Question about brake pads (front)

[KHIEM]

Hi everyone,

I have just purchased a set of Bendix brake pad (DB1431) for my ZZE122 rolla and got it done this afternoon. it was done by a mechanic near my place. After doing everything, I don't know why the brake pedal is still "deep", not shallow as I had expected. I think if the new pads are fitted in, the pedal should be very shallow cos the pads are much thicker.

I asked the mechanic about that and he told me that because he didn't sharp the discs before fitting the pads in, the brake pedals would be a bit "deep" at first; after about 50 or 80 kms, it should wear more even and the pedal will be shallow again. He told me try to get to 60 kmph, then brake hard and do that several times for the pads and the discs to fit well together. I am not sure if this is true or not, not sounds too rasonable to me.

Have you guys met this before?

When he tried to fit the new pads into the caliper, he used a tool to push the walls of the caliper apart. I saw some liquid dropping on the floor from the engine bay, I asked him what was that and he said :"it's the brake fluid, because i press this out so the fluid is pushed out, it's normal, don't worry"?!! Is that actually normal?

Thanks everyone!

Cheers

TK

Edited July 6, 2009 by KHIEM

[SuperDave]

Everything he has said is right. Tapered rotors/pads (in your case it will be rotors) will cause a soft pedal. That is about right for bedding pads in, just don't come to a stop during or soon afterwards as you risk ruining the rotors.. As for the brake fluid he really should have taken some out so it didn't over flow. Give your engine bay around the brake master cylinder a gentle hosing to remove the brake fluid in there.

[KHIEM]

Everything he has said is right. Tapered rotors/pads (in your case it will be rotors) will cause a soft pedal. That is about right for bedding pads in, just don't come to a stop during or soon afterwards as you risk ruining the rotors.. As for the brake fluid he really should have taken some out so it didn't over flow. Give your engine bay around the brake master cylinder a gentle hosing to remove the brake fluid in there.

Thanks Dav,

Yea, i saw him opening the hood, flush water in the Brake fluid reservoir, now i know why he did that. So the answer is: just be patient with this for a short time, then it should get hard back soon, is that correct? He mentioned something about the master cylinder (a very smally chance that this part might be broken, he confirmed), but I told him that there must me nothing wrong with that cos i ve only done only 75k, not that much to get that cylinder broken or something.

Is Bendix a good brand for just general purpose braking? i.e. minimal dust and good performance? I got that for $60 for just the front, intended to get the rear as well but they do not stock the rear ones...

Again, thanks for your help, Dave

[lateralus]

if you have the bendix ct pads, then yes theyre good for general purpose with minimal brake dust.

with regards to the master cylinder, it quite possibly could be worn at 75k. it could be a couple of things, such as the brake booster pushrod, worn caliper piston seals, or just that the brake lines havent been bled properly.

what brake fluid have you been using?

[KHIEM]

if you have the bendix ct pads, then yes theyre good for general purpose with minimal brake dust.

with regards to the master cylinder, it quite possibly could be worn at 75k. it could be a couple of things, such as the brake booster pushrod, worn caliper piston seals, or just that the brake lines havent been bled properly.

what brake fluid have you been using?

ow :(.

I don't know what fluid in there, that came with the car from the last owner. This is the first time i service the car "by my-self", normally, i got it to the dealer and they did everything for me there. The old pads are of Toyota.

So what's your advice for me? Should I just try to run that way for several kilometres? I plan to go interstate this weekend, do you think i really need to get it checked again by Toyota?

[SuperDave]

He mentioned something about the master cylinder (a very smally chance that this part might be broken, he confirmed), but I told him that there must me nothing wrong with that cos i ve only done only 75k, not that much to get that cylinder broken or something.

If the pedal was fine before the pad change and went soft afterwards then the pads will wear to the required taper and be fine. A way to avoid this is to have the rotors machined at the same time, however I am not a fan of it for two reason; it costs money to do and you have to replace rotors more often which costs more money again. If the pedal was long before hand then it might be something more serious. Seals in the master cylinder can go that early and cause a long/soft pedal. Since brake fluid is hydroscopic it aborbs water and that can cause a soft/long pedal too.

[KHIEM]

He mentioned something about the master cylinder (a very smally chance that this part might be broken, he confirmed), but I told him that there must me nothing wrong with that cos i ve only done only 75k, not that much to get that cylinder broken or something.

If the pedal was fine before the pad change and went soft afterwards then the pads will wear to the required taper and be fine. A way to avoid this is to have the rotors machined at the same time, however I am not a fan of it for two reason; it costs money to do and you have to replace rotors more often which costs more money again. If the pedal was long before hand then it might be something more serious. Seals in the master cylinder can go that early and cause a long/soft pedal. Since brake fluid is hydroscopic it aborbs water and that can cause a soft/long pedal too.

Let say 100% is the hardest a pedal can have and 0% is nothing, means we can press the pedal all the way down with the no resistant. Before the pads replacement, it's about 60% or 70%. I had expected after the replacement, it should be as hard as 80% or 90%, cos the new pads that are thicker are fitted in! But after replacement, it's still the same as before, so it's still at 60% to 70% even the brakes performance is a bit better than before.

[KHIEM]

... in addition, i have just opened the engine bay, and have a look at the brake fluid reservoir, the fulid inside is about 2 cm over the MAX level :( :( :( It looks not ok, doesnt it?

Edited July 7, 2009 by KHIEM

[SuperDave]

If you wanted to you can remove some of the brake fluid. A spoon, syringe or something similar will do the job. Usually you would just bleed a little fluid from one of the calipers but I'm assuming that that is beyond your mechanical knowledge (no offense, just don't want to confuse you with too much information).

Thin or thick pads won't make a difference as the piston in the caliper keeps the pads close to the rotor at all times. Different brands and compounds of pads can create different 'feels'. I have never used Bendix before so can't say if they are a soft pad or not. As long as the car pulls up in a good distance then I wouldn't worry too much. After bedding the pads in don't be surprised if they glaze slightly. The glaze wears off after about 20-50km. Glazing can also take some braking performance away.

[KHIEM]

If you wanted to you can remove some of the brake fluid. A spoon, syringe or something similar will do the job. Usually you would just bleed a little fluid from one of the calipers but I'm assuming that that is beyond your mechanical knowledge (no offense, just don't want to confuse you with too much information).

Thin or thick pads won't make a difference as the piston in the caliper keeps the pads close to the rotor at all times. Different brands and compounds of pads can create different 'feels'. I have never used Bendix before so can't say if they are a soft pad or not. As long as the car pulls up in a good distance then I wouldn't worry too much. After bedding the pads in don't be surprised if they glaze slightly. The glaze wears off after about 20-50km. Glazing can also take some braking performance away.

Thanks Dave,

I have just taken it to Toyota and asked them for a check immediately. Lucky enought, they did that for me straight away. The mechanic took the car for a test drive and he told me that there's nothing wrong with the brakes, it's just becos there may be some air/bubbles in the fluid, so he may need to get all the air out. He took the car inside and did the job for about 15 minutes. After that, the pedals ddn't feel so much different than before, but he confirmed with me that it is normal and nothing wrong (i did mention something you guys said, about the discs and the master cylinder but he said nah, it should be normal).

He then picked up a screwdriver and tightened something on the calipers of both 2 wheels (he made a full turn to left and right on the steering-wheel in order to do that).

It is not really a big difference afterwards, but as long as they confirmed it's ok, i should not be worried, rite?

Cheers

[DJKOR]

From everything you have described, you will be fine. Your brakes would have been bled by Toyota so the system should be in good running order.

As SuperDave has said, the compound of the brake pads themselves can create different 'feels' and I would say this is the main reason. I have a set of Bendix CT's in my Aurion and I reckon they feel a little on the soft side. They pull the car up really nicely, but they aren't quite up there in terms of feeling sharp on a light press. Needless to say, they won't be in there for long.

[KHIEM]

From everything you have described, you will be fine. Your brakes would have been bled by Toyota so the system should be in good running order.

As SuperDave has said, the compound of the brake pads themselves can create different 'feels' and I would say this is the main reason. I have a set of Bendix CT's in my Aurion and I reckon they feel a little on the soft side. They pull the car up really nicely, but they aren't quite up there in terms of feeling sharp on a light press. Needless to say, they won't be in there for long.

Yea i think so. so i just need to stick with it, i think it should be fine for my next long trip.

Thank everyone :)

[Rolla Boy]

I was gunna say straight away, after pushing the pistons back the system needs to be bled of all air bubbles which your first mechanic didn't do...

Also, with the tapered edge on the discs, the new pads should always be chamfered on the edges so the pad can bed into the disc properly...

Gotta love half ****d mechanics that give people like me a bad name :(