How good should our brakes be?

[Adrian]

This has been a question bugging me for a while. Clearly there can be no comparison to modern systems and older cars have the difference between drums all round and those with discs at the front. The reason I ask is when you see these car restoration programs some of the cars brake so hard they actually lock the wheels and skid (not saying that is a good idea but clearly shows a lot of solid braking).

When I've braked, particularly in the mini before the rebuild, I needed a sun dial to measure the time between applying the brakes and stopping.

Having re-used the Master cylinders on both rebuilds (not refurbished) should I have replaced them for improved performance (GT6 history file suggests the Master is at least 30 yrs old with no documented rebuild).

Do any of you have any standards, tests you work to? I think the MOT principally looks at braking evenness? What sort of braking do you get? 

Cheers

Adrian

 

[dougbgt6]

Adrian,

You have a GT6 with front disks, you should be able to lock your wheels, I certainly can on mine. 

Top of the list, Mintex brake pads, they are not a little bit better, they are MUCH better. 

I've never changed my master cylinder so it's at least 42 years old probably the original, 47 years old. I've put new rubbers in maybe 2 or 3 times. A word of caution my MC is larger than previous models and unobtainable although refurb kits are available.

I've changed rear slave cylinders again 2 or 3 times, new ones are not much more than re-furb kits and saves messing about. 

How old are your tyres? And what pressure are you running? Old rubber ceases to be rubber and no matter how "not very worn" should be changed every 7 years. And tyre pressure relates to rubber in contact with the road. The more inflated the less contact, you have to get the right balance.

I have a servo, It doesn't make braking better, just easier and more like a modern (I'm forced to say that by the anti servo brigade!) It takes away that OMG! moment when you swap between cars, wouldn't be without it!

Doug

 

[JohnD]

Adrian,

The only ways that braking has advanced since Triumphs were designed includes, yes, discs, but rear brakes  confer so little to the stopping ability of a car that they are fine on drums, except for competition etc.     If rears are too good then you spin!    The other braking 'improvements' include antilock and the developments of that depending on fast electronic control, like stability control.      You'll never get those on your Triumph - well, you could, but they are for people who will welcome autonomous cars.  If you have a Triumph, you're a driver!      The brakes you have are, in their design, state of the art!   But they are at least more than 40 years old.   There may be a lot needed to bring the system back to original efficiency.

Careful inspection of the hard brake lines.    Corrosion is a danger, but dings can limit function.

Replace the flexible lines - a no brainer.

Rebuild the master and slave cylinders, inspecting the bores for corrosion and replacing if necessary.     Ensure proper function of slaves - they must slide on the back plate.

Rebuild the calipers - not an easy home job.  Consider buying an exchange set.

Correct  bleeding - forgive me,  but sometimes people accept what should be a rock hard pedal.

Finally the other big change since the brake sytem was designed is in brake material.   No more asbestos, thank goodness.   I'm a fan of Mintex - 1144 for road use - as they are guaranteed to be good quality.    Never buy cheap.     Others will have a favourite material.

You should be able to lock up all your wheels from almost any speed.    The limiting step in braking should always be tyre traction, not brake friction!

 

You can read the full MoT test requirements here: https://www.gov.uk/guidance/mot-inspection-manual-for-private-passenger-and-light-commercial-vehicles/1-brakes (You have a Class 4 vehicle)

Good luck!

JOhn

PS I see that doug has beaten me to a Mintex recommendation!    He also mentions that he has a Master with a larger bore.    This is NOT a 'go-faster' mod!    A larger bore needs more foot pressure for the same effect at the brakes, but less travel of the pedal.  Combined with a servo, that takes you back to where you were!     If that's what you want, fine, but it will not make you stop any quicker!

[NonMember]

9 minutes ago, JohnD said:

 yes, discs, but rear brakes  confer so little to the stopping ability of a car that they are fine on drums, except for competition etc.     If rears are too good then you spin!    The other braking 'improvements' include antilock

In reality, anti-lock has been the primary driver behind the adoption of rear disc brakes on modern cars. The combination of sensors and actuators suitable for the ABS module is readily available for discs, not for drums.

[dougbgt6]

19 minutes ago, JohnD said:

PS I see that doug has beaten me to a Mintex recommendation!    He also mentions that he has a Master with a larger bore.    This is NOT a 'go-faster' mod!    A larger bore needs more foot pressure for the same effect at the brakes, but less travel of the pedal.  Combined with a servo, that takes you back to where you were!     If that's what you want, fine, but it will not make you stop any quicker!

Mine's not a mod, the very last GT6s just had a larger MC, not very many made, which is why you can't get them anymore!  And for the reason John says why the servo became standard on the last models.

And yes, Mintex 11/44s I didn't say the number, I always get it wrong dyslexia rlues! Or is that dyscalculia?

Doug

 

[Clive]

11 minutes ago, dougbgt6 said:

Mine's not a mod, the very last GT6s just had a larger MC, not very many made, which is why you can't get them anymore!  And for the reason John says why the servo became standard on the last models.

And yes, Mintex 11/44s I didn't say the number, I always get it wrong dyslexia rlues! Or is that dyscalculia?

Doug

 

I think That is what John meant? a factory mod to accompany fitting the servo? it seems any car that had a servo added during production also went to a larger bore master cylinder. I guess to get the feel right.

And yes, a larger bore master will make stopping the car harder on the legs. 

But I have found brakes, especially with new or good condition discs/drums, good flexi hoses (I don't bother with braided, I reckon much of the difference noted is that the old rubber hoses were well beyond their best, and new rubber hoses would feel very similar to braided. Tin helmet now on)  quality pads, and properly adjusted rear brakes and the car will stop very well indeed. (asbestos pads have superb cold bite, but not available any more. Mintex 1144 the nearest you will find and brilliant for a road car). Our old mini (front discs/rear drums) stopped on a sixpence. As do most of my Triumphs, the only one that struggles in my Toledo with tiny discs and a fair bit of weight, but I have a plan for that!!

And Doug, if you need to replace your master cylinder, they are sort of available, but either the small integral reservoir, or as a separately supplied reservoir type. So you can sleep well in that knowledge.

[Adrian]

Thanks for the replies

Mintex pads on. New braided flex hoses. New rear brake cylinders in box but not on car - yet. New tyres all round this year - pre lockdown so not been out. Calipers relatively new. Easibleed, bleeding undertaken. 

No corosion, but not actially inspected lines for distortion but will check photos etc. 

I was wondering if there was some wear in the Master that may limit braking force. I suppose its the definition of firm pedal after bleeding that is somewhat subjective.

I have no issue about adding a servo - seems a sensible upgrade to emulate modern pedal function but not on the cards yet at least until I get them performing as they should. Could it be that the easi bleed leaves the odd bubble in awkward areas that an original two man bleed would dislodge?

My gut feel is that the Master is possibly letting it down.

I'm intending to swap to silicone at some point.

Interested that locking the wheels should be easily within reach of a good system, hence why I'm erring towards the master. Any other ideas?

[dougbgt6]

20 minutes ago, clive said:

I think That is what John meant?

I think so to, just wanted make it clear. No go faster bits on my motor, keep it original! Apart from the shiny bling and the gauges, lots of gauges.   

I have silicone, it's fine, but I'd get this sorted out before you change. Silicone does seem to hold the air bubbles and mine needed re-bleeding 3 times a week apart to get it right. 

I've never had a problem bleeding the brakes on my own just a jam jar, spanner and plastic pipe, no easy bleed or fancy equipment.

Just how firm is your pedal? Mine has free travel then hard, no spongy in between. Once hard I'm I'm pushing on a solid surface.

Doug

 

[Pete Lewis]

never forget the bedding requirement  its simple 

Pete

mintex bedding.pdf

This is from TMD
 1) Clean discs with brake cleaner 
 
2) Following Bedding Procedure for M1144 / M1155 / M1166 initial brake test start with 3 – 4 light applications from 30mph down to 0mph. 
 
After these, follow the steps below according to Material. 
 
M1144: 6 / 7 medium pressure applications 70mph down to 30mph 
 
M1155: 8 / 9 medium pressure applications 90mph down to 30mph 
 
M1166: 9 / 10 medium applications 90mph down to 30mph 
 
 
When carrying out the bedding process, do not allow the brakes to drag, do not left foot brake. To do so may result in damage to, or failure of the brake system. 
 
Leave the brakes to completely cool. 
 
For Further information please contact Richard Barton on 0127485403 

 

[Adrian]

The mintex were on when I got the car.

[Clive]

2 hours ago, Adrian said:

Thanks for the replies

Mintex pads on.

Any other ideas?

Are they 1144 pad formula? std mintex are £10 a set, fine on a car with bog servo etc but are NOTHING like the 1144 pads. Sounds picky, but they are chalk and cheese.

[JohnD]

Pete, "leave the brakes to cool"? Stopped?

That means that the sectors of disc or drum next to pad or shoe will take much longer to cool than the rest.       Better, drive like a granny for twenty mins or so, with minimal brakes, to allow the whole to cool, before stopping.

 

[Adrian Cooper]

Or maybe the PO put in a set of 1155s thinking that these were an upgrade but they are only for racing use as they do very little until they are hot.

[Pete Lewis]

John  i didnt write it im sure theres another letter from mintex which does say dont stop 

i would agree

pete

[Colin Lindsay]

11 minutes ago, JohnD said:

Pete, "leave the brakes to cool"? Stopped?

That means that the sectors of disc or drum next to pad or shoe will take much longer to cool than the rest.       Better, drive like a granny for twenty mins or so, with minimal brakes, to allow the whole to cool, before stopping.

 

That's what Mintex says on their blurb for bedding in; it's on their website and about a dozen other classic sites on the Net; just search for 'Mintex Bedding In'.

For a real driving experience try a drum brake Herald; that really makes you pay attention.

 

[dougbgt6]

Or an Austin 7 with cable brakes, who needs hydraulics! 😆😳😳

Doug
 

[Adrian]

I found a reciept for Mintex M1144 pad type 16 calipers @ £64.80 from the club in 2014. I was told they were on and reciept indicates that being the case. I assume these are the front pads? Given the price I assume they are the right ones. No idea about the rears.

Brake pedal is solid or at least very firm halfway down.

[poppyman]

45 minutes ago, dougbgt6 said:

Or an Austin 7 with cable brakes, who needs hydraulics! 😆😳😳

Doug
 

Or a 103E Ford Popular with cable brakes, proper scary.

[dougbgt6]

Adrian,

description and price sound right. As John says the rear brake don’t add much to the braking provided by front disks. However they should be well adjusted and not leaking.

Pedal half way down wouldn’t do for me, I’d want it 1/4 of the way down or better. Sounds like you’re moving too much fluid about, which is down to adjustment or/and the MC.

Doug

[Clive]

1 hour ago, Adrian said:

I found a reciept for Mintex M1144 pad type 16 calipers @ £64.80 from the club in 2014. I was told they were on and reciept indicates that being the case. I assume these are the front pads? Given the price I assume they are the right ones. No idea about the rears.

Brake pedal is solid or at least very firm halfway down.

Have you adjusted the rear brakes? The most important thing is to disconnect the handbrake cable, or slacken it off. The adjust the shoes up on the adjuster, regularly formly pressing teh bake pedal too to keep it all centralised, although it should centralise as the shoes hit the drum, but using the pedal is easier than the adjuster. Make sure the rears are locked up solid, then slacken off enough to just be able to rotate freely, no more. Then adjust the handbrake cable. This makes sure the pedal is not taking up shoe adjustment, and some people do not understand how to adjust them correctly. (apols if this is what you have done)

[Adrian]

It's been a couple of years since doing the underside and TBH it was just the same prior to the rebuild HOWEVER I was just reviewing another thread along the same lines and will have a look this week and check it is all OK prior to going into the master cylinder.

As the GT6 is the first old car I haven't actually got a yardstick against which to judge, hence the question which has been very useful and clearly shows something is lacking in the setup.

[Colin Lindsay]

22 minutes ago, clive said:

Have you adjusted the rear brakes? 

You just beat me to it, Clive! I was halfway down the thread and was thinking the same thing. 

For a time there the GT6 needed two pumps of the pedal for a good feel at the brakes, but after refitting the rear axles and adjusting the rear brakes properly they feel a lot better.

[dougbgt6]

1 hour ago, dougbgt6 said:

Adrian,

description and price sound right. As John says the rear brake don’t add much to the braking provided by front disks. However they should be well adjusted and not leaking.

Pedal half way down wouldn’t do for me, I’d want it 1/4 of the way down or better. Sounds like you’re moving too much fluid about, which is down to adjustment or/and the MC.

db

[Clive]

Adrian, the master cylinder either works or doesn't. Typical issue (apart from leaks) is that when you apply the pedal if feels firm, but the pedal will slowly sink to the floor. But that doesn't sound like your issue. I reckon the problem is elsewhere. Maybe more shredded wheat are required!

[PeteH]

Hi.

6 hours ago, JohnD said:

Pete, "leave the brakes to cool"? Stopped?

That means that the sectors of disc or drum next to pad or shoe will take much longer to cool than the rest.       Better, drive like a granny for twenty mins or so, with minimal brakes, to allow the whole to cool, before stopping.

 

Hi. There is somewhere online a series of posts, which highlight this and blame it for "disks warping?". Suggesting that differential cooling is causing uneven thermal stress.

Pete