Savannah VG brakes

[dave66]

I have just finished skimming my brake discs on a Savannah VG 2010, I found that the brakes were useless when doing full power check anything over 2000 RPM and off it went, I did not build this aircraft but I do have all the build manuals ect. I find the differential toe brakes less than satisfactory and also discovered it has hydraulic oil in the system not DOT 4 brake fluid. I am wondering if this oil is a bit thick for the fountain pen sized master cylinders and that could be the reason they don't hold ? Has anybody else had this problem ? I trained in a Jabiru with a single lever and a escort clutch master cylinder

 

 

[Skee]

Build manual says to use mineral oil.

 

If you would like to change wheels and save a few kilos, there is a kit from Beringer.

 

 

http://www.beringer-aero.com/en/products/wheels-brakes-14.htm?force

 

 

[facthunter]

Quite a lot of these systems use a mineral oil. The rubber?parts have to be compatible. If it is OK there is much less corrosion. . Nev

 

 

[dave66]

Quite a lot of these systems use a mineral oil. The rubber?parts have to be compatible. If it is OK there is much less corrosion. . Nev

Thanks Nev, I found it eventually in the manual, however it said "Hidrolic Minarar" I reckon that means Hydraulic Mineral !

 

 

[Ultralights]

i have never had an issue with the savannah brakes, they work really well, can easily hold back the 100Hp until they start to slide, still locked up at near full power. the only issue i ever have had with them, is the pads will fall out when about 75% worn, so i thought i still had some good use in them, while trying to land short (on a 1.5km runway) i hit the brakes hard, and the pad pushed out and dumped all the fluid over the wheel. so i only had 1 brake, and had to turn the ignition on and off to taxi at a safe speed. fix was to take the old worn pads to a brake reliner, and get them relined, was pretty cheap.

 

if the stock brakes arn't up to par, then try bleeding them, i havnt not heard of stock savannah brakes being bad, and if they are, then mine would have been the worst, as the discs are not quite flat at one stage, they have been hit when the aircraft fell off a jack, and the disk was hammered back to a flat. they still work fine.

 

 

[dave66]

i have never had an issue with the savannah brakes, they work really well, can easily hold back the 100Hp until they start to slide, still locked up at near full power. the only issue i ever have had with them, is the pads will fall out when about 75% worn, so i thought i still had some good use in them, while trying to land short (on a 1.5km runway) i hit the brakes hard, and the pad pushed out and dumped all the fluid over the wheel. so i only had 1 brake, and had to turn the ignition on and off to taxi at a safe speed. fix was to take the old worn pads to a brake reliner, and get them relined, was pretty cheap.if the stock brakes arn't up to par, then try bleeding them, i havnt not heard of stock savannah brakes being bad, and if they are, then mine would have been the worst, as the discs are not quite flat at one stage, they have been hit when the aircraft fell off a jack, and the disk was hammered back to a flat. they still work fine.

i have never had an issue with the savannah brakes, they work really well, can easily hold back the 100Hp until they start to slide, still locked up at near full power. the only issue i ever have had with them, is the pads will fall out when about 75% worn, so i thought i still had some good use in them, while trying to land short (on a 1.5km runway) i hit the brakes hard, and the pad pushed out and dumped all the fluid over the wheel. so i only had 1 brake, and had to turn the ignition on and off to taxi at a safe speed. fix was to take the old worn pads to a brake reliner, and get them relined, was pretty cheap.if the stock brakes arn't up to par, then try bleeding them, i havnt not heard of stock savannah brakes being bad, and if they are, then mine would have been the worst, as the discs are not quite flat at one stage, they have been hit when the aircraft fell off a jack, and the disk was hammered back to a flat. they still work fine.

Thanks for the info, my savannah does not have a kennel and so lives out in the elements, my discs were very rusty as were the slider rods on the callipers, I am in the process of rectifying these problems hence skimming the discs, parts seem a lot cheaper in your area, for instance I just paid £105 for a new front leg bungee, from our one and only Savannah agent in the UK . Mine is the Jab 2200 power version and a lovely little plane to fly so I will persevere.

 

 

[aro]

I don't know what sort of brakes the Savannah has, but one reason the brakes might be weak is that the pads need to be conditioned. The procedure is to get the pads hot, which creates a layer on the surface that gives higher friction.

 

This link has the procedure for Matco brakes:

 

http://www.foxbat.com.au/public/editor_images/Foxbat%20Documents/11%20Matco%20brake%20conditioning%20procedure.pdf

 

 

[dave66]

The pads are still good but I will sand the surfaces to remove the glaze from the rusty discs and see where I go from there with a fluid change, apart from full power check they don't really get a lot of use which is most likely a big part of the problem, we find the Savannah generally stops quick enough with full flaps being they are the whole length of the wing we generally land on first stage then put it on full on touch down that seems to work well for us

 

 

[aro]

The pads are still good but I will sand the surfaces to remove the glaze from the rusty discs and see where I go from there with a fluid change, apart from full power check they don't really get a lot of use which is most likely a big part of the problem, we find the Savannah generally stops quick enough with full flaps being they are the whole length of the wing we generally land on first stage then put it on full on touch down that seems to work well for us

The glaze is what you are trying to create with the conditioning procedure. The glaze surface (plus I think material transferred to the disks) is what gives the friction and holding power. Light usage can wear the glaze layer away (rusty disks probably don't help). The brake companies suggest that rust on the disk surface itself will normally be removed by the braking action.

 

From the article linked to above:

 

If properly conditioned, the pads will have a uniform shiny appearance (glaze) on the surface.

 

Conditioning removes high spots, and creates a layer of glazed material at the lining surface. Normal braking will produce enough heat to maintain glazing during the life of the lining. Glazing can be worn off during light use such as taxiing.

 

 

 

[Ultralights]

bringing up an ld thread, just changed my tyres to some tundra type, it appears the tyre diameter has a significant impact on the brakes, now with larger tyres, more rotational force, harder work for the brakes.. so, now time to upgrade the stock brakes.

 

 

[Trackley]

where is the brake fluid reservoir for the toe brakes?

 

 

[planesmaker]

You will find that the only reservoir is the master cylinder itself. Best to bleed from the wheel cylinder up, being careful not to make a mess inside. There is a small cap scew in the top of master cylinder

 

 

[Kyle Communications]

Each pedal has its own master cyclinder. You need to get a bolt the sale size as the one in the top plate. then drill a small hole through it like a tube then you can fill the cyclinder

 

 

[John Nooyen]

I still have original brakes after 1100 Hours. Trellborg tires on the mains, but these are a bit wide for the nose-wheel. I'm still on the original pads, with plenty life left on them. The original ventilated rotors wore out before the pads, so I had some cut from 304 stainless.

 

I use dexron ATF in the master cylinders, as it is mineral based and doesn't draw moisture.

 

Be careful not to overfill the master cylinders, as they will overflow. I've never had an issue with the brakes, and don't plan to change them.

 

 

[facthunter]

IF you can avoid using the "usual" brake fluid you are better off. It's pretty corrosive on anything it lands on and is not the usual fluid used. Stainless discs usually don't grip as well as cast iron. IF your iron discs wear fast use a softer pad material. Cheaper than discs. Nev