Primary cover misalignment

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MikeG

MikeG

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My 71 roadster came to me with only one locating dowel in the inner primary case. When I tried to put the second one in the outer cover holes didn't line up so I just left it be. I've had a very minor/occasional leak at the location of the lower missing dowel and I now want to cure it. Is it unusual for either of the covers to be warped or distorted, and if so how/why?
Thanks
 
There should be a washer cum spacer on the mounting stud that comes off the engine /gearbox plates.. If its missing and the outer chrome nut is tightened then it may well have disorted the inner.. The trouble is that to rectify you will have to strip the whole primary transmission
 
I've been in at it before, stripped it down to just the inner cover with the center stud removed and made sure there that the stud was spaced out properly so there was no strain being put on the cover. Just wondering if the cover could be distorted to the point of non alignment without cracking?
 
Mine suffered from the washer behind being missing, I stripped the complete primary off and then shimmed the back of the cover so there was no rock fore and aft and top to bottom. Result no leaks, in your case the cover(s) may be distorted and need straightening first or your covers are mixed. Then you can do the shimming at the back.
 
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kommando said:
Mine suffered from the washer behind being missing, I stripped the complete primary off and then shimmed the back of the cover so there was no rock fore and aft and top to bottom. Result no leaks, in your case the cover(s) may be distorted and need straightening first or your covers are mixed. Then you can do the shimming at the back.
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Mixed covers is a possibility. Do you know of any differences aside from the Mk3 electric start covers?
 
A MK3 cover is completely different and is retained by lots of screws on the periphery. In pre CNC days parts not made together at the same time could have reference points in the wrong place due to slack in the jigs, worn tools etc. Sometimes even if made together they could be out but you would hope this would have been sorted on the production line, but the temptation to bodge and get it out the door could have meant they just removed one dowel and called it fixed. I have a B44 crankcase which came from the factory with a sump retaining stud and its threaded hole completely missing, it was replaced by a self tapper screw too one side.
 
kommando said:
A MK3 cover is completely different and is retained by lots of screws on the periphery. In pre CNC days parts not made together at the same time could have reference points in the wrong place due to slack in the jigs, worn tools etc. Sometimes even if made together they could be out but you would hope this would have been sorted on the production line, but the temptation to bodge and get it out the door could have meant they just removed one dowel and called it fixed. I have a B44 crankcase which came from the factory with a sump retaining stud and its threaded hole completely missing, it was replaced by a self tapper screw too one side.
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Understood...a case of a 50 year old machine based on a 70 year old design, built on 100 year old machinery that survived the blitz. I think I'll just try a bit of the RTV till riding season is done and then dig in.
 
Actually the primary chain case was designed in the late 60s. Usually it is oiltight and by far the best fitted in the British industry. Yes I would use RTV in the meantime you might ask if any Alton equiped owners would like to sell their redundant inners.. To press it back into shape to alleviate cracking you would need to heat would imagine to a couple of hundred degrees centigrade...find out what the actuall alloy is first
 
oldmikew said:
Actually the primary chain case was designed in the late 60s. Usually it is oiltight and by far the best fitted in the British industry.
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IIRC, Royal Enfield used a similar setup. My Interceptor and Constellation both had heavy cast alloy covers with a single center fixing nut and large O ring. Difference was the transmission was bolted ridged to the engine so no chance of misalignment or shimming issues.
 
Remove the top dowl and put it in the lower hole then put your cover on to see where it sits, when you put the two dowls in place put some blue engineers marker stuff on (bearing blue) put it where the dowls sit and try to put the outer cover on to see how far the holes are out, the bearing blue will show you where the dowls are sitting, if its only slightly out you should be able to force to outer cover to sit right.
On the outer case push down where the dowl top dowl is on the case and the bottom dowl push up to see if it will go into place, I can't see it being to far out.

Ashley
 
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Or take an extra dowel, sand it down to a slip fit in either hole (so you can get it out easily) and put a polished taper on the outer end.
Install the other full size dowel, put the outer cover on and off again, and look carefully at the taper to see which side is scraping.
If lucky, it will mount up with just one partial taper. If not, both pins can be tapered. If way off, the tapers won't help.
 
MikeG said:
IIRC, Royal Enfield used a similar setup. My Interceptor and Constellation both had heavy cast alloy covers with a single center fixing nut and large O ring. Difference was the transmission was bolted ridged to the engine so no chance of misalignment or shimming issues.
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Very underrated bikes ,didnt realise they had used heavy cast alloy covers ..
 
MikeG said:
IIRC, Royal Enfield used a similar setup. My Interceptor and Constellation both had heavy cast alloy covers with a single center fixing nut and large O ring. Difference was the transmission was bolted ridged to the engine so no chance of misalignment or shimming issues.
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I had read that when Norton acquired Royal Enfield they decided to use their primary set up.
The stud boss on the inner primary is the same plain as the engine where the primary bolts to it. You can use a known flat edge such as a level, lay it across the engine case where the primary bolts to it. You can then see how many shims you need for the primary without taking it on and off
Primary cover misalignment
 
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