Author Topic: breather gear doubt  (Read 426 times)

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Offline evo58

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breather gear doubt
« on: February 05, 2018, 08:41:01 AM »
the engine its a evo 1996, the plastic breather gear went south !!!
can i use a shovelhead steel on this evolution?????
thanks in advance
evo

Offline Mule

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Re: breather gear doubt
« Reply #1 on: February 05, 2018, 09:24:07 AM »
late shovelhead yes, it's the same as the Evo, The early shovel with the small nib for shim no.

Offline dubepj

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Re: breather gear doubt
« Reply #2 on: February 05, 2018, 02:19:10 PM »
Sorry to learn about your breather gear troubles.  Just curious what were the symptoms when you r breather gear broke.

Offline bagga

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Re: breather gear doubt
« Reply #3 on: February 05, 2018, 02:39:57 PM »
i had a plastic breather break on my 85 evo. one of the valve springs broke and made it's way into the plastic breather and broke it. if it was a steel breather in there the cases may have been destroyed. if it were mine i  would stay with the plastic.
1985 flhtc
1976 fxe

Offline kd

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Re: breather gear doubt
« Reply #4 on: February 05, 2018, 02:47:52 PM »
 :agree:  The same thing happened to me with a piece of the pinion bearing rim from my 98 bottom end. I did damage the oil pump key and did disassemble the cases to clean them but there was no serious damage because the major metal fragments were imbedded into the plastic breather valve and stayed there.
KD

Offline Mule

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Re: breather gear doubt
« Reply #5 on: February 05, 2018, 03:22:06 PM »
Yes plastic breather gears are known to get embedded metal , then act like a file on the breather bore in the case. Everyone has a different take on things! I have quite a few in a box somewhere that I replaced with steel breathers, all of them look the same with fine metal particles embedded in them.

Offline 72fl

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Re: breather gear doubt
« Reply #6 on: February 06, 2018, 05:22:39 AM »
Is there a reason NOT to use a S&S Reed Valve steel breather ?

Offline packrat56

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Re: breather gear doubt
« Reply #7 on: February 06, 2018, 05:29:35 AM »
Is there a reason NOT to use a S&S Reed Valve steel breather ?

  I don't know , maybe because it wont pull a vacuum. I'm using one on my shovel
works great, stopped the dripping problem I had 
Now I know, why some animals eat their young.

Offline Scott P

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Re: breather gear doubt
« Reply #8 on: February 06, 2018, 06:01:38 AM »
A degree wheel mounted on the sprocket shaft,(not with the engine running...lol) can insure proper width, and length, and location, of the breather opening, once attended to via a die grinder.
Otto Knowbetter sez, "Even a fish wouldn't get caught if he kept his mouth shut"

Offline kd

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Re: breather gear doubt
« Reply #9 on: February 06, 2018, 07:11:58 AM »
A degree wheel mounted on the sprocket shaft,(not with the engine running...lol) can insure proper width, and length, and location, of the breather opening, once attended to via a die grinder.


That used to be a must when we first started building stroker engines. Great improvement to crankcase breathing.

On the plastic versus steel subject, I hate to admit I am a proponent for plastic over steel anything but I have never seen a picture of a crank case blown out from a plastic breather gear failure. I have seen several from a steel gear.  :nix:
KD

Offline Scott P

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Re: breather gear doubt
« Reply #10 on: February 06, 2018, 08:49:21 AM »
Degree wheel was an absolute MUST, back in the day, to include checking ignition timing.
Also to check cam timing, as not all cam gears were pressed on correctly.
Not used as much here, anymore.
Otto Knowbetter sez, "Even a fish wouldn't get caught if he kept his mouth shut"

Offline Mule

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Re: breather gear doubt
« Reply #11 on: February 06, 2018, 08:50:43 AM »
Breather gear does not blow out cases, Something else gives it up first to cause damage to the breather gear cavity, usually an engine that has not been maintained well run hard and put away wet. Most  but not all of the time it is tappet rollers!

Offline kd

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Re: breather gear doubt
« Reply #12 on: February 06, 2018, 09:37:58 AM »
Well, blown out may be a harsh descriptive but serious damage can and does does happen. When it does, what actually causes it is irrelevant. I know the cracked ones I've seen did not come to me in a dream.  :nix:  The really neat thing about engine building is you get to choose the route you take and base your decisions on what ever criteria you deem important.  :up:

I have run both styles and know that one personal failure of a pinion brg where the outer main brg rim broke away while on a trip (2,000 miles from home) would have been a catastrophic case failure if not for the fact the breather was the plastic one. (that based on the witness marks left by the debris on the rotating assemblies)  What I found in the breather and oil pump was not small grit and it jammed up the gear and pump. This was on a meticulously serviced 1998 Evo with about 10,000 miles on it. You will notice that I did not recommend one over the other.  I simply stated my experience and observations. The OP can make his decision based on his own research.   :wink:

« Last Edit: February 06, 2018, 09:46:39 AM by kd »
KD

Offline Mule

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Re: breather gear doubt
« Reply #13 on: February 06, 2018, 09:52:52 AM »
 :SM:The OP can make his decision based on his own research.  I agree!

Online ecir50

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Re: breather gear doubt
« Reply #14 on: February 06, 2018, 10:11:16 AM »
the plastic breathers get out of round. The metal one from S&S is modified with a longer slot to allow more time for the oil to stay in the engine and not forced out the crankcase breather. Fixed my lower crankcase breather from spitting oil while riding.

Offline jeffscycle

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Re: breather gear doubt
« Reply #15 on: February 06, 2018, 11:10:05 AM »
   They do make .030" oversize metal breathers to clean up any damage, or the hole can be sleeved to OEM size. Metal valves benefits out weigh their faults, and I can't count how many plastic ones I've seen loose teeth & start puking oil. I'm not a fan of the S&S reed valve, and have seen oil puking. but if they are used on '92 up engines, they're fine, and no need to worry about hole damage.
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Online ecir50

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Re: breather gear doubt
« Reply #16 on: February 06, 2018, 11:15:53 AM »
Agree wasn't talking a reed valve.