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Discussion Starter #1
Since everyone seems to be so knowledgable on all things quad, here's one for ya ...

I've been working on my Honda 400EX for awhile installing +2 arms, new brake rotors, new hubs and bearings, etc. and ran into a problem yesterday. I just finished getting the thing back together but cannot figure out why I have a terrible front brake drag on one side. The hub seems to spin fine with the caliper in position but as soon as I tighten the mounting bolts, the rotor drags on the pads virtually preventing any rotation whatsoever. I've taken the pads out of the caliper and checked for any debris, reinstalled them, and it still drags. Is something wrong with the caliper itself in terms of the piston or something? Would it just be the brake pads themselves?

Please help, I'm completely clueless at this point. Thanks.
 

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Since everyone seems to be so knowledgable on all things quad, here's one for ya ...

I've been working on my Honda 400EX for awhile installing +2 arms, new brake rotors, new hubs and bearings, etc. and ran into a problem yesterday. I just finished getting the thing back together but cannot figure out why I have a terrible front brake drag on one side. The hub seems to spin fine with the caliper in position but as soon as I tighten the mounting bolts, the rotor drags on the pads virtually preventing any rotation whatsoever. I've taken the pads out of the caliper and checked for any debris, reinstalled them, and it still drags. Is something wrong with the caliper itself in terms of the piston or something? Would it just be the brake pads themselves?

Please help, I'm completely clueless at this point. Thanks.
Try cracking the bleader screw to see if any pressure is in the caliper, then bleed the brakes and see what happens.
 

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Discussion Starter #3
I've bled the brakes more times than I could count. I installed new stainless lines with the longer a-arms so bleeding was the first thing I had to do. There is pressure built up as the caliper will squirt fluid if cracked open.
 

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How old are the calipers? Sounds like they might be do for a rebuild. They could be sticking causing your drag.

The other thing is the rotor dragging on something besides the pad. Is it only dragging on one pad or both pads? Are you sure you got the correct hubs, rotors,etc? if they are offset incorrectly it would cause a drag. Go mount everything up besides the wheel and thoroughly inspect it to see where it is dragging at and if the caliper is possibly sticking. Let us know :D




Paul
 

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As stated above is both sides sticking or just one. If just one side is sticking then you may have a missalignment where the banjo fitting holds the line to the junction block or master cylinder. Also there could be a blockage in the line causing the fluid to not return to the master cylinder. If only one side is sticking try installing the old brake lines and see if the problem is still there. Blow some clean air threw each brake line both ways to see if there is a blockage inside the line. In the auto industry sometimes a piece of rubber can come loose inside the line and act like a trap door allowing fluid to only travel one way.
 

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Discussion Starter #6
Only one side is dragging. Before mounting everything up, both calipers seemed to have good pressure in the lines. The hubs are OEM replacements and the brake rotors are correct for the application. I guess I am just wondering why all of the sudden one side doesn't work. Before I changed brake lines and rotors, everything seemed fine. It seems as though the rotor is only dragging on the "outside" pad, that is the one further away from the piston. It doesn't matter if the wheel is on or not, still doesn't work. Could it have something to do with the new hub bearings and the hub nut itself not being tight enough or something? It seems like if it was tighter it would prevent the hub from spinning, and if it was looser the cotter pin wouldn't stand a chance.

I'm confused.
 

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Can you push the piston all the way inside the caliper, you may have to lube the pistons with some WD-40 or equivelant lube. Sqeeze the brake and alow the piston to come out but not to far and then lube the piston and compress it back in. See if that frees it up. Also when everything is mounted and it is sticking can you releive the pressure by opening the bleader. meaning if the brakes are dragging with the brake lever released and you open the bleader do the brakes free up.

There are 4 pistons in each caliper so you may have one sticking, or possibly a block in the new line.

You can also swap sides with each part one at a time to see witch one is causing it. I would start with the calipres, then the lines. I know it's a pain and alot of brake fluid lost but its the only way to isolate the problem. Let me know what you come up with.
 

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Discussion Starter #8
Can you push the piston all the way inside the caliper, you may have to lube the pistons with some WD-40 or equivelant lube ... Also when everything is mounted and it is sticking can you releive the pressure by opening the bleader. meaning if the brakes are dragging with the brake lever released and you open the bleader do the brakes free up.

There are 4 pistons in each caliper so you may have one sticking, or possibly a block in the new line.
By the looks of it, this quad is only a single piston or possibly a dual setup, but not four like on the KTM. I will try to lube the internals to see if that helps because it does seem like it is sticking. If I open the bleeder valve, the dragging still occurs. I'll have to put more time into it on Wednesday when I'm off. This project is never-ending, I swear. I'm about ready to pay somebody else to do it :angry:
 

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Sorry I wasnt paying attention to the 400ex part. Everything still aplyies for the brakes though. It does sound like you might have an alignment issue. Try swapping the hubs and see if what happens maybe you got a part that was machined wrong.
 

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Sorry I wasnt paying attention to the 400ex part. Everything still aplyies for the brakes though. It does sound like you might have an alignment issue. Try swapping the hubs and see if what happens maybe you got a part that was machined wrong.
I'm not familiar with 400ex front calipers but if it is a single piston it sounds like tha caliper slide pins are seized up. Remove the pins and coat them in a moly type grease.
 

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I'm not familiar with 400ex front calipers but if it is a single piston it sounds like tha caliper slide pins are seized up. Remove the pins and coat them in a moly type grease.
Found a break down of the front caliper







Buy mounting bracket I am assuming that you are talking about #8 and are tighting it down with bolts #24 when the hub locks down. You need to remove pins #11 & #13 and lube them up. Hope this helps
 

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If you installed new hub bearings im assuming you installed new bearing races also. You may have not seated the bearing race on the inside bearing and that may be causing it sit a little further out. Just a thought.
 

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Ya if its the outside pad dragging only check the slides. The caliper isnt sliding into the correct position, which is why its dragging. If it was the caliper piston, the inside pad would be dragging, not the outside fyi. :D





Paul
 

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Discussion Starter #14
If you installed new hub bearings im assuming you installed new bearing races also. You may have not seated the bearing race on the inside bearing and that may be causing it sit a little further out. Just a thought.
The hubs come from Honda pre-assembled with both bearings, dust caps, etc. already pressed and ready for mounting. I examined each and they appeared to be correctly assembled and were identical to the stock ones.


Ya if its the outside pad dragging only check the slides. The caliper isnt sliding into the correct position, which is why its dragging. If it was the caliper piston, the inside pad would be dragging, not the outside fyi. :D

Paul
I'm not sure what you mean by "slides?" I've pulled the long pins out already (#21 I think) to check the condition and remove the pads but I don't think that is what you are referring to. Please clarify. Thanks!
 

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Try mounting the hub on the other side then try the caliper on the onther side and see if the problem follows the hub or the caliper. That should norrow things down alittle.
 

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your caliper is not sliding freely on the caliper pins, I've seen this numerous times on various quads..... strip it down, probably got gunk or even rust on one or both pins sticking it in the rubber sleeves. Clean the pins and lube with some water proof grease and the caliper will float on the pins like it is supposed to.
 

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By mounting bracket I am assuming that you are talking about #8 and are tighting it down with bolts #24 when the hub locks down. You need to remove pins #11 & #13 and lube them up. Hope this helps
 
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