Front brakes dragging - Suzuki Z400 Forum : Z400 Forums
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post #1 of 11 (permalink) Old 11-14-2019, 10:40 AM Thread Starter
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Front brakes dragging

Long story short... 2 years ago i got some race driven pads. only installed the rears. 1 year ago, i installed the fronts, and then the quad sat unused... life, and other quads, have gotten in the way. couple months ago i tried moving the 400 and the front brakes drag pretty bad. enough that its hard to move, but i can get them to rotate when driving, i just come to a very quick stop when i get off the gas.

ive read that it can be a variety of things... collapsed brake line, master cylinder, calipers... basically anything involved in the brake system. but i also read that it can be brake pads that were too thick.

i sent an email to race driven to see if they have had reports of pads being too thick for that model, but im not counting on honesty in that regards, to say the least. anyone have experience with those pads?

more importantly, can anyone give me some sort of way to diagnose the issue? i cant just throw parts at it. IMO, and correct me if im wrong here, but i wouldnt think it would be the calipers, unless they both miraculously went out at the same time? same with brake lines. if one went, i would think it would be the one above the split? so... master cylinder, or upper brake line? or pads?
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post #2 of 11 (permalink) Old 11-14-2019, 12:55 PM
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Has it done this since the pad install? or Did it start after sitting? Brake fluid will hold moisture, and if the problem started after sitting a long time, I'm wondering if the calipers are sticking from some internal corrosion?

Something else I've encountered is bent spindles. It would become more noticeable with new pads. Loosen the caliper mounts and see if they try to stay parallel with the mount tabs, or if they WooterWooterWooterWooter to the side. Lonestar makes replacement spindles that are much stronger than stock.
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post #3 of 11 (permalink) Old 11-14-2019, 01:09 PM Thread Starter
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thanks for the response.

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Originally Posted by CFM View Post
Has it done this since the pad install? or Did it start after sitting? Brake fluid will hold moisture, and if the problem started after sitting a long time, I'm wondering if the calipers are sticking from some internal corrosion?

Something else I've encountered is bent spindles. It would become more noticeable with new pads. Loosen the caliper mounts and see if they try to stay parallel with the mount tabs, or if they WooterWooterWooterWooter to the side. Lonestar makes replacement spindles that are much stronger than stock.
im honestly not sure. idk if i rode it after the install... certainly not more than to shuffle machines around the shed/shop/garage.

are the spindles the rods that the caliper slides on?

sounds like what i need to do first is pull the calipers and see if there is any room left in the pistons to compress them farther. if not, then i think the pads would be to blame. if there is room for more compression, its likely something else. would compressing the caliper pistons free them possibly?
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post #4 of 11 (permalink) Old 11-14-2019, 02:45 PM
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Have you tried bleeding them? Had some guy on here awhile back that insisted swapping worn out pads with new thick pads didnít change the position of the caliper pistons. Like they would just magically know where to go and not be squeezing on the rotor. 🙄

'05 Z
94mm bbk, +4 stroker, Hot Cams, Vertex piston, FMF Power Bomb header and Power Core can, KW black diamond valves/dual springs, FCR39, K&N, Elka long-travel LT fronts and rear, Houser +3, +3/4 LT A-arms, American Star pro xs chromoly tie rods, Dyna non-programable, Tusk +3 axle.
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post #5 of 11 (permalink) Old 11-14-2019, 03:02 PM Thread Starter
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Quote:
Originally Posted by jetmech25 View Post
Have you tried bleeding them? Had some guy on here awhile back that insisted swapping worn out pads with new thick pads didn’t change the position of the caliper pistons. Like they would just magically know where to go and not be squeezing on the rotor. ��
are you saying that it is a requirement to bleed brakes after changing pads? sorry, but that is not accurate at all.

when you compress the piston into the caliper, the fluid squeezes back past the master and into the overflow. im not saying the thicker pads dont change the position of the caliper pistons, but new thicker pads dont require anymore magic than the calipers knowing which position to be in while they get thinner from use.

do a quick google search for "do i have to bleed my brakes after changing brake pads. youll see the answer is a universal... no.
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post #6 of 11 (permalink) Old 11-14-2019, 03:16 PM
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Calipers and master cylinders get stuck sometimes when forced open. Taking the pressure off may free them up. I’ve seen it said that it isn’t required, but I do it anyway and don’t have brake problems. ��Wooter♂️
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post #7 of 11 (permalink) Old 11-15-2019, 12:22 PM
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Good point Jetmech, I hadn't thought of that. I've seen that before too. Sometimes there's not room in the res for the extra fluid displaced from pushing the caliper pistons back in. Definitely try that first.


The spindles are pressed into the knuckles on each side in the front suspension. It is the part that the wheel hub mounts to. For racing, we try to make sure that everything moves freely, as to not waste any more energy than necessary. I have run across quite a few bent spindles, and the first sign is that the brake drags. If it has a bent spindle, and I loosen the caliper mount bolts, it usually takes away the brake drag. Then if you look close, you might see that the disk and caliper are trying to live at different angles than each other.

When I have found this, I press in new LSR spindles, and put everything back together. It all lines up, and you can spin the wheel freely, provided the other parts are good.

This is more of an outside the box thing, but it's worth a look. I've changed a lot of spindles.
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post #8 of 11 (permalink) Old 11-15-2019, 12:31 PM Thread Starter
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Quote:
Originally Posted by CFM View Post
Good point Jetmech, I hadn't thought of that. I've seen that before too. Sometimes there's not room in the res for the extra fluid displaced from pushing the caliper pistons back in. Definitely try that first.
try what first? bleeding the brakes? or making sure the master cyl res isnt over-full. the latter makes sense... not the prior.

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The spindles are pressed into the knuckles on each side in the front suspension. It is the part that the wheel hub mounts to. For racing, we try to make sure that everything moves freely, as to not waste any more energy than necessary. I have run across quite a few bent spindles, and the first sign is that the brake drags. If it has a bent spindle, and I loosen the caliper mount bolts, it usually takes away the brake drag. Then if you look close, you might see that the disk and caliper are trying to live at different angles than each other.

When I have found this, I press in new LSR spindles, and put everything back together. It all lines up, and you can spin the wheel freely, provided the other parts are good.

This is more of an outside the box thing, but it's worth a look. I've changed a lot of spindles.

id be very shocked if both spindles happened to bend. but i will certainly check alignment of the pads with the disc.
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post #9 of 11 (permalink) Old 11-15-2019, 01:31 PM
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Originally Posted by idiggplants View Post
try what first? bleeding the brakes? or making sure the master cyl res isnt over-full. the latter makes sense... not the prior.
Opening the bleeders briefly, would release any pressure that is in the system. An occasional flush by bleeding the brakes is good maintenance, and can pull some trash and moisture out of the system.
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post #10 of 11 (permalink) Old 11-15-2019, 01:47 PM Thread Starter
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Opening the bleeders briefly, would release any pressure that is in the system. An occasional flush by bleeding the brakes is good maintenance, and can pull some trash and moisture out of the system.
i do appreciate the advice, and flushing brake fluid is important maintenance, but that is not at all how the brake system works. when the brake isnt being applied, the system is vented/bled/depressurized into the reserviour. that's the entire purpose of a reserviour. the concept of bleeding the brakes to relieve pressure after compressing a caliper piston is an absolute exercise in futility.


in case anyone doesnt get what im saying.
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post #11 of 11 (permalink) Old 11-15-2019, 05:23 PM
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Just about every master cylinder Iíve looked at is overfilled, so it has nowhere to go. If youíre going to push the caliper pistons in, at least remove the reservoir cover so it has somewhere to go.

'05 Z
94mm bbk, +4 stroker, Hot Cams, Vertex piston, FMF Power Bomb header and Power Core can, KW black diamond valves/dual springs, FCR39, K&N, Elka long-travel LT fronts and rear, Houser +3, +3/4 LT A-arms, American Star pro xs chromoly tie rods, Dyna non-programable, Tusk +3 axle.
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