Swing Arm ?

[RACR_73s]

Could someone please tell me what moving the swing arms up or down on the chassis will do to the car? I have an 08 Rayburn combo car and need to tighten entry(alot) and nothing Rayburn has said has helped and can't get anyone to tell me what moving these will do? ~Thanks~

[racin6mod]

they control forward bite the upper bars going back control the rearsteer. has cj told you to go to a 6 or 7 inch offset wheel on the rr or to adjust the wheel base on the r side.our car was way to tigt going in so we ended up spacing the rr out to loosen it up on entry.

[RACR_73s]

they control forward bite the upper bars going back control the rearsteer. has cj told you to go to a 6 or 7 inch offset wheel on the rr or to adjust the wheel base on the r side.our car was way to tigt going in so we ended up spacing the rr out to loosen it up on entry.

Moved rearend left 1" and LR swing arm is 1" longer than RR.
LF 650 RF 450
LR 350 RR 500

[dirtdiggerracing]

try pulling rr foward to shorten rr wheel base ! and may also try more comp. in lr shock! do you have 2 10/90 shocks on top of rearend ? is it good center off ? is it slamming down ?

[RACR_73s]

try pulling rr foward to shorten rr wheel base ! and may also try more comp. in lr shock! do you have 2 10/90 shocks on top of rearend ? is it good center off ? is it slamming down ?

My rr swing arm is as short as it can go @ 15" and the left is 16". I have 2 of the shocks Rayburn uses on top of the rear end. I am going to use a 7/2 shock on LR this Sat. Yes its good center off, Its picking the LF up on throttle and doesnt put it down until I let off. Someone on here said raise the ride hight and I did and it pulls the LF up so high I can't see the car below me so I am getting away from that. Somebody else suggested dragging the brake entering and it helped a little but made me slower.

My problem is corner entry and I want to know what changing the swing arms on the chassis will do??????

~Thanks~

[washeduptoo]

I'm a mod guy but it should work the same, you can lower the rr forward bar down on the chassis to tighten up the car on entry. We had to reset the ride ht and scale numbers when we did that. You could use a heavier spring to help entry. On a mod, when you raise the forward bar on rr it increase forward bite and loosens and downward on frame does the opposite. The rearward bar up on frame tightens car and downward on frame increase forward and loosens. This again was on a mod, but it should be close to what a late model does IMO.Maybe this helps some and good luck.

[dualdj1]

Give me a little more detail on your setup. Is this when it's tacky or slick? you runnin up on the bank or down on the flat? Where is the pull bar at? how are your trailing arms set on left and right? J-bar puple bar or left side straight bar?

And does it feel loose letting off coming in, or when you're picking up the throttle?

If you're still running swingarm RR I'd consider going to Z and putting the shock/spring on the birdcage, see if you like that better. start off with like a 275-300.

[MasterSbilt_Racer]

Give me a little more detail on your setup. Is this when it's tacky or slick? you runnin up on the bank or down on the flat? Where is the pull bar at? how are your trailing arms set on left and right? J-bar puple bar or left side straight bar?

And does it feel loose letting off coming in, or when you're picking up the throttle?

If you're still running swingarm RR I'd consider going to Z and putting the shock/spring on the birdcage, see if you like that better. start off with like a 275-300.

I agree. Going to z on rr would immediately help with the spring layed in. Then you can lower the rr swing arm without effecting ride height/bite as well.

[RACR_73s]

Give me a little more detail on your setup. Is this when it's tacky or slick? you runnin up on the bank or down on the flat? Where is the pull bar at? how are your trailing arms set on left and right? J-bar puple bar or left side straight bar?

And does it feel loose letting off coming in, or when you're picking up the throttle?

If you're still running swingarm RR I'd consider going to Z and putting the shock/spring on the birdcage, see if you like that better. start off with like a 275-300.

It never feels tight going in(tacky or slick) but is extremely loose in the slick. Start with trailing arms in positions according to Rayburn and then drop LR down 4(bottom) and have moved RR up to top(2 I think) and have left it alone(Can't tell any difference). On purple bar except for one week on J(car was still extremely loose and lost forward drive) so went back to purple bar. Race @ Peoria which lends it self to alot of bottom but have tried moving up and makes no difference.

Going to do what CJ says this week
put 400 on RF
compression sock on LR
change the swing arm lenghts to 15 1/2" on RR and 15" on LR

~Thanks~

I have thought of going to birdcage on RR...what will that change? How will I be able to use the "swingarm" bar to adjust the car with it on the Z?

[dualdj1]

Yeah knew you were at peoria, wasn't sure if you were trying high or low groove.

Going to the cage will tighten it, because it moves your moment center left, which lets the car roll more. Remember though that your spring rate needs to be about half that of swingarm, i like about a 200-250 there. You can still leave the swingarm on there and just mount the shock to the cage with no probs.

How's the purple bar set? clear down on the frame?

Where's your pull bar at? Further left is more drive, and we go clear out with it at times.

softer right front will help, we're goin down to 450, but i was thinking about trying a 400. And they seem to respond well to adding rear weight if you have some.

That RR bar won't really affect your drive much, just how much the tail is hanging out as you corner. As banked as Peoria is you can put it to 2 on the slick.

let me know how the compression shock helps, been contemplating getting one of those, and how well the soft rf does.

[RACR_73s]

Yeah knew you were at peoria, wasn't sure if you were trying high or low groove.

Going to the cage will tighten it, because it moves your moment center left, which lets the car roll more. Remember though that your spring rate needs to be about half that of swingarm, i like about a 200-250 there. You can still leave the swingarm on there and just mount the shock to the cage with no probs.

How's the purple bar set? clear down on the frame?

Where's your pull bar at? Further left is more drive, and we go clear out with it at times.

softer right front will help, we're goin down to 450, but i was thinking about trying a 400. And they seem to respond well to adding rear weight if you have some.

That RR bar won't really affect your drive much, just how much the tail is hanging out as you corner. As banked as Peoria is you can put it to 2 on the slick.

let me know how the compression shock helps, been contemplating getting one of those, and how well the soft rf does.

Purple starts @ 2 1/2" and then goes to framerail at feature but may start at frame this week.

Pull bar left 1 to start then 1 more left for feature.

What do you mean by put it(swingarm bar?) on 2 for slick? 2 from top/bottom?

~Thanks~

[dualdj1]

sorry meant your right trailing (back) bar on 2 (top of the 3 that are together, not the clear top).

down with purple should be tighter, lowers roll center.

And most Rayburn guys I've talked to are now running right side on the bird cage, and like it much better. swing left still, and z right.

but I'd try the changes CJ says, that should help you going in. if it's still loose rolling in, you can stiffen LF too, which will help keep it good coming out. Taking some bite out should help it going in too.

[britt77]

Try raising the purple bar as high as you can get it on the chassis, make sure you leave clearance for the fifth arm. Helped me out alot in the slick.

[stevo]

Higher pan bar on frame more side bite.

[racin6mod]

the purle bar comes of the right side frame rail so you adjust the opp. of say a j-bar(down to tighten up to loosen) we ran double swingarm and a couple other rayburn guy's at our track ran the z-link rr. they ran hard in the heats and were tough but we ran off and left them in the features.the track champion was also on double swing arm with the long lr top bar. what's steve l on over at peoria this year?

[4bangerhotrod]

sorry racin6mod but you are wrong up on the frame adds sidebite but kills forward traction and down takes away sidebite but keeps the traction in the car. the purple bar attach's to the left side of the rearend so when it is high on the frame it is pulling the LR tire up which in return plants the RR tire, but when it pulls the LR up it takes the traction away from that tire. when the bar is down on the frame it is pulling straight across and not trying to pick up the LR tire which holds more weight on the LR tire adding traction to that tire. if people are going to give advice you should really know what your talking about before you do. all you have to do is have a mechanical mind and visualize what the change is doing this is the reason some of us can setup a car and when big races and some cant. take a pencil lay it down, tie a string to the left side of it and hold it to the right side about a inch above the pencil and pull on it, it will try to pick the left side up. then hold the string down against the pencil and pull on it, it will not try to pick the left side up. this is the same thing the purple bar is doing to the rearend.
thanks,
4bangerhotrod

[dualdj1]

4 banger you're partially right, the purple bar is a pulling action. as the car goes into the corner, the axle is trying to move left to the driver side, and in turn the purple bar applies tension between the right side frame and the left side of the axle. This can effectively cause a slight lifting on left sid axle, and extra downward force on right side frame. On the opposite side, J-bar or left side straight bar applies pressure outward between the left side frame and the left/right side of the pinion as the axle tries to move left. This can effectively cause left side hike, and extra either LR (left short) or RR (j-bar) force.

When you change mounting points on the panhard bar, it raises or lowers the moment (roll) center of the rear end. the height is the middle of the mounting points. The higher it is, the more resistance to roll the rear suspension applies. The lower the height, the more efficient the suspension works allowing for "easier" roll. Less roll generally equates to more side bite, more roll to more forward drive; but it is also dependent on other settings.


Believe Steve is still on the purple bar, but not positive.

[RACR_73s]

Here is how this week went...

LF650 (same) RF450(was 500)
LR300(was 350) RR600(was 500)
pull bar left 1(same)
purple bar 2 1/4" up on frame(same)
RR swing arm down 1 hole(4th hole from top)
LR 7/2 Pro compression shock(was standard Koni)
#158 LR(been anywhere between 140-186)
2 1/2" stagger(same)
12" fuel

Car was much better going in, first time that I felt that it was putting the RR in the track. Led 1/2 the heat before caution and never could get rhythum back and faded to 4th.

Feature changes....
RF 375
pull bar left 1 more
LR rear bar down 4 to bottom
RR rear bar up 2 to top
4 round out of LR
grind rear tires
No fuel added(less rear to tighten, correct ???)
forgot(ran out of time) to lower purple bar.

Track was the best it has been all year for the feature so can't compare apples to apples but car was good in feature. Started 8th and after a couple of laps started to come to the front. Got caught in lapped traffic(new driver all over the track and didn't want to dump him or wreck car any worse than what he was doing to it...lol) for a few laps and lost several spots. After caution started moving back up and spun with a few to go trying to get under another car.

washeduptoo - Thank you for telling me what the swing arms will do. I was wanting to lower the RR but wasn't sure if that was right.

dualdj1 - not sure on front spring and compression shock but it seems to be a step in the right direction. Going to leave 600#RR spring, 375# LF and 4 rounds out of left rear at start of next week and move everything else back. Maybe this will be a good starting point.

[wishiwasfast]

So you went down on RF, down on LR, and up on RR, but the LR bite # stayed pretty much the same? All that should've taken quite a bit of LR bite out of the car, right?

[dualdj1]

wish, there's really no way to measure bite at the track, but yes taking rounds out of the left will take bite out.

Glad you're making progress. On the fuel thing, add fuel to tighten. More rear percentage = more drive, by planting both rear wheels more so you get more straight line "push". less fuel/weight will loosen you. So if it felt good without putting more fuel in, you may need to go back up on that RF since you may develop a push with a full(ish) tank of fuel.

Just keep good track of all your settings. That way next week if you try something different and it's better/worse, you can have a better chance at figuring out what changes actually gave you the effect you wanted.