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Old 05-04-2011, 08:28 AM   #31 (permalink)
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reducing drum brake drag

I've noticed a similar issue on my '95 Metro. One indication of the problem is the amount of travel of the lever or pedal when setting the parking/emergency brake. My 92 Metro brake lever clicks 5+ to set the brake. My 95 just 3 clicks. There is a problem in the automatic brake adjuster that is allowing it to set the brake shoes so that they don't retract completely off the drum when not using the brakes. I've not gone back in to fix it but I think the adjuster is pretty simple star wheel and lever. If the lever is bent a little and engages the star wheel at the wrong point it could cause the brake to adjust too tight. I've noticed my mileage has suffered, I hope this improves things.

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Old 05-04-2011, 08:33 AM   #32 (permalink)
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Remove or block the automatic slack adjusters totally, and use the park brake cable adjustment for quick adjustments, then once a month, when you check your car over, etc, back the cables off and tighten the star wheel or whatever adjustment you have.

On my Golf, the adjuster is a wedge on a spring, so there isn't an easy way to stop it from doing its job, other than replacing the spring with an adjustable rod.
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Old 10-03-2011, 02:26 PM   #33 (permalink)
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Sorry if I'm bringing back a dead post but I'm currently trying to find a way to reduce my brake drag and Google poped this post up.
I'm starting with my front disks and will worry about my rear drums later.
There was a lot of talk in this thread but no numbers.

Only thing I have is that when jacked up spinning either of my two front wheels as fast as I can by hand they will only make it 3/4 of a turn once I let go of them.

I removed the brake caliper and pads and put the wheel back on and started spinning them again. They would make it 1&1/2 rotations and were much easier to start spinning.

Nothing is wrong with the brake system in my car so it's not an issue of a part that needs to be replaced.

I'm looking for sugestions, I know a small amt of drag is required for safty but i'd like to be able to get an extra 1/4 - 1/2 rotation out of the tires if spinning by hand.

I'm just getting into learning about cars so when I read a lot of do it yourself guides online I tend to get lost at times if they aren't detailed enough.
I heard in a few that there is some sort of square rubber seal that should pull back the brake caliper when you take your foot off the brake pedal. I also heard that you can get a slightly larger one to pull the brakes back a bit further. Anyone have any info or pics of this and if it's possible?

Also somone mentioned hooking up a spring to pull the brakes back when not in use. Anyone have any info on how something like that would be set up.
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Old 10-05-2011, 12:43 AM   #34 (permalink)
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brake caliper seal cup is a spring

the brake caliper piston seal / ccup is really a spring , the rubber seals the piston but also pulls back a wee bit after the brake is released , if the rubber is worn or cracked , the return spring function is diminished or non existent , keep the caliper slides free of rust and well lubed with sil glide or silicone based grease designed for that purpose and , make sure the pads float and can slide easily in their mounting bracket , they must not be stuck in place or binding in the mounts , they must move freely , mounting points must be free of rust and must have the same brake grease applied .

sil glide has anti rust chemicals in the grease , it will turn bare steel black .

drive the car at 60mph long time , use the brake as little as possible , after stopping , measure rotor temp with infared temp probe or the back of the fingers , no rotor should be warmer than the rest and none should be hot to the touch . a binding brake will heat the rotor , bigger binding = higher temp , temps can easily reach 500f on a binding brake , so use the back of your finger and approach the rotor slowly ... better to use an infared temp probe
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Old 10-05-2011, 08:47 AM   #35 (permalink)
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Quote:
Originally Posted by Fr3AkAzOiD View Post
Sorry if I'm bringing back a dead post but I'm currently trying to find a way to reduce my brake drag and Google poped this post up.
I'm starting with my front disks and will worry about my rear drums later.
There was a lot of talk in this thread but no numbers.

Only thing I have is that when jacked up spinning either of my two front wheels as fast as I can by hand they will only make it 3/4 of a turn once I let go of them.

I removed the brake caliper and pads and put the wheel back on and started spinning them again. They would make it 1&1/2 rotations and were much easier to start spinning.

Nothing is wrong with the brake system in my car so it's not an issue of a part that needs to be replaced.

I'm looking for sugestions, I know a small amt of drag is required for safty but i'd like to be able to get an extra 1/4 - 1/2 rotation out of the tires if spinning by hand.

I'm just getting into learning about cars so when I read a lot of do it yourself guides online I tend to get lost at times if they aren't detailed enough.
I heard in a few that there is some sort of square rubber seal that should pull back the brake caliper when you take your foot off the brake pedal. I also heard that you can get a slightly larger one to pull the brakes back a bit further. Anyone have any info or pics of this and if it's possible?

Also somone mentioned hooking up a spring to pull the brakes back when not in use. Anyone have any info on how something like that would be set up.
Take the front brake pads out and the wheels will still not turn much more than before. The drag is primarily in your differential and transmission output shaft.

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Old 10-05-2011, 12:26 PM   #36 (permalink)
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Quote:
Originally Posted by Old Mechanic View Post
Take the front brake pads out and the wheels will still not turn much more than before. The drag is primarily in your differential and transmission output shaft.

I did that.
Rotation was 0.75 with pads in and 1.5 with pads removed.
Rotation was cut by 50% due to brake drag.


I will get some brake cleaner and grease and clean them up to see if they work any better.
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Old 10-05-2011, 01:59 PM   #37 (permalink)
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Follow mwebb's advice.
If the pad drag is equal the differential drag then you should be able to improve that.
Rebuild calipers
Turn rotors Make sure the floating pins are free and not binding.
Flush the system with new brake fluid
Make sure the brake hoses are not restricting fluid flow.

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Old 10-06-2011, 12:12 AM   #38 (permalink)
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*sigh*

Ok, was driving home from work, had been doing 45 mph for around 30 miles and hadn't touched the brakes for a least 10 miles.
There is an intersection at the top of a hill and the side street is a business park so it's empty at night.

I slow down going up the hill then take the turn and drop to second gear and once my speed drops into the teens I use e-brake to stop.

I check rotors with the back of my hand and don't feel any heat.
Feeling a bit foolish I touch the rotor, stone cold.
Check both inside and outside of both front rotors and it's the same deal.

So I figured that once the car gets warmed up maybe the brakes aren't dragging.
I get home and immediately jack the front of the car up and give one of my front wheels a spin.

Same 0.75 rotation.

I am left baffled...

Friction creates heat.
The brake drag makes enough friction to cut their spin amount by 50%.
Then after going 45 mph for 30 miles the brake pads should be hot or at least warm.


*idea*

I have a slight down slope from my garage to the end of my driveway. I'm thinking of just doing a couple of drift runs and timing how long it takes to get 1/2 down my driveway and then pulling the front brakes and doing it again and using the e-brake to stop.
I doubt I'll be going any more then 10 mph so it shouldn't be a problem.

That way if it's only like a 5% difference I'll just forget about it but if it's 10%+ it will be worth looking into.

Problem being this would be the third day I have had off that I ended up playing grease monkey and I think I've pushed that bit far enough with the misses.
This may have to wait a week.

Anyone see any dangers is doing this?
Obviously I would do 2 or 3 dry runs with the brakes in place using e-brake to stop just to make sure.
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Old 10-16-2011, 02:27 AM   #39 (permalink)
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I pulled out the auto adjusters from my Civic's rear brakes. The shoes were definitely dragging before I did this.

I know the front pads aren't dragging. I have no anti-rattle clips on the calipers and I can hear the pads rattle on bumps at low speeds.
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Old 10-16-2011, 08:08 AM   #40 (permalink)
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Excellent thread.

I used to be one of those that bought into the hype of 4 wheel discs. I still believe they do belong on the front as they do provide better braking, particularly in hilly areas where heat build up becomes a factor.

At the rear, I'll take drums any day since rear brakes do little in normal driving. Also, changing the pads on rears can be a PITA due to the ebrake. I still have a big C clamp that I bent trying to push the piston back on my old supra. Read the manual afterwards to discover they were screw in.

Also, rear drums last pretty much forever.

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