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Car Discussion Touring cars, Rally Cars, Drifters, whatever!
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  #46  
Old 06-03-2013, 06:39 PM
Frederik Frederik is offline
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May I ask what is the diameter of your unused rear disks? And I assume the thickness is the same as the fronts.

If they can fit on my struts (not too small, I would have to do some verifications) I could maybe use them and maybe make them fit on mini wheels. That is if you are at all interested to sell them!

I looked at venom front bike brakes 1/8 like yours, they also sell separate packages, like calipers only. Still not sure what I'll do but I am weighing options haha
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  #47  
Old 06-03-2013, 07:16 PM
Trini2DBone Trini2DBone is offline
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Originally Posted by Frederik View Post
May I ask what is the diameter of your unused rear disks? And I assume the thickness is the same as the fronts.

If they can fit on my struts (not too small, I would have to do some verifications) I could maybe use them and maybe make them fit on mini wheels. That is if you are at all interested to sell them!

I looked at venom front bike brakes 1/8 like yours, they also sell separate packages, like calipers only. Still not sure what I'll do but I am weighing options haha
Hey Frederik, the unused discs ( the smaller set) are 30mms diameter and the thickness is 7mms.
I also have the same separate packages that you mentioned, I bought them as spares incase I broke or lost a part while trying to get them to fit! See pics in post #41.
Don't see myself using either the discs or the caliper and disc pad packages in the near future, so if you interested in them, let me know via pm and I will work out a price for you!
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  #48  
Old 06-04-2013, 12:48 AM
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kungpow kungpow is offline
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Haha yes now that you say it I remember you were initially learning to control the brakes with this setup. I was thinking I could drive the esc and a servo at the same time by tapping into a servo cable and feed the same signal to both the esc and brake servo? The extra travel caused by fwd movement would just be lost in loose cable. But then I guess I would be sending brake signal when trying to actually go reverse mmm.... Why no simple? Lol
You could use a 3 channel radio and have a micro servo on the 3rd channel that activates a momentary switch hooked to the brake servo so when you hit the third channel it disables front brakes so you can go in reverse. Kind of like the dig switches on moa crawlers.
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  #49  
Old 06-04-2013, 12:18 PM
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You could use a 3 channel radio and have a micro servo on the 3rd channel that activates a momentary switch hooked to the brake servo so when you hit the third channel it disables front brakes so you can go in reverse. Kind of like the dig switches on moa crawlers.
thats pretty good idea. just like you actually have to put the car in reverse
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  #50  
Old 06-04-2013, 04:18 PM
Frederik Frederik is offline
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Mmm... thanks for the ideas guys. right now I only have one radio and it is 2 channels... I would like to find an automatic way of activating the brakes, ideally with my current radio. If I need to buy another radio I will likely buy a versatile model with more possible configurations (to handle what I want to do, if such thing exists).

I think for now I will try splicing the throttle (esc) signal to an additional mini servo, and see if I can adjust the brakes linkage so it starts braking only passed a certain position (say 25% reverse signal) so there is enough signal for a moderate/slow reverse without activating the brakes, and beyond 25% the brake will start grabbing.

So on first reverse hit, it will be first 25% rear braking and remaining 75% all wheels brakes. Then if you release and reactivate reverse it will actually go reverse, up to 25%. I am willing to sacrifice full speed reverse for somewhat automatic front brakes, hopefully that can work!
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  #51  
Old 06-04-2013, 04:22 PM
Frederik Frederik is offline
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Regarding the caliper themselves, I dont quite understand how they can work without some kind of binding? Usually this type of calipers is mounted on floating discs, so the disc can move a little when sqweezed by the caliper. Here the disk is fixed, so depending on the pads adjustment the disc will either be pushed out because the outer pad is not contacting, or e outer pad is constantly dragging to avoid such condition? Preston, as you have seen the calipers first hand, do you understand what I am trying to say?

Or is the binding so little that it does not cause any issue?
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  #52  
Old 06-04-2013, 05:13 PM
Trini2DBone Trini2DBone is offline
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Regarding the caliper themselves, I dont quite understand how they can work without some kind of binding? Usually this type of calipers is mounted on floating discs, so the disc can move a little when sqweezed by the caliper. Here the disk is fixed, so depending on the pads adjustment the disc will either be pushed out because the outer pad is not contacting, or e outer pad is constantly dragging to avoid such condition? Preston, as you have seen the calipers first hand, do you understand what I am trying to say?

Or is the binding so little that it does not cause any issue?

Yes the calipers are floating! The caliper mount is attached permanently to the hub. The calipers are then bolted to the mount via shoulder screws which allow the caliper assembly to slide on the shoulder screws ( like in a real car).
The caliper is actuated by a cam ( instead of a piston, but does the same job) which forces the inner pad against the rotor and at the same time pulls on the caliper assembly forcing the outer pad against the rotor at the same time. When the servo is at rest there is a 1mm space shared between both pads and the rotor allowing the disc to spin freely!
Hope that makes sense!
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  #53  
Old 06-04-2013, 05:35 PM
Frederik Frederik is offline
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Yes the calipers are floating! The caliper mount is attached permanently to the hub. The calipers are then bolted to the mount via shoulder screws which allow the caliper assembly to slide on the shoulder screws ( like in a real car).
The caliper is actuated by a cam ( instead of a piston, but does the same job) which forces the inner pad against the rotor and at the same time pulls on the caliper assembly forcing the outer pad against the rotor at the same time. When the servo is at rest there is a 1mm space shared between both pads and the rotor allowing the disc to spin freely!
Hope that makes sense!
Wow yes it does make perfect sense, I just did not think they would do actual floating calipers in that scale! I am definately interested by your leftovers, I will PM you in a minute haha
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  #54  
Old 06-04-2013, 09:22 PM
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i ordered a brake kit from A-main hobbies last night. they had a special on postage so i snapped it up. pretty interested to see what i can come up with
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  #55  
Old 06-06-2013, 09:36 AM
Trini2DBone Trini2DBone is offline
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i ordered a brake kit from A-main hobbies last night. they had a special on postage so i snapped it up. pretty interested to see what i can come up with
Hey Klampykix ! Is that for the wraith? That would be pretty cool! I'll be following along on your thread as well to see how it turns out!
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  #56  
Old 06-06-2013, 07:18 PM
Frederik Frederik is offline
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It looks like a neat kit! I too am getting one for this build, and I will reuse Trinity's rear smaller discs. Today I finally received the gd600 tranny! and also the m-chassis tires I bought. Still waiting for the wheels though.

Here is a size comparison with tamiya touring car tires. The m tires are tamiya too, the medium size is 60D (60mm) and the small one is the 55mm model.

I think the medium size (60mm) will be perfect for the escort! By the way the disc in this picture is from the crappy chinese kit, but are almost same size as the one Trinity will be sending me!



Last edited by Frederik : 12-26-2018 at 04:55 PM.
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  #57  
Old 06-06-2013, 08:00 PM
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klampykixx klampykixx is offline
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Hey Klampykix ! Is that for the wraith? That would be pretty cool! I'll be following along on your thread as well to see how it turns out!
yep for the wraith. im highly contemplating using 2.2 rims just for the extra space inside the wheel, and coz they look better than the 1.9s.

not sure what wheels, i wanted the new axial TR rims but i dont wanna pay $30 for wheels and then $30 for postage....

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  #58  
Old 06-06-2013, 08:39 PM
Frederik Frederik is offline
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Depending if you end up changin wheels or not, maybe you could use the smaller rear discs like I plan to do, so it fits the smaller wheels.
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  #59  
Old 06-06-2013, 08:42 PM
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even if i stick with the 1.9 rims im sure i will have just as much room as Triny did. im thinking ill end up using RC4wd discs tho, coz they bolt onto the wheel rather than hex mount, and theyre pin on the back.

edit: it keeps the offset down.
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  #60  
Old 06-13-2013, 11:32 AM
Frederik Frederik is offline
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Just got the mini wheels to go with the mini tires. Regarding the brakes fitment, I have not been at home to test fit the rotors and calipers in the wheels, but the inner diameter of the wheel near the hex is approx. 33.5mm, tapering out to 36mm at the outer edge.

The discs are 30mm so that leaves 1.75mm each side for the caliper, it will be tight but sounds like it is doable. Worst case is I will put the rotors on the lathe and "turn" them down a little lol (in diameter that is haha)

But I am questioning clearance towards the wheel inner face, because the hex is flush with the inner side spokes, so if the hex sits fully in the hex cavity, that leaves no space whatsoever between the disc and wheel spokes. If that is the case I might dremel the inside spokes a little to make room for the calipers. I will update once I do some actual test fitting.

Fred
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