ATE caliper pistons...

[cosmikdebriis]

I'm expecting to pick up four ground (to the correct OD) chopped lengths of stainless that will be slightly too long. I will then mount them in the soft jaws of a four jaw chuck (to get it centred properly), face one end, drill and then turn out a hole in one end (though this hole isn't strictly necessary) turn the groove for the rubber dust cover. Turn the job around and face the back to length.

Depending on the finish. Turn up a suitable piece of hardwood to be a very tight fit in the piston, stick the other end in a hand held drill chuck and then spin it against my (bench grinder mounted) buffing mop (ooh err missus).

If anyone has any advice opinions I'd be glad to hear but I don't want to over complicate what seems to be a relatively simple task.

[Barry]

Sounds like you've got it covered and have more than enough ingenuity to get the job done.

I particularly like the buffing method.  Reminds me of when  I had to slim down a socket for access to the swinging arm lock nuts and couldn't be bothered waiting to do it at work on the lathe.  I mounted the socket in the bench drill and attacked it with an angle grinder while it was rotating.  Did a very neat job and you'd be hard pressed to tell it wasn't done on a lathe.

[Tony Smith]

If anyone has any advice opinions I'd be glad to hear but I don't want to over complicate what seems to be a relatively simple task.

 

Let me say at the outset that you are over complicating what is (as you rightly point out) a simple job.

Firstly, the OD is not particularly critical, the first time I ever made caliper pistons I fussed a lot to get the "right" OD. Fact is given the type of seal anything less than .3mm will be just fine (and no I did not forget a zero).
 
Secondly, my view is that finishing with crocus/polish mop is less complicated than sending out a round bar to be ground to size. Do it first and you will save time later though

Thirdly, If the chuck and drive shaft of your lathe is hollow and can accommodate a long enough piece of round bar to make 4 (or perhaps 2) pistons you can greatly cut down your machining time by commencing by hollowing out the first one (and I really do suggest leaving a "spire" that you can chuck in a drill, it saves the time turning hardwood etc. Hollow out, cut the seal grove, then part off at the correct length - 1 minutes work with a file, or a brush with the bench grinder will remove the "center". Then proceed to the next one.

Fourthly, I applaud your commitment to accuracy in using a 4 jaw chuck, would you believe that the  ability to quickly set up a 4 jaw chuck is becoming a lost art. Although I must say that in making these pistons, a 3 jaw self centering chuck is more than accurate enough and I would have used mine if it had not been on loan at the time. (I don't like loaning tools, particularly machine tooling or parts, but the Guy I loaned it too lets me use his mill and mig so it is sort of fair exchange.

[cosmikdebriis]

To be honest, I'm pretty sure the ground bar will be good enough an not need any further polishing. It's just a contingency plan.

If it is good enough then I probably won't bother to hollow the pistons out either as the only reason I can think of doing so is to save a small amount of weight.

Out of interest my old lathe is a Smart and Brown. Nice old lump of cast Iron but imperial (for my Brit bikes).

Used to have a Chinese lathe... For about a week...

Oh, and I've seen people with tool post attachments holding angle grinders. Finish is not bad but I don't really fancy all that grit landing in the workings of my lathe

[Tony Smith]

Out of interest my old lathe is a Smart and Brown. Nice old lump of cast Iron but imperial (for my Brit bikes). Used to have a Chinese lathe... For about a week...

I am envious. My first lathe, which was bought in partnership with a friend (who now has sole custody of it) was a Crowthorne, it had a 12 ft bed, the 3ft closest to the chuck was a "drop bed", it could incorporate a 24" swing with the drop bed in place and God knows how much with it removed (I don't think we ever did). Power feeds in all axis it was and is a truly lovely lathe.
 
Shortly after I moved I bought a nasty Chinese 7*10 which ?I improved a lot by throwing away all the bearings and re-doing the bushes. I was about to start properly scraping the ways and making a new tailstock (the one that came with it was off center and not adjustable!!!!) when I realized I was throwing good time and money after bad.
 
I sold the pile of cr@p and bought a 12*36 gear head with QC gearbox. I actually got a very good deal as my lathe was supposed to be CNC, but the importer had robbed the CNC components off it to honour someone's warranty claim. I like the idea of CNC, but as I am not planning to mass produce anything I can happily live without CNC.

It was missing a couple of bibs and bobs (I had to make my own traverse and feed control wheels) but the price I paid more than reflected those omissions ($AU600)
 
I can only think of 2 or 3 jobs where the old Crowthorne would have been able to do a job that I could not do on my new one, so I guess I'm very happy.

I do want a mill and frankly I'd love to have a shaper again. The downside of a shaper is that there is virtually nothing you can do with a shaper that you cannot do in 1/5th the time on a mill. But the huge advantage of a shaper to a hobby user is that because of the low speed of cut, you can hand make your cutters out of tool steel and get good life from them.

[steve hawkins]

One of the reasons I ditched the ATE's for a second hand set of Brembo's.  It was cheaper and easier at the time.

this might not be the case now though.

Cheers

Rev Light

[arvo92]

I did not order new brake pistons initially cause of the financial cost of it. I replaced all the rubber components etc. Assembled it all together, the pistons retracted but there was still some contact with the brake disc and I could not get rid of it.
Therefore I decided that safety first and I purchased new pistons as well. I took the brakes apart again after a month and what did I see - the pistons went on rusting like hell and there was already crudge in my brake fluid even though I had not ridden the bike or used the brakes at all.

Just a picture of how bad my brake pistons are and how they kept on corroding. I am amazed I tried to re-use them. Huh. Good I did not get them operating properly and decided to go for a full re-build instead. Now there is no old parts in my brakes at all. Hopefully I do not slide down the road anymore as these pistons served me my first crash in my lifetime.

[nhmaf]

Yikes - those did corrode substantially!   It was a good call to replace the whole lot.

I believe that JustinB on this forum machined himself some fancy replacement pistons out of stainless steel, but they were for the Brembo calipers and not the ATEs.   I think, though quite close, the dimensions are not quite the same particularly with respect to the  groove for the  seal.

[livingdeadhead]

i'll have one if theyre reasonable mate!

[Ed Miller]

http://etypeparts.myshopify.com/products/ate15-bmw1

I think that's the US guy's new web page, hopefully a direct link to the R65 piston.  Does that measurement look right?  Arvo, it looks like you have some handy to measure.

[arvo92]

I will take the measurements of the current pistons but it will take me a few days. I just ordered the Vernier Caliper as I am building up my hardware and actually do not yet have one! Old russian bikes I worked on in my youth never required more tools than a hammer and a screwdriver.

[arvo92]

i got the vernier caliper from the mail and I can confirm that the ATE caliper pistons I removed are in fact 1.415" as

the site reccommended by Ed miller - http://etypeparts.myshopify.com/products/ate15-bmw1


So pretty good price for the pistons. Cheaper than we have to pay in England.

[livingdeadhead]

how much is post , any idea?

[Barry]

i got the vernier caliper from the mail and I can confirm that the ATE caliper pistons I removed are in fact 1.415" as
the site recommended by Ed miller - http://etypeparts.myshopify.com/products/ate15-bmw1  

1.415" sounds right being just over 2 thou under the published nominal size of 36mm. Maybe that's the clearance in the caliper bore.

[livingdeadhead]

nearly 40 quid at motorworks! wish i'd access to a lathe! lol