Classic Mini Workshop - Brake Upgrade 8.4 inch Vented 4 Pot Calipers

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In this update I upgrade the brakes on my Classic Mini with some Paddy Hopkirk 8.4 inch four pot brake calipers with vented and groved brake discs and EBC greenstuff brake pads. The brake upgrade kit is supplied by Mini Sport, they do their own version, Cooper branded and Paddy Hopkirk.
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[@aaronmartin4495]

Hi Keith, I bought a 1995 Mini Cooper back in May and since then your videos have helped me out massively, I genuinely don't think I'd have fixed half of things on the car that I have without your videos, so thank you massively for that. I know this is an older video but I'm hoping you'll be able to help me out with an issue I'm having on my own brakes. I recently upgraded to the Mini sport 8.4 brake kit with new calipers, discs and flanges and I've got them all fitted on the mini. The issue I'm having is with the brake calipers and the brake hoses. The first time I installed the calipers was with the bleed nipple at the top, I spun the caliper onto the line as much as I could but to get it tight it required me to twist the line 1/2 way from straight. I messed around with this for a while but still couldn't get them tight without a twist, any looser and brake fluid was leaking out. So yesterday I decided to try swapping the calipers around and it has solved the issue. The lines are on and fully tightened with less than a 1/4 twist. My problem now though is that the bleed nipples are positioned on the low side of the caliper. I'm happy to leave the calipers on the way they are but did you find you were able to get them properly bled the way you tried to in this video, by taking it off the disc and holding it flat to allow the air out? Had you wanted, could you have kept your calipers on in this configuration? I'd love to go ahead and bleed them as is but I'd just love a bit of advice beforehand about whether I should even try or should I keep looking to find a solution to the twist in the lines when the calipers are on on the correct sides?

[@classicminiworkshop]

Hi Aaron, even 1/4 of a twist in the brake hose could be enough to affect the braking and will likely fail an MOT if spotted. Unfortunately they only way to untwist the hose is to loosen the end that fits in the subrame on the metal pipe which can be a pain to get to especially if it's all seized up. You could bleed the brakes the way you say by removing the caliper and disc and holding so the nipple is at the top but ideally it would be better just to fit the correct way and loosen the brake hose at the subframe.

[@aaronmartin4495]

@@classicminiworkshop Thanks Keith, I hadn't even thought of that. I'll take a look at the brake line connection at the subframe, might upgrade to braided brake lines while I'm at it. Nothing I've worked on so far has been too badly seized so hopefully this'll be the same. Thanks so much for the advice! Have a pint on me, cheers Keith!

[@grahaminaus]

Great Vid Keith, I kept thinking, he's got them on the wrong side?...… Then when you explained I thought oh well, maybe you had two L/H calipers, or Minisport only machined them one way? Well done for leaving it in the video and showing a mistake, it will certainly help others! Many thanks, really enjoy your videos, Cheers, Graham.

[@ClassicCarCave]

Keith, The brakes look brand new top buy great video problems an all, Cheers Dave

[@thedjse]

Great video haha well done for uploading many would of let that go to the archives haha

[@Dagowly83]

Heat won't be an issue mate, you'll need to paint more onto the disk if you want to prevent rust appearing. It's about 10mm from the edge of your current paint line where the pads finishes on the friction surface. Found that out the hard way 🙄

[@classicminiworkshop]

I was going to paint half way up the disc and let the friction take off the paint to get the perfect line

[@1chish]

As I think we mentioned elsewhere there is nowt wrong with showing 'warts and all' because we all make mistakes, its how people learn and it shows how easy little upcocks can happen. I once rebuilt an 12 Litre MAN 6 cylinder engine and set the exhaust valves to the later high pressure 'Common Rail' fuel system setting ..... Luckily I put the later labels on so at least had a pointer. And I was a Chargehand ffs ....

[@franktaylor7617]

😎👍

[@mephiskapheles6]

it would be great if you did a video on how to do an alignment.

[@robertnehrbass7745]

Another grate video.What type of solution are you using that you spray on to clean up?

[@piperdoug428]

Hmmm, so what were you having for supper tonight? you never said......lol.

[@classicminiworkshop]

Chicken Curry with Singapore fried rice and some crispy sweet and sour beef washed down with a couple of pint of cider :)

[@forward160]

Great looking breaks Keith do you do your own tracking.. Maybe we can see a video off that if you do . Got new track rod ends to dig myself.. And having 10" wheels most of the local places don't like doing the tracking .

[@classicminiworkshop]

I've borrowed some Dunlop type tracking gauges to do mine. I tracked it up last night but didn't video it. A couple of people have asked so if I get a chance I will video a bit later. The first time I tracked it up I've just used string and a tape measure

[@forward160]

@@classicminiworkshop cheers Keith I'm going for tape measure and sting watched a few videos about it .. look forward to future videos 👍

[@classicminihaha2508]

Made the exact same caliper mistake myself. Wasn't until I'd tried bleeding them for the 10th time that I realized what I'd done

[@classicminiworkshop]

Glad it's not just me LOL

[@Peakwanderer]

An important point to mention when shimming pads is that if the inner flat part of the pistons is hard up against the caliper the brake fluid can't get in the gap to push the pistons out. I'd also have probably removed the red abrasion coating especially with new discs.

[@bradleycrandon24]

At 2:39 you took off that bracket, to keep the pads tight, do you have to put it back on?

[@classicminiworkshop]

The pads on the 4 pot calipers do not require the retainer clip like the original pads

[@bradleycrandon24]

Classic Mini Workshop okay great thanks, it's just I did the smaller cooper S brake conversion and forgot that spacer so the pads wiggle only slightly.

[@eiriktell3972]

I recently replaced the front drums on my mini with 4pot calipers, but I've been having a few issues since. Do you happen to know alot about the various braking systems on minis, or do you know anyone else very knowledgeable? The forums always seem to fail me and I'm not sure who to ask. Cheers, Eirik :-)

[@classicminiworkshop]

What problems are you having Eirik?

[@eiriktell3972]

@@classicminiworkshop My front brakes start dragging really bad after I've used the brakes to come to a full stop, not even an emergency stop. The brake pedal goes very firm aswell. As mentioned I replaced the front drums with 4pot calipers, wich are even on the right way round thanks to Cole! My Mini has a split line master cylinder, not sure wich type/tag but it has a circular container. Pdwa valve on the firewall and an inertia valve in the rear subframe. I remade several brake pipes and replaced all 4 flex hoses with new braided ones, I also replaced the rear brake cylinders with the ones I was recommend, I believe 5/8 but I don't recall at this time. It was recommend both by a forum post and a technical advisor from Minispares. The braking system worked flawlessly before I switched out the drums. I haven't really looked all that much for the fault as I have yet to work out what would be the most likely culprit. Thank you in advance for any guidance with this issue. Eirik

[@1chish]

@@eiriktell3972 If you have a PDWA valve ('78 on Metric unions) on the front bulkhead you should not have another valve on the rear subframe. Just a plain 3 way union. You say its a 'split line' system but is that Front / Rear or LH / RH diagonal split? This could be affecting the new calipers which don't have the double retracting springs each side the TLS drums have and only rely on seal retraction to return the pistons. Although you don't mention a servo I doubt this would be the cause as it just (basically) passes fluid through although again the TLS drum system is pushing fluid back by use of 4 springs which the calipers are not. Just a guess here on your problem but I would certainly remove the rear valve and fit the correct 3 way union (p/n 3H2424) as that conflicts with the front PDWA valve. Hope this helps somewhat.

[@eiriktell3972]

@@1chish Thank you, this does indeed help. And to answer your questions, It's a front rear split without a servo and the PDWA valve is a pre 78 one, it has 5 holes, bleed screw in one of them. It's a 73 Austin Mini 100, I suppose the previous owner might have replaced the braking system but leaving the inertia valve in. After writing my initial comment I have since out of frustration ordered more parts.. Yellow tag master, 78 on pdwa valve and appropriate fittings, T-union and such, going by a different example of the braking system. I will be removing the inertia valve, hehe.

[@1chish]

@@eiriktell3972 Well that should pretty much do it! The GMC227 (Yellow Tag) Brake Master Cylinder is the only option these days and the FAM7821 PDWA Valve matches it. Be careful you have the right pipes from the Master Cylinder to the PDWA as they differ from earlier versions (metric vs Imperial) Good luck.

[@ryanharriss7950]

Be interesting to measure brake performance up to 1000 miles. Seems a long wear in...

[@classicminidetails8887]

Burn Marks brakes out on bolt instead 😂 give him some practice replacing them

[@Alexnse10]

‘DOH’ 🤪🤪🤪