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I've got the same ABS pump setup in my 93. Brakes work well but they do have a strange feel.Quote:
Originally Posted by Richard93Vogue
I think it may be possible to convert this system to single line using early P38 ABS parts. But it's a project I haven't looked further into.
That would let us use the bigger calipers but retain the same setup and rear wheel traction control.
There are three types of construction available, most commonly used for brake lines, both OEM and A/market. The goal of replacement is to remove a worn hose that may split without notice and from an improved performance point of view reduction of the flex inherent with a non steel or Kevlar reinforced rubber material.
- Rubber. The standard for road going vehicles, rubber hose is made most commonly with woven cotton reinforcing layer/s. This eliminates some of the flexing under pressure but over time the cotton breaks down itself and the rubber perishes & cracks and augments the flex. Occasionally you'll get a bubble in between the inner, thicker rubber layer and the thin outer layer. Additionally you have the inner break down and pieces get flushed into the piston chamber. This can be dangerous (as I've found through personal experience) as pedal pressure pushes the pieces in and then blocks the hole, keeping the pressure applied.
*You can also get a plain rubber with a steel reinforcing layer. This is your best bet to keep it looking OEM but get improved feel and performance through reduced flex. Still suffers from internal and external degradation.
- Rubber, with stainless braid outer. Basic construction as above (may be cotton or steel) and the braid is slipped loose over the hose and crimped under the ends to keep in place. External appearance is improved and mechanical damage is virtually eliminated. Downside you cannot see any cracks or other degradation to the rubber and also suffers from internal and external degradation.
- Teflon with Stainless braid outer. About as good as it gets. A Teflon core, can have a Kevlar liner between the Teflon and braid to prevent any last opportunity for rubbing between the braid and Teflon. For all intensive purposes zero distortion under pressure.
*There are some hoses available with other materials for the braid, all offer similar levels of protection and the performance is equal as it doesn't affect the liner.
In practice: When you apply pressure to the pedal force is applied to the fluid an fluids apply pressure in all directions/against all surfaces. So initially you get piston movement in the calliper but when the pressure between the pad & rotor reaches a point higher than that at which the hose will start to deform then any increase in pressure is transferred to deforming the hose and not applying more braking force.
Pedal feel can be hard to define as everyone will "feel" differently and have a different expectation of a vehicle and different thought on what constitutes good and bad brakes. To this day, after growing up in Series LR's, I still occasionally pump up the pedal until I realise by rapid approach to the windscreen it's not necessary.
By progressive, do you mean a continual increase in braking force in line with a continually increase in travel/pressure applied?
I would describe it as an increase in braking force in direct relation to pressure applied. That said master cylinder size, piston size/qty, pad and rotor material & fluid condition all contribute to how well it works and what you feel.
You missed the kevlar braided rubber covered hoses. IMO the best for protection and function.
I think you might be mistaking nylon/kevlar braid for cotton. I can't imagine cotton being durable enough for any brake hose.
There is a huge amount of misinformation in the bike industry about brake hoses. Very few realise that all hoses are braided or how abrasive stainless exterior braiding can be.