Primary Chain Alignment

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danfr

danfr

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Hey guys! I'm just piecing my '71 Roadster back together and noticed that the primary chain is way out of alignment. I believe either the gearbox or the engine is crooked. I understand there is a bit of wriggle room with the triplex chains but I believe this is out of it's limit. I've changed out the isolastics and i've had the gearbox in and out. I'm not too sure if it's the engine or the gearbox that I should use as a starting reference. Any tips are greatly appreciated!

Primary Chain Alignment


Primary Chain Alignment


Primary Chain Alignment


Cheers
Dan
 
Must be some tips already posted up here on forum .... you got that shop manual right ?
 
In the direction that it's off, it looks like the engine is tilted to the left. That can happen if the mounting holes in the crankcase to cradle get wallowed out. Had that happen to mine and actually had a crack in the cases around one of the holes -

Primary Chain Alignment


I fixed it with brass sleeves -

Primary Chain Alignment
 
Hey guys,

Thanks for all the replies.

Ya I have a Haynes manual, but I find it's not the best reference. Yes I do have the spacer on the top gearbox bolt. I noticed the top bolt was installed backwards. I doubt that may make a difference, but I'll turn it around to rule it out.

I measured the distance from the left face of the cradle to the top face of the clutch basket in a couple areas and it is definitely the gearbox that is crooked. Yes the cradle face isn't a machined surface, but It's quite obvious when measuring that the gearbox is pulling to the right (clockwise when looking from above). I'll check all my hardware and make sure all bolts are torqued and go from there.
 
Check the distance from the outer teeth to the cradle, it will be around 3 - 1/4".

Be careful or at least put the horn back in first.
 
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Hey guys,

So I pulled the spacer on the top bolt and measured it to be about 1/8" which is correct. I checked for burrs and ovaling in the holes on the cradle and everything looked ok. I put everything back on, torqued the mounting bolts to 55lbs and it squared right up. I'm really not too sure what was causing the issue but it appears to be gone.

Thanks for all your feedback. It's great to have a supportive forum like this.

Dan
 
Time Warp said:
My 71 FB never had one when I got it. :rolleyes:
Click to expand...
And if the previous owner torqued up the top bolt the without the spacer the cradle could be bowed inward, creating a problem to get the gearbox/primary chain adjustment properly set.
 
Bob Z. said:
And if the previous owner torqued up the top bolt the without the spacer the cradle could be bowed inward, creating a problem to get the gearbox/primary chain adjustment properly set.
Click to expand...

They had, I got another cradle off Mike V ( Mikes Vintage Cycle Parts) in Iowa.

​

 
chaztuna said:
Even with the Mk III style Isolastics, you can make side to side adjustments at both the front and rear. Do that by changing the "stop" [side without threads all the way out to the end] side's location.
Click to expand...

Hm ok, good to know. I followed the instructions when installing them. In the future, if I do find things a little off, I’ll be sure to check that the engine and cradle are centered.
 
danfr said:
Hm ok, good to know. I followed the instructions when installing them. In the future, if I do find things a little off, I’ll be sure to check that the engine and cradle are centered.
Click to expand...
I think ensuring that the crankshaft and gearbox mainshaft are parallel is equally important for your primary chain. Providing that both shafts are parallel, you can shim the clutch chainwheel out, per Section C 34-8 in the manual.
 
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