fitting stronger clutch springs and the mess involved - BMW G310 R/GS Forum
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post #1 of 15 (permalink) Old 08-24-2019, 10:24 AM Thread Starter
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fitting stronger clutch springs and the mess involved

so I got 15% stronger clutch springs and attempted to fit them, with my young Indian mechanic, who does not know much about the modern sophisticated bikes. If you intend to do it, don't, unless you are really experienced!

First, to remove the clutch cover is a complete pain in the a... Then, after installing the springs, we could not put the clutch plate back, because, as I later got to know, the piston has to be in TDC, and even then it is difficult. The two cams inside the clutch need to be aligned vertically, or else the clutch cover does not enter. My mechanic made the mistake of removing the higher cam to reposition it, and this messed up the timing. So we needed to open the top of the engine and finding a way to realign the upper timing cams. It is actually much complicated than this. I will not bother you with details. It took us 2 days to fix the bike.

First, when we closed the engine, it was making a terrible sound...something was very wrong! The BMW service manual is a piece of crap, an abomination; I have never seen so unclear instructions...maybe it was created for dealers who already gone to some bmw courses? Even to find something simple there, like Water Pump, you have to be a genius to find it. So the guidelines I got from the manual were at the most approximate. Anyway, in the end, we manage to fix it. Was it worthy? For me, it was, as I learned a lot about the internals of the bike. But for someone else, I would never recommend it.

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post #2 of 15 (permalink) Old 08-24-2019, 12:00 PM
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I've never seen a clutch whose operating mechanism was linked to the piston position. In what way does it differ from a conventional multiplate clutch?
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post #3 of 15 (permalink) Old 08-24-2019, 01:04 PM Thread Starter
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I've never seen a clutch whose operating mechanism was linked to the piston position. In what way does it differ from a conventional multiplate clutch?
a good question. it is not that clutch itself is connected to the piston position. but clutch in small gs is connected to two cams/gears next to it, the bigger one linked to the coolant pump. and if these gears are not aligned vertically, the clutch cover cannot enter due to some misalignment in regards to two pins next to the upper cam. I cannot explain it properly, as I do not know the terms, but this what happens. so in order to fit the clutch cover, the piston has to be in TDC (there are two chains, one in the timing gears, and one in the lower clutch compartment gears, both connected) and the lower gears need to be in the right position, the dots aligned vertically. I wish the manual explained it better.

so in all, what is inside the clutch cover, besides the clutch are two cams, and the upper one is linked to the water pump (via a thing called interlloper?), and there is also an oil pump mechanism on the very right side of the interlloper, which needs to be in the correct position. it kinds of annoy me that BMW does not explain it in their horrible manual.

so when my mechanic pulled out the upper cam in the clutch side, he disturbed its connection to the timing cams in the cylinder head. what I have learned now, we should have rotated the TDC via that entrance on the left side, several times until the TDC position is aligned with the clutch gears before attempting to fit the clutch cover. One needs to turn it anticlockwise several times before they are fully aligned. I think that one can speak of false and true TDC in this case. it is not that clutch itself is connected to the piston position, but rather that the clutch in small gs is connected to two cams/gears next to it, the bigger one linked to the coolant pump. and if these gears are not aligned vertically, the clutch cover cannot enter due to some misalignment in regards to two pins next to the upper cam. I cannot explain it properly, as I do not know the terms, but this what happens. so in order to fit the clutch cover, the piston has to be in TDC (there are two chains, one in the timing gears, and one in the lower clutch compartment gears) and the lower gears need to be in the right position, the dots aligned vertically. I wish the manual explained it better.

anyway, the bottom line is that the two gears inside the clutch cover need to be aligned vertically while the two-timing gears in the cylinder head need to be aligned horizontally (inlet/exhaust) for that whole thing to work.

so in all, what is inside the clutch cover, besides the clutch are two cams, and the upper one is linked to the water pump (via a thing called interlloper?), and there is also an oil pump mechanism on the very right side of the interlloper, which needs to be in the correct position.

so when my mechanic pulled out the upper cam in the clutch side, he disturbed its connection to the timing cams in the cylinder head. what I have learned now, we should have rotated the TDC via that entrance on the left side, several times until the TDC position is aligned with the clutch gears. One needs to turn it anticlockwise several times before they are fully aligned. I think that one can speak of false and true TDC in this case. it annoys me that the manual does not explain it. even if you reach TDC (piston on top) it does not mean that the lower cams in the clutch case are aligned. And if they are not aligned, you have no chance to fit the clutch cover! Luckily I have some old bikes where I do not need to deal with this bs.

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Last edited by Kris; 08-24-2019 at 01:31 PM.
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post #4 of 15 (permalink) Old 08-26-2019, 03:23 AM
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Thanks for the explanation. Sounds like your mechanic, unnecessarily, removed the clutch drum thus disturbing the alignment of the gears driven from the primary drive.
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post #5 of 15 (permalink) Old 08-26-2019, 09:22 AM Thread Starter
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Thanks for the explanation. Sounds like your mechanic, unnecessarily, removed the clutch drum thus disturbing the alignment of the gears driven from the primary drive.
yes, he made a big mistake. what we should have done is to rotate the crank counterclockwise, up to 3 or 4 times, till both the gears in the clutch side are alined, the top one with the dot down and the bottom one with the dot up. and then one can fit the clutch cover back. still, it was a learning experience, as in the future I plan to check valve clearance by myself.

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post #6 of 15 (permalink) Old 08-28-2019, 07:34 PM
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Why do you need stiffer clutch springs?
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post #7 of 15 (permalink) Old 08-29-2019, 03:54 AM Thread Starter
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Why do you need stiffer clutch springs?
Stronger clutch springs prevent slipping and give you a better response when you change gears: as the bike wants 'jump' forwards. Changing springs made a big difference in my crf250. In gs, the difference is less dramatic but still noticeable, and the clutch lever is still soft enough.

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post #8 of 15 (permalink) Old 08-29-2019, 04:09 AM Thread Starter
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by the way, if there are any modern bikes wizards here - according to BMW manual, you need to put the piston in TDC. But since there are 4 valves in our engine, what TDC? How can one know that the bike is in true TDC without opening the engine? I think there are ike 4 TDC-s. I am not much knowledgeable about modern bikes. I am used to the vintage bikes, with two valves. I am disappointed that this information is not present in the gs manual. Ok, I put the bike in TDC, but still I could not fit the clutch cover, because it was the wrong kind of TDC.....

Even with 2 valves engine, one TDC is false and the other one is True.

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Last edited by Kris; 08-29-2019 at 04:28 AM.
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post #9 of 15 (permalink) Old 08-29-2019, 05:33 AM
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The number of valves makes no difference - there is a TDC on both the compression and exhaust strokes.


Normally there would be a mark on the ignition flywheel to show TDC, I'd be suprised if there is not such on the BMW.


Watch for the exhaust valves opening when you turn the motor over, the next TDC is compression, so check clearances then.
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post #10 of 15 (permalink) Old 08-29-2019, 06:43 AM Thread Starter
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The number of valves makes no difference - there is a TDC on both the compression and exhaust strokes.


Normally there would be a mark on the ignition flywheel to show TDC, I'd be suprised if there is not such on the BMW.


Watch for the exhaust valves opening when you turn the motor over, the next TDC is compression, so check clearances then.
Thanks. I am afraid there is such a mark. Unless the top of the head cylinder is open I cannot see when the exhaust valves are opening (it is a good tip for checking the valves clearance through). And as far as the cams/gears in the clutch box are concerned, they can be aligned only in one position; so I need to turn the ignition flywheel several times to make it happen...unless i missed something.

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