Brakes...Are 2 calipers per wheel better than one

[Guest Andys@coffs]

People

 

My J230 single caliper brakes suck and I want them fixed. Do the dual caliper brakes perform better than the single?

 

What do you people who have flow both types think? If it were you would you be spending the extra $$ on the upgrade?

 

Secondly the actual discs on mine are just plain old round ones but I note that the newer ones arent perfectly round they seem to have a sinusoidal wave around the diameter. Do these have any effect? or more precisely does anyone know why the plain round ones where replaced?

 

Andy

 

 

[jetjr]

Yes new dual calipers work much better

 

Wavy rotors also work better but wear pads alot more

 

Jab sell a kit to upgrade - not that hard to fit but quite expensive

 

They did the upgrade because single calipers and round rotors didnt work very well

 

In US they use Matco upgrade. Needs new wheels too I think but supposed to be even better again.

 

 

[Tomo]

or more precisely does anyone know why the plain round ones where replaced?

Generally as a rule the wavy discs don't get as hot as quick... or to put it better, has a better cooling property.

 

If the discs get to hot, you'll develop what is called "Brake Fade" basically that means there isn't much friction and the brakes won't work very well, if at all. So wavy or discs will holes all through it were developed to enhance cooling.

 

 

[Guest Andys@coffs]

Tomo thanks, I guess that makes sense.

 

Jetjr have you flown both sorts (in the same type) and is the improvement significant? I expect you havent measured the improvement down to the reduction in rollout, but im trying to understand if we are talking 10% improvement or 80% improvement, where the later equals buy and the former doesnt...."much better" suggest the latter but I want to check before spending...I pressume with reference to Tomo's points that twice the calipers equals twice the source of heat for a reduced cooling surface area. Do the doubles fade more quickly than the originals (which fade pretty quickly in my opinion under strong braking)?

 

Andy

 

 

[Yenn]

Ive been reading these forums for quite long time and notice sometimes that ilots lower the nosewheel as soon as the mains are on the ground. How about keeping that nosewheel off and landing slower, that way you don't need the brakes so much. Try flying a plane without brakes to see what you can do.

 

 

[Guest Howard Hughes]

Two calipers(of the same size) are always better than one, have a look at the number and size of calipers/discs on a HRT or FPV vehicle!

 

I have flown two aircraft with single and then double calipers, in both cases the dual caliper brakes reduced the landing roll considerably!

 

As far as heat goes, energy = heat! So assuming every landing is similar, you should only be dissapating the same amount of energy/heat wether you have one or two calipers! If the disc can't handle it, then the disc also needs changing.

 

 

[Vev]

Andy,

 

These guys make bakes for Jabs including a differential braking set up if you want a Rolls-Royce solution.

 

 

 

 

Matco Mfg | Welcome

 

 

 

Cheers

 

Jack

 

 

 

[turboplanner]

Correct Howard, and Tomo brake fade occurs on drum brakes, where the heat expands the drum diameter beyond the reach of the shoes. I'f you've ever experienced that you'll know all about it.

 

Disc brakes (with suitable linings) will still operate when white hot - up to melt point in fact.

 

I've flow J160 with single calipers and J170 with dual and they're both on a par with a 1950's Norton motor bike.

 

I experimented on speedway cars where we needed to lock up the rear wheels to back into a crash, and found that increasing the disc diameter made the 100% improvement, after experimenting with caliper sizes and pressures.

 

 

[Ding]

Calipers / brakes.

 

Surely we are not trying to stop something as heavy or as often as a Commodore/Falcon. Therefore if we increase the friction area (twin calipers are used with bigger pads) then we are increasing the likelihood of locking the wheels, particularly on grass. So there is a down side to just increasing caliper/friction area without looking at the pressure being applied per square area etc.

 

Of course removing heat from the system is a good thing to do. Larger pad area, means a larger area not open to the cooling air.

 

Presumably, the Jab people have done their homework if they sell an upgrade kit. Probably includes a different master cylinder.

 

My Skyranger has drilled disk brakes and single calipers, and I have to be very careful not to lock things up. Locked wheels just add to breaking distance, and wears flat spots on the tyres.

 

Just my view, there will be people with differing views.

 

Next step ABS ?????

 

Cheers, Ding.

 

 

[turboplanner]

Ding, the vehicles I was talking about were a lot lighter than a Jab, but it's true you can't take any aspect of the system to a size where it's detrimental.

 

Worrying about locking up the brakes on a Jab was certainly my humour spot for the morning though.

 

 

[Tomo]

Tomo brake fade occurs on drum brakes, where the heat expands the drum diameter beyond the reach of the shoes. I'f you've ever experienced that you'll know all about it.

Don't want to argue the point, but brake fade does occur on discs also - not as prevalent as drums, but it can still happen. It actually has a lot to do with your pads - race cars that get white hot need to replace the pads, discs very often. And they are of the highest of quality usually.

 

There is also the issue of brake fluid fade (boiling) but I don't think we'll have to worry about that in the Jab!

 

For the size of the brake system on a jabiru, they do a great job really. My motor bike has a bigger set up!

 

 

[Ding]

Calipers

 

Hi Turbo,

 

I was refering to Howard's post where he mentioned HRT and FPV. I agree, your speedway cars would be very light. Braking is very much an exercise in balance. Get it right, and its fantastic, get it wrong,,,,,,,

 

Because our runways etc vary from wet grass to dry bitumen, its a compromise all the way. It comes down to pilot skill.

 

Cheers.

 

 

[Modest Pilot]

Matco brakes used on U S A J230's are the external model. They give a heat sink area about four times greater than the standard Jab disc. Assumed worst case; 700 kg wt, 10 kn downwind, touch down at 50kn; requires they dissapate 12280 ft-lb K E at 10ft/sec deceleration. The standard Jab brakes won't do half that. Single calipers at 450 psi pressure on the brake pads should do the trick, for the eight cylinder J250 being built up here, if it requires to much pedal push another set can be added without any trouble.

 

 

[turboplanner]

Terms Tomo, terms

 

 

[Tomo]

Terms Tomo, terms

Yeah, thought it may have been. :big_grin:

 

 

[Spin]

Yeah, thought it may have been. :big_grin:

Going to have to side with Tomo on this one, brake fade, although less prevalent in disc braking systems is none the less possible. The mechanism of the diminishing effectiveness of the brakes is however different.

 

We're swerving away from the original question however. I don't have any personal experience with a single caliper set up, but do recall reading about a fella who replaced his single caliper brakes on a 4 seater with dual and was fairly fulsome in his praise. I'll keep digging for the reference and post it when I find it.

 

 

[Guest rocketdriver]

And sometimes the brakes don't get hot enough to work properly .. had this happen on a racing car I built when I put really hard pads on to get rid of fade ....

 

To clarify ... if the brakes are good at the start of the landing run but then are awful when taxiing in, suspect brake fade. If they are never any good, see if there is a softer pad material available that is legal for the aircraft .... and make sure the master and slave cylinders are all good,the lines are bled and have no restrictions in them .....

 

Like Tomo said, for a given set up and assuming no installation/maintenance issues, its all down to the brake pad matl when we are talking discs ....

 

 

[brilin_air]

If you want to help the brakes from fading,you could try fitting the callipers to the rear of the wheel so as the disc can get some clean air and cools the disc better, we have our brakes fitted in this way and have never had any problems with braking performance.

 

Brian

 

 

[Steve Donald]

If you want to help the brakes from fading,you could try fitting the callipers to the rear of the wheel so as the disc can get some clean air and cools the disc better, we have our brakes fitted in this way and have never had any problems with braking performance.Brian

I Have noted on a few Jab"s on single caliper that they have not been ajusted correctly, they must be square i use a feeler gauge about 30 thou even all the way through the pad and disk both wheels, and use a high performance brake fluid , this worked for me and other i have helped out, about 50% better or half as crappy, but not as good as them great USA systems.

 

 

[jetjr]

Ive had both single then double on a J200

 

Singles hopeless, Doubles much better - im guessing 50% - double the force.

 

Yes with 6cyl you can lock brakes especially on grass or gravel. Full power ground running will pull AC along grass with wheels locked too. Probably not at full weight.

 

Ive found they do fade quite badly in a long hard stop - good advice is to use them as little as possible, ie slow down other ways as first option

 

Also I think brake hard then release, then repeat seems to work better, allows some cooling between use. Leaving spats off is good too,

 

I recently had one caliper jam on after heating up severely during some high speed ground testing, spat began to deform from heat and pads broke up BUT it still worked and stopped OK. Misalignment of one caliper may have caused it.

 

They run same Master cylinder on single and double calipers (its plenty big enough)

 

The bolts on the caliper need adjusting regularly but pumping the lever makes them work OK if they are out of adjustment. So not critical. Important to adjust close but ensure they will release 100%

 

The caliper mount plate arrives flat and needs to be bent slightly, slight S bend, to position inner caliper properly. Only outer one can move really so need to bend so inner pad sits VERY close to rotor. Make sure they all sit even and square in relation to rotor.

 

New wavy rotors have right and wrong direction for rotation.

 

Theres a few tricks to riveting on pads - make sure rivet tails?? will fit into holes in inner mount plate once hammered down,

 

They have different pad orientation for each pad location, which is easy to get wrong too

 

 

[Jabby]

Brakes

 

Hi Andys@Coffs, From experience I can tell you not to waste your money on a second set of calipers. Go to Matco and get a proper set of brakes. I have ordered six sets for my mates at Cessnock and are all extremely happy Cheers jabby

 

 

[Guest ozzie]

messed around with a set of these on a storch. The owner had a fair bit of trouble pulling the aircraft up. make sure the supplied pad material is not to hard. once i changed the pad to a softer set worked great.

 

has anyone tried carbon fibre discs?

 

 

[Guest Andys@coffs]

Jabby

 

For me, and others that will find this thread by search, after its all done and dusted, what exactly is it you order from Matco. I went on their website and was somewhat put off by the vast amounts of stuff available.

 

Can you let me know what components you ordered and what the $USD cost was last time for this configuration.

 

I also note that at times these forums dont do anything but cloud an issue, Ive seen equal amounts of people saying the dual calipers work well, and others, including, but not limited to yourself suggesting they are a waste of $. I rang Jabiru and got the cost from them for the upgrade kit, currently $571.

 

Im intersted in the Matco solution, and want to understand if the master cylinder is replaced in this solution, Its been suggested that the current Jabiru one is undersized. But for the moment Im relatively clueless as its outside of my area of expertise. For example suggestions are that disc based brakes dont fade, yet I know absolutely that the first 10 seconds of braking performance at the moment leaves the next 10 seconds for dead. It may not be "fade" but it is certainly performance challenged!!

 

Andy

 

 

[mch]

JabbyFOr me and the others that will search this after its all done and dusted for me, what exactly is it you order from Matco. I went on their website and was somewhat put off by the vast amounts of stuff available.

 

Can you let me know what components you ordered and what the $USD cost was last time for this configuration.

 

I also note that at times these forums dont do anything but cloud an issue, Ive seen equal amounts of people saying the dual calipers work well, and others, including, but not limited to yourself suggesting they are a waste of $. I rang Jabiru and got the cost from them for the upgrade kit, currently $571.

 

Im intersted in the Matco solution, and want to understand if the master cylinder is replaced in this solution, Its been suggested that the current Jabiru one is undersized. But for the moment Im relatively clueless as its outside of my area of expertise. For example suggestions are that disc based brakes dont fade, yet I know absolutely that the first 10 seconds of braking performance at the moment leaves the next 10 seconds for dead. It may not be "fade" but it is certainly performance challenged!!

 

Andy

Hi Andy and Jabby,

I would also be very interested in the exact Matco part numbers. As for my experience, I can only speak for the 2 caliper solution.

 

It does work well enough for me at the moment. However, I have the fortune of a 870 m asphalt home strip and when I go abroad I also select long asphalt strips. So I can let the Jab bleed off speed by air braking and the wheel brakes don't get much stress.

 

But this summer (here it is summer) I would like to go to places with shorter grass strips and I suspect I will have to use the brakes more than in the past.

 

Quite frankly I also have more confidence in the wheel assy from Matco than the original Jab ones. The previous owner has had a flat foot, I keep hearing that flat tyres are not that uncommon on Jabs.

 

So if I replace the whole assy (beginning with the axle stub) with a Matco solution I think I'd feel somewhat better.

 

But I also have to say that up to now I have had NO brake or tyre failure.

 

Mike

 

J400

 

 

[Tomo]

For example suggestions are that disc based brakes dont fade

Disc brakes Do fade. I've seen it, and had to fix them.

 

There is also clutch fade, as one poor trucky discovered when going down the range.... with a double deck , B double combo loaded with cattle. What that was, was hot spots on the pressure plate, and flywheel surfaces. Possibly due to ridding the clutch to much, (backing up etc...) It never let go completely, just slipped/shuddered every now and then, scaring the heck out of the driver each time.