Thread: I now know why my brakes were pulsing and giving a shimmy

Originally Posted by jboot51

2 questions......

130 300 tdi cab chassis.Almost 3t.
I have EBC green pads in the rear and mintex in the front.

Would this be why my front locks up in the wet under heavy braking?.
Should you run the same pads front and rear ?.

it could be a contributing factor but theres other things invovled.

the 130 is a little tail heavy when loaded so theres less weight on the front
the brakes are proportioned to be heavier at the front
front wheels do more work so may be more worn
bigger brakes up the front smaller at the back.

and

almost no vehicles run the same brakes front and rear in the same way as you should have the same type of tyre on all 4 corners of a vehicle you should have the same make and pad compound on all 4 corners but its not compulsory, being the same left to right on the same axle is a requirement. Have a look at most non all wheel drive trucks, they use one kind of tyre on the steers and another on the drives. For the same reason some vehciles have different pad compounds front to rear as well.

Originally Posted by Roverlord off road spares

Then OP says he's putting in Solid Discs, it will be interesting to see if heat effects them also as Vented discs are to dissipate heat

It does, they heat up faster, and cool down slower, while they suffer less from the distortion caused by heating them up and keeping the brakes on with the vehicle stationary while they cool they are more susceptible to it. Generally a solid rotor will have a bit more metal to them for the minimum thickness so will have a smaller minimum thickness for vehicles where the minimum thickness for the rotor is not governed by the spacing required by the caliper to retain the pads.

Originally Posted by V8Ian

Are ally ones better than the plastic ones you fitted for me?

only if you've been bothering to keep the throw off from the rotors, the ally rotor throw off is recyclable and kamalco gives you 60c/kg for them.

on the other side of the coin, once the plastic ones have worn down sufficiently you can take them to one of those places that are now selling records again and you can have your favorite sound tracks recorded over the grooves worn into the plastic rotors by the brake pads.

Originally Posted by Slunnie

Or my "air" brakes?

most trucks running air brakes have a drum configuration and big brake chambers to actuate the shoes.

While I apprecaite the low cost, ease of installation and availablitly of the specialized nitroxy gas mixture correctly retro fitting it into the hydraleak system in a landrovers brakes requires you to significantly up the actuation pressure. I think the last time I checked the numbers you need to raise the pressure by a factor of 14 over the normal hydraleak pressures. While in simple terms its doable it involves either reversing the pump flow direction of the brake vac pump so it becomes a cam driven not spring returned plunger action (for the TDI), Reversing the porting on the alternator vac pump (for the isuzu and td5) or removing one of the glow/spark plugs and fitting a once way valve on one cylinder and routing pressurized air directly to the Brake MC.

You can also feed it into the reservoir if you wish to retain a simple method of returning to the normal hydraleak brakes by means of replenishing the original fluid and bleeding the system. Doing this is not reccomended as retaining the plastic brake reservior has 2 pitfalls

1. the tank has a vented lid so due to the nature of the nitroxy mix to exert equal pressures on all areas of the container in which it is stored you will be spilling a lot of the new brake fluid out the vent hole. (the hydraleak fluid is not insignificatnly denser so under normal conditions it takes the shape of the bottom of the container in which it is kept with only its fractional vapour pressure being exerted on the top) Which isnt a problem in and of itself as nitroxy is not as corrosive or hygroscopic as the normal braking fluid but the pump does work harder for longer and will suffer a premature failure, More significant is the following,

2. its a plastic tank and its made from the same stuff as the white expansion tanks of the early D1s so is prone to cracking occasionally with heat and pressure. When the container breaks you loose the bulk of the reserve of fluid.

Doing this conversion you may also find causes a little bit of brake lag on release due to the small diameter of the brake pipes and the lack of return springs in the caliper pistons the typical system relying on just the deformation of the piston seal to pull the pistons back just a small amount to allow the rotor to knock the pad back.

OF course you can get systems that utilise both but they are typically german are therefore expensive over complicated and given that you're installing it in a landrover have twice as many opportunities to develop leaks. Its also got the hinderance that being german its also EURO spec stuff which means you need the euro spec fluids which is simply not readily available here in Aus.

in short, I dont know why you would bother trying to change over from the hydraleak system landrover put in, a bottle of brake fluid and a small sponge leccy taped to the escape points installed in the system to prevent drips is a much cheaper option and retains the factory progressive ABS function of pumping the brakes up to over come the pressure drop points build into the system that provides the superior braking action that landrover developed very early on in the development of the marque surpassing the dual band rear brakes or the wedge block system that were still fitted on some competitors earlier model vehicles by significant margins.