Boxerworks.com

Rob Frankham wrote: ↑Sat Jun 18, 2022 5:07 am ....it's a bad idea to source new bearing shells until you know the state of the engine...

We absolutely agree on that...
I initially said: "I would tear it down for an accurate complete diagnosis before investing one red cent."
kmisterk found this impractical given his situation.

Rob Frankham wrote: ↑Sat Jun 18, 2022 5:07 am Suffice it to say that I have known a number of reground cranks go on to give perfectly good service for years.

Where we disagree is that I say "NOBODY on the planet can PROPERLY regrind these cranks".
And that's without even factoring the cost vs. a new one.
You say it can be done but can't provide a link to someone who has a good track record of doing it.
A long time ago (pre-internet) our BMW Canada service rep inquired directly to the BMW factory division where the cranks were made to see if they could regrind a few cranks for us. The factory manager's response was "Our business is to fabricate and sell new parts, not to repair old ones".
Over the years a few independent shops invested in what they thought was needed to do the job. They all quit doing it after repeated (and almost instantaneous) failures.

All repair shops will polish up a lightly worn or lightly blued crank, install new stock sized bearings and shells and call it a 'bottom end rebuild'. And there's absolutely nothing wrong with that. That's the way to do it. These 'rebuilds' will usually run 'virtually' forever. Just don't confuse this job with a regrind with oversize bearings and shells of a severely damaged crank. Some shops will say "Sure we can do anything, send us your crank" only to call you back a few weeks later and say " Sorry, your crank is just too worn/damaged to regrind, you'll need to buy a new one." By then your on the hook.

BTW RobF- You still didn't answer my question...
Can you provide a link to one of these airhead type 247 crank regrind 'experts'?
Can anybody?

gspd wrote: ↑Sat Jun 18, 2022 9:24 am
["NOBODY on the planet can PROPERLY regrind these cranks".

I'm sorry and don't want to seem derogatory but that is a totally fatuous comment. How the blazes do you think that BMW made the cranks in the first place?

No, I didn't answer your question. In my opinion it's irrelevant to the discussion.

Rob

My crank was reground over 120Kkm ago. Sent to some place in South Oz.

I do have a spare one that I kept from a cheap engine I pulled apart. It's been checked professionally as perfectly good. It's back up.

SteveD wrote: ↑Sun Jun 19, 2022 5:44 am My crank was reground over 120Kkm ago. Sent to some place in South Oz.

Do you have a link to that place in South Oz?
Maybe Airbear or ME109 know about this specialist?
I'm assuming the one pictured is your polished up spare, if not my hat's off to the guy who reground it. It looks perfect. That radiusing is perfect. Never seen one done so well, not even close to that.

If in fact the one pictured is your spare, do you have a pic of the reground one before you installed it in your bike? If you still have the invoice could you please verify that the shells in it are not #11 24 1 258 460.

Is there the slightest possibility that the one presently in your bike was just finely polished and re-fitted with stock size bearings? There's a thin line between the terminologies used by the repairers, whether to intentionally mislead or not. Refurbished, repaired, repolished, rebuilt, renewed, restored, reground, reconstructed, renovated, revamped, reconditioned, etc.
In my book, reground means it was machined down from 48 to 47.75 and .25 oversized bearings were fitted to close the gap. (all numbers rounded out for clarity)

The reason for all this discussion is that I have access to a cache of over a dozen scrap (but regrindable) crankshafts and if I could get them redone perfectly at a reasonable price, I would. A new one is $2000, I could easily sell them for $1000 on ebay, if they're re-done perfectly. The last 'regrinder' I showed one to took one quick look at the bobweight setup and said "forget it, I'm not touching that".
EDIT: This was after he told me on the phone that he could get past the 'too short for his machine' issue by fabricating spacers.

Rob Frankham wrote: ↑Sun Jun 19, 2022 5:05 am How the blazes do you think that BMW made the cranks in the first place?

They made them properly.
But they wont regrind one for you or me, unless you have some intimate connection with them that nobody else has.

I always thought that the names of Chris Chambers, Joe Groeger, and Ed Korn and possibly Dan at Cycleworks were capable of regrinding cranks.

Kurt

gspd wrote: ↑Sun Jun 19, 2022 9:59 am
Maybe Airbear or ME109 know about this specialist?

Unknown to me, and I'd say not known to Charlie either.
When my oil filter bypass spring broke and eventually took out the rear crank journal, Nick Ploeg from NZ kindly sent a very nice s/hand crank to me.
I've not heard of many successful crank regrinds either.

My engine wasn't rebuilt by me. The local guys at BM Motorcycles in Ringwood, Victoria, Oz did the work in September 2005. They sent it out to a place in Sth Oz. I don't know that place but I do remember asking if repair was wise. They were very confident.
The receipt for the work just describes

Additional grind-main bearing journals
Remove crank weights and crank grinding re rivet balance weights

That picture of my spare crank is after I polished it slightly. It looked ok so I had it professionally measured to be sure.
Here's a thread on advrider with pix...https://www.advrider.com/f/threads/conr ... t-40669561

Kurt in S.A. wrote: ↑Sun Jun 19, 2022 1:44 pm I always thought that the names of Chris Chambers, Joe Groeger, and Ed Korn and possibly Dan at Cycleworks were capable of regrinding cranks.

Thanks Kurt, I emailed them for info, awaiting a response, but I'm pretty sure they only do /2 cranks. I'll report back when I get an answer.

SteveD wrote: ↑Sun Jun 19, 2022 10:46 pm My engine wasn't rebuilt by me. The local guys at BM Motorcycles in Ringwood, Victoria, Oz did the work. They sent it out to a place in Sth Oz. I don't know that place but I do remember asking if repair was wise. They were very confident.

So I guess there's no way to know for sure if it was actually reground and fitted with oversized bearings. Maybe it was, maybe it wasn't. I hope it lasts forever for you. The only way to really know is if something goes wrong, otherwise there is no reason to take it apart.

SteveD wrote: ↑Sun Jun 19, 2022 10:46 pm That picture of my spare crank is after I polished it slightly. It looked ok so I had it professionally measured to be sure. I can't remember if that pic is before or after the inspection.

I guess there's nothing wrong with having it professionally measured, but just for the record, if you know what to look for, and it looks that good, it IS that good. A bad crank just can't look that good.
"You don't have to be a weatherman to know which way the wind blows". - Bob Dylan

RANT (does anybody actually read this shit?)
I was taught by more than one of my bosses that smoke and mirrors is a HUGE part of doing business, it's part of "the customer experience". For example, a client walks in with a box of parts and pulls out a cylinder he would like inspected. He wants to know if he needs a new one. At first glance you notice a 1/8th inch ridge at the top, a few very deep rusty scrapes, all the original honing marks are totally worn away, and there are visible signs of a partial seizure.
Don't immediately tell him it's scrap.
Instead, wipe off the counter, pull out the fancy velvet lined bore gauge box loaded with its shiny precision tools from the top shelf in the office, wipe the cylinder down with some brake cleaner and a clean shop rag, carefully take a dozen measurements of the cylinder in different directions, top, center and bottom of the bore while meticulously writing each one down. Then, pull out the 'big book' shop manual, and after a bit of page flipping, pull up the spec sheet and ramble off some numbers to the customer, who is now looking at you like you're Einstein. To add icing to the cake, do some simulated math on a piece of paper for a few minutes.
THEN, and only THEN, tell him it's scrap.
Customers love that kind of service.
The bonus is that if the customer choses not to buy a new cylinder from you, or chooses to buy one elsewhere, you can charge him something for your 'inspection' time.

SteveD wrote: ↑Mon Jun 20, 2022 1:32 am (yes, I did read it)
Big end bearing shells were replaced. 0.25+
I wonder if the expertise issue is the balance weights and re riveting?
Here's my good spare crank just after I removed it.

errr...hmmmm...i'm perplexed.
Maybe it's because I'm not sleeping well in anticipation of my first real vacation/long ride since covid started.
Only a few more days before official launch. My body's still here but my mind's already gone.
Why exactly was this crank removed?
Is there something I'm not seeing in the pic?
Oil pressure was obviously A-OK....
No visible sign of a knock (translation: no knock)....
I would have slapped in some new stock size big end shells and smashed that sucker back together and beat the piss out of it for at least 100,000 miles before even considering an extraction.
I'd even give a guarantee on it if I thought the customer wasn't a total moron.
But, hey, that's just me, the mechanic from hell.