End of start up first shift clunk !?
the earlier the start the louder the clunk seems
Cruiser
Joined: Dec 2009
Posts: 181
Likes: 0
I never really paid attention to my transmission. Maybe it don't clunk, or maybe it don't clunk loud enough to concern me. But, what you can consider, is what causes the clunk. Here is my thoughts on it. When the engine is cold, or has been sitting for a while, the clutch plates are all compressed together by the diaphram spring. Under compression, the oil is forced out from between the clutch plates and steel plates. So when you go to start your bike and put it in gear, you pull the clutch lever in, and the plates are still sticking together or dragging (for those of you old enough to remember coasters and a cold beer, the coaster would always stick to the bottom of the coaster when the bottle sweated, picking the coaster up with the beer). With the clutch plates all stuck together and not free to float, you get the clunk. As soon as there is some drag on the clutch, they release or free them selves up. So, by blipping the throttle before putting into gear would possibly free up the clutches, and there fore eliminate the clunk.
So, we come to the next question, "what can we use in our primaries to help keep the clutches from sticking together on cold starts"?
This is just my theory on this subject. Please tell me if I'm way off base, just crazy, or possibly insane. Till then, Happy blipping. TJ
So, we come to the next question, "what can we use in our primaries to help keep the clutches from sticking together on cold starts"?
This is just my theory on this subject. Please tell me if I'm way off base, just crazy, or possibly insane. Till then, Happy blipping. TJ
Seasoned HDF Member
Joined: May 2008
Posts: 21,175
Likes: 12,747
From: South Carolina
I never really paid attention to my transmission. Maybe it don't clunk, or maybe it don't clunk loud enough to concern me. But, what you can consider, is what causes the clunk. Here is my thoughts on it. When the engine is cold, or has been sitting for a while, the clutch plates are all compressed together by the diaphram spring. Under compression, the oil is forced out from between the clutch plates and steel plates. So when you go to start your bike and put it in gear, you pull the clutch lever in, and the plates are still sticking together or dragging (for those of you old enough to remember coasters and a cold beer, the coaster would always stick to the bottom of the coaster when the bottle sweated, picking the coaster up with the beer). With the clutch plates all stuck together and not free to float, you get the clunk. As soon as there is some drag on the clutch, they release or free them selves up. So, by blipping the throttle before putting into gear would possibly free up the clutches, and there fore eliminate the clunk.
So, we come to the next question, "what can we use in our primaries to help keep the clutches from sticking together on cold starts"?
This is just my theory on this subject. Please tell me if I'm way off base, just crazy, or possibly insane. Till then, Happy blipping. TJ
So, we come to the next question, "what can we use in our primaries to help keep the clutches from sticking together on cold starts"?
This is just my theory on this subject. Please tell me if I'm way off base, just crazy, or possibly insane. Till then, Happy blipping. TJ
You are right on the money about the cause of the clunk.
Stellar HDF Member
Joined: Dec 2005
Posts: 3,234
Likes: 106
What is it with everyone and the Harley clunk.
God people they have been doing it since the 40's. If you want something that makes no sound when it goes into gear buy a frikin honda.
The transmission is constant mesh. The gear clusters never disengage. A 6 tooth dog slides along the mainshaft or countershaft between gear clusters.
The teeth on that dog are the size of your thumb. If there is any free spin caused by the fluid picked up by the clutch pack, on the shafts it's gonna clunk and lurch when the dogs teeth drop into the gears slots.
Get over it.
God people they have been doing it since the 40's. If you want something that makes no sound when it goes into gear buy a frikin honda.
The transmission is constant mesh. The gear clusters never disengage. A 6 tooth dog slides along the mainshaft or countershaft between gear clusters.
The teeth on that dog are the size of your thumb. If there is any free spin caused by the fluid picked up by the clutch pack, on the shafts it's gonna clunk and lurch when the dogs teeth drop into the gears slots.
Get over it.
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