Suspension Geometry Guide

[JC3]

I'm building a Gspeed chassis with Enduro axles and trans. I'm struggling with the front three link and getting it setup correctly. Main struggle is the proper length of the panhard and steering links to prevent axle shift while maintaining full suspension travel and flex. I've got things pretty good but I'd like to make them better if possible.

I searched here for "links" and didn't really come up with anything meaningful that would be a guide for understanding 3 links better. Not really sure what else to search for. lol A net search yielded little regarding setup as well.

Any resources here or elsewhere on how to properly setup 3 links?

[HumboldtEF]

A 3 link with chassis mounted servo will always shift the axle. I think whats more crucial in this regard is getting the the drag link and panhard the same length an angle to minimize any bumpsteer.

So all you want is to make the axle shift less?

[Xx Losungen xX]

Originally Posted by HumboldtEF

A 3 link with chassis mounted servo will always shift the axle. I think whats more crucial in this regard is getting the the drag link and panhard the same length an angle to minimize any bumpsteer.

So all you want is to make the axle shift less?

X2.

Can't eliminate axle shift.

Center your axle at ride height, that's the length of your panhard bar and drag link, easy peasy.

You want them as long as possible and as close to the same angle as you can get.

[JC3]

Originally Posted by HumboldtEF

A 3 link with chassis mounted servo will always shift the axle. I think whats more crucial in this regard is getting the the drag link and panhard the same length an angle to minimize any bumpsteer.

So all you want is to make the axle shift less?

My panhard is 105mm and steering link is 85mm. They are pretty much parallel with each other. Well, I want to better center the chassis between the front axle and also minimize the axle shift at full extension and compression. Right now the axle is shifted a couple of millimeters to one side at ride height and axle shift is around 4mm at extension and 2mm at compression.

Steering link is shorter because I'm using a TRX4 servo mount putting the servo across the chassis (servo horn is more towards chassis center) instead of inline and offset from center like the stock Enduro and TGH servo/winch mount would orient it.

[Xx Losungen xX]

Originally Posted by JC3

My panhard is 105mm and steering link is 85mm. They are pretty much parallel with each other. Well, I want to better center the chassis between the front axle and also minimize the axle shift at full extension and compression. Right now the axle is shifted a couple of millimeters to one side at ride height and axle shift is around 4mm at extension and 2mm at compression.

Steering link is shorter because I'm using a TRX4 servo mount putting the servo across the chassis (servo horn is more towards chassis center) instead of inline and offset from center like the stock Enduro and TGH servo/winch mount would orient it.

Shorten or lengthen drag and panhard till your axle is centered at ride height, good to go.

Don't obsess about full extension and full compression, you'll never see it on both wheels at once anyways, unless your suspension set up is pure ass.

[JC3]

Originally Posted by Xx Losungen xX

Shorten or lengthen drag and panhard till your axle is centered at ride height, good to go.

Don't obsess about full extension and full compression, you'll never see it on both wheels at once anyways, unless your suspension set up is pure ass.

Makes sense now that I'm thinking about it. Maybe I'm being a bit too picky.

One other thing is happening that mystifies me. If I settle the suspension the chassis will always tilt towards the side that the front upper link is mounted on. I built the shocks very carefully, the springs are the same, the shocks are all mounted in the same holes and all pivots points are free. Weight distribution is all centered and none is on the skids. I moved the shocks around and no difference. In addition, the torque twist on this thing is horrible. Again, the chassis will always twist (rise) towards the side with the upper link when moving forward. Any tips on how to mitigate that?

[HumboldtEF]

I've noticed this on a number of rigs. I think its just the fact that there are extra links on one side (panhard and drag link) and they add enough extra resistance to make that side a bit less fluid.


This might get a little better after the ball ends break in and loosen up, or maybe I just get less picky after a rigs honeymoon is over


Also have you weighed this thing? They are most often not perfectly balanced side to side, close but not perfect. I prefer adding and extra items like the electronics on the side that lifts during a torque twist moment so in theory the weight works for me not against me.


And back to your first comment, yes I think you are being a little bit too picky. but theres nothing wrong with asking questions.



You can play around with shock oil and spring rates. Stiffening the rear will reduce the effects of TT. For spring rates I prefer to use softs up front and the stiffs in the rear.



Oh and do you have any sort of binding going on? I would look it over to check that. I just saw 2 separate issues with different rigs that had some binding that was causing the rigs to lean heavily under load, fixing the binding cleared this up. One was a corroded driveshaft on a friends rig and the other was from front axles being shimmed too tight.

[JC3]

Originally Posted by HumboldtEF

I've noticed this on a number of rigs. I think its just the fact that there are extra links on one side (panhard and drag link) and they add enough extra resistance to make that side a bit less fluid.

This might get a little better after the ball ends break in and loosen up, or maybe I just get less picky after a rigs honeymoon is over

Also have you weighed this thing? They are most often not perfectly balanced side to side, close but not perfect. I prefer adding and extra items like the electronics on the side that lifts during a torque twist moment so in theory the weight works for me not against me.

And back to your first comment, yes I think you are being a little bit too picky. but theres nothing wrong with asking questions.

You can play around with shock oil and spring rates. Stiffening the rear will reduce the effects of TT. For spring rates I prefer to use softs up front and the stiffs in the rear.

Oh and do you have any sort of binding going on? I would look it over to check that. I just saw 2 separate issues with different rigs that had some binding that was causing the rigs to lean heavily under load, fixing the binding cleared this up. One was a corroded driveshaft on a friends rig and the other was from front axles being shimmed too tight.

Rig is brandy new so I agree, it will probably get better when broken in.

Weight distribution is virtually perfect side to side and corner to corner. I thought centering the weight would be an advantage but now I see that that may not be entirely true.

I'm running light weight shock oil and the lightest springs. Clearly that doesn't help. I'll have to play around with that to find what works best.

Everything is bind free. However, I don't like the way the front end moves with the panhard and steering links installed. As it's been pointed out, maybe I'm just being too picky. The true test is how it crawls!

Thanks for the help guys!

[Xx Losungen xX]

Originally Posted by JC3

Makes sense now that I'm thinking about it. Maybe I'm being a bit too picky.

Oh I get it, my ocd kicks in and a faff about with stupid details like this myself, in the end it really makes no difference, don't stop us though does it