73 750 commando, bolt damage in primary

franko

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Good afternoon: I had a bolt that attaches the primary cover to the crank case come loose and get stuck in the engine sprocket. The inner front cover was broken apart and the trans was jerked forward.
I have disassembled the primary drive. The inner primary case is toast, along with the clutch basket bearing.
I put a dial indicator on the crankshaft on the section that the rotor attaches to, next to the tapper. I have .0015" run out there. On the trans shaft on the section that the clutch basket rides on, I have .005" run out.
Would this amount of run out cause problems?
The engine sprocket, I will look at cleaning up, after I get the bolt out of it. The clutch basket bearing I will replace. Would a roller bearing be better, as it always had about a .125" wobble to the side of the basket, even after replacing the bearing?
The primary chain I will replace. How are the two row chains working out? A little less weight and vibration maybe?
It has been about 7 years and 20,000 miles since I had the case off to replace the trans sprocket with a 19 tooth one. Would it have been better to use blue Loctite on the three bolts to the crank case?
Your thoughts please and thank you. Frank Coleman
 
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Re: 73 750 commando, loose bolt in primary

Replace the chain for one of Andy's double chains and with the 3 bolts that hold your inner case on the crank , put 3 new locking tabs and put some sort of sealent on the 3 bolt threads so oil don't get past the bolts, the sealent will also work as a thread lock and you shouldn't have any more problems there, replace the clutch brearing with a sealed bearing and all should be good to go again, I take it you don't pull your primary case apart to often, it should be done as part of any maintenacne work, I do mine once a year or depends on how many miles I do, its a good thing to do regularly to make sure everything is ajusted and maintenance kept up, clutch plates clean, its not a major job to pull the primary apart for servicing if your got the right tools etc.

Ashley
 

franko

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Ashman: Thanks for the reply.
I go into the primary during the spring time when weather for normal riding arrives.
This year I had to clean the clutch plates. I have the bronze ones and they seem to gum up every year or two. I use type F auto trans fluid. I use Heavy Shock gear oil in the transmission. When I removed the Dyno Dave Clutch Rod Seal, I could see that the pink fluid was held at bay, so I think it's just from it being the bronze plates.
I didn't check the bolts from the inner case to the crankcase, but will in the future.
Andy Chain is going to be sending a chain in a week or so and I think a chain case will be on the way in a day or so.
Now I need to buy a bearing for the clutch basket and bolts with tabs to attach it.
Do you have any thoughts as to if the run out on the two shafts will cause any problems?
Thanks for your time, Frank Coleman
 
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Ok, I'll chime. When I do someone will usually supersede. So, either way you can get the info you need. Or, some asshole will interject and send the thread off the tracks..........na, that couldn't happen here.

Anyhow,
Although .0015 isn't perfect, I do not think you should be too concerned about it. My only concern is how it might effect the rotor/stator clearance relationship. I think you'll be just fine up front.

Again, .005 at the main shaft is not perfect but not that far out of spec, if at all. If you have some miles on your gearbox, swapping out the main shaft is not a huge deal (unlike a crankshaft) and along with fresh sleeve gear bushes, will offer an added piece of mind. But unless you have undue axial play at the main shaft, you should be fine out back also.
 
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franko said:
Ashman:

Do you have any thoughts as to if the run out on the two shafts will cause any problems?
Thanks for your time, Frank Coleman
Frank,
You will need to check the run out on the rotor to the stator which requires at least 0.008" - 0.010" clearance all around. 0.0015 run out should not be a problem. Check for radial cracks on the primary side engine case if you say the transmission got pushed forward.
Thomas
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franko:

Do you have .0015 total deflection at the crank on your dial gauge? If so, the actual run out is half of that or .00075 from center. Just like measuring piston clearance with a feeler gauge. A .006 tight fitting feeler gauge means .003 piston clearance.

Bob
 
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Frank you shouldn't have much problems with your bronze plates, just the usual clean every so often, I am still running my orginal bronze plates from new, have done well over 150k on them now and the clutch is still light as, its not so bad getting the Ford tranny oil on the plates its getting the gearbox oil on them that make them slip and gunge up, I myself have never had that problem with the gear oil getting into the primary, I just don't over fill my gearbox and a bit of grease on the clutch push rod stops any gear oil getting into the primary.

Ashley
 

franko

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CanukNortonNut: I did a dye-pen. The crankcase looks OK. Thanks.
Bobunome: Yes, that was total run out. I have forgotten to bring the dial indicator back, but pulling and pushing on the mainshaft, I can't feel or see any movement. As I turn it though I see oil weep through the bushing, so that could be why the clutch plates are gumming up (she was leaning on the sidestand).
I will wait until winter to work on the transmission, besides the weeping oil, the splines are showing wear.
Ashman: I have a surface plate and used it a few years ago to true up bronze and plain clutch plates. I do like how the clutch works when it's all cleaned up. Fixing the weep should slow down the gumming up.
QUESTION: As the clutch basket has always had a wobble and I am going to replace the bearing again, if I can find a roller bearing, would this help the situation or make it worse?
Davenport is this week, (http://www.chiefblackhawk.org) so hopefully I will find a vendor with the last of the parts that I need.
Thank again for all the advice. Frank Coleman
 

franko

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I bought the primary covers from the BRITBIKE.COM web site. Thanks J in KC. A new bearing was $21. The tab washers and bolts I bought from Sunset Motors. The stator and rotor had some rubbing damage from when the case was jerked forward and the front broken off, so I had them checked at the auto electrics shop in town (they also work on farm tractor magnetos),and they said they were OK. I'm just waiting for the chains now. Thanks again for those who replied with advice. I will get deeper into this when the weather turns.
 

comnoz

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bobunome said:
franko:

Just like measuring piston clearance with a feeler gauge. A .006 tight fitting feeler gauge means .003 piston clearance.

Bob
??? please explain

That would mean I have been fitting pistons wrong for the last 45 years...
 
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comnoz » Wed Sep 14, 2016 8:10 am

bobunome wrote:
franko:

Just like measuring piston clearance with a feeler gauge. A .006 tight fitting feeler gauge means .003 piston clearance.

Bob


??? please explain

That would mean I have been fitting pistons wrong for the last 45 years...
"If the facts don't fit the theory, change the facts." Einstein
You're never too old, to learn something stupid.
nortonmachineshop.com


You beat me to it JIM. ?????????????????????????????????????????????????????????????????????????????
 
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comnoz said:
bobunome said:
franko:

Just like measuring piston clearance with a feeler gauge. A .006 tight fitting feeler gauge means .003 piston clearance.

Bob
??? please explain

That would mean I have been fitting pistons wrong for the last 45 years...
Franko: It is my understanding that piston clearance is a clearance all around the piston (360 degrees). If you shove the piston tight against one side of the cylinder by inserting a feeler gauge on one side you will measure twice what the all around 360 degree clearance is (ie: the piston clearance will be half what you are measuring.) I may be wrong about this and welcome constructive input.

Bob
 

comnoz

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bobunome said:
comnoz said:
bobunome said:
franko:

Just like measuring piston clearance with a feeler gauge. A .006 tight fitting feeler gauge means .003 piston clearance.

Bob
??? please explain

That would mean I have been fitting pistons wrong for the last 45 years...
Franko: It is my understanding that piston clearance is a clearance all around the piston (360 degrees). If you shove the piston tight against one side of the cylinder by inserting a feeler gauge on one side you will measure twice what the all around 360 degree clearance is (ie: the piston clearance will be half what you are measuring.) I may be wrong about this and welcome constructive input.

Bob
Piston clearance is always total clearance. A snug .006 feeler on one side of the piston would mean the piston clearance is .006.

Runout is a different story. Usually given as a TIR figure. [total indicator reading]
If a shaft is turning in a bearing and gives a TIR reading of .010 then that would indicate the shaft has a bend of .005. It will move the indicator .005 each side of zero for a TIR of .010. Jim
 
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Jim and Franko:

I think we are saying the same thing. A .006 snug feeler gauge with piston gives a total piston clearance of .006. I am referring to what I call piston to wall clearance which would then be .003 all around the piston.

Sorry for the confusion and thank you for helping clear it up. Also sorry for getting this thread off topic.

Bob
 

franko

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The chains were sent out on September 19th and I received them on the 22nd. Thanks Andy. Everything is back together again. The two row primary chain looks like it might save some weight (I didn't weigh either of them) and maybe vibrations. She Is riding nice now, so I will still get about 2 more months riding in. We will be heading to Holy Hill https://www.google.com/search?q=Holy+Hi ... 66&bih=659 in a week to look at the fall color in the country side from the top of the spire. The area has a lot of nice bimble roads. Thanks again for the advice, I'm glad she is back for this time of year.
 
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