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ianc
2009.06.18, 01:01 PM
Hi folks,

I'm getting to the point where I'm ready to start adding electronics and get the steering working in my MRCG1.1, but the included nylon tube is just not doing it for me. It's too big for the tie rod horn and would bind, and I just don't like the idea of using a flexible piece for the steering linkage (albeit it may provide some protection for the servo in a crash...). I've thought about trying to source some small length of metal bar or tubing of the correct diameter, but would really rather use a ball socket linkage as I've seen others doing here.

I've read that Brian has fabricated a small adapter piece from CF that's available here in the shop, but I'm interested in getting specifics of the parts others have used to make this work so I can order them.

Unlike the rest of you old timers, I don't have bits from 75 different RC cars laying around, just Mini-Z's, so my spares bin is a bit limited in this regard. ;)

Can anyone give me a list of the necessary parts and part #'s they used and how well you think it's working? Pics would be nice as well... ;)

Thanks for the help everyone; I really hope to get this one on the road soon, then spend the next couple of months getting it sorted...

ianc

color01
2009.06.18, 08:43 PM
http://img213.imageshack.us/img213/8440/img0207fo9.jpg

Atomic RM DPSII shock, cut down to size and then superglued together. Hasn't failed me yet. :)

Other people have used helicopter joints, but since you specify Mini-Z I figure that the Atomic parts would be the ones you're most likely to have (it was the same case for me :D).

ianc
2009.06.19, 11:24 AM
Hi Brian,

I do have one of those spare shocks at home, but I'm loath to cut it up for the ball joint. I was thinking if I had another, I could cut the threaded portions off short, then cut the head off an M2 screw to join them, but I'm not sure I could get it down to an appropriate length and still have the strength I want. I'm not too crazy about the superglue option I'm afraid. plus I would require another to sacrifice as well, which I'm not that keen to do...

I don't mind buying helicopter joints if that's what will work best, but I just need some part #'s to work with. More suggestions please, and thanks again!

ianc

color01
2009.06.19, 08:30 PM
I wouldn't worry about strength if that's what you're wondering... CA glue melts the plastic a little so essentially you end up with one rigid linkage.\

For the heli parts, EMU or MK2kompressor would probably know better. :o For now, I have found some parts online for the T-Rex 250 micro heli that look like they'd work, but -- disclaimer coming -- I've never tried them out so I'm not guaranteeing anything.

EMU
2009.06.22, 12:29 AM
I found my ball links in a parts bin that I got from someone else... so I dont know the part numbers, or even what brand they are. I shaved down the ends, where the screws go in to make them a little shorter. I then cut a head off a screw, and threaded it with pliers into one ball link, and then the other... I wish I knew which heli it was for...

Im going to throw a bunch of links up, that look like they would work. I just have no idea what size ball or screw is needed.

http://www.helidirect.com/h50054-500-ball-link-short-p-5582.hdx
http://www.helidirect.com/plastic-ball-linkages-and-rods-set-hdx450-setrex-p-1303.hdx
http://www.helidirect.com/beam-linkage-rod-whardware-p-12980.hdx

No screw on link
http://www.helidirect.com/gaui-double-link-set-hurricane-200sd-p-6922.hdx

http://store.hkshobby.com/product_info.php?products_id=5072
http://store.hkshobby.com/product_info.php?products_id=4784

If you know anyone into heli's, then you can try to ask them for better feedback about the sizing. Or you can try to be like Brian, and work with Mini-Z parts :P

mk2kompressor
2009.06.22, 02:25 PM
most ball links with 2mm thread on the ball stud will be the same size as the socket.

try ebay 190101767953

ianc
2009.06.22, 05:10 PM
Hi EMU and MK2,

Thanks for contributing the links. This one seems particularly interesting:

http://store.hkshobby.com/product_info.php?products_id=5072

because some of the linkage elbows have the ball studs already attached, and perhaps they are removable. But size? Just don't know.

I guess I'll just wait around for the adapter piece to show up from tinyrc, and then I'll have a bit better idea of my actual size constraints. Was hoping for a plug and play solution, but I guess that's not gonna happen for the moment...

Will keep looking; I still have other work to do on the car first, so not in a huge hurry. Thanks again,

ianc

color01
2009.06.22, 09:41 PM
Regrettably I have yet to find a plug and play solution because of the size constraints of the entire chassis + the desire to keep the linkage more or less centered on the tierod. I found one that was the right size, but it wasn't a ball joint -- it was just a 2.1mm diameter hole, causing a bit too much steering slop to be useful.

Those Walkera #38 ball joints... the original heli is a pretty big one I think, so I'm not entirely sure that would work. Feel free to correct me though, I'm no heli specialist.

mk2kompressor
2009.06.23, 06:17 AM
those walkera ones are no good as the ball cups are really wide(outer circumfrence).
the closed type ball cups tend to be thinner like these eb4y number; 380131421779

the problem with those is the white ball cups are a little long

cowboysir
2009.07.08, 10:29 PM
So I wound up trying something a little different to make my steering linkage.

I wound up using two stock top shock ends and modifying them a bit to combine them into one.

http://i13.photobucket.com/albums/a258/CowboySiR/Mr-CG-MM021.jpg

I wish I had documented this mod with some photos but I'll do my best to describe how it's done.

1. Trim three millimeters off each shock end on the end that threads onto the shaft.
2. For one cup, trim the part that threads onto a shock shaft in half on the flat side of the cup.
3. For the other cup, trim the part that threads in half with the cup on its end.
4. Use a piece of 3/16th tubing (I used alloy) to mate the two half cuts together into one full round piece. I used CA glue before mating the pieces inside the tubing...

you'll wind up with a linkage like one in the photo. One stands on its side to mount to the servo arm and one lays flat on the steering arm extension. From bench testing it moves super smoothly and I hope it has decent strength for racing.

Thanks for looking.

herman
2009.07.08, 11:44 PM
hmm... here's an idea that you might want to incorporate into the steering linkage...
a servo saver... this was done on a kawada tripmate waaay back... thanks to donut...

servo saver is made by dubro...
http://www.mydestiny.net/~hobbyshop/donutsrc/clkgtr/clkgtr10.jpg

or you could make one yourself...
http://www.mydestiny.net/~hobbyshop/donutsrc/m24servo/saver01.jpg
http://www.mydestiny.net/~hobbyshop/donutsrc/m24servo/saver02.jpg

hope this helps...

color01
2009.07.09, 03:08 AM
Cowboy- nice DIY! But now people have to find metal tubing... :p

herman- Dubro-style works, but not well enough for modern pan cars. On the very first MRCG prototype I tried out this kind of servo saver; hated it, I'd rather not run a saver at all. The way the saver is built, it always allows a tiny bit of movement inside, so you never have the confidence that the steering will stay at a certain angle. And because of the springs there's always a little more delay between when you first turn the wheel to when the car noticeably steers.

Personally, the Futaba servo horns are already soft enough to be servo savers -- I haven't stripped any gears yet with no saver at all. And with JR servos there is the option to use a Mini-T servo saver as EMU has already done or a Micro-T saver as MK2 has done.

ianc
2009.07.09, 12:27 PM
Cowboy, your idea is interesting and bears looking into. Don't think I have a couple of stock shocks laying around, but will dig a little and see what I can come up with.

As regards the servo saver, my personal feeling is that as long as you keep your front offsets to the point where the tires don't protrude beyond the car body under heavy cornering, it shouldn't be necessary.

Thanks for contributing!

ianc

Davey G
2009.07.10, 11:13 AM
I am still using the same setup as my original pics except now with the Futaba servo that COLOR01 suggests. On a pan car body I am using 2mm offset rims, the tires sit well inside the wheel wells which would make it impossible for the servo gears to strip. Like COLOR01 said the servo horn is flexible enough to act like a saver. My tierod bracket is simply a PN H-plate cut to shape and I am using BLUEBIRD (www.bphobbies.com) servo mounts.

http://i178.photobucket.com/albums/w277/Dgraboski/black3.jpg

EMU
2009.07.11, 02:50 PM
That is the best use for a PN t-plate I have seen :P

I will be testing both the Futaba servo and the JR servo back to back when I get the MRCG to the track... I had a chance to drive daves car a couple days ago, and really liked the servo response. Which is making me rethink the JR servo and saver, which I feel has more torque, but less speed.

ianc
2009.07.11, 06:14 PM
Hi Dave,

I'm interested in the little purple gizmos you have holding your servo in place. You mentioned them (blue bird) above, but can you provide a specific link for them? I'm finding that tire tape is just not holding the servo in place like it should and something like those braces looks like just the ticket.

Would these still work if the servo is mounted opposite to yours with the horn towards the rear?

Also, could you provide some more detail shots of your ball linkage arrangement and a parts list for it?

Thanks much,

ianc

P.S. Get some tires on that thing; I guarantee it will have more grip! :)

Davey G
2009.07.11, 09:34 PM
The servo mts are from www.bphobbies.com, not sure if they are sold seperately. Give them a call and ask for Dave Peru, tell him DAVE GRABOSKI sent you. The other parts are simply helicopter linkages made by Hirobo (www.modelrectifier.com) ask for TIM and also tell him I sent you.

Here is another pic showing the mounts:

http://i178.photobucket.com/albums/w277/Dgraboski/black1.jpg