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swatdoc

another method for perfect chain alignment

20 posts in this topic

Since I'm installing a Graves chain block on my swingarm to keep the chain off my rear tire and VERY expensive Marchesini wheel , I needed to get the sprockets and chain aligned as perfect as possible. The block needs to be mounted so it just touches the chain, but does not deflect it.

So what I did was to take 2 pieces of 1/8" aluminum flat stock and drill holes on either end - I stacked them while drilling so they were aligned perfect - this is critical as they must be perfectly parallel when in use. Then I bolted them together using 6mm bolts with a 1/4" spacer between them.

This is put on the rear sprocket and held in place with 2 spring clamps.

IMG_1872.jpg

Then take a section of 1/4" steel rod and place it on top of the rails. (the rod must be perfectly straight - to test, rotate it while on the rails to make sure the far end by the countershaft sprocket stays in one place and doesn't make a circle)

Adjust chain tensioner bolts until the rod lines up with the front sprocket.

IMG_1870.jpg

IMG_1871.jpg

Your chain is now in perfect alignment - or about as close as you can get.

I actually tried a laser instead of the steel rod, but the cheap ass laser pen from radio shack was useless - the beam didn't come out of the pen straight. If I can find a cheap laser with a straight beam, I'd rathe use that than the rod.

Got the chain block mounted real well now -

IMG_1874.jpg

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Thanks Gray - yes it's just a variation on the method you describe. I just wanted it to go from the center of one sprocket to the center of the other, and show some pics of how to do it. I find pics to be very helpful when trying something for the first time. I had been using a sag meter to verify distance from swingarm pivot to rear axle, but the ends don't fit the holes in the axles perfect, and I found this new way to be more accurate. Anything's better than using the marks on the swingarm and axle blocks!

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One thing that someone using this method will immediately notice is how little rotation of the the adjuster bolts it takes to move the rod a half an inch off the center of the front sprocket. This method is very precise, depending only only the rod (and the sprocket) being straight.

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this is off topic, but wow, that bikes looks sick from teh pictures. Do you have any pics of the entire bike? Im really impressed.

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Even though the sprockets are aligned, how do you adjust chain slack while still keeping the alignment?

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Once aligned, note the way the marks look on the blocks. If they line up, use them. If they don't make a note of the discrepancy and adjust accordingly.

To be more precise, measure from the front of the block to the swing arm at the base of the adjuster bolt on both sides once aligned and make a note of any difference. add the difference in when you set the chain tension.

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Once aligned, note the way the marks look on the blocks. If they line up, use them. If they don't make a note of the discrepancy and adjust accordingly.

To be more precise, measure from the front of the block to the swing arm at the base of the adjuster bolt on both sides once aligned and make a note of any difference. add the difference in when you set the chain tension.

I see, so I carry the measurement of each difference to my next adjustment. Now, is there anything else that can be a factor of the bolts giving me a misreading Ex. the swing arm not being symmetrical? Thank you

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The list is "endless". Imperfections at the swing arm, the pivot, where the mark was placed, the way the block rotates slightly in the slot when tightened.

Motion Pro makes an alignment tool similar to swatdoc's rig that can be used with the chain in place, BTW.

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The list is "endless". Imperfections at the swing arm, the pivot, where the mark was placed, the way the block rotates slightly in the slot when tightened.

Motion Pro makes an alignment tool similar to swatdoc's rig that can be used with the chain in place, BTW.

I've seen that but it looks so darn cheesy. I would still be eye balling it. I'm pretty disappointed now and afraid to use the method of counting from the back. I'm not sure what to do

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I have used this since my Montesea VR 250 1974

That bike was bullet proof.

No head gasket ,No cage on wrist pin bearing.

there was no way to break that motorcycle.

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Since I'm installing a Graves chain block on my swingarm to keep the chain off my rear tire and VERY expensive Marchesini wheel , I needed to get the sprockets and chain aligned as perfect as possible. The block needs to be mounted so it just touches the chain, but does not deflect it.

So what I did was to take 2 pieces of 1/8" aluminum flat stock and drill holes on either end - I stacked them while drilling so they were aligned perfect - this is critical as they must be perfectly parallel when in use. Then I bolted them together using 6mm bolts with a 1/4" spacer between them.

This is put on the rear sprocket and held in place with 2 spring clamps.

IMG_1872.jpg

Then take a section of 1/4" steel rod and place it on top of the rails. (the rod must be perfectly straight - to test, rotate it while on the rails to make sure the far end by the countershaft sprocket stays in one place and doesn't make a circle)

Adjust chain tensioner bolts until the rod lines up with the front sprocket.

IMG_1870.jpg

IMG_1871.jpg

Your chain is now in perfect alignment - or about as close as you can get.

I actually tried a laser instead of the steel rod, but the cheap ass laser pen from radio shack was useless - the beam didn't come out of the pen straight. If I can find a cheap laser with a straight beam, I'd rathe use that than the rod.

Got the chain block mounted real well now -

IMG_1874.jpg

the best part of this post is the cute dog in the backround.

i love the fact you have the dod bed in your shop.

we love our little guys the same

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LOL - she's a big help when I'm working on my bikes! Especially when I'm laying on my back like when I'm working on linkage or something similar - it really helps at that time when she jumps on my chest and want to lick my face! Ha Ha

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use feller gauge in between the bolt and the axel block. if you need to go tighter loosen he axel and place them in. if you need to go looser leave the axel tight and loosen the adjuster bolt. place the feeler gauge in then tighten the adjuster. then pull the feller gauge out loosen the axel and push the wheel in to the adjusters tighten the axel. make sure to use small sizes like 0.030 because a little bit goes a long way.

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use feller gauge in between the bolt and the axel block. if you need to go tighter loosen he axel and place them in. if you need to go looser leave the axel tight and loosen the adjuster bolt. place the feeler gauge in then tighten the adjuster. then pull the feller gauge out loosen the axel and push the wheel in to the adjusters tighten the axel. make sure to use small sizes like 0.030 because a little bit goes a long way.

do this after you get the sprockets lined up useing the rod method

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IMG_1872.jpg

Just curious about the small wheel on the back of your extended axle block... I'm assuming it's for laying the bike over and not letting it get scratched up on the pavement?

When I'm adjusting my chain, I simply measure the length of each adjuster bolt with a set of calipers. Works great for me.

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Just curious about the small wheel on the back of your extended axle block... I'm assuming it's for laying the bike over and not letting it get scratched up on the pavement?

When I'm adjusting my chain, I simply measure the length of each adjuster bolt with a set of calipers. Works great for me.

Yep, the black stub is called a "slider", and its purpose id to minimize damage in a spinout.

Measuring the adjuster bolts assumes a level of precision in the manufacture of the frame, swing arm, etc., that isn't always present. If you verify the alignment by the means laid out here and then find that both bolts are the same length (or not what the difference is), then that method will work.

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this is off topic, but wow, that bikes looks sick from teh pictures. Do you have any pics of the entire bike? Im really impressed.

Look in his garage. It's an amazing looking bike!:smashpc:

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Once I get the sprockets aligned right, I adjust in steps of flats on the chain adjuster bolts. It may not be perfect, but I think it's good enough. Just adjust in terms of flats on the bolt, keeping an eye on where/how the bolt was aligned when perfect.

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