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Author Topic: Geared Primary Drive  (Read 5948 times)

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Offline turboguzzi

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Re: Geared Primary Drive
« Reply #150 on: March 21, 2019, 02:47:28 am »
nice that you wan to set it at 0.01mm steps, but just think about the expansion of an alu crankcase under racing heat and your adjustment will soon become +0.3m...

those flat shims are also available at 0.05mm steps, but even that is over the top. if you had seen the backlash in bikes that have geared primary you'd understand why.

Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #151 on: March 21, 2019, 05:50:37 am »
yoss I am not sure. I mean steel idler will expend exactly 0.09mm from initial 100mm length when it gets to 100C... I don't believe it gets warmer  ? Maybe 120C

but everything expends....

My idea is that I need around 0.03 - 0.05mm of clearance between teeth of coupling gears. I think it is important to get it right because of longevity of the gears. But maybe I am aiming some impossible tolerances. 

Idler should not push crank in to crank bearings. It would ruin crank bearings fast ? It is important to be able to correct that

Assembly faze would demand some plastiguage before finial assembly

Offline Don R

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Re: Geared Primary Drive
« Reply #152 on: March 21, 2019, 10:27:37 am »
  As the steel idler expands, the aluminum crankcase will also, so will some of that expansion be offset by the movement of the other components?  The valve lash of my pushrod V8 race engine is .006 looser cold than hot but that's over a pushrod length of 7+ inches and a combination of aluminum, iron and steel parts. An apples and oranges comparison for sure.
  Many things to consider, I have confidence you'll get it right.
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Offline Tracksnblades1

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Re: Geared Primary Drive
« Reply #153 on: March 21, 2019, 10:29:31 am »
guys, tnxs for confirming my thoughts on AL=steel..... exposed to elements is another story of course, TT.

Mirko, if you are in need of shimming material, just come and grab some next time you are in milan.

if not search for Hasberg shims

would design say for nominal 0.5 shim so you can go both up and down in .1mm steps

for X, cant see the problem making the holes a bit oval, with 4 M8 bolts (?) exerting a few tons of grip it's not going to go anywhere....

you are in good company, even works GP hondas had to shim their cam gear drives :)

I want to be able to shim in finer steps of 0.01mm. Will look if that company has finer shims. I will machine everything in -0.1mm(maybe -0.2mm) position. And then you can add shims to infinity position ;)

It is not a problem to add oval shaped holes... But how to position it , let say, 0.03mm from original X position?

There are 4 M10 bolts holding the idler and two bolts have locating dowels around them in current design,

Mirko,
Wow....
While I'm not sure how your 4 M10 bolts are employed in reference to the 97% up force (shim pack compression)?  In some machining center applications the adjustable x minute (very small)  movements have been accomplished with jack bolts on each end while incorporating tracked or recessed machine groove to eliminate side movements or yaws. The jack bolts are used similarly as opposing 4 jaw lathe chucks. The track or way machining is only to maintain squareness during x movements and re torque using slotted bolt holes.

Have you ran the reverse loads imparted on your idler mount? I was just trying to visualize a 5th to 2nd gear down shift with a sticky on back. And the opposite force on those 4) 10mm bolts.

Additionally on the subject of expansion. When you stated idler gear expansion rate, does this include the expansion rate of the idler's mounting fixture also? I wonder, as TG made reference to, how wide the manufacturers back lash specs are for current primary gears. I don't want to see you beating yourself up for nothing.😩 My own experience with straight cut gears? They tend to complain quite loudly when they prefer more back lash.

👀 Looking good Mirko. patiently, impatiently, watching and waiting.
👍

« Last Edit: March 21, 2019, 10:53:42 am by Tracksnblades1 »
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Offline cr750

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Re: Geared Primary Drive
« Reply #154 on: March 21, 2019, 01:32:14 pm »
What is the round hole on captains idler gear fixture ( few pages back )  doing ?

http://forums.sohc4.net/index.php/topic,171740.msg2053043.html#msg2053043

I wonder...is it located around crank someway as in to index idler fixture with accuracy ...Obviously a fixed center to center index from gear on crank Vs idler gear, saves you a lot of shimming worries.... My engineering guts tells me he's indexing it of the crank...that's what I would do...but I might be wrong.
« Last Edit: March 21, 2019, 01:40:53 pm by cr750 »
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Offline Captain

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Re: Geared Primary Drive
« Reply #155 on: March 21, 2019, 03:03:43 pm »
 Here you go......... Should answer your questions....................Also look back on page 2 of this thread (fitted into the cases).
  I'll also add to the discussion as I obviously have a gear drive operating and subsequently some experience on the operational forces that I anticipate problems without any form of attachment of the carrier  that does not include at least two planes at 90 deg to each other. 

 Captain
« Last Edit: March 21, 2019, 05:06:41 pm by Captain »

Offline 754

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Re: Geared Primary Drive
« Reply #156 on: March 21, 2019, 06:00:02 pm »
 At one point you have to try it. It may or may not meet your expectations,
 It might exceed it.
 If it lasts 3x as long as chains,  it's an improvement..

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Offline cr750

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Re: Geared Primary Drive
« Reply #157 on: March 22, 2019, 01:29:36 pm »
Thnx captain, your solution makes sense to me, missed your previous post.
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Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #158 on: March 23, 2019, 04:45:35 am »
Here you go......... Should answer your questions....................Also look back on page 2 of this thread (fitted into the cases).
  I'll also add to the discussion as I obviously have a gear drive operating and subsequently some experience on the operational forces that I anticipate problems without any form of attachment of the carrier  that does not include at least two planes at 90 deg to each other. 

 Captain

Captain did you try system without connection of idler to the main shaft ?

I am looking on picture of RC engine. It looks like it is similar to my solution. Put idler is just partially visible. Does anyone have more pictures of idler in Rc engine?

I have a solution how to attache it with one more plane. Will make render later
« Last Edit: March 23, 2019, 05:07:12 am by MessnerMoto »

Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #159 on: March 23, 2019, 11:32:21 am »
Thanks to Rolf Faeh! Also member here, we have some pictures

there are 4 bolts holding the idler carrier  down. I am guessing M10. Two locating pins. Also you can see that on idler carrier there is a hole for oil feed.

And from the look of shaft diameter... there is no bearing inside. Idler gear is floating on oil.

more pictures here

https://www.facebook.com/pg/TeamRCBCaillouBedier/photos/?ref=page_internal
« Last Edit: March 23, 2019, 12:01:16 pm by MessnerMoto »

Offline livefast_dieold

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Re: Geared Primary Drive
« Reply #160 on: March 23, 2019, 02:08:20 pm »
Massive finding! Bravo Mirko!!!

Offline Tracksnblades1

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Re: Geared Primary Drive
« Reply #161 on: March 23, 2019, 06:38:40 pm »
How did they accommodate that near 40 tooth crank gear driving the transmission.
I've read the 28 tooth cb900 crank speeds up trans 8% but haven't actually done the math.
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Offline simon#42

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Re: Geared Primary Drive
« Reply #162 on: March 24, 2019, 03:33:17 am »
that made for a good read , thanks for posting the link
much as i hate replicas they seem to have made a decent job of this one . not just a collection of parts from a later roadbike

Offline turboguzzi

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Re: Geared Primary Drive
« Reply #163 on: March 24, 2019, 12:52:12 pm »
OMG, still trying to recover my jaw from a massive drop. pretty shocking what these guys are doing.
sure an one-off crank is a nice way to solve a problem, that part alone must be in the 10K$ i guess. then the head casting. Nowadays you can use 3D printing for one time investment casting cores, but still....
Mirko, it could be a needle bearing in there. considering the RPM maybe not best, but as for load capacity, a good option.

Offline cr750

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Re: Geared Primary Drive
« Reply #164 on: March 25, 2019, 06:45:06 am »
Are you sure it's a one off crank ?
Could also be a modified crank, because all I see in the pictures is broaching of the gear teeth ( probably to 'fix' the profile ).
But what puzzles me is the duplex chain gear... Do not have a crank that comes to mind that could fit. They might have welded it on and machined it.......zoom in real close to that picture...you see an fillet edge around the outer gear....not on the inner one...

But....Considering they also cast the head for the double camshaft and duplex chain...you might be right... ;)
« Last Edit: March 25, 2019, 11:46:15 am by cr750 »
Wanted: PERIOD cr750 or rc750 parts.
In specific; plastic cr31 velocity stacks, foot levers(+cable), rear brake. Got any of these parts or other period cr/rc750 parts/leads; Pm or E-mail me !

Ps. I know where to find the MODERN reproductions.

Offline simon#42

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Re: Geared Primary Drive
« Reply #165 on: March 25, 2019, 11:23:22 am »
guy coulon knows his stuff he has been in motogp for years , designed the moto2 mistral chassis and in his spare time made a 6 cylinder engined
bike from scratch , making a cylinder head and a crank would be easy !

Offline turboguzzi

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Re: Geared Primary Drive
« Reply #166 on: March 25, 2019, 11:46:39 am »

Offline cr750

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« Last Edit: March 25, 2019, 12:27:26 pm by cr750 »
Wanted: PERIOD cr750 or rc750 parts.
In specific; plastic cr31 velocity stacks, foot levers(+cable), rear brake. Got any of these parts or other period cr/rc750 parts/leads; Pm or E-mail me !

Ps. I know where to find the MODERN reproductions.

Offline simon#42

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Re: Geared Primary Drive
« Reply #168 on: March 25, 2019, 12:35:02 pm »
the people doing the head are these
https://www.vintair.com/single-post/2018/02/06/Derni%C3%A8res-op%C3%A9rations-dusinages-sur-la-Culasse-RCB

they make allot of other interesting stuff as well
i think guy coulon is tech3 classic , i cant see herve being very interested . will ask him when i see him .

Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #169 on: March 25, 2019, 02:36:54 pm »
beautiful work!

I like the part where they simulate how melted Aluminum will behave when casted in to molds..

back to the topic...

I think I am close to Honda idea about idler. I will add more material on sides of idler holder. But from what I have saw I over engineered everything. Look at lower case in picture where oil pan surface on case is up. You can see that there is not a lot material holding the idler in case. One side of idler is attached to oil line and below other side there is also "space". Any thoughts ?

I will keep ball bearings inside for sure.

« Last Edit: March 25, 2019, 02:42:23 pm by MessnerMoto »

Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #170 on: March 27, 2019, 02:01:49 am »
I am pretty sure there is no needle bearing inside.

Probably a bronze bushing, some carved oil lines on busing and thats it

look at the picture
« Last Edit: March 27, 2019, 02:08:28 am by MessnerMoto »

Offline cr750

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Re: Geared Primary Drive
« Reply #171 on: March 27, 2019, 04:09:56 am »
I also noticed that hole. My idea is the hollow shaft indeed allows for extra lubrication on those gears trough that hole. I wonder if it is just one, or 2 or 3 holes...
Could be that it's just running on a bronze bearing, hard to tell, without my rontgen eyes.
Hole size is also critical as in not to lose too much oil pressure/lubrication on the axle then  ;)
« Last Edit: March 27, 2019, 08:59:54 am by cr750 »
Wanted: PERIOD cr750 or rc750 parts.
In specific; plastic cr31 velocity stacks, foot levers(+cable), rear brake. Got any of these parts or other period cr/rc750 parts/leads; Pm or E-mail me !

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Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #172 on: March 27, 2019, 04:18:44 am »
If there was a bearing inside it would be blocking that oil feed hole

Offline slikwilli420

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Re: Geared Primary Drive
« Reply #173 on: March 27, 2019, 05:32:11 am »
What about a needle bearing? The cage on it is open and would allow the oil to lube the bearing then pass up through the hole(s) to splash on the gears as they mesh. A small line from the feed side of the oil pump right to the middle of that shaft with an oil jet to restrict flow would work nicely.
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Offline cr750

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Re: Geared Primary Drive
« Reply #174 on: March 27, 2019, 09:07:00 am »
I was thinking the same (needle option). And even with a cage bearing you could make the oil pass, you also have special ones with a groove all around the cage.
But of course crank and cams do very well on just oil, so considering the forces the Honda engineers might have thought along those lines.
Kiss method.

Also wondering what are those flanges ( and which material) on either side of the idler gear ? Shims ?




Could be the bearing bushing consists of two halves with flanges... pushed in from either side ?

Or this (below) could also be the case..and with the shims on either side ?




But Mirko, might be worth to just ask our French connection instead of the (calculated) guessing game...
A mail with a tel nr for some whatsapp conversation can't hurt anyone.
Maybe they also think sharing is caring, I am sure they know all about it.... could speed up the process ;-)

How about the modern motocycle engines ? Bearing or not on the idler ? In bigger automtive engines I see many with the above bushing or needle bearings.
« Last Edit: March 27, 2019, 12:58:09 pm by cr750 »
Wanted: PERIOD cr750 or rc750 parts.
In specific; plastic cr31 velocity stacks, foot levers(+cable), rear brake. Got any of these parts or other period cr/rc750 parts/leads; Pm or E-mail me !

Ps. I know where to find the MODERN reproductions.

 

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