Page Index Toggle Pages: 1 [2]  Send TopicPrint
Very Hot Topic (More than 25 Replies) Maybe I'm paranoid... (Read 1325 times)
georgesgiralt
God Member
*****
Offline


I Love YaBB 2!

Posts: 1131
Location: France
Joined: 10/14/12
Gender: Male
Re: Maybe I'm paranoid...
Reply #15 - 12/18/17 at 17:05:22
Post Tools
Tony,
The parts I've got can't be reamed. The metal is around one mm thick.... And if I open up the split in order to match the internal diameter to the external gudgeon pin, the split is about 4 mm wide.
Add to this the parts are made of steel with something slippery deposited onto it. So I bet if I ream them, gone is the treatment...
Next week I'll try to find an engineer apt to supply the correct bushing and adjust it to fit.
I agree with you that tools are easy to get second hand because a lot of people are retiring and nobody will take their job anymore.
I'll try to make a couple of pictures tomorrow.
  
Back to top
 
IP Logged
 
Justin B.
YaBB Administrator
*****
Offline


I love my Beemers

Posts: 5778
Location: Crowley, TX
Joined: 11/08/05
Gender: Male
Re: Maybe I'm paranoid...
Reply #16 - 12/18/17 at 17:18:51
Post Tools
I've only swapped out pistons on two BMWs but I was able to press the wrist-pin (gudgeon pin to you guys on the wrong side of the pond -  Wink ) with a finger, no press required.  They were both on original untouched engines.  There was a fair amount of "drag" when pushing them in and out.

Or, maybe I don't understand exactly what you are referring to.
  

Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!
Back to top
WWW  
IP Logged
 
Tony Smith
God Member
*****
Offline


Graduate, Wallace and
Gromit School of Engineering

Posts: 1965
Location: Cairns, Australia
Joined: 07/23/13
Gender: Male
Re: Maybe I'm paranoid...
Reply #17 - 12/18/17 at 18:45:29
Post Tools
georgesgiralt wrote on 12/18/17 at 17:05:22:
Tony,
The parts I've got can't be reamed. The metal is around one mm thick.... And if I open up the split in order to match the internal diameter to the external gudgeon pin, the split is about 4 mm wide.


It was a while ago but if what you have is actually a gudgeon pin bushing then BMW have changed them since i bought a pair in 2013 when I recommissioned the R65 - the ones I got were not split, required that I give the bore in the connecting rod the lightest touch with a hand reamer to clean up the bore. The interference fit still required that I shrink the bush in my local doctor's mole removal liquid nitrogen and heat the rod in an oven.

Once pressed into the rod I borrowed the correct sized reamer and finished the bore.

The part I got was definitely not finished, in fact I would be gravely suspicious of one that was supplied in finished condition as the interference fit of the bush into the little end would alter the diameter.

Maybe BMW have gotten very lazy if they are supplying split and finished bushes.

  

1978 R100RS| 1984 R65 | 1984 XT350 | 1992 KLE500 | 2002 R1150GSA
Back to top
 
IP Logged
 
Tony Smith
God Member
*****
Offline


Graduate, Wallace and
Gromit School of Engineering

Posts: 1965
Location: Cairns, Australia
Joined: 07/23/13
Gender: Male
Re: Maybe I'm paranoid...
Reply #18 - 12/18/17 at 18:48:37
Post Tools
Justin B. wrote on 12/18/17 at 17:18:51:
I've only swapped out pistons on two BMWs but I was able to press the wrist-pin (gudgeon pin to you guys on the wrong side of the pond -  Wink ) with a finger, no press required.  They were both on original untouched engines.  There was a fair amount of "drag" when pushing them in and out.

Or, maybe I don't understand exactly what you are referring to.


It usually requires nothing more than the application of very mild heat to get the pin to slip in and out of the piston easily. When I was young I used rags soaked in boiling water, in more modern times a hot air gun does the same job faster and with less mucking about.

The little end bush is what we are actually talking about, the idea being that this is a load bearing bush that must deal with rotation - the pin does not rotate in the piston, or at least it shouldn't really.
  

1978 R100RS| 1984 R65 | 1984 XT350 | 1992 KLE500 | 2002 R1150GSA
Back to top
 
IP Logged
 
Justin B.
YaBB Administrator
*****
Offline


I love my Beemers

Posts: 5778
Location: Crowley, TX
Joined: 11/08/05
Gender: Male
Re: Maybe I'm paranoid...
Reply #19 - 12/18/17 at 18:52:20
Post Tools
OK, we're on the same "page."  On the '82 R65LS and the '81 R100RT they just slid out with finger pressure.  Guess I am just lucky!
  

Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!
Back to top
WWW  
IP Logged
 
Tony Smith
God Member
*****
Offline


Graduate, Wallace and
Gromit School of Engineering

Posts: 1965
Location: Cairns, Australia
Joined: 07/23/13
Gender: Male
Re: Maybe I'm paranoid...
Reply #20 - 12/18/17 at 22:45:06
Post Tools
georgesgiralt wrote on 12/18/17 at 17:05:22:
Tony,
The parts I've got can't be reamed. 



The 4mm gap made me think. I think what you have is a little end bush for a G650, not an R65. I think this because the pin diamater is less and the rod is pressure cast so actually would have a reliable and repeatable bore size (still lousy engineering practice though - but typical of the way BMW has gone recently).

  

1978 R100RS| 1984 R65 | 1984 XT350 | 1992 KLE500 | 2002 R1150GSA
Back to top
 
IP Logged
 
Motu
Senior Member
****
Offline


My Cow is my friend! ;)

Posts: 380
Location: New Zealand
Joined: 12/23/08
Gender: Male
Re: Maybe I'm paranoid...
Reply #21 - 12/19/17 at 01:43:39
Post Tools
The little end bush needs to be honed, any machine shop should still have a Sunnen hone, not a big job.   I have adjustable reamers, but I wouldn't use them on a little end bush, they leave a 6 sided hole - that's ok for king pins, but not engine parts.

Fit them and check first. I did king pins in a Mitsubishi Canter a few years ago, got my reamers out ready, pressed the bushes in and then checked to see how much to ream out - and they were a perfect fit !    That's how much machining of parts has improved.
  
Back to top
 
IP Logged
 
Tony Smith
God Member
*****
Offline


Graduate, Wallace and
Gromit School of Engineering

Posts: 1965
Location: Cairns, Australia
Joined: 07/23/13
Gender: Male
Re: Maybe I'm paranoid...
Reply #22 - 12/19/17 at 02:26:32
Post Tools
Motu wrote on 12/19/17 at 01:43:39:
The little end bush needs to be honed, any machine shop should still have a Sunnen hone, not a big job.   I have adjustable reamers, but I wouldn't use them on a little end bush, they leave a 6 sided hole - that's ok for king pins, but not engine parts.



Speak for yourself. I am very confident that I can produce a very round hole with a reamer, but it took me a lot of failure to learn how.

OTOH I would not hone a yellow metal bush, it absorbs the media like a sponge.


But I do admit that honing technology has changed, I understand they you can even hone Nickasil bores now, something I thought would have been a recipe for disaster.

  

1978 R100RS| 1984 R65 | 1984 XT350 | 1992 KLE500 | 2002 R1150GSA
Back to top
 
IP Logged
 
Motu
Senior Member
****
Offline


My Cow is my friend! ;)

Posts: 380
Location: New Zealand
Joined: 12/23/08
Gender: Male
Re: Maybe I'm paranoid...
Reply #23 - 12/19/17 at 21:40:17
Post Tools
Little end bushes have been honed forever without a problem. I bet they are honed rather than reamed at the factory. You can't ream a porous bronze bush, it blocks the pores, but you can hone them. I've always bottle brush honed nickasil and alloy bores, and are recommended for the job.
  
Back to top
 
IP Logged
 
Tony Smith
God Member
*****
Offline


Graduate, Wallace and
Gromit School of Engineering

Posts: 1965
Location: Cairns, Australia
Joined: 07/23/13
Gender: Male
Re: Maybe I'm paranoid...
Reply #24 - 12/20/17 at 01:23:53
Post Tools
Motu wrote on 12/19/17 at 21:40:17:
Little end bushes have been honed forever without a problem. I bet they are honed rather than reamed at the factory.


You would be wrong. In a production line setting a hone requires more skill to use than a fixed sized reamer in a mill (or at least a pedestal drill with a big quill) as the workers are usually paid as little as possible the reamer wins.
Motu wrote on 12/19/17 at 21:40:17:
You can't ream a porous bronze bush, it blocks the pores, but you can hone them.


That would be Phosphor-bronze and you definitely cannot hone them for the very reason you state - the hone lays the grain/pores over and blocks them - they are universally drilled and reamed.

Motu wrote on 12/19/17 at 21:40:17:
I've always bottle brush honed nickasil and alloy bores, and are recommended for the job.


Actually if you read the product notes on Mahle's website (the people who made Galnickal/Nickasil affordable in a mass production setting) they specifically recommend against honing such bores unless you are using a special and very, very hard hone. The reason is in two parts and quite simple - Nickasil/Galnickal is bloody hard itself and much, much harder than old style hones, particularly readily available bottle brush type hones - those sorts of hones either wear very quickly and clog the Galnickal/Nickasil (the very reason why hot soapy water and scotchbrite is recommended for servicing and acid for severe alloy (from pistons) clogging).

The secondary reason traditional hones are specifically not recommended is that as the hone sacrifices itself whilst doing nothing helpful it creates local high temperature spots which can cause the Nickasil/Galnickal coating to de-bond from the alloy cylinder, with obvious fatal results to the cylinder.

If you have got away with using bottle-brush hones on carbide bores I can only suggest that the inevitable disaster is overdue.

As a brand Sunnen made/make excellent honing machines and I am sure that suitable hones are available for those machines.

BUT

The carbide coating on OEM cylinders tends to be very thin and it is quite unlikely that an otherwise unserviceable barrel will be recovered by trying to hone out  imperfections or re-introducing hatching - this is not true of all OEM cylinders (Ducati being a good example)  and is generally not true of cylinders processed by aftermarket carbide coaters - but it is universally true for OEM BMW cylinders.


  

1978 R100RS| 1984 R65 | 1984 XT350 | 1992 KLE500 | 2002 R1150GSA
Back to top
 
IP Logged
 
davidpdx
Full Member
***
Offline



Posts: 187
Location: Portland, Oregon USA
Joined: 10/16/11
Gender: Male
Re: Maybe I'm paranoid...
Reply #25 - 12/27/17 at 19:51:43
Post Tools
"accurate beyond my ability to measure the difference."

      I like that phrase a lot and am going to have to find a way to work it into conversation.
  

1984 R65 60K+
1946 Triumph Speed Twin

Being shot out of a cannon will always be better than being squeezed out of a tube.  That is why God made fast motorcycles, Bubba…

— Hunter S. Thomps
Back to top
 
IP Logged
 
georgesgiralt
God Member
*****
Offline


I Love YaBB 2!

Posts: 1131
Location: France
Joined: 10/14/12
Gender: Male
Re: Maybe I'm paranoid...
Reply #26 - 12/31/17 at 02:55:33
Post Tools
Hello !
The wrist pin problem will be settled, I hope, at engine dismantling.
I've measured (roughly with my caliper) the bushings and the wrist pin.
The wrist pin is at 22.0 mm dia. the bushing with it's opening closed is at 21.6 mm interior diameter. I expect it to be at around 21.5 or a little lower when fitted on the connecting rod.
The thickness of the bushing is 1.1 mm ... So I hope this will do.
My last concern is the interference. The set I have on the bike (original) has the wrist pin not moving in the piston skirt. And I suppose it is with some small play on the connecting rod... The new piston have the wrist pins free to move in the piston skirt. So I wonder if they should have the same play on the connecting rod or have some little interference ?
Of course all this is theoretical because I've not checked the connecting rods so I do not know if they will be reused or not.
I've started research on the heads. I've one with damaged exhaust threads. I've found a guy doing an aluminum threaded sleeve which it then solder in place; Very neat job. he is willing to repair my head. So far so good he can also replace the exhaust seats (I think they are questionable on my bike) and grind them with the proper angles. So I've started to spare money for the head job...
Slowly progressing but progressing  Smiley
check this out. In French but with pictures...
http://www.flat-twin-bmw.com/t36417-une-reparation-du-filetage-d-echappement-sur...
  
Back to top
 
IP Logged
 
Tony Smith
God Member
*****
Offline


Graduate, Wallace and
Gromit School of Engineering

Posts: 1965
Location: Cairns, Australia
Joined: 07/23/13
Gender: Male
Re: Maybe I'm paranoid...
Reply #27 - 01/12/18 at 16:01:56
Post Tools
What was the outcome please? Were those split little end bushes really for an R65 or not?
  

1978 R100RS| 1984 R65 | 1984 XT350 | 1992 KLE500 | 2002 R1150GSA
Back to top
 
IP Logged
 
georgesgiralt
God Member
*****
Offline


I Love YaBB 2!

Posts: 1131
Location: France
Joined: 10/14/12
Gender: Male
Re: Maybe I'm paranoid...
Reply #28 - 01/13/18 at 02:45:22
Post Tools
Well, for now, they sit with the other parts on the garage shelf.
I'm still saving for the valves and the valve job.
I plan to go to the local Guru and ask him, but it could be the correct part given how little metal I should have to remove to have the bushes fit.
Add to this that i won't do this myself and the engineer doing the job could make a bushing if needs be...
I'll report back in a few month when all the parts will be gathered and the job done.
Stay tuned Wink
  
Back to top
 
IP Logged
 
Page Index Toggle Pages: 1 [2] 
Send TopicPrint