38 replies to this topic

[Ethel]

Yep metro,s are different to mini's

[ginigwunkle]

just a thought.....dont have a go if im wrong and dont try it til confirmed but

if its not the top nipple out of the three on the caliper can you just blank the broken one off say with a weld?

the top one will bleed the air out still or are there specific chambers inside

as i say just a thought...

[benno]

Just a cautionary tale....
I sheared off one of the nipples on my Mini calipers in much the same way. A had a mate with a steadier hand, and better tools, drill it and use his Snap-on extractor. On first inspecion it appeared to have worked a treat, until that is I checked that the channels were all clear by blowing cleaning fluid through the calipers (mine are in half at the moment!). I then noticed that the bleed hole wasn't clear, so I gently ran a small drill down an realised that it was blocked with metal.
What had happened was that the bleed nipple had sheared AGAIN right down low. The shear face being at 45degrees had meant that it looked alright initially. I tried drilling last night and am pretty convinced the seating face is now knackered, not to mention the lower threads, so it's another set for me )0:

[dklawson]

Benno, go back to the first page of this thread and read my post. The ball bearing fix may salvage your caliper.

Ginigwunkle, I don't know about that weld idea. The multiple bleed nipples were certainly put on the parts for a reason.

[benno]

Benno, go back to the first page of this thread and read my post. The ball bearing fix may salvage your caliper.

Ginigwunkle, I don't know about that weld idea. The multiple bleed nipples were certainly put on the parts for a reason.

Doug L, read your bit about the bearing earlier - top idea! Not sure if I've damaged the bottom of the hole, or the thread, too much for even the bearing fix...is there any way that I can test this without putting it all back together?
Thanks for the reply.

[Ethel]

I can't see a way that you could pressure test the seal of the nipple without putting the caliper together so you can pressurise it.

The bleed nipple has to be at the top of the cylinder in order to let the air out, the 4 pot calipers have 3 nipples because the lower 2 pistons are connected at the bottom so each needs it's own nipple.
To bleed the system you just need a means for the air to escape, I drove a car for years with 2 nearside calipers, it was just a bit of a pain if I needed to bleed the one on the offside as I had to unbolt it and turn it the right way up first. You could even replace the nipple with a plain machine screw and seal it with a copper washer but it would be messy to bleed.

[benno]

I can't see a way that you could pressure test the seal of the nipple without putting the caliper together so you can pressurise it.

The bleed nipple has to be at the top of the cylinder in order to let the air out, the 4 pot calipers have 3 nipples because the lower 2 pistons are connected at the bottom so each needs it's own nipple.
To bleed the system you just need a means for the air to escape, I drove a car for years with 2 nearside calipers, it was just a bit of a pain if I needed to bleed the one on the offside as I had to unbolt it and turn it the right way up first. You could even replace the nipple with a plain machine screw and seal it with a copper washer but it would be messy to bleed.

Sorry if this has been asked one million times before but I've not got the hang of using the search tool to just look at technical issues.
Plus it looks like I've got some pro's on line at the mo!!

I went to put the good caliper back together the other day but am having trouble getting the seals in. They look very big and ruck up when you try to get them in place. Bought them from mini speed with a new set of pistons - I'm sure those boys supplied me with the right ones! Whats the deal? Any tips on getting them in?

[Doodle]

i know this is a bit of a side issue, but i've just found some proper penetrating oil and cheap too from toolstation, picked some up today seems good, currently in the process of following Dougs suggestion.

heres the link for anyone who needs some

http://www.toolstati...a...il&Search=1

[partsguy1]

[attachment=50990:bleeder_repair_kit.jpg]
If you can find these or order them, they will help repair damaged bleeders. Basically you drill out the old bleeder and tap the hole to 1/4" npt, thread in the new seat and now you have new bleeders. I have used them and they work great.

http://www.raybestos...amp;pageType=40

Terry

[dklawson]

Terry, I've used those repair kits before on our VW. They do work, but I'd caution anyone who uses them to be careful and cautious when following the torque guidelines supplied/called for. I found the installation torque value to be too high and this causes the threads for the nipple to become tight. If you use those nipple repair kits, torque to perhaps 75% of the recommended setting then check the fit of the bleed nipple. Increase the torque values in small steps checking the fit of the nipple between each torque setting. Stop at the first instance where you observe resistance when threading the nipple in.

Edited by dklawson, 20 February 2008 - 08:36 PM.

[partsguy1]

Doug, that makes perfect sense because the adapter is a tapered thread. I use a little pipe sealant and thread the adapter in until snug, I had a fear that over tightening would crack the Caliper casting. The use of sealant was just precautionary, as relying on the mechanical seal of the pipe thread alone would surely lead to leaks.
I only suggest these if the original threads or seat are beyond repair. Which generally happens when a hand drill and an unsteady hand are used to remove stuck bleeders.
Terry

[Ethel]

I can't see a way that you could pressure test the seal of the nipple without putting the caliper together so you can pressurise it.

The bleed nipple has to be at the top of the cylinder in order to let the air out, the 4 pot calipers have 3 nipples because the lower 2 pistons are connected at the bottom so each needs it's own nipple.
To bleed the system you just need a means for the air to escape, I drove a car for years with 2 nearside calipers, it was just a bit of a pain if I needed to bleed the one on the offside as I had to unbolt it and turn it the right way up first. You could even replace the nipple with a plain machine screw and seal it with a copper washer but it would be messy to bleed.

Sorry if this has been asked one million times before but I've not got the hang of using the search tool to just look at technical issues.
Plus it looks like I've got some pro's on line at the mo!!

I went to put the good caliper back together the other day but am having trouble getting the seals in. They look very big and ruck up when you try to get them in place. Bought them from mini speed with a new set of pistons - I'm sure those boys supplied me with the right ones! Whats the deal? Any tips on getting them in?

The fluid seals shouldn't cause you problems, fit them round a piston to check they are the right ones. Thoroughly scrape out the grooves in the calipers and they should fit in quite easily with some brake fluid as lube. The dust seals are swines, you really need a fitting tool to get the metal rings back in.

[benno]

The fluid seals shouldn't cause you problems, fit them round a piston to check they are the right ones. Thoroughly scrape out the grooves in the calipers and they should fit in quite easily with some brake fluid as lube. The dust seals are swines, you really need a fitting tool to get the metal rings back in.
[/quote]


When put around the piston, there is a fair bit of slack evident, ie they are quite a bit bigger. Is this right? If not, how could they have given me the wrong seals - is there a mini with bigger caliper pistons than the 8.4" lockheeds? I've got them soaking in fluid at the moment as advised by a mate, will this make them shrink a bit?

[Doodle]

[attachment=50990:bleeder_repair_kit.jpg]
If you can find these or order them, they will help repair damaged bleeders. Basically you drill out the old bleeder and tap the hole to 1/4" npt, thread in the new seat and now you have new bleeders. I have used them and they work great.

http://www.raybestos...amp;pageType=40

Terry

are these a viable option for all 6 of the nipples?, i've found some in the UK but i'm questioning whether it would be worthwhile to fit these rather than just buying some rebuilt non vented calipers, as expected the other two from that caliper sheered off after following Dougs advice about the penetrating oil and i'm thinking that i still have the drive flanges from the hubs and a set of stainless hoses that came with, which can be used and faced with having to drill out and tap to 1/4 all 6 of the bleed nipples, then remove and renew all the pistons, then replace all the seals and reassamble I just wonder if the smart money is on buying calipers that are already done by pros, the last thing i would want is them leaking or failing. for the money i've still got a bargain, but i dont want to kill myself using defective brakes lol

any opinions?

[Ethel]

Do the maths - they may serve as exchange units if you buy refurbed ones. I reckon Metro calipers are far worse for sheared nipples 'n I put that down to them being over torqued because the hex head is bigger.