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Author Topic: Are my brakes faulty or have the never been that good?  (Read 4968 times)
Moes
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« on: April 20, 2016, 12:58:12 pm »

Hi

I have never really been satisfied with the brakes on my Bagheera. When I compare the brake capasity with other cars with the same brake setup and weight (but of a newer date) then the brakes on my Bagheera are not that great..  

The discs, pads and brake lines are new.

My Bagheera went through MOT with no remarks, but I really would enjoy some more braking capasity  Smiley

So now when my other projects are stalling, I would like to upgrade or repair the brakes if possible.

Therefore I would like to hear you guys, what are your experience with Bagheera brakes, before I start to disassemble the master cylinder and brake servo ?

I have been wondering if my break servo might be faulty?  Huh I have a new vacuum hose and a new one way valve, but it did not change anything.

When I start the car, the brake pedal drops as it should.

Could a new remote brake servo and master cylinder increase the braking capacity (in the case that everything is actually okay)? any experiences? see link.

http://www.carbuildersolutions.com/uk/compact-remote-brake-servo
  
Best regards Frederik
« Last Edit: April 20, 2016, 03:32:02 pm by Moes » Logged
roy4matra
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« Reply #1 on: April 30, 2016, 10:47:17 am »

Hi

I have never really been satisfied with the brakes on my Bagheera. When I compare the brake capasity with other cars with the same brake setup and weight (but of a newer date) then the brakes on my Bagheera are not that great..  

The discs, pads and brake lines are new.

If that is the case, then I suggest you have something wrong with your Bagheera braking system.

Bagheera brakes should be really good.  With discs at each wheel and a servo, and reasonably light front weight but no anti-lock system, they should have no problem locking the front wheels under very heavy braking.  And the hand brake should be able to lock the rear wheels on a brake test roller (as we use on our M.o.T. in the U.K.)  If it can't do that, then they are not up to spec.

The rear brakes are the same as the Murena and my 2.2 can lock the rear wheels with the hand brake on the rollers and I know a Bagheera can too.  Both cars are unlikely to lock the rears on the road because of the rear weight bias, and in normal driving the brakes generally do not lock, even in wet weather if you have good tyres.

So how does your Bagheera brakes compare to those statements, Frederik?

Roy
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Moes
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Posts: 130



« Reply #2 on: May 10, 2016, 02:10:21 pm »

Hi Roy

Thank you for your feedback!

I belive that my brakes are okay.. As you state Roy the front brakes can lock on the rollers and the rear brakes can not (I remember from the last MOT).

I have also testet the brake servo, and it is surprisingly  airtight. I can not feel my food moving the brake pedal down, when I starting the engine efter pre pumping the brakes, as I can on other cars. But when I try to move the angle-mount pushing the rod into the brake servo by hand, with and without the engine started, I can feel a great difference. So it must be working just fint.

But all in all I stille have to put some serious weight onto the pedal to make the car stop  Undecided

Frederik
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roy4matra
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« Reply #3 on: May 14, 2016, 05:29:20 pm »

Hi Roy

Thank you for your feedback!

I belive that my brakes are okay.. As you state Roy the front brakes can lock on the rollers and the rear brakes can not (I remember from the last MOT).

I have also testet the brake servo, and it is surprisingly  airtight. I can not feel my food moving the brake pedal down, when I starting the engine efter pre pumping the brakes, as I can on other cars. But when I try to move the angle-mount pushing the rod into the brake servo by hand, with and without the engine started, I can feel a great difference. So it must be working just fint.

But all in all I stille have to put some serious weight onto the pedal to make the car stop  Undecided

Frederik

Be careful not to compare the brake servo action of more modern cars with the Bagheera Frederik.  Ever since about 2000 many modern cars have too powerful a servo and if you push on their brake pedal hard (vehicle standing still) you can feel their pedal sinking like there is air in the system or a leak.  We had this with the early MB Sprinters and you could get the pedal almost to the floor if you just kept pressing hard!  Eventually MB corrected the problem but they were too powerful and various mountings were bending!  I believe they have tried to accommodate people who don't have the strength to push as hard, and with anti-lock braking and computer controls such as this horrible system that even takes over under certain conditions they have ended up with systems I don't like at all.  They call it progress...  I say well you can keep progress in somethings and I would not want one of these systems thank you.  People should be taught to drive properly and know what the limits are and not expect the systems or car to compensate for their bad driving.  These are the people who probably look forward to cars driving themselves.  I hope they won't be around before I have stopped driving (or I'm already passed on) because I certainly don't want one!

Anyway enough of my ranting! Regarding your Bagheera brakes, since the effort you have to put in seems a lot, what pads are you using? (brand and type)  Pads that are too old tend to become hard and inefficient as you probably understand.  However, pads that are not bedded-in correctly can be inefficient as they become quickly glazed.  Obviously the pad to disc fit is also important so new pads against worn discs for instance can take a while to bed in and be touching on the full surface area, and until they are touching over the full surface area they won't give the full efficiency.

So in your case with new pads and discs the fit should be good, so the first question is how did you bed them in?  And the second is what pads are you using?  EBC Greenstuff pads are available for the front and rear of a Bagheera, (for Bagheera using Girling front calipers and Bendix rear - I'm not sure about the ATE front calipers as I've only seen them once and I'm not sure what pads they use)  and these Greenstuff pads generally give around 20% better grip and in every car I've changed over to them, you can feel the better braking as soon as they have been bedded-in.

So it may be if everything is correct, you could get some improvement from better pads.

Roy
« Last Edit: May 14, 2016, 05:31:51 pm by roy4matra » Logged

Moes
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Posts: 130



« Reply #4 on: May 31, 2016, 10:57:38 am »

Hi Roy

I have not been familiar with the term of bedded in breaks before.

I just read a little about it, and I have to say that I have not done anything to bed the breaks in properly. I actually have to say that I thought that new breaks would bed in by them self during every day driving. Guess I was wrong..   

How do you bed-in your breaks, Roy?  Do you heat the breaks/discs to a specific temperature or?

The Discs and pad I am using are standard from my local parts dealer. The pads might also be of some age, if the have been on the shelf for 20 years, but can age alone deteriorate pads?


Best regards Frederik
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Moes
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« Reply #5 on: June 09, 2016, 03:16:38 pm »

Just had some time to read a little more about the bed -in procedure, and watched some youtube videos. And I wonder how I have never heard about this before  Huh Guess I need to try it out, and see if I can bring the brakes to life, if it is not to late..

 - Frederik
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roy4matra
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« Reply #6 on: June 14, 2016, 09:28:41 pm »

Hi Roy

I have not been familiar with the term of bedded in breaks before.

I just read a little about it, and I have to say that I have not done anything to bed the breaks in properly. I actually have to say that I thought that new breaks would bed in by them self during every day driving. Guess I was wrong..   

How do you bed-in your breaks, Roy?

Hello Frederik,

This partly depends on whether the new pads are against old already used discs or fitted at the same time as new discs, as in your case.  When new pads are being fitted with new discs they should both have nice flat surfaces and consequently bed-in much quicker.  With already used discs, the surfaces will have small (or sometimes large) grooves and the pads will take a little longer to wear to a corresponding shape.  Until the surfaces match, the peaks of the metal will cause the pad in contact at that point to get very hot as a lot of the pad area is not yet touching to spread the load.

The aim of the bedding-in period is to bring the new pads up to working temperature gently over a small period.  So the speeds should be kept low (no more than 50 kph and light or gentle and short braking periods, so they don't heat up too rapidly.  Do this for between 80 and 200 kms.  I usually fit mine then use the car in and around London where the speed limit is often 50 kph anyway so it is easy to stick to that; and leave plenty of room so you can do short gently applications.  Used discs will mean the pads take a little longer to wear to the discs, new discs mean they should bed-in faster.  Obviously if you did have an emergency then you would have to use the brakes accordingly, but if you are driving correctly at low speed and leaving plenty of room, you should not have an emergency anyway!

If the pads are used at higher speeds or in heavy braking, they will heat up too quickly and may become glazed which will cause a loss of efficiency.  I once tried some of those brake dust shields (as an experiment - not for me as I never liked them but for other club members).  They fit behind the alloy wheels to keep them cleaner, but they also caused the pads to glaze/loose efficiency because they became too hot.  I described this in our magazine and said owners should not use these dust shields because they stop the cooling air flow.

Quote
The Discs and pad I am using are standard from my local parts dealer. The pads might also be of some age, if the have been on the shelf for 20 years, but can age alone deteriorate pads?

Yes age can cause a deterioration in the pads.  Usually they get harder and have less efficiency - especially with these horrible non-asbestos pads.  The older asbestos pads were much better but we all know they stopped these because of health concerns.  (however the non-asbestos pads are not a lot better because of the excess black dust they produce!)

My view is the Kevlar based EBC greenstuff pads are what you need today.   Similar to the old asbestos, less disc wear, less dust than the latest pads, 20% better braking too.

Roy
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roy4matra
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« Reply #7 on: June 14, 2016, 10:15:23 pm »

Just had some time to read a little more about the bed -in procedure, and watched some youtube videos. And I wonder how I have never heard about this before  Huh Guess I need to try it out, and see if I can bring the brakes to life, if it is not to late..

 - Frederik

I'm sure you must have heard about running-in a new car Frederik?  Well it is no different to that.  When you are running-in a new car you are bedding-in everything at one time.  It is not just the engine as some people think.  Running-in a new car was for the engine, gearbox, diff. brakes, tyres, steering, suspension, electrics, etc.etc.

When it reached between 800 and 1200 kms approx. or say a couple of weeks you took it back for the 'Free' running-in service where they re-torqued the head down, and changed the oil and filter; and gave the car a good check over to make sure everything was as it should be.  This check over was most important and often not done properly as even the mechanics didn't understand its importance.  If anything is going to go wrong it is usually just after it is new and being used extensively for the first time; or after some service or repair when things have been disturbed.  These are when you need to be alert for problems.

So brake pads or new tyres are often the time when bedding-in is required on an older car, and for just the same reasons as when new.  With tyres they have a fluid on them which allows them to be released from the moulds but this makes them slippery until it is worn off.  Also the tyre carcass should be heated gently just like pads, so you bed-in new tyres and they will be better and last longer.  I've seen people come in, have a new tyre fitted and go straight out and drive at high speed and then have it blow out, because they don't understand the importance of bedding-in.

Roy
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bert1
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« Reply #8 on: June 25, 2016, 10:45:08 am »

As people here have already said, brake bedding is essential for optimum braking performance. One thing that has not been mentioned though is that one of the main jobs of bedding is to "mature" the pads - which actually involves releasing the volatiles of the resins and other binding products from the pad material. When these gasses release, they form a barrier between the pad and rotor and this is why poorly bedded pads give a hard pedal with poor retardation in emergency stops. This often feels like your booster isn't working well. Sufficient heat is required for a proper bedding procedure. The manufacturer of my race pads has a strict bedding procedure that would take most of a track day - and is probably dangerous if you are on track with other people hence they offer "pre-bedded" pads for a little extra. Obviously this is not something available for road-car use though so I won't detail it here....

For road cars, effectively what you do (once you have lightly braked for a while to "true" the pads to be square with the disc as described above) is progressively faster moderately hard stops, allowing the brakes to cool between applications by not using them at all. I live in a relatively quiet neighbourhood where I can "lap" my block without much chance of having to deal with other road users (if I pick the right time of day!). What I do is a stop from 40km/h to ALMOST stopped, with a cooling lap between, and I repeat this 4 or 5 times, Then I repeat at 60 and 80. Yes its a lot of laps! then I go to a motorway and do 4 or 5 close to panic stops (never locking brakes or bringing the car to a complete halt) from 100km/h (make sure no-one is behind you!) and then returning to legal speed for a good distance between each stop for cooling.

From the above you will probably have realised that during bedding it is important to try to never bring the rotor to a dead stop - which makes heavy traffic bedding very difficult! Hot brake pads should NEVER (and certainly not during bedding) contact a stopped rotor. Doing this creates hot and cold areas of the rotor (causing them to warp) and also impregnates the rotor with pad material in that location (I'm sure you will have seen a rotor with a "shadow" of the pad clearly visible - that's a "thick" spot!) - resulting in brake shudder (different rotor materials behave differently in this regard - top quality rotors are high in Nickel for this reason - although that also makes them more expensive). Parking brakes should only be used after a hot rotor/pads have had a chance to cool - and this holds true for the life of the brakes.

For my money the best pads available are "Pagid Fast Road" although they are now hard to get. "Remsa" pads are also brilliant - they have a higher friction co-efficient than the Pagids - but they do wear quickly and create a lot of dust - which I do not see as a major negative on our lightly used classics. I can't honestly say I'm a fan of the EBC Green though. I've tried them several times - and driven other's cars where they are fitted - and they seem to stop OK - but the pedal always feels "wooden" to me and lacks feel. I run a Kevlar clutch on my racecar and it also lacks feel so i suspect this is a feature of this material.

I also concur with the comments about tyre bedding. My race tyre supplier (I use Avons) recommends 2 laps at 20%, 4 laps at 40%, 4 laps at 60% and then go for it. On the road I just go easy on the cornering for 200km or so....
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