No end float

Hi, my name is Art and this is my first post on this forum. I have this subject posted on the Britbike.com forum but I think there’s a wider audience for Norton's on this one. This is my problem. I’m refurbishing my newly acquired 1973 Commando. In order to paint the motor cases I removed the inner primary and timing cover. After painting the engine cases I put the motor back on the work stand. I happened to grab the crankshaft and noticed there was no longer any end float, nothing. I had measured 12thou end float before I removed the timing cover. The oil pump is off, the rest of the gears and chain were not removed. I had the crankcase laying on its side for painting but had it blocked up so no weight was on the pinion gear. The timing and cam gears move freely, just no end float. This is the way I had the motor sitting for painting.



I noticed that the sealing washer, part #45 turns in the bore. Is that supposed to happen? Also, should the outer rim of the washer be flush with outer edge of the case? It's about 1/16" recessed into the bore.




Does this scenario sound possible? I painted the cases outside. They were in the hot sun for several hours. I lifted the motor by the crankshaft which was facing up with one hand with the other hand supporting the weight by holding the timing pinion gear. I heard a distinct click when I picked it up but assumed it was the intermediate gear and camshaft sprocket hitting against the case. Could the sun have heated the case enough so that when I picked it up, the weight of the motor pushing down on the timing pinion gear caused the sealing washer to recess further into the bore pressing against the crank bearing?
Any help will be greatly appreciated.

I didn't pain my cases! Just brushed them with a stainless steel brush and looks great. No painted surfaces to deal with! Don't know about the end float.

Is it possible a connecting rod 'flopped' when you picked it up and jammed the crank a bit. # 45 does turn with crank if I remember right. The end play is adjusted with shims on the crank side of the bearings. You couldn't have tightened anything up just by picking the engine up. Does the crank turn nicely? and last but not least, depending on how long the motor was out and sitting around, it's possible that the end play is just not as evident because the internal parts have 'dryed' a bit. With the motor sitting as you have pictured, using a dial indicator, gently pry on the crank from below and measure at the top.

Biscuit said:

Is it possible a connecting rod 'flopped' when you picked it up and jammed the crank a bit. # 45 does turn with crank if I remember right. The end play is adjusted with shims on the crank side of the bearings. You couldn't have tightened anything up just by picking the engine up. Does the crank turn nicely? and last but not least, depending on how long the motor was out and sitting around, it's possible that the end play is just not as evident because the internal parts have 'dryed' a bit. With the motor sitting as you have pictured, using a dial indicator, gently pry on the crank from below and measure at the top.

Click to expand...

Thanks for your response. There is zero end play on the crank. I can barely turn the crank by hand. Is it safe to gently tap the crank in either direction to mabey freeing it up somehow? I'm at a loss here.

Its possible the TS bearing bore is a bit worn so only took sun heat case expansion to allow lifting by DS crank to pull the bearing out of bore somewhat. The cover disc is not much an interference tight fit and may turn by hand but should not turn with crank friction on it running. Cam should by loose to shift r/l but tach drive will pull it to TS agasint the spacer and thrust washer. If it was running good prior i'd reheat and bump the crank to TS and see if that don't center it again for more long term running looking good as new outside. Don't want to rap too hard sideways on the bearings is all and crank self centers d/t the rods.

I'm goint to put a halogen work lamp against the TS. That should heat it rather quickly as compared to the sun. Then give it a few taps.
Thanks

Just to clarify...


Was the engine running OK before you disassembled the various sections to do the painting?

As I understand, none of crankcase assembly (crank/rods/bearings, etc) was disassembled, right?

Have you checked to be sure that nothing could have fallen/lodged into the crank assembly while all this work was being done?


IMO, if the answers to the above are all "yes," and there are no other unmentioned factors, I wouldn't worry about it at all, the end play is fine because nothing could have changed it. If you are really concerned, tap the rotor end of the crank with a soft mallet (or use a hard mallet and block of wood) and the endplay will re-appear.

mike996 said:

Just to clarify...


Was the engine running OK before you disassembled the various sections to do the painting?

As I understand, none of crankcase assembly (crank/rods/bearings, etc) was disassembled, right?

Have you checked to be sure that nothing could have fallen/lodged into the crank assembly while all this work was being done?


IMO, if the answers to the above are all "yes," and there are no other unmentioned factors, I wouldn't worry about it at all, the end play is fine because nothing could have changed it. If you are really concerned, tap the rotor end of the crank with a soft mallet (or use a hard mallet and block of wood) and the endplay will re-appear.

Click to expand...

That is correct, the crankcase was not disassembled, I just removed the whole top end, timing cover and inner primary. I masked off the pistons, rods etc so no paint entered the crankcase.
After heating the timing side case for about 1/2 hour I gave the crank a few taps. I still have no measurable end play but at least now and can turn the crank by hand and it moves freely.

The sealing disk is attached to and rotates with the crankshaft.

The endplay would grow considerably with the cases in the hot sun. I doubt you have anything to worry about. Jim

OK! desaster averted, after 1 hour under a halogen lamp and a few taps with a soft hammer the crank is back to 10thou end float. I never would have believed that the sun could heat the cases enough to cause this to happen.
Thanks for all your responses, I can sleep tonite

Art

As Jim mentions, the al. Cases expand when heated by the sun , which should create a little more endplay, not make it disappear? if I understand correctly, you had 12 thou endplay intially at room temp, then zero after the cases sat in the sun? This seems wrong way round, if 12 thou at room temp, there should be a bit more if heated up 30 or 40 degrees F. You can calculate the amount using the coefficient of thermal expansion for al. , but it isnt much, maybe one or two thou for that temp change x case width.

worntorn said:

As Jim mentions, the al. Cases expand when heated by the sun , which should create a little more endplay, not make it disappear? if I understand correctly, you had 12 thou endplay intially at room temp, then zero after the cases sat in the sun? This seems wrong way round, if 12 thou at room temp, there should be a bit more if heated up 30 or 40 degrees F. You can calculate the amount using the coefficient of thermal expansion for al. , but it isnt much, maybe one or two thou for that temp change x case width.

Click to expand...

What I now believe happened is this. I started at 12thou end float before I removed the timing cover. The top end was removed leaving the rods and pistons in place. They were masked to prevent paint from entering the cases. I painted the cases outside, leaving them to cook for several hours in the sun. When I picked up the motor by the crank (primary side), the crank pointing up, I heard a distinct click that appeared to be the TS bearing moving just enough in its bore to take up all the end float.
After some discussions on the forum I put the cases under halogen work lamps for 1 hour, then tapped the crank on the primary side with a soft hammer causing the bearing to move slightly back into its bore. I then measured 10thoud end float. I put the lamps back on for another 2 hours, gave another tap with a soft hammer and I now have the origional 12thou end float. The burning question I have is should the TS bearing have moved in the first place?

Art

I suppose heating of the cases by the sun also makes the interference fit of the bearing outer race lose some of its grip, though not as much as when the engine gets hot when running.

At normal operating temps there is no interference fit to the bearings, they are free to float. With a used case the sun could easily heat the case to where there is no interference fit.

That is why guys who install a timing side ball bearing thinking it will locate the crank are doing nothing unless they install screws to hold the bearing stationary in the bore. Jim

Ok TS crank shield turns with crank, cool. If the bearing don't stay locked in bore by sun or heat lamp its sure ain't going to be held tight with running temps and vibes but d/t crank's attachments helping hold it centered likely main issue will be race spun in case bore, eventually, as bearing decays or drag sprinting into redzone. After running again might check to see where crank ends up on its own shifting wise. What would the experts say if he finds ~.006" slack on either side when rechecking? Impending damage or waste of time to worry with crank shims? Ugh, of course above assumes the clink didn't come from inner race letting go of crank, but unlikely as alloy expands way more than the inner race could or crank.

comnoz said:

At normal operating temps there is no interference fit to the bearings, they are free to float. With a used case the sun could easily heat the case to where there is no interference fit.

That is why guys who install a timing side ball bearing thinking it will locate the crank are doing nothing unless they install screws to hold the bearing stationary in the bore. Jim

Click to expand...

Exactly. And that's the main worry you have IMO. Jim has talked about spun bearings in the past (probably many times).
I devoured a lot of good advice from this forum when I was in the process of rebuilding my engine, and I'd say that what Jim doesn't know about engines isn't worth knowing.

If the bearing starts to spin it will wear the case and get even looser.

John Hudson's engine building notes recommend using bearing retaining compound to prevent bearing spin. He claims that the factory used it on new engines and I suppose he would know.

My cases showed signs of minor spin - I'd bet they all do.

I chose to fit my bearings with Loctite 641 bearing retainer.

While you have the engine on the bench, it's something worth looking into.

Cheers
Martin

Are the bearings in the 73's motor superblends or something else? If I was to split the cases should I replace or reuse the existing bearings? Just to let you know, my racing days are over so this motor will never be overstressed.

Art

All 850 motors got superblends.

bentrod said:

Just to let you know, my racing days are over so this motor will never be overstressed.

Click to expand...

You will never ride or rev it enough to enjoy it ?!

If the bearings in this basket case rescue are old or worn or pitted or rusty, then riding it without inspecting it is a bit of a crap shoot ?
Not inspecting the sludge trap inside the crank, unless you know the PO ALWAYS changed the oil on time, likewise....

Late Mr. Hudson was perfect example of Norton production quality and was still alive on my Commando arrival, On his video can watche him sand paper the TS crank end till ball bearing slipped on/off real easy cold which left him smiling smug on job well done. So which is more proper to leave most loose to spin, on crank steel or case aluminum? Tach worm in those with em and oil drive both pull their shafts to the right so might only have to shim that side to help center under rod loads?

Martin please please please remember to let us know when able, if the off the shelf made for it bearing glue actually holds in our application. I am rooting for you to be the 1st with such success. JIm uses JBWeld which I'm quessing if just right escess might pile up slipping bearing in to act as its on shim behind race.

Late Mr. Hudson was perfect example of Norton production quality and was still alive on my Commando arrival, On his video can watche him sand paper the TS crank end till ball bearing slipped on/off real easy cold which left him smiling smug on job well done. So which is more proper to leave most loose to spin, on crank steel or case aluminum? Tach worm in those with em and oil drive both pull their shafts to the right so might only have to shim that side to help center under rod loads?

Martin please please please remember to let us know when able, if the off the shelf made for it bearing glue actually holds in our application. I am rooting for you to be the 1st with such success. JIm uses JBWeld which I'm quessing if just right escess might pile up slipping bearing in to act as its on shim behind race.