R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 11-10-2013, 03:39 PM   #1
Tech Addict
 
chasingthepack's Avatar
 
Join Date: Apr 2013
Location: hanworth uk
Posts: 728
Default lets talk about arm sweep and its effects

as above,when and why would you use it?
__________________
yokomo bd7 16_lrp works team-trinity d4 17.5_futaba 4pks_futaba bls
wet/damp car xray t4-14-r10 pro-team wave 17.5 savox 1251
chasingthepack is offline   Reply With Quote
Old 11-10-2013, 03:45 PM   #2
Tech Champion
 
ThePanda's Avatar
 
Join Date: Jul 2013
Location: Michigan
Posts: 7,040
Trader Rating: 65 (100%+)
Default

I think I will monitor this thread…I want to see what people have to say.
ThePanda is offline   Reply With Quote
Old 11-11-2013, 02:16 AM   #3
Tech Regular
 
kneedeeppow's Avatar
 
Join Date: Mar 2009
Location: new zealand
Posts: 307
Default

i used it on my tc5 drifter to try and gain more 'castor'. and for the most part it worked
__________________
https://www.facebook.com/Fresh10drift/

Eagle Racing GRT FRD. Tamiya F103GT. Tamiya Blackfoot............ORIGINAL
kneedeeppow is offline   Reply With Quote
Old 11-11-2013, 08:15 AM   #4
Tech Elite
 
mike ivy's Avatar
 
Join Date: Feb 2002
Location: Comin at ya from a distant galaxy
Posts: 2,795
Trader Rating: 50 (100%+)
Default

Hey Guy's,

I think what I does it Give’s the car more Mid corner to exit Steering. ( You Loose a little turn in ) but you can ad anti dive to to bring back the steering into the corner.
__________________
[-eXpress motorsports-] [-TQ Wire-]

1/12th Fo' Life!!! R.I.P Mike Reedy, R.I.P John Williams

[-Horsham RC-] [-Jackson RC-] [-RC Car World-] [ Black Out Free 2015 ]
mike ivy is offline   Reply With Quote
Old 11-11-2013, 09:24 AM   #5
Tech Addict
 
Lessen's Avatar
 
Join Date: Jan 2008
Location: Aurora, OH
Posts: 594
Trader Rating: 2 (100%+)
Send a message via MSN to Lessen
Default

Quote:
Originally Posted by mike ivy View Post
Hey Guy's,

I think what I does it Give’s the car more Mid corner to exit Steering. ( You Loose a little turn in ) but you can ad anti dive to to bring back the steering into the corner.
That's the way I understand it as well. I think about the direction the weight is moving upon entry and the angle that the suspension moves relative. With sweep the motion is slightly more opposing of that weight transfer. As the car begins to settle that angle may allow the load to transfer from outer front to outer rear giving the car better rotation in the center and likewise when one get's back on the power... the angle opposes weight transfer from outer front to inner rear (too much causes the understeer upon exit). That's just what I see in my head. I'm also interested to read others' takes on this as well.
__________________
"Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. "
Lessen is offline   Reply With Quote
Old 11-11-2013, 04:48 PM   #6
Tech Regular
 
Adam B's Avatar
 
Join Date: Nov 2010
Location: Detroit, Mi
Posts: 412
Default

pin sweep can be used two ways, but the most common set up is positive pin sweep, where the front of the pins aim away from the center of the car. I have seen this on a lot of MOD set ups. Without all the fancy thinking Lessen did above, here is what I think of it as, and how it works. First, I feel it actually helps turn in harder and act as "TOE GAIN" on the inside tire. So lets say straight ahead you have 0 degrees of toe adjusted in, as you turn the car left, due to the angle of the A-Arm the left tire will start gaining positive toe, where the right tire is going to stay neutral or even be a little "behind". I don't think it will change the castor on most cars as that is adjusted with the c-hub, but it will give the feeling of increased castor. IMO
__________________
Franchise Racing Products * Fantom Racing * Pro One R/C Tires * RC America/Xray * Discount R/C Store * F1 R/C Lab * NORCAR @ The Gate
Adam B is offline   Reply With Quote
Old 11-11-2013, 06:44 PM   #7
Tech Addict
 
Lessen's Avatar
 
Join Date: Jan 2008
Location: Aurora, OH
Posts: 594
Trader Rating: 2 (100%+)
Send a message via MSN to Lessen
Default

It sounds as if you are explaining the geometry action known as bump steer, except I don't really see how arm sweep has any affect on bump steer. It may however, have a minor effect on ackermann (in an active manner) because the angle of the pin now causes the entire suspension (most notably the steering link pivot at the hub) to move ever so slightly forward as it goes through it's motion. As it moves slightly forward it would be gaining ackermann as it progresses. I think that would be quite minor.
__________________
"Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. "
Lessen is offline   Reply With Quote
Old 11-12-2013, 02:19 AM   #8
Tech Addict
 
chasingthepack's Avatar
 
Join Date: Apr 2013
Location: hanworth uk
Posts: 728
Default

the way i see it is arm sweep is generally moving the end of the arm backwards,this will give less castor,shorten the wheel base,and affect ackerman,so will obviously affect the car in a big way,so why use it if alot of other settings are changed?
this is taken into account when setting up the car,but what i really want to know is what it actually does,and why it does it,is it just a mod thing as i only run 13.5?
if you do use arm sweep would you move the shims around to get back to the original wheelbase and ackerman leaving just the castor with arm sweep changed?
__________________
yokomo bd7 16_lrp works team-trinity d4 17.5_futaba 4pks_futaba bls
wet/damp car xray t4-14-r10 pro-team wave 17.5 savox 1251
chasingthepack is offline   Reply With Quote
Old 11-12-2013, 02:41 AM   #9
Tech Elite
 
Skiddins's Avatar
 
Join Date: Feb 2006
Location: Windsor, UK
Posts: 4,759
Default

Arm sweep won't effect castor as that's set by the blocks and the 'kick-up' and 'anti-dive' settings of the pivot pins
__________________
Xray T4'18, T4'14 (Wet Car)
Xray X12 2018
Xray X1'16
wlrc.co.uk (West London Racing Centre)
RCDisco.co.uk
Skiddins is offline   Reply With Quote
Old 11-12-2013, 02:48 AM   #10
Tech Addict
 
chasingthepack's Avatar
 
Join Date: Apr 2013
Location: hanworth uk
Posts: 728
Default

Quote:
Originally Posted by Skiddins View Post
Arm sweep won't effect castor as that's set by the blocks and the 'kick-up' and 'anti-dive' settings of the pivot pins
doh! yeah i just turned blond for a minute,it does move the top link further back,i know its minimal but would that have an effect?
__________________
yokomo bd7 16_lrp works team-trinity d4 17.5_futaba 4pks_futaba bls
wet/damp car xray t4-14-r10 pro-team wave 17.5 savox 1251
chasingthepack is offline   Reply With Quote
Old 11-12-2013, 06:05 AM   #11
Tech Elite
 
jlfx car audio's Avatar
 
Join Date: Nov 2007
Location: jackson,tn
Posts: 3,361
Trader Rating: 36 (100%+)
Default

My thinking was it places the wheel base further back shorting wheel base , which puts more weight over front tires affectively softining front suspention which in my theory delays turn in response and gaining mid corner exit . I'm sure it affects Ackerman also (acts as if u added more shims to steering link
__________________
Justin & Matt Lyons
Awesomatix USA, EA motorsports, Sanwa, Protoform, Avid, Gravity Rc , TSR!
a800s sanwa m12s
jlfx car audio is offline   Reply With Quote
Old 11-12-2013, 08:20 AM   #12
Tech Elite
 
artwork's Avatar
 
Join Date: Sep 2004
Location: Thornton, CO
Posts: 3,109
Trader Rating: 62 (100%+)
Default

Front Arm Sweep:

Front mounts are wider then the rear in the front of the car.

This provides less initial steering, but more mid corner steering.
__________________
Sanwa | R1 Wurks | Avid | 2mm Designs
artwork is offline   Reply With Quote
Old 11-12-2013, 08:26 AM   #13
Tech Champion
 
RedBullFiXX's Avatar
R/C Tech Elite Subscriber
 
Join Date: Mar 2003
Location: Intergalactic Planetary
Posts: 6,542
Trader Rating: 34 (100%+)
Cool

Quote:
Originally Posted by artwork View Post
Front Arm Sweep:

Front mounts are wider then the rear in the front of the car.

This provides less initial steering, but more mid corner steering.
This ^
__________________
--> 12th scale Information Source <--

"Men do not quit playing because they grow old; they grow old because they quit playing."
― Oliver Wendell Holmes Jr.
RedBullFiXX is offline   Reply With Quote
Old 11-12-2013, 11:17 AM   #14
Tech Elite
 
CristianTabush's Avatar
 
Join Date: Oct 2002
Location: Houston
Posts: 2,839
Trader Rating: 11 (100%+)
Default

The biggest effect that arm sweep achieves is how it creates suspension bind. The more angled a hinge pin is, the more suspension bind you will create as forces work against each other when compressing.

Arm sweep essentially makes the front end stiffer because the hinge pin is essentially angled towards the opposite direction that the outside arm is trying to hinge in compression in a corner.

Like most set-up changes, when stiffening the front end of a car a harder front end will delay weight transfer and create less grip going into a corner. However, as the car starts to turn and lean the increased rate on the tire will create more pressure on the tire essentially creating more traction, hence more middle and exit steering.

I use arm sweep in everything. To me it's a default set up thing. I feel it makes the car easier to drive going into the corner. I am not saying this is the best approach, but most of the time it works. Only if I am looking for more initial reaction will I take it out, however most of the time a little more camber, shock angle change or an adjustment on the inner camber link can get me the reaction I want.
__________________
REFLEX RACING/ RSD/ GIZMO RACING USA/ HOBBYWING/ AXON/ QTEQ/ TEAM PRIME
CristianTabush is offline   Reply With Quote
Old 11-12-2013, 11:46 AM   #15
Tech Elite
 
jlfx car audio's Avatar
 
Join Date: Nov 2007
Location: jackson,tn
Posts: 3,361
Trader Rating: 36 (100%+)
Default

I think I have to disagree on one of Ur points (at this time )
Don't see how adding arm sweep (back) makes suspention stiffer .
It places more weight on front arms /tires thus making it feel like a softer spring .
Example . pushups .. Do pushups 3 different ways . arms strait out from shoulders (normal)
Arms more tward Ur stomack (hard ) ,arms out from Ur head (easy )"girl pushups"lol
This is why i have my idea about sweep
__________________
Justin & Matt Lyons
Awesomatix USA, EA motorsports, Sanwa, Protoform, Avid, Gravity Rc , TSR!
a800s sanwa m12s
jlfx car audio is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 11:30 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net