Disc brake kit (master cylinder rubber seal)

Post by **yellowpinky** » Tue Jan 10, 2006 1:27 pm

Last summer I had a Bull Motif disc brake kit fitted to my van. The mechanic and I didn't have enough time to remove the rubber seal that sits inside the master cylinder. I have been driving it since and there has not been a problem. However, I am aware that my front brakes may not be releasing though it is quite hard to tell. I am having some work done soon and I was wondering if i should bother taking out my recently installed master cylinder to remove this rubber bit? Is it worth it? Opinions welcome.. Thankyou..

Post by **Peetee** » Tue Jan 10, 2006 2:44 pm

I understand the purpose of this modification is to allow the calipers to back off. You described that the pads may be rubbing (which would support the theory) but what makes you think this?

I would imagine the problems would range from noisy brakes and pad glaze at one extreme to overheating, fade or failure at the other.

Post by **bigginger** » Tue Jan 10, 2006 3:39 pm

It's a pain to do, but I'd be doing it as a rather major priority since all the manufacturers say you should

Post by **bmcecosse** » Tue Jan 10, 2006 8:44 pm

But if your brakes are not obviously getting hot or wearing away the pads too quickly - leave well alone !

Post by **Matt** » Tue Jan 10, 2006 8:49 pm

But if your brakes are not obviously getting hot or wearing away the pads too quickly - leave well alone !

Hang on.... one of the calipers on my dads modern car had siezed just touching the disk, it wasn't obvious but after a few hundred miles the disk had tempered and the pas had worn hollow (dont as me how :s) I would sort out your M/C

Post by **bigginger** » Tue Jan 10, 2006 9:40 pm

bmcecosse wrote:But if your brakes are not obviously getting hot or wearing away the pads too quickly - leave well alone !

As long as you aren't too keen on staying alive. Only a fool would just leave them.

Post by **jonathon** » Tue Jan 10, 2006 9:46 pm

yellow pinky,
I'd definately recommend that you modify the m/c. You can either drill a 1/16 hole through the seal, making sure that it does not close up after drilling, or remove the whole top hat seal. Do you have a header tank/additional brake fluid reservoir, this is also a must as the capacity of the original m/c is borderline to insufficient.

Post by **Stig** » Wed Jan 11, 2006 10:23 am

jonathon wrote:Do you have a header tank/additional brake fluid reservoir, this is also a must as the capacity of the original m/c is borderline to insufficient.

So what exactly would happen with, say, a Marina disc conversion without an additional reservoir? Is it just that the m/c level needs checking more frequently, more difficult to bleed, gets air in the system... ?

Post by **paulk** » Wed Jan 11, 2006 12:56 pm

No. As far as i'm aware the problem is that Disc brakes pistons are much bigger than the tiny little drum brake unit. this means every time you press the pedal most if not all of your fluid is being used, there is no spare fluid left for when you have any wear in the pads.

No fluid (when pads wear down) equals no brakes. You can keep topping the m/c up but as soon as you change the front pads and crank the piston back you will fill up the chassis member with brake fluid and have to start again.

Post by **jonathon** » Wed Jan 11, 2006 7:23 pm

Paulk is correct about the m/c caopacity and the requirement for it on all disc convertions. I've never had a chassis leg flooded with fliud after changing from worn to new pads, this would indicate a major problem with either the caps or seals in the m/c itself. At worst the level of fluid should rise in the header tank, this can be removed to reduce to the correct level

Post by **bmcecosse** » Wed Jan 11, 2006 8:02 pm

If all the fluid was used each time you pressed the brake pedal - the pedal would need to go down to the floor - and on another 6 inches! It's just not possible - the pedal travel will be no more than normal and the fluid displacement will be no more than before. The pads should be hovering just off the discs - and the slightest fluid flow into the caliper pistons clamps them to the disc. The fluid reservoir is there to make up for the wear on the pads - as they wear the pistons move in and take a little more fluid from the reservoir. So provided you check regularly there will be no problem.
At the start of this thread I did say only leave well alone if the brakes are not heating and not wearing away.
Si fractum non sit, noli id reficere!
All these worrys and complications/problems with disc brakes - dear oh dear, there is a much simpler and equally effective system you know!

Post by **wanderinstar** » Wed Jan 11, 2006 8:09 pm

Here here!!

Post by **jonathon** » Wed Jan 11, 2006 8:22 pm

BM, there are absolutley no complications/problems with the fitting of our disc brake kits so long as the instructions are read and adhered too. There are some inherent design problems with some kits, these have been discussed at length in previous threads.
The reason that a header tank is used is to compensate for the greater cylinder capacities, and as you state to allow for the wear of the pads. You should try and appreciate that some of us are responsible for our designs and have fully researched or products. I'm afraid that uninformed opinion has no place on this or any other forum where fellow minor owners are to act on what we recommend.May I boldly suggest, with respect, that until you have had first hand experience of both my products and any other topic related ones, that you carefully consider your contributions.
We are all well aware of the drum brake conversion that you are keen on, and I think that we all respect your views on them. I do not see the brake upgrade topic as a reason to be confrontational.

Post by **bigginger** » Wed Jan 11, 2006 9:21 pm

Hear hear.

Post by **Skeggysteve** » Wed Jan 11, 2006 10:25 pm

bmcecosse wrote:......

........

I am staggered by your comments - I have deleted them because they are incorrect and could be life threatening.

If the OP has not done as the fitting instuctions said then he/she is at great risk of brake failure.

Any manufacture (sp) has to have liability insurance, at great cost, and any claim on that can stop them getting insurance and therefore close their business.
So they tend to get the fitting instuctions right.

Ill informed comments such as your could endanger someones life.

I appreciate that your comments where perhaps meant to help but remenber that brakes are not something to be taken lightly,
If you don't know what you are doing with brakes them pay some one who does.

It could be someone else you hurt or even kill with faulty brakes on YOUR car.

Post by **bigginger** » Wed Jan 11, 2006 10:40 pm

Hear hear again...

Post by **chrisd87** » Wed Jan 11, 2006 10:57 pm

Just as a bit of an aside, I always fail to see why people would bother to upgrade the brakes on a standard 1098cc moggy. I find them perfectly adequate for a non-modified car as long as you can press the pedal properly, and the brakes are in reasonable nick. If you struggle to press the pedal hard enough, why not just fit a servo? Obviously if the car is heavily modified then I can understand the need for more stopping power.

Post by **pskipper** » Thu Jan 12, 2006 11:47 am

I think it's less the car and more the other drivers on the road, when someone cuts into your stopping distance and then slams their brakes on it can be pretty hairy!

Post by **Pyoor_Kate** » Thu Jan 12, 2006 4:04 pm

Just as a bit of an aside, I always fail to see why people would bother to upgrade the brakes on a standard 1098cc moggy. I find them perfectly adequate for a non-modified car as long as you can press the pedal properly, and the brakes are in reasonable nick. If you struggle to press the pedal hard enough, why not just fit a servo? Obviously if the car is heavily modified then I can understand the need for more stopping power.

Well, there's a multitude of reasons. The brakes on a standard minor are, and I use this word carefully, 'adequate'. They will stop you in a reasonable space of time.

However, some people, like me, do in excess of 15k miles a year. And I tend to do it in batches, because I'm on placement some of the time - and racking up huge milages. And frankly, anything that saves me playing 'adjust the brakes' or 'oh crud, they've worn out' really is good (bear in mind that in 3 years and 50k miles I've never had to deal with the front brakes (disks) but i've had to replace the rear ones twice).

Also, because I do high milages I like to be able to stop like a modern car. And I can, with disk brakes. It's quite a significant difference; infact they're quite the best brakes of any car I've driven.

And finally, I like mountains. I like them a lot. And I live in an area with lots of steep hills, including several on which the handbrake simply won't hold the car. On these hills, drum brakes are a liability - and one I can do without.

As for why not fit a servo? Because servos on drum brakes are, it is suggested, more likely to lead to situations where you have brake fade.

Post by **ianselva** » Thu Jan 12, 2006 5:04 pm

I am surprised that on the subject of brake fade with drums that no-one has ever mentioned different brake linings , with or without a servo. I race a drum braked car ( Not a Moggie) and would never expect to use standard linings. I don't have any specific recommendations - just surprised no-has explored the possibility.