Thank you for the information; it is more than interesting. The quoted language leaves room for other understandings:
I see nothing that says reamer 000 589 03 53 is an adjustable reamer, but merely language saying to use it "or a suitable commercially available, adjustable reamer with guide bushing," in other words, either use the Benz tool or an adjustable reamer of the generally available commercial pattern. I see nothing that says that a multi-step ream, trial assemby, ream again, procedure is required or needed. Let us all recall that Eli Whitney developed the concept of interchangeable parts about 200 yr ago, and that industrial production has not used trial assembly and iterative resizing as a routine method since then. Things are manufactured to size, which includes some tolerance. If sizing is critical and must be more accurate than can be manufactured readily, parts are sorted after manufacture to tighten the tolerance on accepted parts. Clearance (same meaning as radial play) 0.3 - 0.5 mm, wear limit 0.8 mm. Auf Englisch, 1 mm = 0.039 in., clearance 0.012 in. - 0.020 in, wear limit 0.032.in. unless I busted the conversion pretty badly. That is hardly a close fit. It is just a bit more precise than scale accuracy, that is, measurements that can be made well enough with a steel pocket rule, which is accurate to at least 1/64 in. or 0.016 in. . A nice oiled slip fit, which is what I said in the first instance, will be plenty good, and automobile king pins work fine with either no or tiny visible play as shown by rocking. Either clearance will endure indefinitely if kept greased. If one insists on actual measurements, caliper the pin, caliper the hole. Use nice modern digital calipers for easy results. Use Starrett Yankee spring calipers if you wish, and check the difference between inside and outside calipers with a feeler gauge or micrometer the inside and outside calipers. King pin bushings are one of the simplest auto machine shop jobs. There is no sense in trying to make them a federal case. --------------------------------------------------------------- Tom Hargrave <[EMAIL PROTECTED]> wrote > Date: 10/12/2007 9:11:06 AM > Subject: RE: [MBZ] King pin installation > > From the Series 108, 109, 111, 113 service manual, Section 33-3/3.17: > > "Ream bearing bushings by means of reamer 000 589 03 53 or a suitable > commercially available, adjustable reamer with guide bushing until the > specified radial play of the kingpin has been attained (for dimensions refer > to Job No. 33-0)." > > Job No. 33-0 lists: > --------------------------------- > Radial play = 0.3 - 0.5 > Perm. Wear limit = 0.8 > > And the measurement includes the total kingpin + threaded bolt mounting on > steering knuckle top and bottom. In other words, the actual king pin radial > play is even less because the bolt threads have some play so that they can > receive lubricant. > > To do this "by the book", you have to ream, assemble, measure, disassemble, > ream a little more, reassemble, etc, etc. I'm sure that machine shops > shortcut the process by measuring the kingpin with a micrometer, choosing > the appropriate reamer, reaming and then trial assembling to make sure it's > not too tight by feel. I'm just as sure that they don't verify it's not too > loose. > > > Thanks, > Tom Hargrave > www.kegkits.com > 256-656-1924 > > Robert Bigham [mailto:[EMAIL PROTECTED] wrote Friday, October 12, 2007 4:29 AM > To: Tom Hargrave; mercedes@okiebenz.com > Subject: RE: [MBZ] King pin installation > > Wow. I believe you about what the Benzes say. I would love to see > it somewhere in their writings. Of course I can't find it in my 123 > manuals. > > If that's what they say, that's what they say. I am amazed. BTW. what > size radial clearance are we talking about? > > What, if anything, do they say to do if the last reaming results in a > radial > clearance just a fuzz greater than the specification? Scrap the job and > start over? > > There are much simpler and easier ways to attain the same end. And > adjustable reamers are one of the poorest ways to attain an accurate, > that is, equal to a specification, clearance. > > The much older ways of calling fits, i.e., slip, thumb push, palm push, > light > press, and so on, all represent clearances or interferences, as the case > may > be. In this case they are radial, between pin and bushing, and are not > different in principle than (MSWord would say "from"; I say to hell with > them.) > the clearance between connecting rod big end and crankpin. These ways of > calling fits were developed by the 19th century railroad shops, who wrote > that part of the book on machining and machine work, and are still true > today. > > > Tom Hargrave <[EMAIL PROTECTED]> wrote > > To: <[EMAIL PROTECTED]>; Mercedes Discussion List > <mercedes@okiebenz.com> > > Subject: RE: [MBZ] King pin installation > > > > Mercedes specs a adjustable reamer with instructions to ream the bushings > > until you achieve the correct radial play in the king pin. > > > _______________________________________ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
