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Author Topic: Brakes  (Read 17140 times)

Slack Alice

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Brakes
« on: 14 July 2019, 10:39:22 pm »
I need to seriously upgrade my braking system. It will have to be hydraulic...any good recommendations?

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RhysN

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Re: Brakes
« Reply #1 on: 15 July 2019, 07:58:04 am »
Why does it have to be hydraulic? That's only the actuating system.
Anyway, the biggest issue is that the master and slave cylinders come from the same unit. There are plenty of motorcycle rear hydraulics.
A disc with the ability to shed heat, so size, thickness etc that's compatible with the caliper, big and thick as you can. The mountain bike one you had/have was going to be a parking brake, or back up had I used one.
BTW David I was with Thunderbug yesterday, definitely yellow and black (not dark blue as we discussed)

Slack Alice

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Re: Brakes
« Reply #2 on: 15 July 2019, 09:10:22 am »
I’m really envious! Thunderbug in the flesh!

RhysN

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Re: Brakes
« Reply #3 on: 15 July 2019, 09:43:50 am »
It was like being a kid in a candy store. I only watched about 3 cars go up the hill.
Laugh of the day (and OT) was the commentator who said that the White "must have a badly blown head gasket" It's a steam car and the exhaust...
Back to brakes. The Freikaiserwagen, had one cable operated drum brake, always had, always will do. (That's another one to look up :) )

Chris Brown

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Re: Brakes
« Reply #4 on: 15 July 2019, 12:07:23 pm »
I'll second your "kid in a candy store" comment Rhys, Saturday was mind boggling. Photos of Thunderbug, and the rear end of Freikaiserwagen attached.

StefanN

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Re: Brakes
« Reply #5 on: 06 November 2019, 06:18:21 pm »
It would be helpful to get a feel for what brake set-ups people are using.  With this being such a critical component the more understanding we can get of what works the better.  Please could you share the following any information you know about your:

Master cylinder/piston (bore/stroke)
Calliper (make, number of pots, bore)
Pads
Disc diameter, thickness, design (slotted/drilled/dimpled/vented), material and carrier
Number of discs
Any ventilation to the discs
Plus any comments on performance.
What it was designed for

Photos and links to anything you've bought would also be helpful.


GeoffM

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Re: Brakes
« Reply #6 on: 06 November 2019, 10:36:55 pm »
Check out 20180201151146 on youtube it may help, although I have changed the front brakes to hydraulic as the cables would pull when turning. I used motorcycle clutch slave cylinders to operate the mechanical levers,cheers, Geoff

https://youtu.be/N09ejgUD_Gk
« Last Edit: 07 November 2019, 07:06:45 am by StefanN »

Little French

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Re: Brakes
« Reply #7 on: 07 November 2019, 10:53:50 am »
Hello all,

Personally I tried both systems (mechanics on my 1st CK then hydraulics on my second)
For my 3rd, I'm planning the mechanical system.
In fact, the braking of our Ck is a false problem, either it is effective and the wheels blocked by our Ck are light enough
Either the braking system is ineffective, and the result is the same

By return of experience:

The hydraulic type is difficult to adjust, and the stroke of the piston is relatively short, which requires a precise adjustment between the disc and the pads (not always easy to obtain with our CK "DIY")...

For the mechanical type to give complete satisfaction, several essential things must be done
1 large brake pads
2 A disc of large diameter
3 A great race that allows a moderately precise adjustment
4 Easy adjustment of the stroke of the brake pads

here is the model of brake caliper which gives me satisfaction for a very correct price
I used this model on 2 other Ck built for friends, and so for my next Ck too
All this is only my point of view, and therefore questionable ....  ;)
[ Guests cannot view attachments ]

PS : This model has 2 cable tie, so 1 for the foot brake, and the other for the parking brake!
« Last Edit: 07 November 2019, 10:55:50 am by Little French »
Aging is mandatory, growing up is optional .....

ChrisS

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Re: Brakes
« Reply #8 on: 07 November 2019, 01:55:37 pm »
I've got a Gemini 10inch disc and a Gemini mechanical caliper which is operated by a 6mm rod from the pedal.

It easily locks when only driving one wheel, but with both wheels being driven it hasn't got the power to lock them up, so it would be nice to have just a little more.

RhysN

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Re: Brakes
« Reply #9 on: 07 November 2019, 04:06:23 pm »
I have tried whatever has been available!
Remember that either hydraulic or mechanical has no effect on the performance of the brakes, it's just an operating system, and hydraulic is usually more difficult to get right. First up is that the master and slave cylinders MUST be matched as a system, unless of course you are able to get all the maths right without experiment, and that's pretty specialised. So, if you are going to get some old motorcycle parts, get both  the master and slave.
Then you have the leverage ratio on the pedal to the system.
Brakes for a CK often need to be different to a go kart type, wheel diameters are not the same, and according to a brake designer that is a huge factor, even with the same weight of vehicle, all relates to the torque applied by the wheel, so our wheels, overall diameter of around 25" are vastly different to a go kart where the overall diameter is about 10", and it's some sort of mathematical ratio, not just a factor of 2.5. I guess that's why motorcycle systems are a better solution?
The disc has to get rid of the heat, again all very well to get cool air to the disc, but unless the heated air can escape you gain nothing. Just like getting cool air to the engine.
More mass in the brake disc(rotor) will absorb more heat and radiate it more quickly so less fade, bigger pads = less fade, slots, cross drill etc also help dissipate heat, but not as well as more disc mass. More diameter helps too. Extra calipers on the disc is a negative help, as it simply shields the disc more.

StefanN

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Re: Brakes
« Reply #10 on: 07 November 2019, 04:36:01 pm »
Agreed.

Hydraulic also has the issue of fluid contamination with water and heating of the fluid, but can provide some advantages in terms of efficiency of transferring force and gaining mechanical advantage.

Wheel radius and brake disc radius are absolutely relevant with regard to "stopping power" and torque is of course directly proportional to the radius.  The bigger wheels however also carry a larger angular momentum.  However, whilst cyclekarts are generally a bit heavier that go karts, go karts typically travel much faster and as the kinetic energy increases with the square of velocity, I suspect the energy that needs to be dissipated is in the same ball park if not higher for go karts.

Rhys, you say you've tried whatever has been available.   Have any of them worked well in your opinion and assuming they have, it would be helpful if you could give some details of a system that has worked well on a cyclekart you've built and driven.

Chris Brown

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Re: Brakes
« Reply #11 on: 07 November 2019, 04:43:29 pm »
"Hydraulic also has the issue of fluid contamination with water", the cure for that is silicone brake fluid, I used it many years ago on my Scimitar, https://www.ebay.co.uk/itm/Dot-5-Silicone-Kart-Brake-Fluid-250ml-Why-Pay-More-BEST-PRICE-on-Ebay/401728080201?hash=item5d88dc0949:g:ML4AAOSwqCJciBps.

RhysN

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Re: Brakes
« Reply #12 on: 09 November 2019, 02:32:20 pm »
What I have tried has yet to let me down, I guess because I come from a background of old cars I have never really expected too much of brakes. Lifting off the go fast pedal will slow you down too!
The double cable kart brake, just as Fabrice showed worked well, disc was about 250 mm and 5 mm thick, both levers pulled with a bridle as you would find on a cycle. Both pads need to be working to "squeeze" the disc rather than one rubbing.
The hydraulic kart one which was on Kim was great, hydraulic, matched master and a very thick (10 mm?) cast iron disc. That was a set ex the hire kart. I did spend a fair bit of time making sure that the caliper could "float" to make sure both pads were working.
The very basic cable or rod ones as you can buy in the US from every kart supplier are adequate for a few stops, then they fade, when you know that you drive to the ability of the system.
I do know that the mountain bike ones, as Dave had on Thunderbug, go from OK to nothing in a heartbeat, and that's terrifying which is why I would only ever suggest as a secondary.
The one I'm using next has been previously used is from a Honda CB400 master and calipers (rear) with aftermarket race pads. I'm not yet sure about the disc itself, that's a large "fun kart" one, but it does match the diameter and thickness of thee Honda, but simple steel. (I know that on Austin 7 race cars the steel drums are not as good as the cast iron ones)
I know this seems odd, but if there is someone with fantastic brakes , and who drives that way, could well be a danger to others who may run into the back of that one?

Chris Brown

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Re: Brakes
« Reply #13 on: 11 November 2019, 10:21:32 am »
My experience is limited to the cable operated drum on mine, it's spongy (cable stretch?), and lacking in bite (new shoes probably don't help). Hopefully it'll improve when I get the pedals moved and a straighter run for the cable, currently a bit of an s shape.

When it comes to the next one I'll use the front calliper off the scooter, paired with a pit bike rear cylinder, with a wheel mounted motorbike disc.

My feeling is that we need to use automotive brakes, be it kart, or motorbike, whether cable or hydraulic, anything else is unlikely to be up to stopping 100+ Kg of kart plus the driver.

RhysN

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Re: Brakes
« Reply #14 on: 16 November 2019, 02:13:44 pm »
I'm just back from the Motorsports industry symposium and exhibition in Germany. While there I took the opportunity to ask 3 of the brake companies who have staff I know, all asked a question whether we had return springs on the brake pedal. Now I have never done that on a cyclekart, but they all, independently, suggested it, and a relatively strong one too, so that amongst other things of benefit, you know you are pressing.
I had a good look at a few pedal box systems, and it was notable how much spring load is on the accelerator too. Without attachment to anything, cable etc, they were around 500 gm push", more than I have used, but the industry seems to thinks that's about right, or even more!