Author Topic: Timing gear lash and lubrication.  (Read 4484 times)

Online Huzo

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Timing gear lash and lubrication.
« on: April 15, 2022, 09:35:40 AM »
I have a set of Caruso timing gears that I fitted to my Norge.
Here is an image


Question is..
I consider the lash between the crank and cam gears to be absolute minimum. What is the consensus regarding this lash ?
Will it increase or decrease when hot ? My educated guess is that the cases will expand when at operating temp, resulting in them “growing apart” a very small amount, thus increasing the lash. But that is only a guess, does anyone have an educated opinion ?
I would like to hear from Tusayan as well as anyone else.
« Last Edit: May 25, 2022, 12:54:21 PM by Huzo »

Offline Sye

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Re: Timing gear lash
« Reply #1 on: April 15, 2022, 09:41:14 AM »
Won't everything expand at the same rate and the lash will remain constant?

Online Huzo

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Re: Timing gear lash
« Reply #2 on: April 15, 2022, 10:42:27 AM »
Won't everything expand at the same rate and the lash will remain constant?
I think the coefficient of expansion is greater for the aluminium. Given that there is more mass, I think the crankcase will get “taller”, thus increasing the lash.
On my first assembly, I started the bike and it just sounded......”tight”.
The thought of the two shafts closing up with no clearance was a concern, so I temporarily threw the chain back in.
I considered rigging up a jig to spin them under load for a time to bed them in before refitting.

Unsure as yet... :popcorn:

Offline Sye

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Re: Timing gear lash
« Reply #3 on: April 15, 2022, 10:47:39 AM »
Hmmm, the only thing I can compare it to are the gear driven cams on my Vfr750, although they are slash cut gears. Four cams and two connecting gears were in aluminium casings and went on forever.

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Re: Timing gear lash
« Reply #3 on: April 15, 2022, 10:47:39 AM »

Online PJPR01

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Re: Timing gear lash
« Reply #4 on: April 15, 2022, 11:19:16 AM »
Hi Peter...what difference in sound or performance are you noticing with these new gears?  When you say tight, do you mean the bike feels restricted in performance, or just tighter as in you're breaking in a new engine?
Cheers
Paul R
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Offline RinkRat II

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Re: Timing gear lash
« Reply #5 on: April 15, 2022, 01:07:19 PM »

    Have you discussed this with Mr. Caruso?

     Paul B.
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Online Huzo

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Re: Timing gear lash
« Reply #6 on: April 15, 2022, 02:31:02 PM »
Hi Peter...what difference in sound or performance are you noticing with these new gears?  When you say tight, do you mean the bike feels restricted in performance, or just tighter as in you're breaking in a new engine?
Cheers
Because I knew there is zero lash in the pair and mindful of the torture that I would be inflicting if they got any tighter, I did not know if the sound was normal.
I was expecting a whirring sound, but this was more of a subdued scream. I re installed the chain, out of an abundance of caution.

Online Huzo

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Re: Timing gear lash
« Reply #7 on: April 15, 2022, 02:32:50 PM »
    Have you discussed this with Mr. Caruso?

     Paul B.
Not yet.
But I think I will.

Offline lucky phil

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Re: Timing gear lash
« Reply #8 on: April 15, 2022, 05:38:55 PM »
I have a set of Caruso timing gears that I fitted to my Norge.
Here is an image


Question is..
I consider the lash between the crank and cam gears to be absolute minimum. What is the consensus regarding this lash ?
Will it increase or decrease when hot ? My educated guess is that the cases will expand when at operating temp, resulting in them “growing apart” a very small amount, thus increasing the lash. But that is only a guess, does anyone have an educated opinion ?
I would like to hear from Tusayan as well as anyone else.

I have these fitted to a few engines. The tooth clearance will increase as the engine cases get to operating temp.

Ciao
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Online Huzo

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Re: Timing gear lash
« Reply #9 on: April 15, 2022, 06:34:27 PM »
I have these fitted to a few engines. The tooth clearance will increase as the engine cases get to operating temp.

Ciao
Ok Phil, that’s good news.

Offline lucian

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Re: Timing gear lash
« Reply #10 on: April 15, 2022, 06:47:52 PM »
precisely the reason there is  a determined clearance between gear tip and root  of its mate.

Online Huzo

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Re: Timing gear lash
« Reply #11 on: April 15, 2022, 09:22:30 PM »
I just got an e mail back from Mr Caruso.
He assures me that as the engine warms, the clearance (as expected) will grow.
Also he told me that before he ships a gear set out, he fits them to an engine he has on hand and checks for correctness.
He further states that the shaft centres on these big blocks are known to be accurately machined.

While in Italy, I will get a new oil pump for the Norge and re install the gears if they check out ok.
Thanks all.

Offline n3303j

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Re: Timing gear lash
« Reply #12 on: April 15, 2022, 11:08:43 PM »
'60s BMW established cold timing gear lash at 0.002".
That leaves room for an 0.001" oil film.
I wouldn't want to run any gear set at zero clearance.
That's inviting galling of tooth surfaces.
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Offline jacksonracingcomau

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Re: Timing gear lash
« Reply #13 on: April 19, 2022, 05:16:43 AM »
 
Because I knew there is zero lash in the pair and mindful of the torture that I would be inflicting if they got any tighter, I did not know if the sound was normal.
I was expecting a whirring sound, but this was more of a subdued scream. I re installed the chain, out of an abundance of caution.
:thumb:
Wise to halt at zero clearance,
Keep us updated

Online Huzo

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Re: Timing gear lash
« Reply #14 on: April 19, 2022, 08:08:18 AM »
  :thumb:
Wise to halt at zero clearance,
Keep us updated
Guissepe Caruso went on to point this out.
Although I don’t think it applies in this case, it is possible to attempt to discern the lash between the crank and cam gear pairing and find none.
This can be because there is none.
Or
The reluctance for the cam gear to turn by hand pressure due to the frictional drag and the loading of the rockers against the lobes. It will feel like the gears have zero lash and are solidly meshing, when in fact they are not.
The go is, to fit them on their shafts and leave the driving pin out of the camwheel and see if any lash exists.
I’m fitting a new oil pump when I get back from Italy with the Norge and I’ll investigate it then.

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Re: Timing gear lash
« Reply #15 on: April 19, 2022, 08:12:53 AM »
precisely the reason there is  a determined clearance between gear tip and root  of its mate.
I think it’s prudent to allow for the fact that zero lash can also occur when the teeth are “wedging” into the corresponding valley.
Any further closing up of the clearance beyond this condition, doesn’t bear contemplating.
I’m encouraged to hear that the shafts travel apart as the engine warms, but I’d like to be able to discern some lash when stone motherless cold.

Offline lucian

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Re: Timing gear lash
« Reply #16 on: April 19, 2022, 08:44:02 AM »
While working on golf course equipment years ago the we had an assortment of various diameter lead wires we would check bearing and gear clearances with.   Perhaps a machine shop supply outfit near you would have some.

Offline Moparnut72

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Re: Timing gear lash
« Reply #17 on: April 19, 2022, 08:48:53 AM »
Wouldn't Plastigage pretty much do the same thing?
kk
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Offline lucian

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Re: Timing gear lash
« Reply #18 on: April 19, 2022, 08:59:35 AM »
Wouldn't Plastigage pretty much do the same thing?
kk

 Plastigauge might work on tooth the interface but would be tough to mic accurately once flattened with a slight curve. The lead wires were very small dia. and could check interface and fatter ones  used on root clearance.   

Offline Moparnut72

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Re: Timing gear lash
« Reply #19 on: April 19, 2022, 12:03:53 PM »
I agree, not what it is made for. Maybe in a pinch it might give ball park idea. Also gear drive conversions are known to be noisy.
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Offline bigbikerrick

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Re: Timing gear lash
« Reply #20 on: April 19, 2022, 01:02:44 PM »
Did Mr. Caruso mention if the gears tend to quiet down after they are run in for a while?
Rick.
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Offline skippy

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Re: Timing gear lash
« Reply #21 on: April 19, 2022, 02:05:15 PM »
Huzo,

I have this exact same set of gears in my Breva right now and can attest to your concern about the sound. For me it was a pleasant change from the tappity-tap-tap cacophony emanating from the left side as my original chain tensioner was complete junk. The sound was replaced by a substantially quieter whirr of the straight cut gears. If I recall you have already upgraded your tensioner and I presume your motor didn't suffer from the calamity of noise that mine had.

In my humble opinion, as long as you can smoothly turn the motor over by hand with the plugs out then I trust the quality of Joe Caruso's workmanship.

I have several thousand miles on mine since installed and all is well.

Skippy   
23 V100 Mandello
20 V85TT

Online Huzo

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Re: Timing gear lash
« Reply #22 on: April 19, 2022, 02:32:09 PM »
Did Mr. Caruso mention if the gears tend to quiet down after they are run in for a while?
Rick.
I didn’t discuss that aspect with him, but did with Pete Roper.
Pete said that they do become quieter after a bedding in period. He told me that he performed a modification to allow more pooling of oil around the gear train, further dampening the sound.

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Re: Timing gear lash
« Reply #23 on: April 19, 2022, 02:33:49 PM »
Huzo,

I have this exact same set of gears in my Breva right now and can attest to your concern about the sound. For me it was a pleasant change from the tappity-tap-tap cacophony emanating from the left side as my original chain tensioner was complete junk. The sound was replaced by a substantially quieter whirr of the straight cut gears. If I recall you have already upgraded your tensioner and I presume your motor didn't suffer from the calamity of noise that mine had.

In my humble opinion, as long as you can smoothly turn the motor over by hand with the plugs out then I trust the quality of Joe Caruso's workmanship.

I have several thousand miles on mine since installed and all is well.

Skippy
Yes I have done the tensioner work on mine and it is now silent.

Offline pressureangle

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Re: Timing gear lash
« Reply #24 on: April 19, 2022, 02:48:24 PM »
Huzo,

I have this exact same set of gears in my Breva right now and can attest to your concern about the sound. For me it was a pleasant change from the tappity-tap-tap cacophony emanating from the left side as my original chain tensioner was complete junk. The sound was replaced by a substantially quieter whirr of the straight cut gears. If I recall you have already upgraded your tensioner and I presume your motor didn't suffer from the calamity of noise that mine had.

In my humble opinion, as long as you can smoothly turn the motor over by hand with the plugs out then I trust the quality of Joe Caruso's workmanship.

I have several thousand miles on mine since installed and all is well.

Skippy

Seconded.

My '97 Sport still had the stock chain tensioner, pretty weak. I installed Joe's gears and was pleasantly surprised to discover the bike a good deal quieter than it was before- it always had a ton of reflected noise in the fairing. The gears are nearly silent, you can hear the whirring if you listen for it but it's not apparent otherwise.
I left the starboard tensioner bolt hole empty to facilitate oil mist on the gears from crankcase pumping.
Something wistful and amusing, yet poignant.

Offline jacksonracingcomau

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Re: Timing gear lash
« Reply #25 on: April 19, 2022, 08:16:09 PM »
Guissepe Caruso went on to point this out.
Although I don’t think it applies in this case, it is possible to attempt to discern the lash between the crank and cam gear pairing and find none.
This can be because there is none.
Or
The reluctance for the cam gear to turn by hand pressure due to the frictional drag and the loading of the rockers against the lobes. It will feel like the gears have zero lash and are solidly meshing, when in fact they are not.
The go is, to fit them on their shafts and leave the driving pin out of the camwheel and see if any lash exists.
I’m fitting a new oil pump when I get back from Italy with the Norge and I’ll investigate it then.

And so the plot thickens!
Perhaps a more appropriate title would be , how do you measure lash ?
Assumption got answers other than one you wanted.
Personally, I fit gears for (permanent) accurate valve timing as much as for reduced reciprocating mass, usually with a new camshaft.
So, rockers off, dial gauges on pushrods, degree wheel on crank, fit pin in appropriate hole on predrilled cam gear.
Original loopy camshaft gears came predrilled like this, I made a jig 40 years ago to do same, 5 holes not one, surprising that these gears are not drilled, perhaps because he originally intended them for Daytona engines which have vernier adjustment at camshaft/pulley. Carcano designed pushrod motor was always intended to have the adjustment at cam gear, original workshop manual shows you how to fit and set up gears.
My 1967 V700 on factory painted marks was 1 degree advanced from Carcano’s figures, I guess every motor was timed by hand then, marks painted by tradesman.
I still do it that way

Without rockers, lash is easily felt and valve timing accurately adjusted (+ or - 1 degree is pretty good for a factory build imho, interesting how your Norge with a few miles and aftermarket gears times up.
Peak lift angle and overlap in and ex at tdc tell you everything, very light (carb) valve springs installed for final check.

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Re: Timing gear lash
« Reply #26 on: April 19, 2022, 11:43:27 PM »
And so the plot thickens!
Perhaps a more appropriate title would be , how do you measure lash ?
Assumption got answers other than one you wanted.
Personally, I fit gears for (permanent) accurate valve timing as much as for reduced reciprocating mass, usually with a new camshaft.
So, rockers off, dial gauges on pushrods, degree wheel on crank, fit pin in appropriate hole on predrilled cam gear.
Original loopy camshaft gears came predrilled like this, I made a jig 40 years ago to do same, 5 holes not one, surprising that these gears are not drilled, perhaps because he originally intended them for Daytona engines which have vernier adjustment at camshaft/pulley. Carcano designed pushrod motor was always intended to have the adjustment at cam gear, original workshop manual shows you how to fit and set up gears.
My 1967 V700 on factory painted marks was 1 degree advanced from Carcano’s figures, I guess every motor was timed by hand then, marks painted by tradesman.
I still do it that way

Without rockers, lash is easily felt and valve timing accurately adjusted (+ or - 1 degree is pretty good for a factory build imho, interesting how your Norge with a few miles and aftermarket gears times up.
Peak lift angle and overlap in and ex at tdc tell you everything, very light (carb) valve springs installed for final check.
Ok mate, I will bear all that in mind as well.
Suffice to say, if I’d installed the gears and felt even a couple of thou’ lash, I would have buttoned it up and off into the sunset.
I have a background in machining and I know what a couple of thou feels like and I could not discern any.
But that may be for the reasons mentioned.
I will forensically check it out when I install the new oil pump.
Thanks for your valued advice mate... :thumb:

Offline n3303j

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Re: Timing gear lash
« Reply #27 on: April 20, 2022, 02:51:09 PM »
Journeyman Tool & Die maker here and I couldn't feel 0.002" lash in the gears when I set up the alternator drive on my Ural. It required a dial indicator on a tooth face for me to get true proof of movement.

Of course I was the other side of 68 then. Might make a difference?

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Online Huzo

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Re: Timing gear lash
« Reply #28 on: April 20, 2022, 02:58:19 PM »
Journeyman Tool & Die maker here and I couldn't feel 0.002" lash in the gears when I set up the alternator drive on my Ural. It required a dial indicator on a tooth face for me to get true proof of movement.

Of course I was the other side of 68 then. Might make a difference?
I’ve got a nice dial gauge, I could clock it up when the time comes.

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Re: Timing gear lash
« Reply #29 on: April 20, 2022, 06:11:02 PM »
So aside from the superb craftmanship of the gears and the change of sound, are you expecting any change in performance (torque or acceleration or top end or fuel consumption or other typical KPI)?  Just curious as to why the route of changing to the gears vs. replacing with the original setup, other than it can be done, and it's cool to do so.

Thanks!
Paul R
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