Brake fades heart sinks!

[surfergirl]

Hey folks, I know this has been covered before ,but just in case theres any new info.
The 1962 van with 8 inch front drums and Mintex shoes has terrible brake fade on down hill runs. It's carrying two people and two heavy old surfboards on the lid, but years ago we used to tow a trailer and could stop fine.I
I suspect the lining material to be too hard compared to older brakes, the drums were replaced a few years ago.
Any help would be cool!
Should say two heavy old surfers and two old surfboards!!

[panky]

Try a brake fluid flush. Old fluid will have absorbed moisture and lowered the boiling point of the fluid and possibly causing the fade you're experiencing.

[surfergirl]

Thanks, would the peddle drop lower if that happened?

[surfergirl]

Sounds mad, but has anyone tried filing grooves in the shoes to dissipate heat?

[simmitc]

Fair credit for an interesting idea, but sounds mad, probably is mad If you mean the pad surface, then you want the maximum possible surface contact with the drum, so filing grooves/ridges would be bad. Also, there's no airflow in the drum, so there would be no cooling effect.

Will the peddle drop if water boils? Possibly - boiling changes the substance from liquid to gas, and gas can be compressed. If it compresses, then it takes up less volume, so the pedal will move further to close the gap. Of course, other things can cause the same symptom, so it might be another topic/problem.

I thought that the Mintex shoes were better than many, but you could consider a disc conversion which normally solves this issue.

[kevin s]

Many years ago I spent a weekend in a wind tunnel looking at how to improve brake heat dissipation on a then new car (with disc brakes). We tried all sorts of air ducts etc but in the end the item which made the biggest difference was fitting alloy wheels.

People did used to drill drums which can help but without proper development testing could lead to the drum cracking.

There are competition brake linings out there so you could try getting the shoes re-lined (though some of these will be terrible when cold), or as above fit disc brakes.

[surfergirl]

I wonder if the lining material on the shoes is harder than it used to be? The van is used daily and I don't have a modern car so I'm used to the stopping distance and lack of servo, but down hill is getting interesting.
Mind you it won't stay in second gear because it pops out, so I'm not getting the engine braking.

[philipkearney]

Yes, I think the new non asbestos linings are not quite as good, are generally harder and go shiny quite quickly. I shouldn't recommend old school asbestos linings, but I usually pick up new old stock linings from autojumbles and such like and find they are much better and the stopping power is noticeably better too.

[mowogg]

I would change you flexis before going too much further. I was amazed at the difference these can make. New ones can give the brakes a lot more bite

[don58van]

Hi Surfergirl

It may be that the surface of the shoes are not well matched to the curvature of the drums. I have heard of a case where the friction material needed to be machined by a brake specialist to correct a mismatch. This resulted in much better braking performance.

If there is a mismatch in your case, there could be only a very small area of the friction material doing the stopping work. It would not be surprising if you experienced fading.

As a first step, it would be worthwhile checking that the leading edge of the friction material has a good chamfer on it (which is a standard requirement).

Don

[philthehill]

I would check for high spots on the lining which will show up as polished areas. If there are high spots rub them down with a piece of sandpaper. May take more than one go. The high spots are normally taken off by use - commonly called bedding in.
The brake linings can get a glaze on the rubbing surface which will reduce braking efficiency. Solution - remove the glaze with a piece of sandpaper.
As regards grooves in the lining - there is no benefit to heat dissipation - good if you are ploughing through mud and water. My off road M/C has grooved brake linings for that purpose.
I agree that the brake shoes should have a chamfer on the leading edge. It does help to bed in the brake lining and reduce the incidence of squeal.

[Bill_qaz]

Have you had the brakes roller tested to make sure both axles are doing their share?
If most of the effort is on one axle it will overheat and fade. Do you know anyone who has a non contact infrared temperature gauge, you can take the brake temperatures after a decent , they have a lazer spot you can put on the brake drum and it will give you the temperatures. Such as
https://www.ebay.co.uk/itm/Thermometer- ... 635-2958-0

[surfergirl]

Thanks, I put my hand the hub caps when I stop at the bottom of the hill, to see if any wheels are hot! That's as technical as it gets!! Not sure which is worse going down or trying to climb back up on a cold engine.

[Bill_qaz]

Surely you can pick up a cheap anchor and rope in that area or bungee cord to assist the uphill return
Hope you can get your issue sorted, you can get a brake roller check without a full mot from most mot garages, money well spent on a safety issue
Good luck

[surfergirl]

Thanks Bill,
Will have a chat with the local garage this week see if they'll put it on the rolling road.Years ago they used to take it for a drive and use a hand held meter in the cab, I think those day have gone.

[Bill_qaz]

Look at fun period gadgetry post in general discussion and you will see the old Tapley brake tester. Old enough to remember using one in my mechanic days

[surfergirl]

Spent the afternoon checking the brakes again. Only this time got someone to push the peddle while I checked each wheel, found passenger side had a handbrake but no foot brake at all!
The piston was seized half way out so it could still slide on the backplate for a handbrake, but not work as a foot brake.
Had a new cylinder in the shed and that's now fitted. Will let you know how the next roll down the hill works out when checking the surf tomorrow!

[Bill_qaz]

4 brakes vs 3 brakes should be some improvement

[liammonty]

Have you checked that all the front cylinders are working properly? I've had one on each side seize before, so the car still pulled up straight (as it had even braking on the front, but only 50% of what it should have been) but of course the brakes were terrible.

I've got the same set up as you on my 948 car which I fitted 8" front drums to, with Mintex shoes. To be fair it was fine on the original 7" drums when they were set up well, but is really good now - brakes can be used quite hard without any hint of fade. So something's not quite right with yours, as the Mintex shoes, in my experience, are very good.

[myoldjalopy]

Driving regularly through a ford and immediately parking (due to a job I was working on at a house) up caused all my wheel cylinders to eventually seize up, first sign was not being able to get up a particular hill in top gear, which had never been a problem before, then the wheels felt hot