18 replies to this topic

[nakeddivy]

When I got my 2002 900 I left it in and paid my local Yamaha dealer less than two years and only 5000 miles ago to strip and clean both my front calipers, replace all the seals and renew the fluid, the pads were like new so I didn't change them.

 

The bike was used for most last year doing a short commute to work and back, used as a shopping trolley and it was my only transport for about a year but now its used for pleasure only, I'm a plodder and seldom use my brakes hard and usually wash and dry the bike if its been out in the rain etc before covering it up so I figured all I should be doing at present as the pads still have loads of meat on them, is just a good scrub up and bleed through of some fresh fluid.... the simplest of jobs always seem to turn into a whole kerfuffle for me and this ones no exception unfortunately.

 

After taking the pads out and giving the callipers a clean I then proceeded to bleed through new fluid but soon realised that it just wasn't happening, nothing at all was coming through the nipples when using a vacuum bleeder so I removed the screws completely and this is what they looked like, yes there is a hole there but it took ages to clear it with a needle and airline and where it screws into the caliper was full of rust.

 

 

 

I ordered new stainless bleed screws in size M8 x1.25 and this is what I got below, I didn't notice the flat bottom until after they arrived and I couldn't get these to make a seal at all.

 

 

 

I then ordered these ones, same size and had my fingers crossed that the pointy bottom in the photo on the website was what I was getting lol, here's what arrived.

 

 

So after lots of gentle scraping with a needle and cleaning with brake cleaner/fluid/cotton buds to remove the rust from the caliper bleed screw threads I find that the new bleed screws are also not making a proper seal. I figured it was leaking through the threads so used some Teflon tape around the bleed screw threads to test my theory and it does make a seal but I would not ride the bike without the bleed screws making a proper seal but I am unsure as to how I should now proceed, I would be very grateful for any ideas please as im stuck? Thanks. 

 

No teflon tape

 

http://i33.photobuck...zpsd6aeea57.mp4

 

 

With tape

 

http://i33.photobuck...zps07752c48.mp4

 

 

Inside thread after cleaning

 

http://i33.photobuck...zps92a226f3.mp4

Edited by nakeddivy, 02 August 2014 - 12:55 am.

[Wildbill]

Why not order genuine replacements from a Yamaha dealer.?

 

It is a far from rare situation you have just encountered.

 

When you install the replacements; use copperslip on the threads and wash out the fluid remaining  in the nipple after bleeding with wd40 or similar and fill it with grease and refit the rubber cap.

Helps to prevent salt corrosion in the nipple.

 

SS is not a good idea in alloy calipers to start with !

Edited by Wildbill, 02 August 2014 - 06:05 am.

[leehenty]

It's the alloy taper at the bottom of the thread  that's the problem, it will be pitted or have embedded flakes of rust from the old nipple. Are you sure you got all of the rusted off tip of the old nipple out ?

You can recut these gently either on a milling machine or a hand reaming tool that screws in the thread.

[nakeddivy]

Why not order genuine replacements from a Yamaha dealer.?

 

It is a far from rare situation you have just encountered.

 

When you install the replacements; use copperslip on the threads and wash out the fluid remaining  in the nipple after bleeding with wd40 or similar and fill it with grease and refit the rubber cap.

Helps to prevent salt corrosion in the nipple.

 

SS is not a good idea in alloy calipers to start with !

I did order genuine ones and then I changed my mind as my local Yamaha dealer had quoted me £8 + VAT each for the oem bleed screws.

 

It also seems that as Lee pointed out above, the second lot of 'M8 x 1.25 fits Yamaha blue spot' bleed screws I bought for £3 each trying to save some money also have a different shaped point taper to them as well and they are not even long enough from the bottom of the thread to the taper tip to make a seal anyway so it looks like I shall just have to pick up the original ones.

 

How is Stainless Steel in an alloy caliper any worse than using the standard  steel ones? EDIT: I had a read about online and I think I understand that the alloy caliper will corrode when using stainless bleed screws but the bleed screw corrodes when its a standard steel screw, if that's the case then I shall be using standard oem ones, thanks.

 

Lee, I also think you are correct that there are still deposits and corrosion in that little bucket seat at the bottom that I have not removed properly. I guess this will still give me problems even with oem bleed screws unless I get it properly cleaned so I have gave them to a friend who's uncle is an aircraft engineer of some sort and has kindly offered to have a look. Fingers crossed.

 

Thanks again.

Edited by nakeddivy, 03 August 2014 - 12:10 am.

[Bobos]

Just to clarify, it's only leaking when bleeding? When the nipple is undone slightly? If it is then is ok to put some PTFE on the threads to get it to bleed. The seal is the conical face (normally JIC -3 or similar) when it's nipped up. Some manufactures take the conical face to a full cone, others to a flat top and both are fine; just ensure you don't get any PTFE on the sealing face or blocking the bleed port. I've found on a few vehicles, 2 and 4 wheeled, that sometimes one nipple has threads that don't quite seal enough when bleeding and let air past them so you can't get the job done.

[Wildbill]

You can get away with SS banjo bolts on an alloy caliper if you coppaslip the threads.

The sealing washer prevents salt ingress and hence corrosion.

 

On a bleed nipple even if coppaslipped; the dia is much less, salt eventually enters the inner passage and lies in the cross drilling gaining direct access to the threads, the thread is not protected by salt ingress by a sealing washer.

 

The nipple does come out of the caliper as easy as pie..............taking all the caliper threads with it.

[dapleb]

The first car I ever owned was a 1974 Golf, the son of the orig owner had tried to put it bacon the road....he used a self tapper in one of the calipots instead of a bleed nipple. 

[Bobos]

The first car I ever owned was a 1974 Golf, the son of the orig owner had tried to put it bacon the road....he used a self tapper in one of the calipots instead of a bleed nipple. 

How much PTFE did you need to sort that one? PTFE and araldite?

Edited by Bobos, 03 August 2014 - 05:12 pm.

[leehenty]

Automec make brass bleed nipples in metric sizes.

If you use 316 stainless bleed screws they do not corrode. At least mine don't, use aluminium based anti seize paste to make sure adding copper into the mix with not help.

 

http://www.automec.c...ss-bleed-screws

[nakeddivy]

Just to clarify, it's only leaking when bleeding? When the nipple is undone slightly? If it is then is ok to put some PTFE on the threads to get it to bleed. The seal is the conical face (normally JIC -3 or similar) when it's nipped up. Some manufactures take the conical face to a full cone, others to a flat top and both are fine; just ensure you don't get any PTFE on the sealing face or blocking the bleed port. I've found on a few vehicles, 2 and 4 wheeled, that sometimes one nipple has threads that don't quite seal enough when bleeding and let air past them so you can't get the job done.

 

Unfortunately even after getting the caliper threads and around seal at the bottom all cleaned up, I still cant get them to make a seal when the screws are fully nipped up, its not just when open for bleeding.

 

The bleed screw kits Im now using are 1J3-W0048-00

 

I guess this gets very expensive now?

[nakeddivy]

Ok, from what I have gathered it appears to be the bottom final turn on the caliper threads that is damaged, stopping the tapered end seating correctly. At over £470 each, I can not afford two new calipers and the used ones on ebay just look like they are in horrible condition. I would like to go down the repair route if I can as otherwise my calipers are in good condition.

 

Has anyone tried something like this before on a bike caliper? http://www.fraserbro...t&product_id=51  Looks interesting but I doubt there would be enough metal around the bleed screw hole to drill into for the new adapter.

 

 

EDIT. I contacted the manufacturer asking for the sizes etc. and just got this reply

 

"The insert is 1/8 BSP. The drill size is 9.6mm.

The easy way is to measure the flat surface round the hole. If you have 13mm. at it's narrowest it will work."

 

I measured across the bleed screw hole and I make it 15mm to the outer edge?

Edited by nakeddivy, 13 August 2014 - 10:21 am.

[leehenty]

recut the bottom threads carefully with a bottoming tap. If you don't feel confident to do this, send the caliper to me, I'll do it for you and post it back to you. I'll pump it up with fluid to check the seal.

Include one of the stainless bleed nipples so I can check the point angle. If it's not correct, I'll pop it in the lathe for a reface.

 

Your threads are METRIC. if the thread is gone, I have kit to repair it with a stainless timesert. Like a double threaded tube.

 

For info, the included angle of the bleed nipple seat is 90 degrees, so a drill won't work as these are usually 118 deg.

Edited by leehenty, 14 August 2014 - 08:52 am.

[dablik]

Good man Lee    presume that means nipple tweaking is not appropriate..

[nakeddivy]

recut the bottom threads carefully with a bottoming tap. If you don't feel confident to do this, send the caliper to me, I'll do it for you and post it back to you. I'll pump it up with fluid to check the seal.

Include one of the stainless bleed nipples so I can check the point angle. If it's not correct, I'll pop it in the lathe for a reface.

 

Your threads are METRIC. if the thread is gone, I have kit to repair it with a stainless timesert. Like a double threaded tube.

 

For info, the included angle of the bleed nipple seat is 90 degrees, so a drill won't work as these are usually 118 deg.

 

Wow! thank you very much Lee, I would be very grateful and will pay you some beer tokens if you would like try to fix them for me as I do no possess the skills for this type of job myself and I don't know of anywhere that can do this type of work. Thanks very much.

[leehenty]

The problem is the alloy threads wear due to the corrosion and the rust deforms the soft threads on the way out, when you take out the rusty nipple.

 

I've got a seat cutter, just have to make a guide bush with the correct outside thread to keep it centered.

It's worth knowing that the seat angle is the same for metric or imperial nipples. The cone on the nipple is often deliberately made sharper than the seat so the seal is a narrow self centering cone. So the seat is commonly 90 degree, the nipple 60. This design mean that small particles of matter won't hold the nipple off the seat.

 

if you think about it, any particle of dirt will stop design A sealing, whereas design B will not trap dirt between the nipple & seat and the seat will distort to meet the nipple ( or vice versa) if the match is not perfect.

 

Edited by leehenty, 14 August 2014 - 05:03 pm.

[Rallyist]

Aaaaahhhhh nipple tweaking  .....  haven't done that for a good few years.

[leehenty]

nipple seat recut.

 

Clean threads with M8 x 1.25 bottoming tap.

 

Fit brass seat reaming tool guide.

 

 

Ream seat gently by hand, alloy is soft.

 

[nakeddivy]

LOL, just like that!  I love how you present that as being an easy fix.

 

Thanks again Lee for taking the time to help me out, I really appreciate it, I'm looking forward to getting out for a spin now, I had been thinking it was going to be off the road for a while.

 

I shall let you know how I get on, cheers   

[nakeddivy]

Brakes arrived back this morning and I have them fitted with nice new pads and all bled up no problems, top job Lee

 

I have the lever back overnight and will check in the morning just to make sure there's no other leaks etc. but it looks like job is done.

 

Thanks again Lee.