Will the Real twin Cam Come forward ? - Page 3

Jeff Higgins · 08-27-2020, 01:08 PM

Stock 2007 and later Twin cam crankshaft assy on ebay right now. The con rod small end clearly has a bushing. Here is one of the photos from the ad:

https://www.ebay.com/i/283796665660?chn=ps

Kibblewhite replacement small end bushings, 2005 through 2017:

https://shop.kpmivalvetrain.com/p/bushing-wrist-pin-std-hd-twin-cam-88-103-2005-2017

Your repair shop is clearly mistaken about this "bushing-less" small end.

And, as I mentioned earlier, the big ends and the crank bearings are still, in fact, roller bearings. They are actually of a larger size and greater load bearing capacity than those used in the Evo motors. Maybe they are no longer sourced from Timken, but there are a number of other manufacturers of high quality roller bearings.

Lower end failure has never been an issue with the Twin Cam. They are well known for going well over 200,000 miles in normal service.

So, yeah, I guess several hundred thousand Twin Cam riders have apparently "escaped the bullet" along with me. I guess we are all "lucky"...

afterburn 549 · 08-27-2020, 01:19 PM

its the timpken part that is important the "tapered part"

Jeff Higgins · 08-27-2020, 02:56 PM

Timken is a bearing manufacturer.

The "tapered part" I believe you must be referring to is the crank pin itself. Evo and earlier crank pins had a Morse taper on each end where they pressed into the flywheels:

The Twin Cam and the Milwaukee Eight improved on that with a far more robust straight pin design:

This improved design has proven over 20 years of use to hold up quite well. Much better than the old Morse taper type of crank pin. Again, the Twin Cam has earned a reputation for very impressive longevity. A large part of that is due to the improved crank pin design, eliminating that troublesome Morse taper.

So, no further comment re the "bushingless" con rods?

afterburn 549 · 04:50 PM

A Timken bearing is what it is known by, It has worked for years .
When the cranks fail, the shops have figured out how to "back date" and go back to the tapered bearing, just like a wheel bearing they are.
It fits on the crank, not the rods.
The rods have been rolllers forever.
Next-
I am working on the bushings omited as of right now, sourcastic?
Just having a conversatrion here.

Rot 911 · 08-27-2020, 05:06 PM

Sweet baby Jesus afterburn, you have quite the hard on for Harley Davidson. The only real issue there ever was with the twin cams was the cam chain tensioner. After 2006 they went with the hydraulic tensioner that solved the problem. And for the earlier models, it’s easy enough to do an inspection of the plastic shoes to see how much life they have left on them.

I’m sure in your world, everything was better in the “old days.“

Here’s my twin cam:

And for old school, here is my 73 Norton commando in all its kickstart, shift on the right glory:

afterburn 549 · 08-27-2020, 05:11 PM

Nope i don't, i just say facts and some people dont like em.

I have owned lots of different bikes, not just the HD.

So, your tea maybe sweet and that is a good thing . For sure i have no horse in the race as i just dont care.
It is just a conversation.
If you would like to argue the point rather then make an accusation that would be great

Jeff Higgins · 08-27-2020, 06:00 PM

The problem is, you have yet to present any "facts", just unfounded rumors. Your "bushingless" small end of the rod was easily refuted, for example. I suppose the same "mechanic" that told you these bushings had been eliminated also told you the modern thrust bearing crank design regularly fails as well...

The dual opposed tapered bearings in the left side case on the Pan, Shovel, and Evo only do one thing - control crankshaft endplay under thrust loads - which motorcycle cranks typically do not see. The clutch, or more precisely the actuation of the clutch, is what applies thrust loads to crankshafts - with the clutch mounted back in line with the transmission, this load is not applied to the crank. So H-D came up with a better way to control crankshaft endplay - a simple thrust bearing. It's all that is needed in this application. Actually, it is far more robust than the earlier tapered bearing design. And, again, it has proven to be trouble free for 20 years, with many engines so equipped lasting well over 200,000 miles.

afterburn 549 · 08-27-2020, 06:23 PM

Quote:

Originally Posted by Jeff Higgins

The problem is, you have yet to present any "facts", just unfounded rumors. Your "bushingless" small end of the rod was easily refuted, for example. I suppose the same "mechanic" that told you these bushings had been eliminated also told you the modern thrust bearing crank design regularly fails as well...

The dual opposed tapered bearings in the left side case on the Pan, Shovel, and Evo only do one thing - control crankshaft endplay under thrust loads - which motorcycle cranks typically do not see. The clutch, or more precisely the actuation of the clutch, is what applies thrust loads to crankshafts - with the clutch mounted back in line with the transmission, this load is not applied to the crank. So H-D came up with a better way to control crankshaft endplay - a simple thrust bearing. It's all that is needed in this application. Actually, it is far more robust than the earlier tapered bearing design. And, again, it has proven to be trouble free for 20 years, with many engines so equipped lasting well over 200,000 miles.

Jeff, you are imposable to have a conversation with.
You get all emotional and snippy. About stuff you are no authority on at all .
Unfounded rumors?
Really?
Unless you want to argue with kevin Baxter about it and win i will watch, see if you win.
LOL
I HAVE proof right here that the rod ends in late Twinks came with out Bushings .
I will get the pix up and the info up ASAP.
SO DONT GLOAT TOO MUCH
AS you are worng , and you do owe me an apology for going off the rails like that.
No reason what so ever
AS you are wrong and as usual I am right.
This is much like arguing the advantages and disadvatages of a mag case in a 911.
There is no disputing it at all.
You dont seem to know how a Harley crank is even put togather! .
You are pointing to the big end of the rod and that was never in the equation.
They are "plug" fit roller bearings, always have been.
The arument i am showing you is the Left side crank bearing,the more expensive timken was deleted for a lessor quality ball bearing .
But alas you have to make this a contest.
You do lose.
it was just a conversation.
It was also pointed out to me the M8 comes without wrist pin bushings too.
You disprove this one.
My point is they turned the Twink into a Bean counters love affair.
Now I did point out the Link to "Dark Horse " and there is a dozen other that will back date the Timken bearing in the crankcase .
it is for good reason.

afterburn 549 · 08-27-2020, 06:25 PM

https://harleytechtalk.com/htt/index.php/topic,88782.msg1015040.html#msg1015040

This will get you started on the small ends NOT having bushings any more
Now fight this rumor....
Apology?

Jeff Higgins · 08-27-2020, 09:03 PM

You very clearly stated that the wrist pin bushings were eliminated in 2006, then go on to post a link wherein guys are saying their 2012 and later motors, when torn down, were found to have wrist pin bushings. *Sigh*...

Harley began a "rolling change" wherein the wrist pin bushing was eliminated in lieu of a redesigned (tapered) small end, which has proven to provide superior oiling. This happened much later than you claimed - you were dead wrong. And you seem convinced this is a "bad" thing, that it represents a "cheapening" of the design, done merely to appease the "bean counters". Nothing could be further from the truth. Many, many manufacturers abandoned the wrist pin bushing years before Harley began phasing them out. Not for cost reasons, although it does save money, but for reliability and durability reasons. Modern materials allow them to do this, thereby eliminating a potential failure point - spun or loosened wrist pin bushings. You are blinded by your biases - even an advancement like this goes down as a "bad" thing in your book.

And, no, I was not "pointing to the big end of the rod" - I was asking which "timpkin" (Timken) you were referring to. There were two tapered features in the old crankshaft assy's that were eliminated in the Twin Cam - the Morse taper on the ends of the crank pin and the two tapered Timken bearings on the left end of the crank. Once you provided clarification that the "timpkins" you were referring to were indeed those two tapered bearings, I addressed the differences and advantages of the non-tapered Twin Cam design. Its more modern, robust thrust bearing design.

The older designs required some end play adjustment on the crank, which was provided by the tapered bearings. Just like the front wheel bearings on our cars. Modern, more accurate manufacturing methods have eliminated the need for this adjustment at assembly, allowing Harley to go with the much preferred, much more robust thrust bearing arrangement - pretty similar to just about every other internal combustion engine on the planet. The old tapered bearings were a crutch, necessitated by sloppy manufacturing, that is simply no longer needed. I've been through this once already. And, oh, by the way - there is no ball bearing in this position on the crank as you have claimed. Again, you could not be more wrong - it is a straight roller bearing coupled with a flat thrust bearing.

afterburn 549 · 03:35 AM

Jeff, don't be a child!
I did say about 2006 and fwd!

About, about about about!

-I was wrong on the year, but completely right on the fact, that you so VEHEMENTLY denied .
You get all upity and sophomoric about it .
Why?
You do owe me an apology for carrying on that way.
You are not able to have a simple conversation without the emotion .
I did not call your family ugly, just pointing out the facts.
It is just a dam Morotcycle .
Why is it you cannot even admit you are wrong about anything?
Is that the Boeing in you? As a engineer you cant be wrong ?
Porsche has made lots and lots of mistakes through the years and we can talk about them, but not Harley?
Weird.

I was wrong about the year,-can you forgive me about that?
BUT, i did say "about 2006"!
I did not stake my life on it .

Time flies when so many kinds of engines go past.
I dont do just Harley crap jeff
Harley is NOT my religion..just a hobby.

The point stands -it is/was a bean counters dream. the ONLY reason to delete rod end bushings is to save a penny per unit.
no other reasonable reason.
Just like the cam plates with running steel against aluminum . In the begaining they had bearing /bushings .
That was and is my stoic point .
Too much peny crunching.

Jeff Higgins · 08-28-2020, 08:02 AM

Do you even understand what a "rolling change" means in manufacturing parlance? H-D did not eliminate the small end bushings - they began phasing them out. Some bikes were delivered with them, some without them, apparently right up to the end of the Twin Cam era. And it didn't even start until at least six to seven years after your claim of "about"...

Worse than that, you apparently cannot understand the difference between an engineering improvement and a cost cutting measure. Sometimes, when the stars align, we get both - a better engineering solution that costs less to manufacture. That is exactly what happened here.

I know it's a long-standing tradition in the Harley world for "experts" such as yourself to assume any change was made purely to cut costs, with the product, and therefor the consumer, suffering. It seems to be the only way guys like you are able to process these changes, with no real engineering background to fall back upon. Such is the case here, with each and every accusation you have made about Harley's alleged cheapening of their product. Each and every one of those accusations only serve to do one thing - they put your ignorance-driven bias on full display. You are merely parroting internet rumors and urban legends promulgated by others without the background to honestly, objectively assess these changes. You all just know they are "bad", because some independent mechanic, or some guy on the internet - who are certainly no Harley Davidson engineers - say so. Your eagerness to believe all of it has made you gullible. You have fallen for their ill-informed "expertise".

I don't blame you, though - like I said, this is a long standing tradition in the Harley world. You just somehow got sucked into this one. I've discussed this phenomena earlier - each new model represents the end of "real" Harleys to owners of the previous model. And everyone likes to pretend they know why, to pretend they are "experts" in all things regarding Harley-Davidson engineering decisions. And, well, they are consistently wrong. Ill informed. Like we used too say at work about guys like that "often wrong, but never in doubt".

Jeff Higgins · 02:07 PM

I've used no "engineering terminology" (I assume that is what is meant by "terminaly") whatsoever. I have been completely unemotional about this. And I am certainly not "bitter" - why on earth would I be? I have no "dog in this fight" - I'm not married to the Twin Cam in any way whatsoever - I could buy any Harley I feel suits my needs tomorrow. And another one the next day... I'm not defending something I'm "stuck" with, of feel I made a poor choice in buying. It's just a machine. I could not care less one way or the other which one is "better". There is none of that - I have simply offered a rather dispassionate rebuttal of your claims. That's all.

In sharp contrast, it's pretty obvious that you have an emotional, possibly even ego driven stake in being "right" about all of this. It seems very, very important to you. I'm sorry, though, your basic premise, and the details you have offered to support it, are simply wrong. Every one of them.

You claim Harley "cut corners" in both the design and manufacture of the Twin Cam series of motorcycles, citing two specific areas in which they did this. You claim they were motivated by the "bean counters" and did not listen to the engineers, and that engineers were forced to accept sub-optimal solutions to cut costs, these solutions leading to a decrease in reliability and service life over the Evolution design that preceded the Twin Cam.

You can provide no real data to support these claims. You ignore what is now a 20 year record of outstanding service and reliability from these machines that absolutely, convincingly puts paid to your assertions. You do not understand the engineering changes that you tout as a "cheapening" of the product - changes that are, in fact, clearly improvements. You lean on internet forum "experts" as your "proof".

I'm sorry, but none of that passes muster. Hundreds of thousands of these machines sold over 20 years, millions upon millions of accrued miles, all serve to resoundingly disprove your claims. I'm sorry - that's just the way it is. I'm not trying to bust your balls here - you're one of the "good guys" - I'm just pointing out that, on this particular topic, everything you think you know is wrong and has been quite thoroughly disproven.

Now get out and go for a ride or something - I just got back from a quick buzz up and down the Snoqualmie Valley. I didn't dare risk going that far on my POS Twin Cam, though, so I took my super reliable Italian bike...