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View Full Version : PN double A-arm setup help ?


redneckracer
2010.10.10, 06:18 PM
Hey guys what springs are u running on your double a-arm mr-02's 98mm on RCP tracks ? And are you using shims under the springs or just the springs? Oh and if iam running 64pitch gears what pinon and spur should i run with a 70T pn motor for the PN race ? Thanks....

vesahyp
2010.12.22, 04:39 AM
A bit of a late reply but what the heck.

I got my a-arm a few weeks back and have about 4 hours of tracktime behind with the new setup. Compared to the regular kingpin setup (with 0 camber) i've shaved off 0.5 seconds off my best time at our local track which is the same layout as the PN 2010 world cup track. My current record is 9.761. I run the a-arm with 2deg static camber, 1.01deg camber gain and .9deg caster. I will try adding more caster at some point.

I run a mclaren gtr shell with 64p gears (52/13 last, trying 14 next to see if the 70t still has enough punch). The thing with the mclaren shell is the front hasn't got much room for suspension travel so i've got quite a bit of shimming under the springs to limit the suspension so that it doesn't hit the shell to badly even when fully compressed. I use atomics yellow springs which are softer than the ones that come with the a-arm package. I've also sanded the inside of the body shell with 2500grit sandpaper so it's smooth.

I'd love to hear what kind of times you run (if the PN race you're referring to is with the same layout).

Davey G
2010.12.22, 12:25 PM
Hey guys what springs are u running on your double a-arm mr-02's 98mm on RCP tracks ? And are you using shims under the springs or just the springs? Oh and if iam running 64pitch gears what pinon and spur should i run with a 70T pn motor for the PN race ? Thanks....

For the most part the most popular setup with the double a arm is the green springs with the kyosho or PN 3mm spring cup. The eccentric pin in the 12 O'clock position with 1mm of droop

I run 54/14 with the 70turn motor.

vesahyp
2011.01.04, 02:53 AM
For the most part the most popular setup with the double a arm is the green springs with the kyosho or PN 3mm spring cup. The eccentric pin in the 12 O'clock position with 1mm of droop

I run 54/14 with the 70turn motor.

I rechecked my configuration and it's the default a-arm spring cup (3mm?) with "PN front racing spring set" springs (yellow - hardest in that category) but with about 2mm shimming *underneath* the cup. This preloads the springs so it feels harder than just the 3mm cup with the default a-arm metal colored springs. It also limits the travel of the suspension so it doesn't hit the body. I used some white plastic nut-type things (from a kyosho small parts set i had) sanded down to the height required.

I'm just wondering if there's a proper way to shim underneath the spring cup? Or is that considered just plaing wrong? :o

Davey G
2011.01.05, 09:44 AM
I rechecked my configuration and it's the default a-arm spring cup (3mm?) with "PN front racing spring set" springs (yellow - hardest in that category) but with about 2mm shimming *underneath* the cup. This preloads the springs so it feels harder than just the 3mm cup with the default a-arm metal colored springs. It also limits the travel of the suspension so it doesn't hit the body. I used some white plastic nut-type things (from a kyosho small parts set i had) sanded down to the height required.

I'm just wondering if there's a proper way to shim underneath the spring cup? Or is that considered just plaing wrong? :o

Hello, please take out all the shims in between the spring and spring cup. Just run the spring over the spring cup and call it a day. Set the arms to be about level (parallel to a table) or a tick below level. Green is still the most popular spring of choice for the double a arm. For 98mm cars either red or the silver one are good too (same exact spring, one is powder coated, one isnt)

Let us know if this helps....

vesahyp
2011.01.12, 08:49 AM
Hello, please take out all the shims in between the spring and spring cup. Just run the spring over the spring cup and call it a day. Set the arms to be about level (parallel to a table) or a tick below level. Green is still the most popular spring of choice for the double a arm. For 98mm cars either red or the silver one are good too (same exact spring, one is powder coated, one isnt)

Let us know if this helps....

Just a quick thank you. I bought the a-arm spring set and am currently running the stiffest ones (yellow) with the front lowered a tad. It's brilliant! I've shaved off .3 seconds and am at 9.375 - only another .2 from the stock track record here.

I'll keep trying to tweak the setup since that's part of the fun!

Juggler
2013.02.18, 11:04 AM
Hmmm...instead of starting a new thread i'll post here to get some help i need!I also have an 98mm MR02 car with PN's A-arm,so...
The Facts:

MR-02MM/Mclaren the short one
Tires: Kyosho 20deg rear $ Kyosho 30deg front,both slicks
Motor:Kyosho stock
Diff:K's ball diff
Rear:Atomic's DPS ssg with green springs top and bottom(+ atomic's standard silicone oil)
T plate:Medium
Front:Pn's double A-arm...caster 0.9,camber static 1,camber gain 0.89,green springs on 4mm spring cups ,no swaybar and some droop(very small)
Tie rod:Kyosho's red No.4 which gives 1.5 deg toe in

This chassis is racing on a high grip RCP.the problem is that the car is quite agile,fact that i love,but not in such level as it has too quick weight transitions,overall too much steering and a bit unstable in a straight line...
I tried all the five springs,but i didn't figure out much to be honest!Also i'm already running 1.5 toe in,so is it normal to add 0.5 more???...I'm still trying to find a neutral behavior...
Any ideas???

NoBrainer
2013.02.18, 11:32 AM
oh. 1.5 toe in...

I like a bit of toe-out on mye setups.
Have you tried that?
Or is that a driving style you don't like??

Juggler
2013.02.18, 11:41 AM
oh. 1.5 toe in...

I like a bit of toe-out on mye setups.
Have you tried that?
Or is that a driving style you don't like??

I started from 0 toe,but the steering was way too much and even more unstable in straight line...
Also i don't want to cut from the Tx,as i want to figure out what can i do directly on the car itself!

NoBrainer
2013.02.18, 11:46 AM
ah ok.
I usually set up my car after recommendations.
Then adjuts front tires to suite the track, then I adjust the transmitter so my car is best to drive.

But I guess some other guys here can help youmuch better than I can.
I have never used the doubla a-arm so.

Good luck and please share some pictures as well... please :D

Juggler
2013.02.18, 12:34 PM
Some quick photos just for reference...
I've installed the hardest springs in front(yellows) and the swaybar to test them tomorrow...

DMALMAD
2013.02.18, 02:03 PM
When I ran the 02 a-arm i used the purple springs with two degrees of caster and the 12 0'clock camper position, I also used the stock tie rod this should take away a little steering but leave you with plenty. Also don't mess with the sway bar it doesn't help it takes away way to much steering.

herman
2013.02.19, 01:29 AM
hi juggler nice to see that you got to the right thread...
if there is too much steering... why not use your end point settings or set dual rate lesser? that is what i would do...

what do you mean by unstable in straight line? does this mean that it doesn't run straight? have you worn down your front & rear tires a bit? or are they brand new?? have you tried toe-out like what no-brainer suggested?

Juggler
2013.02.19, 05:42 AM
hi juggler nice to see that you got to the right thread...
if there is too much steering... why not use your end point settings or set dual rate lesser? that is what i would do...

what do you mean by unstable in straight line? does this mean that it doesn't run straight? have you worn down your front & rear tires a bit? or are they brand new?? have you tried toe-out like what no-brainer suggested?

The tires have enough material on them,toe-out doesn't work for me in this setup,cause i already have too much steering...I'll test it again today on the track...

yasuji
2013.02.19, 09:42 AM
The tires have enough material on them,toe-out doesn't work for me in this setup,cause i already have too much steering...I'll test it again today on the track...
i either use -1 or 0 toe.... never more that this:)
with the std front aa arm flats facing up with-1 toe bar (0) droop should give you, toe out unloaded ,(0)toe at rest , and toe in compressed


fyi toe out is less twitchy in a straight line and gives more on power steering

yasuji
2013.02.19, 09:53 AM
Some quick photos just for reference...
I've installed the hardest springs in front(yellows) and the swaybar to test them tomorrow...

wow... looking at your picture you have the front end loaded alot!
the lower arms should be paralell to just slightly up from the chassis
th knuckle pins should stick up approx 2mm from the top of the toe bar!

Juggler
2013.02.19, 10:55 AM
wow... looking at your picture you have the front end loaded alot!
the lower arms should be paralell to just slightly up from the chassis
th knuckle pins should stick up approx 2mm from the top of the toe bar!

Grant i highly appreciate your help...i'll set it to parallel as you pointed...
The front "photo" setup was just for a point to start with(i already feel that it's tooo loaded!).I also noticed that when i put the white springs on,without the swaybar and with the same droop amount,the car felt very easy to ride.I just want to mess with more springs/toe/droop combinations to see if i can save off a few secs more!Also if i set the lower arms parallel the height at the front will rise and then what?I think i'll have to raise a bit and the rear,cause i've noticed that rear end being lower doesn't work for me...(I guess i can also use much softer springs with the same droop...there is enough space for the knuckles to work as they supposed to)
Finally the parameters that will remain unchanged are 1)the camber(12 o'clock setting) 2)caster...0.9 ,cause i'm really comfy with these two!

Tapir
2013.03.24, 05:46 PM
12oclock setting? Is that with the flat part to the outside of the wheel, or to the inside?

Droop settings. Are you limiting the droop to where lower arms are level, or rideheight to lower arms level?
I I have seen some guys running with lots of droop on their a-arm setups on a high traction rcptrack. Why so?

Preload springs?

My setup:
MR-03
Wide lower arms.
Green springs.
Caster 2
Droop set to arms level.
No preload.

What do you pro's recommend?

chad508
2013.03.24, 05:52 PM
I run the 1* lower arms and have the flat part of the d pointing into the chassis this gives 1* camber. I slightly preload the springs just to bring the lower arms flat, but that more depends on the springs being used. I have used 02 limiters on top and bottom of some springs as some are a little short.

lfisminiz
2013.03.24, 07:14 PM
12:00 = Flat spot pointed up.
6:00 = flat spot pointed down
3:00 = flat spot pointed towards out away from chassis
9:00 = flat spot pointed toward inside of chassis
Hope that helps.:)

Mike Keely
2013.03.24, 09:40 PM
One of the things that I notice when I see how adjustments are being made is there are two settings in what people are calling droop. Ride height is one thing and droop is another. Ride height is in a way to say it, the angle of the lower A arms to the chassis when the car is sitting still on a tweak board with the batteries in it. Droop is the amount the chassis moves up from the ride height till the front wheels come off of the tweak board.

I like to run my cars with very little to sometimes no droop and the lower arm level with the chassis. Most of the time I feel like the car wants to wonder on the straight-away more when I add more droop. With more droop you will usually get more steering though.

Mike Keely
2013.03.24, 10:00 PM
Some quick photos just for reference...
I've installed the hardest springs in front(yellows) and the swaybar to test them tomorrow...

In looking at the pics that you have there. The sway bar does not look like it is sitting in the left A arm properly and if you get the PN front body mount you should be able to lower the front of the cars body a lot. It looks like the chassis would hit the track before the body would. Just my .02 cents

Tapir
2013.03.27, 09:08 PM
But how about preload?
Are you guys preloading the springs? I'm using the green ones, and the front are very soft when arms are level with the chassis.

If I add preload, would I mess up whats good about the a-arm setup?

Mike Keely
2013.04.09, 10:15 PM
To add preload you would need to add washers to compress the spring so you don't change the angle of the lower arm. I mess around with it a few times here and there but most of the time I do run preload.

glider
2013.09.22, 10:09 PM
A number of people including Grant keep saying they run the AA0 tie rod. On my MR03 Double A-Arm even the AA+1 tie rod gives some toe out. I run the AA+1 but would like to have a +2 to try something closer to zero toe.

So are the MR03 toe arms undersized relative to those for the MR02?

mugler
2013.09.23, 12:08 AM
A number of people including Grant keep saying they run the AA0 tie rod. On my MR03 Double A-Arm even the AA+1 tie rod gives some toe out. I run the AA+1 but would like to have a +2 to try something closer to zero toe.

So are the MR03 toe arms undersized relative to those for the MR02?

has anyone tried to see if any of the UID toe bars for 03 will result in less toe when used with PN AA?

yasuji
2013.09.23, 01:05 AM
A number of people including Grant keep saying they run the AA0 tie rod. On my MR03 Double A-Arm even the AA+1 tie rod gives some toe out. I run the AA+1 but would like to have a +2 to try something closer to zero toe.

So are the MR03 toe arms undersized relative to those for the MR02?

for the MR02 i use -1/0/+1 as per this discussion both 0 and +1 lower arms

for the MR03 i use the AA+1 toe bar and the +1 lower arms

glider
2013.09.23, 11:08 AM
for the MR02 i use -1/0/+1 as per this discussion both 0 and +1 lower arms

for the MR03 i use the AA+1 toe bar and the +1 lower arms

Thanks Grant! The only other bit I am experiencing with my MR03 DAA setup is having the knuckles pop out. This may be aggravated by running too wide front rims such that hits pop them. But I have taken to putting a trimmed 1mm cap on top of the spring, in addition to the 3mm cap at the bottom. This preloads the spring more than I like. So I think it would be preferable to have a 3.5-4.0 mm spacer cap for the MR03 version. Greater travel is not needed IMO because the spring pin just ends up grounding out on the track anyway. Overall I love the DAA and it is the best for me after being setup properly.

glider
2013.09.23, 11:21 AM
has anyone tried to see if any of the UID toe bars for 03 will result in less toe when used with PN AA?

What is UID?

The absolute longest toe bar I have measured is the PN AA+1. That includes all the Kyosho ones such as the W+6. I am running the 1 degree lower arms on my MR03 which I think further pushes it to toe out even with the longest bar. If PN ever needs to manufacture another batch of arms for the MR03 it would be best to only make the +1 version but add a +2 size. For now the +1 works very well and there is no other reasonable choice.

chad508
2013.09.23, 11:40 AM
Uid was a forum member that designed parts and had them made by a company called shapeways. Even his longest was not any longer than the pn aa+1. As for the knuckles poping out I always run the 4mm spring limiter.

glider
2013.09.23, 01:12 PM
Thanks Chad! I will have a look for those 4mm cups. I completely missed those!

chad508
2013.09.23, 03:19 PM
they do not come in the kit. i just used some off of an old mr02

glider
2013.09.23, 11:53 PM
Actually discovered I had some 4mm ones already. The last set I bought has 3.0, 3.4, and 4.0 according to the printing on the label. I had thought they were all the same. It was a set of 6 units. Can't remember if it was PN or Atomic.