the amount of torque/antisquat that is transmitted through the rear end housing,along the arm/ladderbar and into the front mount. The more leverage,the more antisquat there is. This antisquat reaction,we call it chassis separation , is what firmly plants the tires on launch. Antisquat is the car trying to EXTEND the rear shocks on launch pushing the tires onto the track surface. Where the front mount is placed determines how much force is available(percent of rise)to cause chassis separation/antisquat.  Look closely at a good drag car on launch and you will see that even though the rear of car may drop,the distance between the wheel well and rear wheel will actually increase. This is antisquat.  What you describe you are feeling in your different cars is almost identical to this but there is no planting of the tires/antisquat with independent rears.   

All that said,I don't think offroad/sand cars would benefit from actual antidive. Antidive might tend to "dig" in too much and possibly add to chances of burying yourself?  The different mounting locations as you describe however,with no antidive as we have now determined does not exist in our cars, would definitely explain your experiences. The higher the mount,the more the tendency to wheelie with more weight transfer to the rear. Physics. The lower the mount,the less weight transfer on acceleration,the more wheel spin/fewer wheelies. Physics.
« Last Edit: November 12, 2017, 12:07:23 PM by fabr »
"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

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

Offline dsrace

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #18 on: November 12, 2017, 02:53:08 PM »
yes, i know this, but have always used that term as it has been the easiest way to describe that. the fundamentals are still felt even if they are not driven forces such as that of a non irs rear.  the only rail  that wheelied, until now, was the rear engine v6 3800 series II. diff animal yet again vs mid engine ( current) but on all the mid engine bike rails i have always found the the best happy med with the lower lateral rod mounted 3" above that at the wheel . never wanted to wheelie but always hooked really well and launched pretty true!
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Online fabr

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #19 on: November 12, 2017, 04:01:56 PM »
I've never understood the fascination with wheelies on dirt or sand. I just don't get it at all. 5: Mind you I  always had the front tires off the ground about 4" for 60-100 feet with the door slammer and about 2" off for the same 60-100 with the dragster as well but that is for 60' performance ,you never really know you are wheeliing and you never feel it set down if suspension is tuned well. Off road I just don't get it at all. Cars that pull big wheelies on command are just not set up well. No offense meant to any of the wheelie lovers here but I always refer to wheelie monsters as rodeo clown cars. All it takes is a high center of gravity,way too much rear weight bias and suspension setups that have the rear suspension mount points too far above axle centerline. It sure doesn't have anything to do with power.  I guess if wheelies are what a person wants they are set up well though. Of course ,that is all personal opinion and it depends what flips your pancake. My pancake gets flipped with wheels down. :m It's all  8) though so long as the car owner likes what they have. That's all that really matters.
"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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 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

Offline dsrace

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #20 on: November 12, 2017, 08:08:53 PM »
 rofl  well once and a while is fun....that v6 did it easily in 1st gear after i stretched the wheel base to tone that down. coming up light in the front sucks when you want the cut and carve and eerie when your climbing a dune. this is why i pre mid engine however this rail does wheelie but only in low gear, punched at the right moment off a steep roller or peak.  however as a mid engine that can get dangerous real fast  rofl  ;) ;)
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Offline Carlriddle

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #21 on: November 13, 2017, 05:53:38 AM »
Old green car with original semi trail arms, I bent first set first trip, bad design.  After learning more, I rebuilt stout never another problem.  Would only do semi trailing so you can get some camber.  Mine was 15* angle on mount tube.  Had +1* at full droop and -3* at full bump if I remember.  Another thing w/ trailing arms, it allows a diff motor tranny to be used and only changing axles if inside cv cups distance changes. 

I'm really happy with current wide spread A-arms I'm running.  Strong, adjustable, non plunge cv's pretty easy to build.  I didn't build in any camber, but that may change with new wheel hubs.  They are harder to build around the center sprocket drive to get no plunge, some real head scratching and banging!!
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Offline dsrace

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #22 on: November 13, 2017, 09:09:18 AM »
well multi link and dual a-arms are definitely more difficult to design and build than trailing arms are to buy lol in your case build on that green single seater but for most they just buy them as 3x3 5x5 7x7 etc etc.   the dual a-arm design imo is more difficult than a 5 or 6 link. principals are the same but getting every tube connected correctly and lined up for proper support in a manner where everything pivots on the correct plane for the cv's and still be able to adjust toe for alignment ......ya, def not for the beginners with a good enough attitude!
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Online fabr

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #23 on: November 13, 2017, 04:51:43 PM »
Old green car with original semi trail arms, I bent first set first trip, bad design.  After learning more, I rebuilt stout never another problem.  Would only do semi trailing so you can get some camber.  Mine was 15* angle on mount tube.  Had +1* at full droop and -3* at full bump if I remember.  Another thing w/ trailing arms, it allows a diff motor tranny to be used and only changing axles if inside cv cups distance changes. 

I'm really happy with current wide spread A-arms I'm running.  Strong, adjustable, non plunge cv's pretty easy to build.  I didn't build in any camber, but that may change with new wheel hubs.  They are harder to build around the center sprocket drive to get no plunge, some real head scratching and banging!!
Zero plunge is not necessary but an a arm rear suspension must be designed as close to zero as possible though . Axle spline slip in the star will easily allow for any small error or deflection. I know you know this. Just mentioning it for any new builders needing info.
"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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 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

Online fabr

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #24 on: November 13, 2017, 04:55:35 PM »
well multi link and dual a-arms are definitely more difficult to design and build than trailing arms are to buy lol in your case build on that green single seater but for most they just buy them as 3x3 5x5 7x7 etc etc.   the dual a-arm design imo is more difficult than a 5 or 6 link. principals are the same but getting every tube connected correctly and lined up for proper support in a manner where everything pivots on the correct plane for the cv's and still be able to adjust toe for alignment ......ya, def not for the beginners with a good enough attitude!
CAD is my friend. Real CAD,notCardboard Aided Design either!  :m   Honestly,I'd find building and properly locating mounting tabs for semi/semi trailing arms just as hard to get right. Extremely small errors in locating tabs make big problems that cannot easily be corrected. I've seen countless trailing/semi trailing arm cars with some crazy alignment issues.
« Last Edit: November 13, 2017, 05:00:37 PM by fabr »
"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

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

Offline dsrace

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #25 on: November 13, 2017, 06:43:16 PM »
true....it all takes skill and learning. cad is very helpful for those that have it and can use it. of course going from cad to real world application also takes skill. there also a number of purchased trailing arms that aren't that great. a arm and multi link do allow for adjust to a point for those minor mistakes but at the same time its that adjustability that ,imo, makes them superior among other reasons.
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Online fabr

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #26 on: November 13, 2017, 08:00:16 PM »
yup!
"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

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

Offline dsrace

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #27 on: November 13, 2017, 08:51:10 PM »
CAD is my friend. Real CAD,notCardboard Aided Design either:m   Honestly,I'd find building and properly locating mounting tabs for semi/semi trailing arms just as hard to get right. Extremely small errors in locating tabs make big problems that cannot easily be corrected. I've seen countless trailing/semi trailing arm cars with some crazy alignment issues.


oh come on now .....i like cardboard or even better yet white marker board aided drafting lol ;D
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Offline dsrace

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #28 on: November 13, 2017, 08:53:22 PM »
on another note i think i found a 2d i may buy for my rail so i can get back to a 4 speed. i'll find out for sure tomorrow.
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Online fabr

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Re: a arm rear ends vs multi link vs trailing arm.
« Reply #29 on: November 13, 2017, 09:09:19 PM »
i like that.
"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

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

 

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