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dt1 crankshaft alignment

  • tvrc18
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dt1 crankshaft alignment was created by tvrc18

So I am putting a DT1 motor together and installed the crank in the left case with a Tusk crank installation tool. Pulled it in till it bottomed out on the bearing.  After assembling the cases and tightened all the screws the crank is tough to turn Not bad but seems it should turn easier.. I did not measure the distance between crank halves and the case sides because it got dark on me and had to stop for the night. Will after installing the primary gear and tightening will it pull the crank over a small amount if it is to far to the left? I need to see if the crank is centered I guess after installing the primary gear.
Last edit: 22 Nov 2021 18:53 by tvrc18.
22 Nov 2021 18:53 #1

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Replied by RT325 on topic dt1 crankshaft alignment

The way you describe assembling it, it should spin free & i'd expect it to be tighter once crank nut is tightened as its then trying to pull the crank away from the left bearing a little bit. So i'm guessing--wondering--if the crank is rubbing on the outer ring of the left bearing which should come right when crank nut is tightened but will need to give the crank a tap on the mag end to settle it once nut is tight. That's assuming the left bearing will stay put & crank move over about 10 thou. If the bearing moves in the case with the shaft then nothing will be gained.
Of course i could be talking rubbish & the crank might be built up too wide. Was the crank just rebuilt for this job?. If it's 'not' too wide the before tightening the crank nut you should be able to flick the washer around on the right side, if you can get at it, or at least get a feeler blade down in there to prove its not too wide. Could get brave & give the crank a tap both ways. to see if it frees.
Other--other thing is 'would' a standard clearance bearing make it tight as i'm thinking C3 or C4 for the mag side as bearing is tight in the case & tight on the shaft. Sorry that was such a long winded an answer.
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22 Nov 2021 20:03 #2

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Replied by shyted on topic dt1 crankshaft alignment

This is a long shot.
I have looked at the parts diagram from Yamaha for the DT 1. I have a DT 3 . I checked the parts diagram for that too. Here's the thing. My bike has bearing shims in between the crank web and the case bearings . NOT SHOWN IN EITHER BIKE IN THE PARTS DIAGRAM !
So, i'm wondering have you refitted them if they were there ( no reason why they shouldn't be ) and did you notice them when you stripped the motor.
That could be a problem and a mistake that's easy to make if you didn't notice them when you stripped the bike. Could broach the web where the shaft protrudes.
If you have fitted them, then, well, That's not the problem.
Regards Dave
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23 Nov 2021 05:50 #3

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Replied by Ht1kid on topic dt1 crankshaft alignment

I agree with Shyted ask me how I know 
23 Nov 2021 06:28 #4

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  • tvrc18
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Replied by tvrc18 on topic dt1 crankshaft alignment

Mine had no shims on either side of the crank. The service manuals makes no mention of shims so not sure if they should be there or not. Pretty sure this motor had never been apart before I dug into it. After installing the primary gear and nut I measured between crank wheels and the case and both sides measure about 10 to 12 thousands. I think the crank was pulled over to the primary side after tightening the primary. Seems to move smoothly now.
23 Nov 2021 16:09 #5

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Replied by msavitt on topic dt1 crankshaft alignment

I have a DT1E and unfortunately it’s my only bike that had a great bottom end so I cannot comment. But if your bike had a shim when you took it apart then I would measure the bearing to case split line surface for both sides and subtract the crank width from this and see how the end play compares to what’s in manual.  Maybe Yamaha produced a zillon yen’s worth of narrow cranks or too deep cases and tossed in a shim vs scrap ?
23 Nov 2021 19:13 #6

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Replied by shyted on topic dt1 crankshaft alignment

Yes that's right the service manual doesn't seem to . My DT 1,2&3 manual doesn't. In fact, neither does my HT1B genuine factory manual, nor show any reference to them in any drawings or photos nor in my CT1 - 3 manual. However ,in all those models there definitely are shims as i have split seven CT,HT and the one DTs and have yet another HT to split today and i know there will be shims in. I even have a bearing from the cases with a shim corroded to it. They will stick to either side and if you don't realise they're there, then you will miss them. They can stick to the sleeve or shaft faces. 
 
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Last edit: 24 Nov 2021 01:29 by shyted.
24 Nov 2021 00:58 #7

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Replied by tvrc18 on topic dt1 crankshaft alignment

I looked at parts diagrams for 69 CT1 and AT1 and they show shims. First DT1 that shows shims is a 72. It shows only one on the primary side. I don't think they used them on 68 thru 71 DT1's but could be wrong. I have another 68 motor and it also has no shims.
24 Nov 2021 05:54 #8

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Replied by shyted on topic dt1 crankshaft alignment

It's strange that most of the manuals don't seem to show them. It could even be as the years went on they revised the manuals too i suppose. 
The HT1 motor i have is from a 69 bike and sure enough, the shims are there and my manual for the HT1 is from 70 as that's for the HT1B.
I see that thing's like this are quite common with Yamaha parts diagrams and manuals. Besides that, you're turning smoothly now so it's kind of un important.
24 Nov 2021 15:21 #9

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Replied by msavitt on topic dt1 crankshaft alignment

I this i have seen crank to case clearance dimensions in manuals fir my dt400e and dt360a

It might be insightful to measure case depth with the stick end of a caliper and one of the super nice square bars that come with your crank puller and to then subtract crank width with and without the thrust washer to see what you get. Can’t imagine you want more than a few thousands of clearance 
24 Nov 2021 16:54 #10

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