AP Racing Brakes
Discussion
I seem to be having problems with the feel of my brakes. The problem can be best described as a 'wooden pedal' feeling. On the roads (as opposed to the track) you really have to stand on the brake pedal and even then there is not enough bite. I would have thought that the spec of the AP brakes should be more than enough. I stared of with Mintex M1166 which came with the car and changed to Ferodo DS2500 pads after some research. During the change I have rubbed the discs with 60 grit to remove any residual pad material as recommended. I have even considered adding remote servos to give power assistance. Has anyone else experienced similar problems and if so did you resolve it to your satisfaction?
Many thanks.
Roj
Many thanks.
Roj
Has the feel changed or has it always been like this?
If it hasn't changed, I suspect that is just the way they feel. Most race/track cars have a brake pedal that doesn't really 'move' very much but only responds to pressure. And when it is unassisted there is a significant amount of pressure that needs to be applied to brake aggressively. It's an acquired taste but ultimately enables you to modulate the brakes very accurately without your leg really moving.
If the feel has changed, it's time to take a close look at the system, bleed it (though I doubt that's the problem because air in the system generally increases the sponginess of the pedal).
V
If it hasn't changed, I suspect that is just the way they feel. Most race/track cars have a brake pedal that doesn't really 'move' very much but only responds to pressure. And when it is unassisted there is a significant amount of pressure that needs to be applied to brake aggressively. It's an acquired taste but ultimately enables you to modulate the brakes very accurately without your leg really moving.
If the feel has changed, it's time to take a close look at the system, bleed it (though I doubt that's the problem because air in the system generally increases the sponginess of the pedal).
V
As Roj says above.
I get this same feeling every time I get in the car after a while of not driving it.
I think the problem is you drive power assisted cars "every day" and of course the pedal travel and feel is a lot different.
I have 360mm discs and HI-Spec (make) "Monster" four piston callipers which in theory have a greater retarding force v's pedal pressure and I still get this wooden feeling as you describe it.
I once drove a Spyker C8 with AP brakes and I was shocked at the amount of pressure needed to slow the car, So much so I felt the need to move my seat forward a bit.
I get this same feeling every time I get in the car after a while of not driving it.
I think the problem is you drive power assisted cars "every day" and of course the pedal travel and feel is a lot different.
I have 360mm discs and HI-Spec (make) "Monster" four piston callipers which in theory have a greater retarding force v's pedal pressure and I still get this wooden feeling as you describe it.
I once drove a Spyker C8 with AP brakes and I was shocked at the amount of pressure needed to slow the car, So much so I felt the need to move my seat forward a bit.
for me much difference is given by the type of pad.
if they are specialized for running, as long as the streets are not in temperature, the pedal seems wooden and not holding back strong.
in the street you have to change the type of pad.
and in ,any case ,there is not the servo brake which helps a lot.....
if they are specialized for running, as long as the streets are not in temperature, the pedal seems wooden and not holding back strong.
in the street you have to change the type of pad.
and in ,any case ,there is not the servo brake which helps a lot.....
deadscoob said:
I've had those mintex and ferodo pads before and wasn't impressed with the initial bite and had little confidence in them on road. I've changed to pagid rs29s all round and theoretically they should be worse, but the bite is definitely better.
Agreed. Get some Pagid's on there and you will feel the differenceThanks Johnny
I know this isn't the first time I've raised subject. I now think it's more than just a type of pad issue. The road going Radical had similar issues. It seems that the brakes need to really hot or the pressure from the master cylinders needs increasing without the pedal pressure increasing. I am seriously considering adding remote power assist servos to overcome the problem. Just bare in mind that on the track the brakes don't cool as they do on the road.
Anybody fitted power assist?
I know this isn't the first time I've raised subject. I now think it's more than just a type of pad issue. The road going Radical had similar issues. It seems that the brakes need to really hot or the pressure from the master cylinders needs increasing without the pedal pressure increasing. I am seriously considering adding remote power assist servos to overcome the problem. Just bare in mind that on the track the brakes don't cool as they do on the road.
Anybody fitted power assist?
Racingroj said:
Thanks Johnny
I know this isn't the first time I've raised subject. I now think it's more than just a type of pad issue. The road going Radical had similar issues. It seems that the brakes need to really hot or the pressure from the master cylinders needs increasing without the pedal pressure increasing. I am seriously considering adding remote power assist servos to overcome the problem. Just bare in mind that on the track the brakes don't cool as they do on the road.
Anybody fitted power assist?
you could use a smaller bore master cylinder, that would increase your braking pressure v's pedal effort.I know this isn't the first time I've raised subject. I now think it's more than just a type of pad issue. The road going Radical had similar issues. It seems that the brakes need to really hot or the pressure from the master cylinders needs increasing without the pedal pressure increasing. I am seriously considering adding remote power assist servos to overcome the problem. Just bare in mind that on the track the brakes don't cool as they do on the road.
Anybody fitted power assist?
I believe there is/was a factory kit for servo assisted brakes, there is a bracket/space for remote servo's on the chassis someone on here has them fitted though I cant remember who.
Anyone have a part number for the Pagid pads. They don't list a cross reference on their site for CP3215D50.
Ferodo does list a street High performance pad FDSR216 any feed back on these?
PS my car will see track time maybe once a year, at which point I would switch to a more race compound.
Ferodo does list a street High performance pad FDSR216 any feed back on these?
PS my car will see track time maybe once a year, at which point I would switch to a more race compound.
Edited by Rscocca on Friday 8th May 17:23
F.C. said:
I believe there is/was a factory kit for servo assisted brakes, there is a bracket/space for remote servo's on the chassis someone on here has them fitted though I cant remember who.
My 15 year old GTR had servo assisted brakes originally. I eventually upgraded to AP brakes, but still have the disconnected servos inside the side pods. It would be quite a job to get them out!If I go the route of power assisted fitting the servos in the side pods isn't that difficult as you would cut a door in the front of the pod with a recess plate fitted behind to allow the cut out section to be bolted back on. You can then face the door with anti chip material. Someone has suggested on a pm to look at putting the brake bias to 60% on the front. As I have adjustable brake bias I am going to try this.
Hi Dom
I first set them up statically, i.e. stationary by having someone sit in the drivers seat (the wife) and gently press the pedal so that both wheels can be turned by hand. I then adjust the bias until I feel that the balance is 60/40. I then take it on a test drive and make any further adjustments on the fly. This was obviously easier on the track in my racing days and also assumes that you have a remote bias adjuster fitted to your Ultima.
I first set them up statically, i.e. stationary by having someone sit in the drivers seat (the wife) and gently press the pedal so that both wheels can be turned by hand. I then adjust the bias until I feel that the balance is 60/40. I then take it on a test drive and make any further adjustments on the fly. This was obviously easier on the track in my racing days and also assumes that you have a remote bias adjuster fitted to your Ultima.
V8Dom said:
how will you know its 60 % front?
ive always tested mine in the wet and set up so it slightly locks up fronts before rear... but not sure if thats the best setting... come on all you racers, how do you set bias to work the best
Brake bias gauge, one of the best things I've fitted, Dom's "seat of the pants" method for fine tuning ive always tested mine in the wet and set up so it slightly locks up fronts before rear... but not sure if thats the best setting... come on all you racers, how do you set bias to work the best
Unlikely to settle your pedal feel doubts though.
Just an update after speaking to others. I have master cylinders front 0.75 rear 0.625. I will be changing to 0.625 front and 0.7 rear. This will give greater pad pressure with the same pedal pressure. From my racing days I remember that the front master cylinder always has a smaller master cylinder bore therefore greater pressure on the front than the rear then in wet conditions we then adjusted bias more to the rear with the brake bias adjuster. We will see how this works.
Racingroj said:
Just an update after speaking to others. I have master cylinders front 0.75 rear 0.625. I will be changing to 0.625 front and 0.7 rear. This will give greater pad pressure with the same pedal pressure. From my racing days I remember that the front master cylinder always has a smaller master cylinder bore therefore greater pressure on the front than the rear then in wet conditions we then adjusted bias more to the rear with the brake bias adjuster. We will see how this works.
Sounds interesting... pls keep us informed how this goes and if you've any links to the master cyls you're using, it'd be great too 
I will let you know how it goes. I gave just ordered a standard Girling remote cylinder 0.7 for the rear. I have noted that some recomend Tilton or AP but at this stage I will just run with the theory on this. I have ordered from Merlin on this occasion. Sorry Mark not sure how to put a link on. Still learning on this.
Roj, be very careful about swapping the master cylinders over. After failing my IVA for lack of front braking, I searched for ages on the web to find a solution (not knowing at this point that i actually had a faulty front cylinder) and during this search I found a thread which I'm now struggling to find for you, but in this thread someone suggested swapping the cylinders over to get more braking in the front. At this point he factory actually got involved with the thread to say it was very dangerous to do this as you will risk locking up the back end when ever you brake hard...this is never a good thing, but even more so for us with the back end weighing considerably more than the front.
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