Forum bmwbike.com

Mark,
I'm, restoring a 1958 BMW R-60, VIN R60618879.

3 of the tappets are pitted; one is perfect. The parts manual gives me 3 numbers -- 320033102, 104 and 105. You list them with no prices; I assume they're no longer available. But you do list 127, which the parts manual says is for the /2. Will that work for me? Can I still use the one original that's good? Thanks in advance for your help. Philip

Philip,

You can have the surfaces of the tappets reground at a fraction of the cost of purchasing new ones. Pitting is a common problem for most all 50-69 BMW's. If you want it done by an experienced shop, email me and I will give you their email address and home page. I just had mine done (4) and the result is like new!

Pierre

Two of my R60/2 tappets were pitted. I sent them to the following person for repair. He welds on new hard material and grinds the face to tolerance. He is also building up my worn out crankshaft bearing seats with hard chrome and grinding them to tolerance. His website describes both services - about $25 per tappet and $130 per seat.
Cycle Works, Inc.
Attn: Ed Korn
170 Jackson St.
Madison, WI 53704
608-246-0404
If the following email address and URL do not show, email me:
edkorn@itis.com
http://www.aetherserv.com/cycleworks/

Hi Philip
The tappets or cam followers with the end numbers 102; 104 & 105 are 4 window cam followers with flat cam surfaces. These cam followers are nice and light, but tend to break between the windows. The cam surface also tends to pit. BMW replaced these with the new cam followers with the end numbers 127; 128 and 129. These had two windows and a very slightly convex cam surface which results in a rotation of the camfollower during operation.

We can only warn you against a good looking but very inferior quality cam follower on the market at present as they will result in motor damage and destroy the ends of the pushrods. If you buy new, then only original BMW parts from your official BMW dealer which are manufactured by us for BMW. They are expensive, but worth it. I cannot comment on the quality of Ed Korns cam follower repairs as I have no experience, but does he regrind a convex surface? and does he know at what angle?

As we manufacture the original cam followers right here in Switzerland for BMW, we have alot of experience and work to the original BMW specs. It is a complicated casting with nitride hardened surfaces and soft walls. It is a science and a complicated and expensive process to manufacture such an unimportant-looking little part. Instead of going into an extremely complex explanation and details, I ask all who read this to just except and respect the fact that this article is to be taken most seriously and don't buy cheap and destroy your motor.

Best regards,

Mark
Mark Huggett GmbH

Hi Mark,
Very interesting about the tappets. I asked Ed Korn if his refaced tappets were convex - he was very aware of the issue and said yes. I would like to pass on his reply here:

All the BMW R50 R50/2 R60 R60/2 R69 and R69s cam followers, both 2 and 4 window styles have convex surfaces. I just once again checked a bunch of pitted but original 4 window BMW ones to confirm that. This, along with the lobes on the camshafts that are not parallel to the axis of the shaft but have a slight "slope" insure that the lifters rotate to distribute wear. You can easily check this convex surface by taking two of your lifters and putting the faces that contact the camshaft against each other. You will see that they don't lie flat against each other, but rather rock, and you can hold the interface up to the light and readily see the convexity. As for the rotation, on any but the most badly pitted you can see the concentric circles that are the sign that they have been rotating. You will find that when you get your exchange lifters back the same degree of convex shape as is present, as well as the proper slope when camshafts are ground. You never see any wear on used lifters, but very frequently some degree of pitting. I've run hardness tests on these lifters and it's clear that to a degree BMW botched the specifications. The face of the lifters are about a 64 on the Rockwell C scale, and the cam lobes about 60. In my view the reason so many lifters pit is they are too hard. Current practice is in the upper 50's for lifters and mid 50's for cam lobes. I can think of more desiable things to have circulating in the engine than flaked off bits of Rc 64 steel harder than even hardened ball bearing steel (Rc 54 to 60 depending on the bearing).
Ed Korn

Hi Allan

Thanks for taking the time and adding the response from Ed Korn. I tried to keep it short and simple as I have little time. You, Ed and others may find the following interesting:

1. All 4 window tappets had flat surfaces before the technical drawings were changed to a convex surface on the 24/05/1961

2. Due to breakages between the windows of the 4 window tappets, BMW changed the technical drawings to 2 window tappets on the 15/11/62.

3. The specified hardness on the tappet face is 50 to 55 HRC, to a depth of 3.5mm

Best regards,

Mark
Mark Huggett GmbH