Frame mounted steering servo?

[slobert]

Hey guys, I have parts on the way to start my 2.2 scaler. Actually its what I consider semi scale. It will have a box frame with bumpers, but it will be fourlink coils with a lexan body so It will crawl pretty good and wont cry when it rolls. So, I have searched this site and have seen a few pix of people with frame mounted steering servos. Do they work ok? Any tips on how to position the servo and linkage to not bind up articulation? Is it worth it on a semi scale model? Thanks for any help / insight / opinions!

[terrible]

I'm intrested in doing the same with my build. I'd like it to look like my 1:1 jeep but that big servo on the axle doesn't look scale at all! I'm afraid of a huge amount of bump steer once the suspension starts to move around. The distance from the knuckle end to the chassis changes by about an inch when cycled completely.

The only way I could think of to remedy that is to run a parallel four link with an equal length track bar. I know it'd look greeat but I'm not sure how well it would perform in 10th scale.

Any luck with yours yet?

[EeePee]

This works pretty nicely and doesn't bump steer too terribly.



You need the link length to be as long as possible, and as parallel to the axle as possible.

[1BadJeepBruiser]

Originally Posted by EeePee

This works pretty nicely and doesn't bump steer too terribly.



You need the link length to be as long as possible, and as parallel to the axle as possible.

EP is 100% correct, the key to making it work is to have the link from the servo to the knuckle to be as long as you can make it and to have them parallel.

[BigBubba]

This is just a mock-up for mine.... it seems to work quite well!! I still need to get proper rod and ends.....







Here's a link to a video.....

http://ca.youtube.com/watch?v=y-INNlJfSUs

Steering is on that side for a reason.... ;)

[slobert]

Thanks for the reply's, I has playing around and figured that long and close to parallel was key, and its great that people who have allready done it have confirmed it. A bunch of parts came today, so I get to go out and start planning my build! yeah for me!:-P
Rob

[slobert]

Originally Posted by BigBubba

Steering is on that side for a reason.... ;)

Its been a long day at work and it took me a minute to figure out what you meant. Then I looked closer at the 1:1 rig....ahhh.

by the way, thanks to both of you for the video; especially the "no bump steer" video I am convinced now.

Rob

[impulse byer]

I was having lots of trouble with this but now i see good work

Time to get building

[wonder squirrel]

I can't seem to get this to work. Suspension travel severly effects steering while its cycled.

I've been working on this tuber for sometime now. I'm at the point where I need to build some upper shock mounts and a servo mount to start wrapping it up. I've ziptied the draglink to the chassis in the area where the servo will be sitting and have been doing my testing like that.

I've got a double triangulation 4 link setup with a dinkylink style axle mount. I've tried changing link mounting positions (inside of mount, out side of mount) on the chassis and axle side, both inner and outer link sets, no notable improvement to steering.

Drag link length changed from 3" to 5" (the same length as the tierod now), no notable improvement to steering.

Draglink angle is only slightly steeper than the picture EP posted up (hard to tell from the picture to be exact though).

Beggining to think switching to a parallel 4 link/ trackbar combo is going to be the only answer. Also wondering how well the suspension is going to cycle with that type of setup..

Any ideas?

[terrible]

Beggining to think switching to a parallel 4 link/ trackbar combo is going to be the only answer. Also wondering how well the suspension is going to cycle with that type of setup..

I really think this is the only way to be close to bump-steer free. There is no way to get around it if you want a large amount of travel but with a four link/track bar you can atleast make the axle travel in a "J" path insted of straight up and down.

[Robb]

Originally Posted by wonder squirrel

Beggining to think switching to a parallel 4 link/ trackbar combo is going to be the only answer.

Granted I only ran this setup for a total of one hour, but I can testify that it works, and works quite well. With RC balljoints, and servos being [relatively] stronger than 1:1 steering boxes, RC trucks don't suffer the same constraints in regards to axle steer as their real scale predecessors. With the panhard at about the same angle as the draglink, and about the same length, axle steer can become almost nonexistent in an RC crawler. And I can tell you that a properly set up parallel fourlink + panhard can run VERY smooth.

[wonder squirrel]

Originally Posted by Robb

Granted I only ran this setup for a total of one hour, but I can testify that it works, and works quite well. With RC balljoints, and servos being [relatively] stronger than 1:1 steering pumps, RC trucks don't suffer the same constraints in regards to axle steer as their real scale predecessors. With the panhard at about the same angle as the draglink, and about the same length, axle steer can become almost nonexistent in an RC crawler. And I can tell you that a properly set up parallel fourlink + panhard can run VERY smooth.

I had put my links in the parallel configuration before but found the suspension cycle wasn't as smooth as the tringulation setup. Probably just a couple bugs to iron out of it. Might need different rod ends, I'm running the stock TLT pieces.

I think I'll try the parallel setup and see how that goes.

[Grizzly4x4]

Flat drag links are not quite as critical if you use a panhard bar suspension setup. But, it's always good to try and get the drag link as flat as possible.

Frame mounted steering is so much cooler than axle mounted, it's always worth the effort in the end.

[SMFtwstdHICK]

Outstanding job Grizz. I tried and tried to get my steering to look more scale. Never panned out. I would get steering, but, the panhard bar was limiting my suspension. Seeing all these frame steering setups make me want to try again. Just looks way better.

[Grizzly4x4]

Originally Posted by SMFtwstdHICK

Outstanding job Grizz. I tried and tried to get my steering to look more scale. Never panned out. I would get steering, but, the panhard bar was limiting my suspension. Seeing all these frame steering setups make me want to try again. Just looks way better.

Thanks man. It takes a bit of work, and I had to make many parts like the drop pitman arm, but eventually you can get it I'm sure.

[SMFtwstdHICK]

Yep Yep, Just bought a new TLT axle housing to just put the servo on the top. But, after seeing this thread and seeing that it can be done. IT's ON!!. lol.. Another problem I see with mine is that my rig just sits too high from the chassis to the axle. I am gonna lower it a bit more. Mount the servo on the side, and see what happens. I just gotta make a bracket or something for the servo. I have an old Diaz Designs scale chassis that I am using, Gotta make it work. Pics have been very helpful guys. thanks.

[nitrousrod]

kick ass bronco beautiful work. yes i just did my frame mount servo 2 days ago got more steering than i can use works great, but it is trial by fire

[wonder squirrel]

Originally Posted by nitrousrod

kick ass bronco beautiful work. yes i just did my frame mount servo 2 days ago got more steering than i can use works great, but it is trial by fire

Some pictures of your setup would be great if you get a chance.

[SMFtwstdHICK]

Originally Posted by wonder squirrel

Some pictures of your setup would be great if you get a chance.

2nd that.

[slobert]

Originally Posted by terrible

Any luck with yours yet?

Yes. After reading all the posts here I decided to stop trying to visualize how it will work and just bolt it up. I fabbed a battery tray out of aluminum and mounted my servo to it right against the inside of the frame rail to get the maximum distance out of the drag link. I couldnt get it too parrallel because I have quite a bit of travel. So I set it up so that it is parrallel ( touching actually ) at full bottom out. Suprisingly, there is hardly any bumpsteer to speak of. Not going to be much of a factor at all. Here is a link to a quick video I took of it to show you. Keep in mind its 1:30 in the morning, so I am somewhat incoherent in the recording.

http://s508.photobucket.com/albums/s...t=MVI_0118.flv