Today I removed one of my brake drums to check for worn linings and found the linings badly scored, especially the secondary shoe. They looked like someone had taken a wire brush to them with grooves about 1mm deep all along the lining. The brake drum has matching grooves but they are barely visible and can hardly be felt when you drag a fingernail across the surface. What I think has happened is that due to the backing plates having no dust covers over the adjusting slots, sand and grit has entered the brake and started the scoring. When the drum was removed, no grit fell out and surprisingly very little brake dust considering the grooving....a live gecko fell out but that's bye the bye.
So, my query is whether my assumption is correct, and also could the grooved linings cause the brakes to grab (which does happen). The surface is as rough as 80 grade abrasive paper whereas it normally should be shiny smooth. I hope to upload pics when I can find the right cord!
Van has just finished a 19000km trip around the block on quite a few dirt roads.
That would be a fair assumption. Is there a reason as to why you do not have the covers for the brake adjustment in place? Is it to help drain water as you go over water crossings? As for the brakes grabbing, mine have done so since new. Can only put it down to the brake controller or the way the brakes are designed to operate. Larry
-- Edited by deverall11 on Friday 24th of October 2014 01:04:39 PM
Larry, all previous vehicles I've owned in the past 55 years fitted with drum brakes never had covers on the brake adjuster slots, possibly from new or from them not being replaced when the brakes were adjusted. Mine were missing on my van although the Alko book says to refit the covers after adjusting the brakes, so really it was my fault they were not there as I was aware that they should have been fitted.
I'll fabricate some covers to keep grit/sand out and see if the brakes improve over the next few thousand kms....then remove the drums and hopefully see that shiny smooth surface. Otherwise it's new shoes and skimmed drums.
Regards
the drums will not repair themselves and the brake shoes will maintain the wear pattern they have now, they will also deteriate quicker. My advice would be to run them out (wear them out) and then replace as a complete assemble at about $120 a unit from memory
cheers
blaze
the drums will not repair themselves and the brake shoes will maintain the wear pattern they have now, they will also deteriate quicker. My advice would be to run them out (wear them out) and then replace as a complete assemble at about $120 a unit from memory cheers blaze
Blaze - surprisingly the wear pattern on the shoes does not exactly match the barely visible wear pattern on the drum so I figure that grains of sand have entered the brake drum, rubbed and rolled along the shoe gouging a groove in the soft shoe material whilst only slightly scoring the steel drum. I'll take thge track you advise and wear them out.
my dual axle'van has electric brakes and is almost new. From the time I bought it, and no matter how much I adjust the electric brake controller, the 'van brakes grab as I brake to a stop, now matter how gentle with the braking I try to be. If a back the controller off too much, then the 'van pushes the tow forward when I brake, especially on loose metal etc
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Cheers Bruce
The amazing things you see when nomading Australia
my dual axle'van has electric brakes and is almost new. From the time I bought it, and no matter how much I adjust the electric brake controller, the 'van brakes grab as I brake to a stop, now matter how gentle with the braking I try to be. If a back the controller off too much, then the 'van pushes the tow forward when I brake, especially on loose metal etc
.. exactly the same as above with mine too .. only 10 months old.
The best I can achieve is to make any adjustment only after the brakes have reached operational temps .. (as my instructions determine) .. This has notably reduced the frequency of my need for adjustment.
I'm still pursuing a satisfactory remedy and will post if I find one ..
If I have the brake controller adjusted so the van brakes are effective at 90 klm/hr, they tend to lock up at low speed, particularly when almost stopped. The lock up is worse on very smooth bitumen. I've been using a prodigy controller for the last 4 years. It's so far ahead of the manual tenkosa (for adjustability) it's not funny.
my dual axle'van has electric brakes and is almost new. From the time I bought it, and no matter how much I adjust the electric brake controller, the 'van brakes grab as I brake to a stop, now matter how gentle with the braking I try to be. If a back the controller off too much, then the 'van pushes the tow forward when I brake, especially on loose metal etc
.. exactly the same as above with mine too .. only 10 months old.
The best I can achieve is to make any adjustment only after the brakes have reached operational temps .. (as my instructions determine) .. This has notably reduced the frequency of my need for adjustment.
I'm still pursuing a satisfactory remedy and will post if I find one ..
I do the same Jonathon, and often use different settings for city and country driving to compensate.
We did a great deal of research on this on the forum about a year ago,,, efficient brakes are warm/hot,,,, but not over heated.
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Why is it so? Professor Julius Sumner Miller, a profound influence on my life, who explained science to us on TV in the 60's.
Pulled the drum off the drivers side and found linings good but scoring where the magnet touches the brake drum. Then I looked at the magnet and found 1 wire broken where it enters the magnet. This must have been caused by flexing of the wire over time although van has only done about 30,000km over 7 years, you'd think the wire would last longer. Anyway, ordered 2 new off road magnets ($86 delivered) and will try sanding the grooved lining. Not sure about skimming the drums as it may cost more than buying new ones. Might even try it as-is just with the new magnets.
machining or smoothing the drums acutely lessons the surface area of contact if the shoes are scored . if grooves worked they would be made like it . i have been defected for scored drums on 1 of my trucks and had a rego refused for scored disks .
machining or smoothing the drums acutely lessons the surface area of contact if the shoes are scored . if grooves worked they would be made like it . i have been defected for scored drums on 1 of my trucks and had a rego refused for scored disks .
dibs
I can understand what you say dibs, however in my case the grooves in the drum are less than half a mm deep which is normal wear. The grooves in the shoes are over 1mm deep, irregular, and do not match the drum grooves which leads me to believe that abrasive material (sand grit etc) has entered the drum, rolled around and gouged/scored the brake shoe whilst not scoring the brake drum as the shoe is softer than the drum.
I've sanded the grooves out of the shoes so they are now quite smooth and will see how they go. The drums should be OK.
machining or smoothing the drums acutely lessons the surface area of contact if the shoes are scored . if grooves worked they would be made like it . i have been defected for scored drums on 1 of my trucks and had a rego refused for scored disks .
dibs
I can understand what you say dibs, however in my case the grooves in the drum are less than half a mm deep which is normal wear. The grooves in the shoes are over 1mm deep, irregular, and do not match the drum grooves which leads me to believe that abrasive material (sand grit etc) has entered the drum, rolled around and gouged/scored the brake shoe whilst not scoring the brake drum as the shoe is softer than the drum.
I've sanded the grooves out of the shoes so they are now quite smooth and will see how they go. The drums should be OK.
Regards
count the grooves measuring each one in width add them together that gives you lining surface area measure the width of the brake drum deduct the measurement you came up with of surface area on the shoe thats the contact your left with on your brakes . secondly you sanded the shoes smooth hmmm by hand ? or on a lathe or special milling machine . now you probably have hollows and humps on your shoes which lessons the contact of your brakes more . your van but in my eyes $200 odd dollars for new drums and shoes sounds safer to me .
count the grooves measuring each one in width add them together that gives you lining surface area measure the width of the brake drum deduct the measurement you came up with of surface area on the shoe thats the contact your left with on your brakes . secondly you sanded the shoes smooth hmmm by hand ? or on a lathe or special milling machine . now you probably have hollows and humps on your shoes which lessons the contact of your brakes more . your van but in my eyes $200 odd dollars for new drums and shoes sounds safer to me .
thats my opinion
dibs
G'Day Dibs, Thanks for your comments which I appreciate and respect and I fully understand where you are coming from - but I'm one of those buggers that likes to have a go a 'making do'. Yes, I appreciate odds on they won't be as smooth as new shoes and drums but the Avan Cruiser they help stop is just over 1 tonne so it's not like we are talking big stuff.
I'll roadtest them fully by using the boost lever on the P3 to get them hot and hopefully bed the shoes in. Then I'll remove the drums and check that the shoe surface is shiny over most of it's contact area. If it's not, or the brakes are grabbing or erratic I'll do as you suggest and rivet new linings onto the shoes and buy new drums. Just want to have some fun first.
So thanks for your comments which have made me do a bit more thinking.
