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malmac
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Toowoomba, Australia
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Hi Folks

I am doing up our R69s and intend to fit a set of new timing gears as the current ones are pretty chewed.

While the distances between the centres of the camshaft and the crankshaft are stamped on the crankcase by the factory, I have heard the crankcase can distort over the decades making the distance between cenres different.
Ours is "0".

Has anyone had experience with fitting new gears to your bike?

Any advice or ideas would be most welcome.

Mal

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mal - R69s
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Micha
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The engine casing has a

The engine casing has a number stamped on it on the left hand side top near the two M8 studs for the upper engine mount.
This is the tolerance of the engine casing between -10 and +10.
The R51/3 to R69 used timing gears with a 20° tooth angle. This was changed in 1960 to 30° and retrofitted to all older models.
That means that you will also have to change the oil pump gear to 11 41 0 052 156.
One also has to change to the later breather plate 11 15 0 031 171 and parts as per the R50-2 to R69S models.
Once you have found the number stamped on the housing, the seller should know all the required parts in need.

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Michael Steinmann
R51/3 1952
Engine Nr. 529466

schrader7032
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Here's Duane's discussion of

Here's Duane's discussion of the gear set:

https://w6rec.com/timing-gear-numbers/

I wonder what Barrington has to say about it.

My recollection is that it may be difficult to find the right set of gears. The factory had the benefit of having numerous gears stamped with various numbers. They could swap fit until them found a set that worked. Rebuilders today can't afford to work that way.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

malmac
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I had heard something like that - but lost the detail

Hi Kurt

Thank you for the link.
I wonder if anyone, maybe Mark Huggett would have the numbers/ready reckoner for what spacing between centres gets which gear set.

I could then measure the diuatance between centres and order the correct gear set.

This engine has been done over before because it has what might be a -3 camgear, which has been crossed out and a -5 etched on the gear but it is a -0 engine case.
Now that sounds like maybe order a -5 set to replace the gears or was that really a -3 cam gear mated to a -5 crank gear? The reason for replacing the gears is because something like a cast iron possum has been fed through the gears at some stage. The crankshaft gear now looks like a file, so I don't want to be pumping lots of crud through an engine which is getting a new crankshaft and new pistons, etc.

Mal

  • mal_0625.jpg
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mal - R69s
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malmac
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If only it was that simple, I would do it

Thank you for your response.

I do have a new breather plate and new oil pump gear to fit to the engine, so have that covered.

As you will see from the photo, I have a cam gear that looks like it was once a -3 gear and someone has decided to rebrand it a -5 gear. I have no idea why.

So am I replacing a -5 gear, a -3 gear but it seems clear from Duane I don't want a -0 gear.

Well these are the fun but potentially expensive parts of rebuilding a rather old engine.

Mal

  • mal_0625.jpg
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mal - R69s
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Micha
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Yes, Mark Huggett will be

Yes, Mark Huggett will be able to help you here. Also send him a closeup pic. of this sprocket.

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Michael Steinmann
R51/3 1952
Engine Nr. 529466

malmac
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Toowoomba, Australia
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Mark Huggetts response.

For the record here is what Mark had to say. He placed his response in the body of my email to him.

"Dear Mal.

Good to hear from you again."

On 20 Mar 2020, at 22:56, Mal

Dear Sir/ Madam

I am currently rebuilding our R69s engine.

I would like to fit a new set of timing gears as ours are badly chewed.

The engine has been worked on prior to our ownership and the gear set that is coming out leaves me in some doubt about which gear set I should consider fitting.

Here is the cam gear that has been removed. It seems like it might originally have been marked as a -3 and then someone has crossed it out engraved the -5.
The engine cases are stamped -0.

I have read Duane Ausherman’s article on high milage bikes and the gradual distortion of the crankcases, which might explain why this engine is fitted with different timing gears to the original specs.

"I doubt if that is the reason. The gears have been replaced with a miss matched set which, when paired, happened to fit."

If I measure the distance between my crankshaft centre and my camshaft centre, would you be able to tell me which gear set would be appropriate?

"Yes, if you have the possibility to carry out such a precise measurement at 22,5°C."

"I would personally rely on the tolerance stamped on the housing (-0) as our gear set matching already considers a slight deviation due to housing growth."

"That means that you can order our 11 31 0 016 389."

"Note that there is no international post between Switzerland and Australia at present as all flights have been grounded."

Thank you in advance for your response.

Mal McIlwraith
Toowoomba
Australia
Best regards,

Mark Huggett
Mark Huggett GmbH
BMW Classic - Geschäftsleitung
http://www.bmwbike.com/

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mal - R69s
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San Arthur
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San Antonio, TX
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Restoration in times of pandemic

Mal it looks like the covid-19 is catching up to us. Good luck!

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'58 R26 '76 R90S '94 R100GS/PD

malmac
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here are some informative pics

First is a picture of a low milage, well maintained R50. Notice the nice fit between the timing gears.

Second pic is of the fit between my timing gears. I think most would agree they don't look that good.

The theory is that this cam gear has been mated to an available crankgear in a way that works but it's not falsh.

Mal

  • grahams_timing_gears.jpg
  • mal_0657.jpg
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mal - R69s
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schrader7032
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This stuff is way over my

This stuff is way over my head, but in your close up picture, it sure seems like the teeth profiles are different for each gear. Is that normal?

In the Barrington manual, the only thing they say is the specified gear lash was between 0.01mm to 0.02mm. I don't really know how/where that is measured. There's also a note about differences in tooth angles. Prior to 1960, the angle was 20 degrees and was changed to 30 degrees from 1960 onward. Clearly the two different angles can't be used together.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

malmac
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Toowoomba, Australia
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Ahh the vertical learning curve

Kurt

I don't know but once I have spent large amount of cash, I may have a better outcome and still not know much more.

You can see from this close up of the crankshaft gear that some unhappy memories are imprinted on that gear.

Mal

  • mal_0662.jpg
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mal - R69s
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