Advice please, front brake caliper woes!
Discussion
Hi all, looking for a bit of advice please.
I suspected my OSF brake has been sticking so thought I'd investigate, once I got the car on axle stands the thing was so bloody stuck I could hardly turn the wheel on the hub. Took the whole thing apart and wanted to see the condition of the brake piston so pumped the pedal a few times and the piston doesn't move out from the caliper, level of brake fluid in master cylinder doesn't move, no visible leaks anywhere - took the NSF apart and it appears fine, piston moves out and brake master fluid level drops a little when pedal pumped.
Any ideas folks - I'm thinking either the caliper/piston/seal is buggered or I've read the brake lines can collapse internally, any easy (and cheap!) way to get to the bottom of this without having to buy a new caliper?
Thanks in advance
I suspected my OSF brake has been sticking so thought I'd investigate, once I got the car on axle stands the thing was so bloody stuck I could hardly turn the wheel on the hub. Took the whole thing apart and wanted to see the condition of the brake piston so pumped the pedal a few times and the piston doesn't move out from the caliper, level of brake fluid in master cylinder doesn't move, no visible leaks anywhere - took the NSF apart and it appears fine, piston moves out and brake master fluid level drops a little when pedal pumped.
Any ideas folks - I'm thinking either the caliper/piston/seal is buggered or I've read the brake lines can collapse internally, any easy (and cheap!) way to get to the bottom of this without having to buy a new caliper?
Thanks in advance
Thanks Simon, I was hoping it wasn't the caliper though, I'd read on another thread (which I now can't find) that someone had experienced the same problem, replaced the caliper, only to find it wasn't the problem and that one of the flexible brake lines had collapsed internally and needed replaced, a much cheaper fix.
I'd rather not swap out parts I don't need to but I suppose I could replace the cheaper flexible brake line and hope it does the trick, at £70 for a caliper or £19 for a hose I know what I'd rather it was
I'd rather not swap out parts I don't need to but I suppose I could replace the cheaper flexible brake line and hope it does the trick, at £70 for a caliper or £19 for a hose I know what I'd rather it was
beeblebrox said:
Why not swap the front calipers over (for diagnostic purposes, not driving obviously 
) and then see if you can actuate the piston with the pedal? Bit of a faff, but would allow you to narrow down the culprit.
Great idea! I'm going to have to take them off either way, so may as well give it a try. Thanks.) and then see if you can actuate the piston with the pedal? Bit of a faff, but would allow you to narrow down the culprit.MX-5 Lazza said:
If you suspect the brake line why not just try bleeding the calliper? If you can bleed it ok then the brake line is fine
Another good, simple idea that I really should've thought of.That's what happens when you've been out working on your car all day and hit problems when you try and put it all back together when it's late, you're tired, cold and have scraped, bloody knuckles - the ability to think clearly for yourself goes out of the window!
Thanks again all.
Or open the bleed nipple and push the piston back into the caliper, if it wont budge then its stuck. Check to make sure the piston is 'true' to the caliper, put something flat over it (the flat middle bit of a big combi spanner) and and give it a gentle rock.
If the copper/steel lines have callapsed you will be able to see/feel it as they will be flat or creased. Give them a good butchers, the break line routing on an MX5 is very very simple.
TBH its not a hard job stripping a caliper and renewing the seal, but getting the seized piston out will be a git.
If the copper/steel lines have callapsed you will be able to see/feel it as they will be flat or creased. Give them a good butchers, the break line routing on an MX5 is very very simple.
TBH its not a hard job stripping a caliper and renewing the seal, but getting the seized piston out will be a git.
Odie said:
getting the seized piston out will be a git.
as suggested I tried bleeding both front calipers which proved the lines were all ok - the OSF caliper piston is stuck, properly corroded rusted stuck! So, new seals, washers, bleed nipple and piston have been ordered, and the old piston WILL be removed tonight with a combination of heat and a vice...and failing that brute force.tbh if it's not popping out with you stamping on the pedal, it's going to take a *lot* of brute force to get it out by manual means.
having refurbed calipers myself, for the hassle and time it takes you're much better off getting a p/x recon.
still, you'll learn that for yourself soon enough
having refurbed calipers myself, for the hassle and time it takes you're much better off getting a p/x recon.
still, you'll learn that for yourself soon enough
I know I'm probably doing things the hard way, but I'd anticipated the piston coming free with a bit of effort and had already ordered all of the parts to refurb (all due to arrive tomorrow) the caliper, so I may as well give it a go.
If I do get the piston out, I'll post up how I did it, might even throw in some photos as it seems it's a common problem! I have a bench vice and a large rubber mallet, so I know how I'm going to go about it
If I do get the piston out, I'll post up how I did it, might even throw in some photos as it seems it's a common problem! I have a bench vice and a large rubber mallet, so I know how I'm going to go about it
Edited by anonymous-user on Tuesday 26th April 11:50
yellowbentines said:
I know I'm probably doing things the hard way, but I'd anticipated the piston coming free with a bit of effort and had already ordered all of the parts to refurb (all due to arrive tomorrow) the caliper, so I may as well give it a go.
If I do get the piston out, I'll post up how I did it, might even throw in some photos as it seems it's a common problem! I have a bench vice and a large rubber mallet, so I know how I'm going to go about it
Got to love percussive engineering. If I do get the piston out, I'll post up how I did it, might even throw in some photos as it seems it's a common problem! I have a bench vice and a large rubber mallet, so I know how I'm going to go about it
Edited by yellowbentines on Tuesday 26th April 11:50
Good luck!
If you get totally stuck, maybe run it through a shot blaster to get rid of the worst of the corrosion? If you're near Cheltenham, you're welcome to borrow mine!
Brute force it was, lubricant/freezing spray down into the bore of the caliper through the brake pipe inlet, a vice and a big wrench, lots of twisting - job done! Piston and seals were knackered so everything replaced, cleaned up and back together.
I'd consider myself an amateur mechanic but I managed it. The seals, piston and bleed nipple were super cheap from www.brakesint.co.uk (cheaper than the mx5 specific places as they sell the piston seal and dust boot without caliper slider rubbers if you don't need them), and this guy's youtube video is a great help on how to re-fit the piston, seals and dust boot - http://www.youtube.com/watch?v=QXcClOfFmlg
I'd consider myself an amateur mechanic but I managed it. The seals, piston and bleed nipple were super cheap from www.brakesint.co.uk (cheaper than the mx5 specific places as they sell the piston seal and dust boot without caliper slider rubbers if you don't need them), and this guy's youtube video is a great help on how to re-fit the piston, seals and dust boot - http://www.youtube.com/watch?v=QXcClOfFmlg
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