Mad Bull Soppy Steering Mod.

[BigSteve]

Hi all I understand that this may have been discussed before but is there a cheap and easy mod to improve the sloppy steering of a Mad Bull. I don't have any turnbuckle bits and pieces lying around and was wondering if there was anything I could do to improve the steering slop.

Thanks Steve.

[Fruitfly01]

Without a short threaded shaft or turnbuckle and a couple of studs and joints, there isn't a lot you can do to improve the front end.

The bulk of the issue lies with the bent wire that joins the servo to the steering bellcrank. There is so much play right there. Replacing it with a straight shaft and ball joints will solve most of your problems.

You'll need to drill a hole further in on the bell crank so the ball joint clears the shock tower at full lock, and mount the servo ball joint under the servo saver so it clears the car body.

I've also fitted DT03 steering rods to my car (Mad Fighter) to improve the toe angle so it's more toe out at rest.

I think other people have also added heatshrink tube or brass tube to the inner hinge pins on the lower arms (like there's an upper arm ) to remove play in the arm movement, improving steering a bit further.

[GregM]

Yeah, I just used heatshrink tube for the A-arm hinge pins as well as for the steering linkage. Some day, I'd like using brass tubing and proper ball-joints. I'd also like to build a new steering post supported by ball bearings, since the plastic steering bushing wears out over time.

[BigSteve]

Thanks for the comment. If I wanted to go down the turn buckle route what exactly would I need.

Steve.

[Fruitfly01]

Crikey, I can't remember the exact items I used - just some odds and ends floating around in the spares boxes.

The ball joints are standard 5mm type, found on lots of models, and are available to buy as as a set, often with other sizes.

The ball studs I used are the servo horn type. Part number 9804154 found in DT02 and DT03 kits and in earlier models such as Super Astute part 3455147. Also available in a pack 3455147

These require a 2mm nut to tighten them to the servo saver. I didn't need to use the nut on the steering bellcrank, just on the servo saver.

The turnbuckle came from out of no where, but any short 3mm threaded rod should do, commonly found in steering set ups in so many buggy kits.

If you want adjustable steering arms, the DT03 turnbuckle set has just what you need Part 54572.

Of course, you don't have to do it exactly how I've done it. I suppose there are alternative parts and ways. I just made it up as I went along.

[speedy_w_beans]

Another example of the turnbuckle mod:

http://www.tamiyaclub.com/forum/index.php?showtopic=68357&page=2#entry474900

As Fruitfly mentions, DT02 servo ball connectors and nuts work. The adjusters were some leftover 3Racing TT01 adjusters. The turnbuckle might have been a really short Yeah Racing turnbuckle. Like Fruitfly, this was leftover stuff in my parts box.

[BigSteve]

Another example of the turnbuckle mod:

http://www.tamiyaclub.com/forum/index.php?showtopic=68357&page=2#entry474900

As Fruitfly mentions, DT02 servo ball connectors and nuts work. The adjusters were some leftover 3Racing TT01 adjusters. The turnbuckle might have been a really short Yeah Racing turnbuckle. Like Fruitfly, this was leftover stuff in my parts box.

Really happy I just had a lengthy search through my spare bits and pieces boxes in my man cave and I think I found everything I need for the mod you describe. Could I be a pain and ask you what is the distance between the two 5mm adaptors. Just need to find my 2 mm drill bit to make the hole you described. The only m2 nuts I could find were the normal type and not the locking type.

Steve.

[speedy_w_beans]

I wish I could take that measurement for you, but I gave my Mad Bull to another TC member. It's in his fleet now...

[BigSteve]

Ok no worries. Yesterday I heatshrunk the Z piece of wire. It's surprising the difference that made. I'll work on the turnbuckle mod tomorrow.

Steve.

[GregM]

Ha! I know this would help a bit

Ok no worries. Yesterday I heatshrunk the Z piece of wire. It's surprising the difference that made.

Hah! I know this would help. At least for the time being. Good luck on the turnbuckle thingies. Cheers.

[TwistedxSlayer]

Google brought me this thread. Im very thankful for it :-)

[GregM]

Yesterday, I modified the steering of my DT-01 Mad Bull.

The steering boss was drilled throughout 6.5mm, and on the ends I drilled 8mm wide, around 2-3 mm deep pockets for 850 bearings (8 x 5 x 2.5). Parts:
- M5 hex socket screw with long shaft (non-threaded portion)
- 2x 850 ball bearings
- M5 washers
- M5 shims (they get into direct contact between ball bearings and regular washers)
- M5 locknut

 

The plastic steering post needed to be removed and a 5mm hole drilled through the chassis.

 

Ball raced steering boss attached (top)

 

View from below. The screw needs to be shortened. I used Knipex Cobolt compact bolt cutters, but you can use a saw, angle grinder or Dremel tool, too.

 

I had trouble finding the right spot for balljointed modified steering link on the steering boss. Either the link would hit the servo on full lock, or it would hit the shock tower. I blame this on the chunky (but strong) Savöx SC-0254MG.
I will alter this by using small ball studs (for M2) and use suitable plastic rod ends that will accept M3 rods (they are available by Tamiya). But then I have to glue the studs into the steering boss and servo saver. What glue is suitable for this job?

 

 

EDIT: I discovered that the ball-raced steering boss has some give when turning, due to the height of the design and having only a single attachment point at the chassis' bottom. There's also only so much clamping force you can apply to the M5 screw before it binds the nylon boss. I will investigate how I can improve my design with respect to:

- having multiple attachment points to the chassis
For brainstorming how to do bracing and reinforcement, I will have a look at the TT-01E chassis upper deck and ball raced steering posts.
- Make screw clamping force independent of the nylon boss
By using a sleeve (5 mm outer diameter / 4.1 mm inner diameter) that sits between screw and ball bearing, and that slightly extends out of the nylon boss by 0.5 to 1 mm. The screw will have to be M4 instead of M5.
- Make the ball bearing spacing inside the nylon boss more accurate
By using a sleeve that gets pressed into the nylon. I've got some aluminium tubing (8 mm outer diameter / 7.1 mm inner diameter) leftover.

[GregM]

Today, I modified the steering further.

A leftover servo horn was cut to fit, got a 5mm hole for the steering pivot, as well as two 3mm holes for mounting to the chassis. I moved the ball joint on the steering pivot further in and bent the M3 rod to clear the servo.

This helps against sideways movement of the steering pivot. There's still some rocking back and forth when turning.
I will convert the steering pivot further to be able to torque it down completely (without crushing the ball bearings). I will also add a third mount for the bracing.

[GregM]

Today I tinkered with the steering for yet another time.

Parts:

- DT-01 steering post, inner diameter drilled to 8 mm. 8.1 mm  would be ideal, if you've got such a drill bit available. Be careful, the nylon is strong, but not easy to drill, since you need to make sure it doesn't crack. Use small steps of 0.5 mm for your drill bits, the hardest part will be the last steps. Use a battery powered drill with a 1-piece chuck that locks itself - this way, you can keep the machine still, while you're turning the steering post manually around it.
Ideally, you'd have a drill press at your disposal, where you can securely fix the steering post into a machine vice, and drill a perfectly straight hole. Saves you a lot of elbow grease.
- M4 button head screw. Will be cut to the needed length.
- M4 washers. You will need at least four, depending on how you brace the steering. They'll distribute the clamping force of your M4 screw evenly on the plastic surface. Also M4 shims might be helpful if needed, Tamiya has them available.
- Aluminium or brass tubing, 8x0.45 mm. Length 6 mm. This acts as a bearing spacer. 7.95 mm od would be ideal.
- Two ball bearings 8x5x2.5 mm.
- Steel, aluminium or brass tubing. 4.95x0.5 mm. Length 12 mm. This will go between bearings and the M4 screw. Tamiya's hollow "5mm" shafts are great to fit bearings. I had bad luck with a generic 5mm brass tubing, since it did not wanted to slide into the bearings, it must have been a hair to wide.
- M4 locknut.

With the help of this assembly, I can tighten the M4 screw fully against the M4 locknut. Since the central tubing is 12 mm long, it will be 1 mm longer than the steering post. Use M5 washers or shims to reduce any movement height wise.

Works like a charm! No need for further bracing apart from what I already did. Now this is a steering assembly that I can wholeheartedly recommend to everybody.

[GregM]

And here's a section for your convenience.

Remember, the assembly with the 5mm tubing needs to extend slightly from the steering post. M5 shims can be added for reducing slop heightwise, depending on how accurate you cut the tubing. But there should always be some little space left between the top of the nylon steering post and the M4 washer, otherwise you can't torque the M4 screw down. If you leave no space, it would press against the ball bearings and the nylon steering post, limiting the free movement of the post.

An M4 shim (not shown) placed between the lower ball bearing and the M4 washer will help avoiding full contact to the ball bearing. The M4 shim gives contact only to the inner race, giving better movement.

If you follow my instructions, you can torque the screw down completely while retaining the free movement of the nylon steering post.

[GregM]

Looks like Photobucket is trying to press money from me

In the meantime, here's an improved drawing for the assembly:

Have fun!

[ALEXKYRIAK]

Awesome Greg. Thanks for sharing. Will have to get another Mad Bull to try it out on..... 

[GregM]

You're welcome!