Rattling Brake Pads on std 76 xs650c

Byarchie

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Hi has anyone come across this problem. i have twin discs and from the moment i start it the pads rattle in the calipers from tickover and on the move. The calipers have been rebuilt and have new lines with ebc pads in. If i just touch the brake lever it all goes away and is temporarily bliss. They function well in pulling up the bike and have std shims behind the pads. Any suggestions would be welcome. I dont know if it previously did it because it had stood for 25 years when i bought it.
 
Did you look at a parts diagram to see if you have all the parts?
 
vastly different. Do your shims have a bend to add spring that you can increase? Can you add a second shim? Are you sure the pistons are all moving freely? You might be able to jam some thin cardboard in places to find out exactly what's rattling. If you're sure everything is right and they still rattle, you might look into some disc brake squeal compound, which might damp it some.
 
have the calipers been rebuilt? if the seals have gunk built up behind them (always do over time) the piston does not slide freely out across the seal. so when you let go of the lever, the rubber seal pulls the piston back slightly from the disk, this leaves a little gap so the pads have room to rattle. A slightly warped disk might push the pistons back enough to cause this also. Are the pads wearing straight? I've seen some pads that were seriously worn at an angle.
 
The shims don't appear to have a curve in them should they? The calipers have been rebuilt with new pistons and seals. The discs have no warpage and pad wear is even. Get this sorted it will be a lovely bike
 
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I'm wondering about a bent axle or bent fork that could cause the pads to widen like a warped rotor would do. I don't see how a bent fork could do it, but an axle bent in the right place could do this. But then, I've never heard of bent axles.

Scott
 
Raise the front wheel and hold something against the fork and close to the rotors, like a poor man's dial gauge, spin the wheel to see if the rotors turn true without wobbling. Isn't there a clearance to check at the caliper/rotor when tightening the axle on dual brake models?

Scott
 
As gggGary mentioned the seal pulls the piston back a little bit, it's supposed to do this. This lets there be enough room between the pads and rotor to prevent dragging.
I have a 75 that I installed a later 35 mm front end and dual disc set up. When stock, using the stock pads, The pads fit snuggly into the caliper. No rattle. Perhaps your after market pads don't fit as snuggly as stock, Do you have enough stock pads to install them in your calipers? If so do this and see if the rattle changes.
I detest RTV, But this is one place I might use it. Put a line around the end of the piston, not to much, don't want excess causing trouble.
Install pads. Use the brakes to seat pads to pistons, This "glues" the pads to the piston, This should stop any rattle.
Leo
 
Just a general comment - brake squeal and other noises are one of the most common and vexing issues that auto dealers have to handle with new car customers. It seems like a totally random thing - some cars are noisy and others aren't and the fix isn't the same for every car.
 
Hi has anyone come across this problem. i have twin discs and from the moment i start it the pads rattle in the calipers from tickover and on the move. The calipers have been rebuilt and have new lines with ebc pads in. If i just touch the brake lever it all goes away and is temporarily bliss. They function well in pulling up the bike and have std shims behind the pads. Any suggestions would be welcome. I dont know if it previously did it because it had stood for 25 years when i bought it.
I have a '76 with exactly the same issue. Everything is rebuilt, all parts are there. Disc runs true. I tired CRC orange Disc Brake Quiet which typically works for this issue in my cars, but it did not ameliorate the rattle. So, I'm interested in further ideas .....
 
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vastly different. Do your shims have a bend to add spring that you can increase? Can you add a second shim? Are you sure the pistons are all moving freely? You might be able to jam some thin cardboard in places to find out exactly what's rattling. If you're sure everything is right and they still rattle, you might look into some disc brake squeal compound, which might damp it some.
I would be interested in a suggestion as to what part of the '76 metal shim might possibly be bent a bit to cure this issue:

08-6007.jpg
 
Checked the rotors were running true everything is spot on. I turned the workshop inside out today and found the pads that came fitted on the bike which I have never used. Fitted them and the rattling has gone on the move still slightly there when blipping the throttle on the stand. Now then the vesrah pads are half worn meaning the pistons are further out, might they work better than fully retracted with new pads. Or maybe the new ebc pads don't fit as well. Progress but not cured yet
 
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I would be interested in a suggestion as to what part of the '76 metal shim might possibly be bent a bit to cure this issue:
I meant if it was supposed to have a bend, was the bend still enough. My '81 brakes have a kind sheet metal spring spider that takes care of some of this. As a last resort if you know everything is right but still have the problem, I like Leo's idea of some mild glue or brake compound to glue the piston to the shim to the pad. I would wrap something around the lever and let it dry overnight like that. It will probably eventually degrade, but maybe it will have enouhg road gunk in it at that point to do the job.
 
Gotta ask the simple question........You're pumping the brake up till you get a hard feel on the lever after installing these pads and calipers, right?

I'm thinking a sandwich of construction adhesive, thin gasket material and another layer of construction adhesive. The gasket will give a separation point when changing the pads again. Yeah, last resort.

Scott
 
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