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Old 04-24-2014, 01:39 PM   #1
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Default Technical question regarding steering rack. PICS included please help.

Hi,

So I am going to modify my TA06 with a floating servo mount and I'm also going to add a different bell crank, well try to at least. Please don't tell me it cant be done, you shouldn't do it, or bash me for doing it.
This is a technical question regarding what happens when the bell crank is not mounted at the exact 90* angle. Not a question of is this doable or not.


My question is this, the current mounting holes for the Tamiya system in place is 24mm, the bell crank I want to use is 21mm.

What kind of a difference is mounting the bracket 3mm wider going to have on my steering angle, will it decrease it?





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Old 04-24-2014, 01:53 PM   #2
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Hi,

So I am going to modify my TA06 with a floating servo mount and I'm also going to add a different bell crank, well try to at least. Please don't tell me it cant be done, you shouldn't do it, or bash me for doing it.
This is a technical question regarding what happens when the bell crank is not mounted at the exact 90* angle. Not a question of is this doable or not.


My question is this, the current mounting holes for the Tamiya system in place is 24mm, the bell crank I want to use is 21mm.

What kind of a difference is mounting the bracket 3mm wider going to have on my steering angle, will it decrease it?





Essentially, you are going to make the links longer. Making it less aggressive steering wise, I believe that means your are increasing ackerman. However when you adjust your ackerman its going to have a greater affect because your increasing the lever size. If that makes sense
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Old 04-24-2014, 02:05 PM   #3
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Depending on the height of your ball studs, I don't think you'll see as large of an effect on steering angle as much as you would your ackerman.

Install it and watch the angle of the center link go further away from parallel to the steering movement. That might make your turnbuckle link on either side, depending on which direction your steering at the time, hit the center link. Then to fix that you would have to add spacers under the ball stud to make it taller....in turn changing your ackerman.

Keep going with it, depending on how many spacers the manual has you start with you may not notice anything at all. Keep us updated.
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Old 04-24-2014, 02:11 PM   #4
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The one thing I would be concerned with is making sure the inner steering link/ball stud mounting location stays relatively the same after you make the change. If you alter where the inner steering links attach relative to the center line of the chassis, it might introduce bump steer to the car.

Since it seems you are just altering the throw of the steering, I would think the biggest effect would be on ackerman (as stated above).

The only other thing I would be concerned with is limited movement of the rack or binding at maximum throw of the steering. You are changing pivot points, so it might have some unexpected results.

It may be a good thing or bad thing, but you won't know until you try it.
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Old 04-24-2014, 02:30 PM   #5
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That's going to cause an S curve in a graph of your ackerman. Depending on the angle of the tie-rods you would either see a huge increase in ackerman for the first few degrees of steering angle which would then start to reverse, heading towards anti-ackerman at full lock or you would see anti-ackerman in the first few degrees and then start getting more and more ackerman as it goes to full lock.
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Old 04-24-2014, 03:49 PM   #6
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The one thing I would be concerned with is making sure the inner steering link/ball stud mounting location stays relatively the same after you make the change. If you alter where the inner steering links attach relative to the center line of the chassis, it might introduce bump steer to the car.

This was something I had thought about aswell, im trying to get the mounting location as close to stock as possible but it is a heavy mod, it will be off by a couple mm though.

The only other thing I would be concerned with is limited movement of the rack or binding at maximum throw of the steering. You are changing pivot points, so it might have some unexpected results.

This is a concern that I had especially with the servo since I don't want to grind the gears because of binding.


After watching this video,
http://www.youtube.com/results?searc...rman+explained

I gather that this is what you are referring to wingracer, either 2 or 3(blue or green) is going to happen...

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Old 04-24-2014, 08:45 PM   #7
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I don't see any harm trying. Next thing you know this would probably lead to multiple mounting holes for steering rack like shock hole positions in future touring car designs!...

Go for it man....
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Old 04-24-2014, 09:21 PM   #8
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I don't see any harm trying. Next thing you know this would probably lead to multiple mounting holes for steering rack like shock hole positions in future touring car designs!...

Go for it man....
the xv01 has that. it lets you move the rack back and fourth a little to adjust steering.
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Old 04-24-2014, 11:01 PM   #9
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Back and forth already existed in previous touring car designs, not sideways though.
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Old 04-25-2014, 11:19 AM   #10
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I don't see any harm trying. Next thing you know this would probably lead to multiple mounting holes for steering rack like shock hole positions in future touring car designs!...

Go for it man....
Interesting, but what I'm trying to accomplish is a complete mod, I'm using the TC6.2 steering rack in the Tamiya TA06, but I get what your saying, seems it would be easy enough to incorporate. Maybe you could get a wider steering angle for easy switch from TC to Drift or something...
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Old 04-25-2014, 11:34 AM   #11
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Well I have a lot more Mods to do but I figured out how I am going to install the rack last night, the next obstacle is going to be clearing the belt that runs above it.
I need to order carbon fiber and some other parts too to redo the battery tray.


If you look at picture two you can see the mounting holes for the ball studs, they are about 3-4mm higher than the stock location, what kind of effect will this have on bump steering?



Before





After





What the Rack is suppose to look like.




Mock up of what I am trying to have it setup like. The ESC will be in the middle behind the steering rack, next to the servo and in front of the battery.
I will need to make new battery side holders out of carbon and a hold down plate since the current one will be to long.


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Old 04-25-2014, 11:40 AM   #12
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If you can raise the outer studs the same amount (3-4mm spacers) it should be the same. If not, you will have a lot of bump steer.
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Old 04-25-2014, 02:01 PM   #13
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You could lower the stearing rack cross piece with 1.5-2mm shims under the bearings, along with longer screws, and raise the ball ends on the stearing knuckles the rest of the way. That way one or the other won't be at an extreme, making the whole more durable.
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Old 04-26-2014, 01:39 PM   #14
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So I had to add a 5mm spacer to the center shaft to ensure clearance but it seems to clear just enough. Ill probably go ahead and drop the front pulley to 38 or 37T for the time being to really make sure it clears.





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Old 05-02-2014, 08:08 AM   #15
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So here is where I am at.
I mocked up the front suspension to make sure that it would work with turnbuckle clearance and what I found out was...
Yes, but, I will have to shave off about 1mm or 1.5mm of the plastic closest to the steering rack arm as it is binding ever so slightly.

Also I am pretty sure I set up the caster blocks backwards? I am assuming I did as it looks like I will have negative caster at this point. Thanks I'm learning as I go, I never claimed to be a pro









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