The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: cosmikdebriis on March 01, 2014, 07:06:40 PM
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I don't seem to be able to find pistons for ATE calipers (in the UK).
So, I'm making some up out of stainless. If all goes to plan would anybody else want any?
Not sure of a price yet but may depend on how many people are interested.
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Hi,
Motorworks does supply them: BRC37256 - just google this code and youll find them.
They are a bit pricy though with almost 40 pounds each. i just finished total rebuild of my brakes but since they were a bit too pricy for me at the moment, I re-used the old but not in perfect condition ones.
I might be interested if you get the self-made pistons work for yourself!
Arvo
R65 in Cumbria
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This subject of producing caliper pistons always interested me. Seems simple enough to obtain some quality round stock and turn to OEM configuration on a lathe. The more I learned about this (which is minimal) the more I discovered the importance of the piston finish being hard and robust in nature through a process called Centerless Grinding on special machinery.
Just wondering if there's any qualified and experienced Machinist's out there that can elaborate on the process and if this is essential towards safety and reliability towards the brake system.
???...
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I'm no machinist but I have worked with a lathe. The ground finish of the OEM items is not going to be reproducible with a normal lathe cutting tool. If I was making them I would turn the best finish possible then polish with 600 grade paper. A good turned finish probably wouldn't leak but a polished surface would be easier on the seals.
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With 600 grit paper you won't match the smoothness or the roundness of a centerless grinding machine.
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FYI...
Mine are being ground to size and then cut to approx length by a friendly engineering company then I will be finishing them off.
Don't worry, I had no illusions as to getting the sort of finish I require on my lathe (even if it is quite a nice one) ;)
I'm not sure of costs but if I can't beat forty quid I'd be amazed.
One of the advantages of stainless (apart from the obvious one) is that it's harder than mild steel*. Perhaps not as hard as chrome but hard enough. (of course stainless steel contains chromium which is what makes it stainless).
*To be exact, there are different grades/alloys of steel so it's not quite that simple, but for our purposes Stainless is more than adequate. (IMHO).
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With 600 grit paper you won't match the smoothness or the roundness of a centerless grinding machine.
You certainly will not. but after using the 600grit (personally I'd use 800), some polishing rouge (or even a good automotive "cut" polish) will produce a result more than satisfactory for brake pistons.
It is much easier to do this using a polishing mop in a bench grinder, even easier if the person making the pistons leaves a "tail" on the inside so that you can hang onto them with a drill chuck. Spinning the piston against a polishing mop with lots of rouge on it will quickly produce a mirror finish on the pistons - the secret is that the mirror finish is more important than the last 10/1000 mm roundness accuracy.
Now a lot of people wont have a bench grinder to mount a polishing mop on, and sadly I suspect that most machinists will not think to leave a small "spire" on the inside of the piston so that they can be chucked in a drill (and I hold my hand up, the first four I made didn't, so I made more).
But given that total roundness is not required, a buffing pad in your drill (or angle grinder if you own one) will quickly achieve the required finish. My suggestion would be to wear gloves and hold the piston lightly and allow it to turn slowly as the mop works on it. If it starts getting too hot too hold you are using too much pressure, back off and go slower.
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FYI...
Don't worry, I had no illusions as to getting the sort of finish I require on my lathe (even if it is quite a nice one) ;)
If you have a lathe, you are cooking with gas - Crocus paper to start (say around 800 - 1200grit) followed by toweling cloth and polishing rouge.
If you have an old and well worn speedo cable, you could linish the pistons with that, but crocus (in long belt like strips you can work against the rotating piston) will be much, much faster - linishing is really only used on cranks and big ends, the theory being that the process lays the edge of the grain over and makes the bearing surface more durable. FWIW I have linished bearings and I have polished bearings with crocus and rouge and I have had cranks finish ground - I think the results were about equal over all, with finish grinding requiring the least effort from me because I paid someone else to do it.
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Justin made a set. We need his input.
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Is chrome plating an option (I wonder)?
It would be interesting to see those pistons that have been privately turned and manufactured after 5 or 6 years of service.
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Well the R65 is a relatively new bike for me. my main hobby is British stuff back to 1920 so, as you can imagine, owning a lathe and other workshop machines goes with the territory.
Although I could spend hours getting the right finish, it's just so much easier getting it done by someone with the right equipment. A lesson I learned over many years of spending hours trying to achieve something it takes only minutes to do if you have the right kit.
I should have these done in a week or so so will post some pictures.
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I posted a link somewhere on this site to a guy here in the U.S. who advertises them for sale, in stainless. I haven't bought from him yet.
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Justin made a set. We need his input.
So did I, well actually I made 2 sets but for reasons discussed above, I tossed the first set.
There is no magic whatsoever, if you know what you are doing with a lathe you should knock out a set of 4 in under an hour.
Bear in mind my comment that when removing metal from the back of the piston, if you are polishing them yourself, leave a central "spire" so that you can chuck them in a drill.
Alternatively, you could turn a length of round stock to size, polish and then part off the individual pistons, the risk you run doing that is marking the surface when you chuck them to "hollow" the pistons.
Last comment - someone mentioned chroming the pistons. - Firstly ATE did that to the originals and the reason we are having this conversation is that it didn't really work out so well. Secondly, the chroming would have to be hard chroming to be worth doing at all and that is expensive.
Take it on faith that a nicely polished set of stainless steel pistons will give a long and trouble free life, by the time they need replacing (say 35 years from now, which is kind of how long the originals lasted, most of us will be dead and the R65 models fitted with them will be 70 years old. (and doubtless worth a King's ransom).
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I'm with Tony. A well polished set of stainless pistons should be plenty smooth (as he can vouch) to seal the piston and allow it to retract. I wouldn't be overly concerned about the piston seal wearing out the piston either. While I've seen a rubber radiator hose abrade an aluminium valve cover (on my lost-love W123 Benz), the piston in the ATE caliper has no wiggle room and the steel should be hard enough to wear the seal out first.
P.S. Tony, I'd imagine you could use an inside-jaw chuck in the "hollow" of the pistons to secure them in the lathe for polishing. You could save a few pennies by not using the extra stock to leave a "spire" on the piston [smiley=2cents.gif]
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P.S. Tony, I'd imagine you could use an inside-jaw chuck in the "hollow" of the pistons to secure them in the lathe for polishing. You could save a few pennies by not using the extra stock to leave a "spire" on the piston [smiley=2cents.gif]
Due to loaning a couple of bits and pieces to a friend the only chuck I had at the time was my trusty 4 jaw, it was too big and cumbersome (it was made for a much bigger lathe than mine) for me to be bothered to reverse the jaws to hold the original set of pistons I made from the inside. Which is really why I decided to bin them and make a second set.
The second set I simply left a 8mm "spire" or column cut off slightly below the level of the back side of the piston so that I could chuck them in a drill. I was also a lot smarter in making the second set as I first turned to size, then polished with crocus, then machined out the hollow and then parted off, then repeat 3 more times, they took me about 5 minutes each. It didn't take much at all to get a mirror finish on the polishing mop.
But, as I, and others (you) have said, a perfectly adequate result can be achieved using hand tools only.
In fact, I reckon that I could make an alloy piston of more than sufficient accuracy on a wood lathe, cathode anodise it and polish and it would last nearly as well as a stainless steel one. In fact when I start on the R100, which I know needs new seals on the rear Brembo, I might even try it......
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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.
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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.
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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.
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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... ;) ;D
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 :o
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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.
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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
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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.
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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.
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i'll have one if theyre reasonable mate!
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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.
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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.
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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.
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how much is post , any idea?
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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.
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nearly 40 quid at motorworks! wish i'd access to a lathe! lol
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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.
Thanks, Arvo. I don't know when I should rebuild mine again but I'm tempted to get them now anyway, in case the guy closes shop before I'm ready. I stock up on other odds and ends for my R65. I guess I'm stuck with it for life.
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nearly 40 quid at motorworks! wish i'd access to a lathe! lol
I am the idiot who actually paid that money for a set of 4! Oh well, better 150 pounds than crashing again. Now I am just waiting for them, Motorworks does not have them in stock and it takes a few odd days for them to arrive.
Ed - jup, better stock up so you do not have to pay twice the amount in few years. As far as I have read calipers should last for 3 decades if greased and maintained regularly. So one purchase should last until the end of the bikes life.
Barry - my digital caliper read me 1.417" reading when I measured. The difference is so sublte that by pressing Vernier caliper very tightly around the caliper itselt, I could get a 1.415 reading. I just thought that that is the measuring error.
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I guess I'll remove the calipers and replace the seals from my '81 R65, never been touched since it was assembled in September, 1980 .
Been putting this off for a long time !!!
Don't know what to expect, 12 years of use in Chicago and the last 21 years in Phoenix .
I have a set of Brembo calipers, if things went real bad with these .
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set of 4? mines a single disc 79 i only need one , we are talking ate's here?
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The '81 model year North American bikes came with dual discs, ATE calipers, early '82 model year LS bikes had ATE's as well .
It was available as a dealer installed option as well .
You do need two, as there is a piston on each side of the caliper .
No matter what caliper you have, ATE or Brembo, they both have two pistons
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set of 4? mines a single disc 79 i only need one , we are talking ate's here?
They came with s single disc. A 2nd disc was always an option and maybe fitted in some markets or to shift them off the sales room floor.
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only been checking the pads thickness up to now , if it works leave it alone , be nice to have some as spares tho £80.00! , do they do one made of steel ? surely these are made of gold hand rolled on the thighs of virgins?
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if it works leave it alone
I must admit regular brake fluid changes aside I take that approach with my 25 year old car because replacing all the pistons would be a major exercise.
On the bike though there may be some merit in early intervention. What I found on the bike is the corrosion starts from the outside under the dust seal and travels inwards towards the part of the piston surface that contacts the piston seal. No amount of regular brake fluid changes will help stop corrosion under the dust seal but if you can catch them early enough the corrosion can be polished out and the pistons saved. The dust seals can then be refitted or replaced with an application of brake grease underneath in an attempt to keep the corrosion at bay.
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I'll be rebuilding the calipers on my 94 miata very soon. I had pulled out one dust seal to free up a stuck piston and it can't go back in without the piston removed from the bore!
When I rebuild I'm going to pack a little bit of brake grease underneath the dust cover to help discourage corrosion on the piston. I'll replace that piston, though... I can get one from rockauto for less than $10 8-)
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i use red rubber grease , renolit i think its called doesnt make seals swell ,good stuff can pack your seals with it , doesnt comtaminate brake fluid either
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Off topic
Luca, I'm a fan of Rock Auto, too. Mucho bucks saved on the F-150 and Cabriolet.
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My 1978 3/4 ton Dodge Van had hard black plastic caliper pistons - something like Bakelite , if that tells you anything. Stainless or anodized aluminum will work just fine. What Tony says is true! Next time I need some, that's probably the route I'll take - turn some on my dinky HF lathe.
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Howdy everyone, this is my first post. :)
I am an engineer with access to modern machine tools
I have recently made a set of these pistons from 304 stainless steel. It is easy to get the correct size and finish on the lathe with some polishing.
I made these for a friend who has fitted them to his caliper and then sent his bike for MOT.He is very happy with them! :D
The originals were chrome plated to give some protection against corrosion. These were then centreless ground to true up the size because chrome is too hard to be machined on a lathe.
The problem with the originals besides the cost is that eventually the steel corrodes under the chrome, the plating lifts off the surface and damages the seal.
Stainless steel replacements are an excellent upgrade.
If there is enough interest i can run off a few sets on the CNC lathe.
In the mean time I have listed a batch of these pistons on Ebay if anyone is intrested? ;)
I can't post an active link here but if you search for them under BMW R45/65 ATE brake pistons you will find them ;)
If anyone can think of any other machined parts that are ridiculously priced get in touch i can manufacture almost anything at resonable cost for other members. :)
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What diameter dimension did you use ???
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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.
Thanks for the link. You say these are stainless? I couldn't find any mention of material on that page.
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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.
Thanks for the link. You say these are stainless? I couldn't find any mention of material on that page.
I can't find anything about the material, either, now. I don't remember why I thought they were stainless. Email the guy and ask him.