Adjusting caster to create heavier off-center steering?

[P3D-R]

I am surprised that there were marks on the original OEM arms. I can see the issue with the Meghan arms not being curved. Only makes a difference of about 1/4 if an inch. But I guess every bit counts. Like the idea of the slip in spacers to test. I am working on setting up the MYP for autocross EV-X series You guys are really helpful.

The design of the Megan arms is horrid imo and lacks so much forethought. The way they do the turnbuckles on the chassis side and then the 3 bolts that allow the ball joint to slid back and forth is just shoddy to me. These are the same design as hardrace arms. I bet they are the ones who make them. I think this is a very poorly thought out design. I can't wrap my head around how you can lengthen this arm to adjust caster without disconnecting it from the chassis. That itself is a pain in the butt since you have to remove the whole carriage to do that. Maybe I'm missing something but this design is quite comedic. Maybe you can enlighten me but it's possible this is why you had a hard time getting your caster back to factory spec before you install them, which should be around +5.5 to +6.0 degs. I presume Megan racing expects you to lay this on top of your factory arm to create the same length/shape so you can get your caster values where they should be. Then you can make those minor camber adjustments at the ball joint.

 

[Motion122]

Find some shock packers of the correct ID and thickness and you are good.

Shock Packers .125” Thick, Fits Shock or Strut Shaft with .625” Diameter, 10 Pk | eBay

This new item is used to limit travel on your shocks.

www.ebay.com

I am surprised that there were marks on the original OEM arms. I can see the issue with the Meghan arms not being curved. Only makes a difference of about 1/4 if an inch. But I guess every bit counts. Like the idea of the slip in spacers to test. I am working on setting up the MYP for autocross EV-X series You guys are really helpful.

Try two of packers of that thickness and you may be good to go.

 

[Yperformance]

Oh shaft size is .866 need to do some more looking. Totally correct in that you get what you pay for. The caster is adjusted by screwing in or out the bushers do yes it's a dismantle job but I found it only took a couple of goes to get them even. The real issue is lining up the bushes on the mount when one is at a slight angle . The bolt system for camber adjustment is a bit of a pain but once it's set I guess it does not need changing. Range of settings is not bad. The real problem is the arms are flat where as the OEM are curved to allow more clearance.. my guess is they designed them not taking into account people lowering their suspension. Anybody got any ideas on how much the suspension can move up from it's nutral position seems even with stock arms once it's lowered by about an inch there is only about 1.5 to 2 inches above the arm.

 

[P3D-R]

Oh shaft size is .866 need to do some more looking. Totally correct in that you get what you pay for. The caster is adjusted by screwing in or out the bushers do yes it's a dismantle job but I found it only took a couple of goes to get them even. The real issue is lining up the bushes on the mount when one is at a slight angle . The bolt system for camber adjustment is a bit of a pain but once it's set I guess it does not need changing. Range of settings is not bad. The real problem is the arms are flat where as the OEM are curved to allow more clearance.. my guess is they designed them not taking into account people lowering their suspension. Anybody got any ideas on how much the suspension can move up from it's nutral position seems even with stock arms once it's lowered by about an inch there is only about 1.5 to 2 inches above the arm.

One benefit of the curve is to alleviate the need for the ball joint to articulate too much. That's one of my biggest concerns and something you should be inspecting as well as chassis clearance. Companies who opt not to include the curve do so to cut the costs of manufacturing. The curve means they need to use a larger piece of material to create the shape which costs them more machine time and material cost.

As someone had mentioned, it's best you remove the spring so that you can check for ball joint articulation and chassis clearance at full compression. Then if needed, use packers as Motion122 suggested to prevent the shock from having too much bump travel that might cause the ball joint to go past its limit of articulation. This process seems a bit cumbersome for such an inexpensive part and ultimately those bushings will wear down. The benefit of sticking with the MPP ecosystem is that they have tested for all these things on their specific suspension. MPP can also advise you on packers if you shoot them a quick email. When you start mixing and matching things it's important you have a solid basis of knowledge to go through the "engineering" steps to ensure a safe and solid install/setup.

 

[Yperformance]

As the fouling point is on the steel frame not in the arm mounting bracket it appears that if the top mount was lowered by 1/2 inch the full travel would be restored. The top mount is not a flush fit on the body frame so the stress of 4 individual steel blocks would have the same contact area on the mount with the requisite high tensile bolts and washers , any body see a problem so far. Lower ride height can be controlled by adjusting the spring perch as usual still within the MPP spring compression settings. Apology to engineer it's a Magiver thing.

 

[Yperformance]

Got some info from good old Jesse at MPP seems I am on the right track.

 

[Yperformance]

Is there someone here who has a decent CAD model of the 3's suspension that they can share (or weigh in on questions)?
Does it even make sense on our suspension to try to trade static camber for more dynamic camber?
I bought a set of Redwood arms to replace my MPP arms and plan on playing with them with the front shock removed to see what one can accomplish. But doing this all in CAD would be much easier.

Hiz How much caster did you get with stock arms. I am about 1.5 inch lower will that help increase positive caster? Thanks

 

[Motion122]

Hiz How much caster did you get with stock arms. I am about 1.5 inch lower will that help increase positive caster? Thanks

No, but you have just added some static negative camber. More caster will help with camber gain for the outside wheel.

The other option is to get MPP adjuster compression rod bearing for additional caster but only if you can tolerate the added NVH.

 

[Yperformance]

Read mixed reports in caster bearings. The only way us redwood or unplugged . I am trying modified megan arms cheap but need grinding on and spacering up the ball joint .

 

[P3D-R]

Read mixed reports in caster bearings. The only way us redwood or unplugged . I am trying modified megan arms cheap but need grinding on and spacering up the ball joint .

Redwood FUCA is complicated to adjust as well. You'll need a crow's foot. The UP ones is a bit easier to adjust for this reason. You just want to make sure you check for chassis clearances when you start modifying the shape of the FUCA the way those are adjusted.

 

[Yperformance]

Been there. Any arm that is flat is a problem. Have cut out the existing gap in top of chassis that gave me a bit more travel. Did find spacing up the ball joint on the cheap Megan arms did work so I got 2.5 inches of suspension travel including the bump stops when car was lowered about an inch and a quarter. Using 20 inch wheels got 6.8 degrees if caster ok. Was worried that rubber arm bushes might not be uori the job. Just about to find out when the drive half shaft inner bearings started to cause vibration when accelerating hard 69 mph up. Thought I had got it spit in till then, grrrrr

 

[Motion122]

Read mixed reports in caster bearings. The only way us redwood or unplugged . I am trying modified megan arms cheap but need grinding on and spacering up the ball joint .

Aftermarket is slow to catch up. There should be more options soon.

 

[Lindenwood]

FWIW, I can confirm even at the minimum setting, the slight caster increase combined with the low-compliance spherical bushing do create a more pronounced “notch” at steering center. I drive and race in “Comfort” mode but do still enjoy how that feels.