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Discussion Starter #1
Taking my '73 Spider out of hibernation here in Oregon where winters are damp and the front brake calipers are holding onto the discs. Not completely bound (with the wheels off the ground I can rotate them ever so slowly with great effort) but the car does not roll freely as it should. I have less than 2,000 miles on a complete brake rebuild of calipers discs and brake pads. What gives? What is the mechanism that should spring the pads back to the "off" position?
 

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But Mad North-Northwest
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Did you replace the rubber brake hoses? If not that's very likely your problem.
 

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Discussion Starter #3
Actually, I don't know if those have been replaced. Can you elaborate on the reason to replace or what would be the cause of failure?
 

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But Mad North-Northwest
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They can fail internally and act like a check valve holding fluid pressure on the caliper. If you didn't replace them you really should, it's a reasonably easy job.
 

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There is no mechanism! Well, the rubber seals in the caliper bores grip the pistons. When the brakes are applied the seals distort slightly. When the brakes are released & the seals relax they are supposed to pull the pistons back slightly.

The rubber brake hoses can delaminate internally causing them act like one-way valves. A quick test is to apply & release the brakes and note if the brakes are dragging. Then open a bleed screw. If a little bit of brake fluid immediately comes out and the brakes fully release the rubber hoses are suspect. Don't forget to close the bleed screw!

If cracking open the bleed screw doesn't make any difference (meaning the rubber hoses are likely not the problem) I'd suggest you try this. Remove one brake pad then have your trusted assistant press the brake pedal while you watch that piston. When it has protruded about 1/4" have her release the pedal. You should see the piston retract very slightly. If so, all is well. Use a strip of rag wet with brake fluid to clean off the exposed piston. Push the piston back into the caliper then repeat with the other pad and then the other caliper.

Or, just drive it... The little bit of free play in the hub.rotor will tend to push the pads/pistons away. As long as they are not dragging so much that the brakes are locked on it will probably improve itself over a few miles.

Something else to consider is to flush some fresh brake fluid through the system. Brake fluid is hygroscopic - it absorbs H2O. Flushing fresh fluid through will remove the absorbed brake fluid with fresh.
 

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Discussion Starter #6
Thank you for the replies! It is a beautiful, sunny Spring day here in Portland and I can imagine nothing I would rather do , besides driving fast with the top down, than crawling under the car. No, seriously. It just helps to have reason to do it with a goal in mind to fix the problem. :cool: I hope I can come back soon and post the result.
 

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I'd take it out and drive it on a safe road somewhere and use the brakes a few times....then bring it back and see if the wheels turn easily once jacked up.

if a shop did the full brake rebuild , they would 'likely' have replaced the hoses...they'd be listed on the invoice.
(imo, it is kinda odd that both front hoses should fail together)

and the rear wheels turn easily?
 

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if a shop did the full brake rebuild , they would 'likely' have replaced the hoses...they'd be listed on the invoice.(imo, it is kinda odd that both front hoses should fail together)
I wouldn't count on the fact that every shop would automatically replace the hoses. But if the brake job was only done 2,000 miles ago, you should be able to tell visually: If the plating on the hose fittings is still shiny, they probably were replaced. If they're corroded, probably not. But as spiderserie4 says, it would odd for both hoses to fail together.

Did the brakes function OK for the 1,999 miles following the brake work?

and the rear wheels turn easily?
Good question!
 

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Discussion Starter #9
Thank you for the replies! It is a beautiful, sunny Spring day here in Portland and I can imagine nothing I would rather do , besides driving fast with the top down, than crawling under the car. No, seriously. It just helps to have reason to do it with a goal in mind to fix the problem. :cool: I hope I can come back soon and post the result.
I'd take it out and drive it on a safe road somewhere and use the brakes a few times....then bring it back and see if the wheels turn easily once jacked up.

if a shop did the full brake rebuild , they would 'likely' have replaced the hoses...they'd be listed on the invoice.
(imo, it is kinda odd that both front hoses should fail together)

and the rear wheels turn easily?
All's well that ends well! I took the advice of Gubi and Ghnl and opened bleeder valve ever so slowly and slightly which does seem to have relieved the pressure on the piston. One wheel immediately rotates freely and the other a little less so but still fine to drive. Now I can get it home from storage and do a proper job of replacing the hoses and inspecting the whole setup at my leisure.

Thanks folks!
 
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