Hi crew.
Can anyone tell me please what my brake maintenance drill should be ?
I have a 5 year old DR chassis (which I think is CRG) rotax twin
I’m about to drop Castrol SRF fluid in it ($100 a litre and non hydroscopic, so hopefully set and forget )
Seals were installed a year ago by the previous owner.
How often should I be dismantling Calipers and masters?
(Anyone answering ‘never’ who knows what they’re talking about gets a 6 pack of beer).
Thanks all.
If they are sealing well I’d go with leaving them alone to be honest. I’ve found it’s not so much age, but the length of time been left idle and the conditions they were left sit in…
Before you replace the fluid, check the type that’s in there first.
Agree with James. If they are working fine, don’t bother touching them. Every system is a little different but I can go a season without really doing anything to my OTK ones other than replacing pads. Some people are much harder on brakes though.
Gentlemen, thank you for sharing your wisdom. This is good information to have, and you’ve both remitted the required answer, being ‘don’t mess with them’.
This would qualify you each for a 6 pack of beer had you not both been teatotallers.
Sadly, life is like that.
Thanks again. Appreciate.
My latest crg chassis is on the old side (2008) and from what i have gathered the master and caliper seals should be changed yearly as well as the fluid. I am using Castrol dot 4.
If all good leave alone. Some argument to changing fluid as it is hydroscopic with the mineral fluids. That is really for corrosion issues in master cylinder. No water will get in caliper end, as volume flow is to small. Kart brake temps are way down compared to car brakes so boiling water contaminated fluid doesnt happen. Unless you have a dragging brake of course.
Compare it to your performance car. Do you change the seals in that every year? No.
If you have a rock solid consistent pedal with no sinking and even pad wear. Then leave alone.
Actually not bedding in brakes properly causes the biggest issues in my opinion.
Martin, Nicholas, thanks for answering.
The implication in your answer Martin (corrosion) is that I should run a silicone fluid (which is dot 5 I think?)
And I’ve read elsewhere that seal material doesn’t matter with silicone fluids.
Am I reading this right?
Thanks again.
Yes dot 5 is silicone based. If you are unsure what you have and want to run dot 5, then replacing all seals is advisable to avoid contamination. Dot 5 and 5.1 one are expensive and unwarranted in a kart brake system. Just use dot 4, which is common.
Corrosion is not really an issue on the wet side of the system, if there is no air in the system.
Just check the clarity of the fluid in master cylinder regularly, if it isn’t crystal clear it has water in it. Then it is time to bleed entire system.
Corrosion is a problem on the dry side of the system. All kart brakes are pretty poor on this side. Under boot/plunger on master cylinder and pistons on the calipers. (Especially if you use detergents to clean kart). These will corrode the respective bores, and when calipers move into this area due to pad wear the seal can leak.
I always regularly spray these areas with some sort of penetrating lubricant.
Hope this helps
“Kinda”
All modern seal types are compatible with both glycol and silicone.
BUT you still cannot switch from one type to the other without flushing the entire system and ideally swapping the seals.
Whenever I have the choice I just run DOT 4 glycol. If I’m feeling fancy, I’ll use something like RBF 600. On the other hand I’ve run common cheap 3/4 stuff from the local gas station and it was just fine. Kart brake systems rarely get very hot.
For the dry side, there’s a castor based rubber grease that smells and works great but I can’t recall the name. I’ll have a look for it tomorrow.
Marin, James:
Thanks for your contributions. The detail and clarity of these answers is gold. I’m sure there’s uses of this site other than just me who will find this useful.
I’ve bought 2 litres of Castrol SRF Dot 4, at a hundred bucks a litre. The best there is, but orders-of-magnitude overkill for Karting based on what you’ve written here. Used for stopping Nascars apparently…
maybe I’ll ask the question before going shopping next time.
Thank you both.
Lee
And James - would love the name of that grease if you don’t mind.
Thanks
Lee,
I have never had a new kart. On one of our used karts I was underwhelmed with the braking. Turns out 3 of the 4 pistons were stuck in the caliper. So I went to work freeing them. I did dismantle the whole system and found in plagued by a complete lack of maintenance. The master cylinder boot trapped water. There was ‘funk’ in the caliper. Once done the system was performing better and have more confidence in it overall. I did it @ the end of a season. Not a project to start @ 10:30 the night before a race. Denatured alcohol can be used to clean out a system.
Make sure it is dry before adding brake fluid. Overall it is a good time to go over everything in the brake system, including chafing of lines and any linkage issues. Bleeding and initial priming might be a pain on a complete. If you plan on keeping the kart start looking for pads now. I have had a couple with hard to find pads. Best case is you find out pads are common.
I like things available locally when possible, so off the shelf locally it was. NAPA can be a good source for obscure items. I used to like Castrol GT LMA for cars.
Dot 5 is Silicone. Dot 5.1 is not. Dot 5.1 is a good way to go.
Best of luck,
Mike Clark
PBR Rubber Grease. You might have to order from Oz.
PBR rubber grease is a high performance castor oil based grease designed to preserve and lubricate plastics, rubber and components such as o-rings, valves, diaphragms, cups and seals. This product has been developed for use with automotive brake assemblies. An ideal lubricant for automotive rubber plastics products
Great for Brake Caliper and Master Cylinder Piston Seals / Cups
James: I’m in oz, so that’s easy. Thanks for pointing this out.
Mike: you’ve got me thinking I really should bite the bullet and pull the system down. I’d feel good about knowing what’s going on in there and starting from a clean sheet. So … overhaul time.
Thanks for your advice, both.
Lee
Hi TJ,
How often do you find you need to change the pads?
thanks Daniel
I changed pads probably every 2-4 race weekends, depending on what class I’m in. A faster, heavier class will eat pads quicker.
After reading an old thread on brakes you mentioned to use dot4. I brought a second hand otk 2018 chassis fa kart. It’s got the brake system on it and I just brought some for 5.1 to top up the brakes… I have no idea what it has in it currently… should I empty the system out first? If so any advice on how to flush it all out? I brought the dot 5.1 because well it sounded like the latest version and it was the same price as the others…
@MoodyM From the interweb…
“Since DOT 4 and 5.1 are both glycol-based brake fluids they are compatible with each other, which means they can be readily mixed without harming your brake system. It is important never to mistake DOT 5.1 (glycol-based) with DOT 5 which is silicone-based and should never be mixed with any other DOT fluid.”
I don’t wrench so I cannot claim to know if above is correct.
Don’t make it harder than it needs to be. Take a few drops of the current brake fluid and then take about the same amount of water and mix. If they mix together its glycol based. If they seperate its silicone based.
Matt Abel, you are banned from giving anyone brake maintenance advice even if what you said is correct!
-Your NCMP125 Partner