stevie_b Posted July 6, 2012 Author Share Posted July 6, 2012 Interesting. If I changed to UK brakes would I need to change the brake discs as well? Quote Link to comment Share on other sites More sharing options...
Dnk Posted July 6, 2012 Share Posted July 6, 2012 The piston bore is a clearance fit to the piston so i don't see that being a problem, any surface rust as long as its not eaten the bore away can be simply removed with a medium grit 600 ish wet & dry paper, the critical area is the undercut where the seal fits. Quote Link to comment Share on other sites More sharing options...
Dnk Posted July 6, 2012 Share Posted July 6, 2012 Interesting. If I changed to UK brakes would I need to change the brake discs as well? Yes and modify or remove the back plates Quote Link to comment Share on other sites More sharing options...
Nic Posted July 6, 2012 Share Posted July 6, 2012 Interesting. If I changed to UK brakes would I need to change the brake discs as well? You'll need, calipers, discs, pads, pad fitting kit and anti-squeal shims. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2012 Share Posted July 7, 2012 I have stainless Jap spec rear pistons in stock, and seal kits. The casting fracture around the nipples on J-Spec calipers is ONLY caused by overtightening. You can apply TOO MUCH tightening torque with a 4 inch long 10mm spanner and your little finger. They need to be just NIPPED up. Read the manual, torque specs in there, but not many people will have such a low torque capable torque wrench. It's not a crank pulley bolt Quote Link to comment Share on other sites More sharing options...
Dnk Posted July 7, 2012 Share Posted July 7, 2012 I would guess the UK calipers get over tightened in exactly the same way but they don't seem to fall apart even though there the same age. Quote Link to comment Share on other sites More sharing options...
Nic Posted July 7, 2012 Share Posted July 7, 2012 The piston bore is a clearance fit to the piston so i don't see that being a problem, any surface rust as long as its not eaten the bore away can be simply removed with a medium grit 600 ish wet & dry paper, the critical area is the undercut where the seal fits. I used an old piston held with pliers and some fine grinding paste to clean up the bores, did the same with some old slider pins and where the slider pin seals seat an old 14mm socket with grinder paste. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted September 30, 2012 Author Share Posted September 30, 2012 Thread resurrection, but I'll be doing this soon. What do you guys use to prevent brake fluid loss when you remove the brake hose from the caliper? I know from this thread that one or two people use a brake hose clamp: any other choices (e.g. a bung) as I don't want to damage the hose. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted September 30, 2012 Share Posted September 30, 2012 Suitable sized through bolt and nut, with a Dowty seal either side of the union. You could use the original copper crush washers but the shape of the bolt underhead could indent them and make sealing against the original banjo bolt iffy when you put it back together. But why not just let the fluid drain away into a tin or jar? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted October 1, 2012 Author Share Posted October 1, 2012 I intend to refurb both the front calipers at the same time, so letting the fluid drain would make getting the pistons out on the other caliper tricky. Just in case I decide to drain and renew the brake fluid, are there any gotchas associated with draining the fluid right down? I remember reading something somewhere about letting the brake master cylinder empty out and the extra step(s) then needed to bring the system back to a working state. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted October 1, 2012 Author Share Posted October 1, 2012 PS do you happen to know the size of the through bolt I'd need? I'd like to get one ready before I start undoing things. Quote Link to comment Share on other sites More sharing options...
Dnk Posted October 1, 2012 Share Posted October 1, 2012 I'd replace the hoses at the same time if there the original rubber type. Quote Link to comment Share on other sites More sharing options...
Nic Posted October 1, 2012 Share Posted October 1, 2012 I intend to refurb both the front calipers at the same time, so letting the fluid drain would make getting the pistons out on the other caliper tricky. Remove a caliper, cable tie/wire it up so it's not hanging from the brake line then press the brake pedal to push out the piston, do the same with each caliper. Once you have all the pistons out then disconnect the brake lines. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 1, 2012 Share Posted October 1, 2012 Just block the pistons from coming right out in one caliper, then address the other, which you have left on the disc with pads still in. When both calipers have their pistons nearly all the way out disconnect the hoses. Bleeding a fully emptied system is no different, nor harder, than a full one, just takes a bit longer, and uses more fluid, of course. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted October 1, 2012 Author Share Posted October 1, 2012 That's reassuring about filling a system from empty being no harder than a small top-up and bleed. It probably sounds like I'm making excuses not to do a full drain-down, but I'd also like to refurb the rear calipers whilst I'm at it. I'll be taking the calipers off with the car in my (small) garage. So, what I'll do is reverse the car into the garage, jack the front up, support with axle stands, take off the front calipers (one caliper at a time preferably as I haven't stripped one down before, but I could take them both off at the same time if I need to), fit the refurbished calipers back on, drive the car out and re-park it nose-first into the garage, jack the rear up and then refurb the rear calipers. If I drain all the fluid out when doing the fronts, I'd need to put some back in to then do the rears. I don't want to do all 4 corners at once: the garage isn't big enough to get to all 4 corners simultaneously, and as I haven't done it before I'd rather disconnect as few calipers as possible in case I find I don't have the tools or skills to see it through. How close to being nearly out do the pistons have to be before disconnecting the brake hose? 5mm? 10mm? I'm just after a rough idea of how you'd do it in my position. I don't want to pop a piston and squirt brake fluid all over the garage floor, but I don't want to remove the caliper which I then can't extract the pistons from. If it helps, I'm pretty sure the pistons are not seized. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 3, 2012 Author Share Posted November 3, 2012 Would the car be driveable (i.e. moveable) with the front calipers completely removed and the brake hoses plugged and secured out of the way of the wheels? I can't see why not, but I intend to get the car out of my garage (not enough room to work inside the garage), take the calipers off, and put the car back inside the garage so I can refurb the calipers at my leisure. Just so we're in no doubt, by "driveable", I intend to drive it in a straight line, very slowly, for about 10 metres, that's all! I'm not going to be cruising around like that. Presumably I can still use the handbrake to stop the car if I seal off the disconnected brake hoses instead of letting the fluid drain out? Can anyone confirm what size banjo bolt the brake hose connection to the caliper uses? I know Digsy thought it was M10 but I'd like to know for sure before taking the banjo bolt off. Quote Link to comment Share on other sites More sharing options...
Dnk Posted November 3, 2012 Share Posted November 3, 2012 (edited) Yes that would be fine The handbrake has nothing to do with the cars main brakes so wont affect the brake fluid or calipers when you operate it Just make sure the handbrake stops the car before you need it to, some don't work that well Edited November 3, 2012 by Dnk (see edit history) Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 3, 2012 Author Share Posted November 3, 2012 Does that mean that the handbrake can operate even when there's no fluid in the braking system? Quote Link to comment Share on other sites More sharing options...
Dnk Posted November 3, 2012 Share Posted November 3, 2012 (edited) Does that mean that the handbrake can operate even when there's no fluid in the braking system? Correct t The handbrake shoes and mechanism sit inside the rear discs Look at page BR-60 in the attachmentBR.pdf Edited November 3, 2012 by Dnk (see edit history) Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 3, 2012 Author Share Posted November 3, 2012 Thank you Dnk, that's a big help. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted November 3, 2012 Share Posted November 3, 2012 BEWARE!! Of course, you can idle the car around or do 100 MPH with no calipers at all on the car, the handbrake is cable operated and totally mechanical in nature, but on cold start, fast idle, an auto box car may have enough torque, when in drive or reverse, to overcome the handbrake. Let it warm to a slow idle, and be ready to knock into neutral when you want to stop. The MKIV has quite a powerful handbrake if it's working correctly, so I would have no qualms about doing what you say at all. In fact, someone I know VERY well indeed, very very well, drove a MKIII Cortina 2 litre GXL from Manchester to Stockport, in the rush hour, with no hydraulic brakes at all due to a mishap with the master cylinder, and just used the handbrake. I, err, sorry, I mean HE probably wouldn't do it again, but when you are young you don't worry about minor defects like that. Quote Link to comment Share on other sites More sharing options...
Dnk Posted November 3, 2012 Share Posted November 3, 2012 beware!! Of course, you can idle the car around or do 100 mph with no calipers at all on the car, the handbrake is cable operated and totally mechanical in nature, but on cold start, fast idle, an auto box car may have enough torque, when in drive or reverse, to overcome the handbrake. Let it warm to a slow idle, and be ready to knock into neutral when you want to stop. The mkiv has quite a powerful handbrake if it's working correctly, so i would have no qualms about doing what you say at all. In fact, someone i know very well indeed, very very well, drove a mkiii cortina 2 litre gxl from manchester to stockport, in the rush hour, with no hydraulic brakes at all due to a mishap with the master cylinder, and just used the handbrake. i, err, sorry, i mean he probably wouldn't do it again, but when you are young you don't worry about minor defects like that. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted November 3, 2012 Share Posted November 3, 2012 Why does quoted text sometimes lose its capitalisation? Quote Link to comment Share on other sites More sharing options...
rider Posted August 13, 2019 Share Posted August 13, 2019 (edited) Adding to an old thread, having just refurbished a jspec front caliper advice would be don't bother when SRD sell them ready refurbed for £150 with an option of £30 cash back on your old caliper. i bought a full set of calipers off the forum ready for when needed and with one sticking front decided its time to refurb these. I found out only one front caliper supplied was OE and the other a really light weight one that got binned, hence the need to buy one in from SRD to make up a full front set. On the overhaul I used compressed air to pop the pistons seeing the calipers weren't on the car to use the brake pedal to pop them out. Anyway, air was fine. Getting both to pop together proved a pain to achieve and the less mobile piston when it finally went disappeared the full length of the garage when it popped. There are plenty of refurb kit options on eBay and elected for new seals, pistons and slider pins. New M10 banjo bolts and washers and new pad clips. Total cost around £65. Add in £10 for the black caliper paint and a bit of masking tape to cover the holes. Cost about half what a SRD refurbed caliper costs. I pushed kitchen roll into the bores and refit the old dust boots so I could spray paint around the bores without painting the bores. All holes were masked up with tape Waited a couple of days for the paint to dry. The piston oil seal is an easy fit (greased up with Castrol Red Grease) but the dust boot is one big fiddly job. Fortunately seeing I was originally planning on refurbing two calipers I had spare parts as I tore two dust boots on the retaining clip trying to fit the clip. Process I used was fit the dust boot and press down into the bore then fit the retaining clip. It's a tight fit to get that clip down into the groove without screw drivers or whatever you are pushing the spring clip down with slipping and tearing the boot. Then I tried fitting the piston into the top of the boot for ages. Wasn't happening. Off to the workshop to use the vice to free up a hand and still wasn't happening. So I got my 3 foot breaker bar upright in the vice and put the piston on the top of that then pulling the dust boot with fingers it was a case of trying to spread the boot wide enough while moving a fairly heavy caliper over the piston and trying to blindly get that boot over and onto the piston. One hit pretty much straight away, the second took a good while. Then light pressure on the piston using the vice to move the piston down past the oil seal and into the bore. The caliper slider bushes were absent from the set I bought in. I was wondering why the new bushes wouldn't fit until i worked out the cups from the old bushes must still be sitting in the carriage. Off to the workshop again and a small chisel soon dispatched those so the new bushes could now seat into the carriage. New slider pins greased and regreased several times until the crud from the bores was all removed and the silicone grease remained clear. Caliper ready to fit. My advice would be if you need a new caliper, just buy one in. Its a faff unless saving £80 a corner is important to you. Picture is my refurb alongside the SRD one. Edited August 13, 2019 by rider (see edit history) Quote Link to comment Share on other sites More sharing options...
Scooter Posted August 14, 2019 Share Posted August 14, 2019 Ah but the rubber seals go in last (still a faff getting the clip into the groove but no struggle re the pistons) http://www.mkivsupra.net/vbb/showthread.php?107717-Refurbing-J-Spec-Brakes&highlight=george Quote Link to comment Share on other sites More sharing options...
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