Jockey Journal Forum banner

Norton Model 99

19K views 146 replies 18 participants last post by  Ratso 
#1 ·
Looks like I don't know when enough is enough...
A friend of mine is getting ready to move back to England and decided to sell some of the machinery he has collected over the years. I took a ride down to his place the other night and pulled the trigger on a heap of metal that used to be a Norton Model 99 Dominator. I have wanted one for years and what with me having a soft spot for the "snortin' Norton", thought it would make a good addition to go along with my '69 Commando and '48 ES2. When this one is done I will probably have to sell one of my other machines to make room, help pay for the work and lessen my work load in terms of maintenance. I won't get too jiggy with it until later in the year, but here's what I have so far:
 

Attachments

See less See more
3
#28 ·
Man, this forum used to be a real busy spot...I wonder why it seems to be getting 'sleepy'?
Anyhow, with Halloween in the rear view mirror, it's time to get going with the winter projects...so I have finally gotten started on the Norton again. Managed to bash out a set of fork shrouds and headlight mounts that are pretty hard to tell from the original equipment. It was good practice acetylene welding and brazing...fact is I think they are somewhat sturdier than the stock equipment. Also fabricated a new instrument bracket. Those old speedometers are only there to fill in the holes. New instruments are en route and that scabby old headlight will be replaced as well.
 

Attachments

#33 ·
Made some pretty good progress this week...started by putting the flywheel back between the crank halves, giving it a really good cleaning up and finally slathering it with oil. I had to clean up the oil seal journal since it had been damaged by water, in the past I have had to repair these by machining the journal down to accept a sleeve and then machining the sleeve down to the original size again, but this time I got lucky: I only had to shave about 0.003" off to get a smooth surface this time, and since there is still plenty of stretch on the crank seal, I'm sure it will be fine. The connecting rods were cleaned and polished and I checked the clearance with Plastigauge before fitting them. The cases needed a lot of careful cleaning, as some of the lower passages had become completely clogged with aluminum oxide (more water related problems), but eventually I was satisfied with the results. After that I heated the cases in the BBQ to remove the old ball and roller bearings (they fell right out on the grill, YAY!!!), then a new set of Superblends were fitted. An end play of 0.005" was easily established with only one 0.010" shim. The breather plate and camshaft were slipped into place along with the crankshaft assembly. Following a light coat of Threebond on the mating surfaces the timing side case was slipped on over the whole lot and the cases were bolted together. Next will come the pistons and cylinders.
 

Attachments

#35 ·
I'm just flaunting my ignorance here, to make everyone feel good about themselves because more knowledgeable than me; but in pic #4 in the post above, are we seeing the crank and flywheel as if from behind the engine? I mean: If the assembly were surrounded by all the bits and pieces that make a motorcycle, would we be looking at it as if (sort of) from the bike's back end, with the imaginary front forks, wheel, etc., on the crank assembly's far side?

The threads on both crankshaft ends look just a little bit smeared. Is that just an effect of the digital image, or are those threads rough? And if so, will they require a cleanup or will they do as is?
 
#37 ·
To answer some questions:

No Stormin, the old pistons were totally shagged. Water got in there and seized everything up...shagged the cylinders too. I don't trust those old 'pop-top' pistons anyhow. Got a replacement set of nice Gandini pistons and rings.

Ratso, you're looking at what would be the back side of the crank with the timing side on the right and the drive side on the left. The threads are fine, you might be getting fooled by the oil I sprayed all over everything. I usually do that after cleaning in varsol to prevent corrosion...a real problem around these parts especially this time of year and in the spring.

Thunderbird, they are *** bearings with what I think is indeed a 'C' class rating if I'm reading the numbers correctly. They were a common upgrade to the later Norton 750 twins after they had so much trouble with crank flex on the Combat engines.
 
#38 ·
Does "pop top" = domed, with cutaways for valve clearance? Was the Atlas designed to run flattop pistons instead?

Do you happen to know, or to have a guess at, stock Atlas CR? Maybe 8.5 or 9.0:1? Thanks for your patience.
 
#39 ·
Stock compression for the Atlas was only around 7.5 : 1.

Lol! No, the Norton twins generally used use flat top pistons...when I say 'pop-top' I literally mean the top can pop right off the piston under severe use. There is was a large cutaway in the old Norton pistons under the oil ring to allow oil scraped off the cylinder walls by the rings to return freely to the sump (I'll post a photo in the next update). I've seen it happen more than once and the results ain't pretty, or cheap to repair.
 
#40 ·
Yessir, I'd like to see that photo whenever you feel like posting it.

Have you owned/run an Atlas in the past? Seems like I've heard a lot of whimpering about them being rather fierce shakers, but c. 7.5:1 sounds as if it could unfiercen things.

Pal of mine had a Mercury, a really very nice bike for all that it was chronically a mite shabby. He claimed, rightly or not, that it was one of those models introduced so as to use up the factory's superceded leftovers -- the 650SS engine, slimline FB frame, '50s/'60s mufflers, tanks, so on and so forth. Any truth to that, as far as you know? I believe it had been sold as a '69, which kind of supports my buddy's claim I think. Supernice bike to ride, leftovers or not.
 

Attachments

#41 ·
A buddy of mine has a Mercury too...his is a 1970, brings it on all our vintage bike runs. It's a honey of a bike, except for the paint colours (silver tank with sky blue oil tank, battery box and primary case), that's the correct colours for that year, but it looks kinda silly, the black trim is much prettier. Anyhow, by by that time I'm sure they were building them out of leftovers as the Commando's had come out in '68. You never know what you're going to get with a Norton...I've seen ones that came from the factory totally mixed and matched. Nope, this is the first Atlas I've ever had, I've got a '69 Commando and a '48 ES2 and they don't vibrate at all (when they aren't running, LOL!). It's going to be interesting to see how the Atlas compares to the Commando.
 
#42 ·
I managed to pry out the oil control ring from one of the old pistons, the picture isn't that great Ratso, but I think you can see the groove cut into the oil ring groove...this is where old pistons tend to loose their crowns.

I had to fix a broken fin on the replacement cylinder and later on found out that this cylinder definitely came from a Commando, not an Atlas as advertised. In any case it didn't really matter much as the bolt patterns were the same and I only needed to drill out four of the cylinder head holes to take the larger Commando bolts. I gave the cylinders a final hone, cleaned them up along with the tappets and got them ready to slide down over the pistons. The new pistons went on text book perfect and the cylinders followed suit. After that I got the cylinder head all cleaned up. Three of the valves were in really good shape, but one intake valve was so severely pitted that I decided to hunt around for a replacement. I came across an old intake valve from the first engine job I ever did on my Commando and decided it would be suitable to return to service. After reconditioning the valves on the old Van Dorn valve grinder and cutting the valve seats, they were lapped in and the the seats checked with machinists bluing. The old cast iron valve guides were just like new, so no need to replace them...so the whole lot got reassembled and it was ready to bolt on to the cylinders. It got a little interesting here because as previously mentioned, the four outer head bolt holes needed to be drilled out and then I made myself busy on the lathe cutting some new threads on a set of 3/8 grade 8 bolts..a new gasket, the four pushrods and the head was finally torqued down. Ready to install the bits and pieces in the timing chest.
 

Attachments

#44 ·
plenty of 'foot print area ' to base flange and I guess not too much finning for heat dissipation needed in that area, but the cylinder outside the liner does strike me as looking mighty thin. did the commando have a reputation for ripping off barrels when pushed hard?

good orderly progression and engineering skills, thanks for shareing.
 
#45 ·
In my experience I have to say no, but when something else lets go...say a piston, or connecting rod, the lower section that sticks down into the crankcase usually gets smashed up pretty bad.

On a slightly different tack, I have had those flange nuts back off on me in spite of the liberal use of locktite on the treads. With the engine idling, I thought something looked a little odd and when I put my fingers on the joint I could feel the cylinder hopping up and down on the crankcase. The funniest thing of all was there was only very minor leakage and the bike seemed to be working better than ever. When I tightened the flange nuts, I got about 3/4 of a turn on every one of them...I carried the appropriate wrench in my pocket for many years after that. ;)
 
#46 ·
Ok, this week I finished up the timing side.

I'm sorry about the lack of pictures, but I was so 'into' getting it back together that it just slipped my mind. Anyhow, putting the chains, oil pump and and adjuster in place was a pretty straight forward affair. The timing cover needed to have some cracks welded up around two of the lower bolt holes. I know a fellow who is a wizard with a TIG machine who took care of it for me. After that I just needed to clean it up and put it in place...a new crankshaft oil seal and oil pump 'O' ring were used, of course. Instead of using a gasket, I just mounted the cover metal-to-metal and let a light smear of Threebond do the sealing. The ignition system was cleaned and lubed and fitted back into the ignition case and the oil lines installed.

With that all ready to go, I decided to work on the 'little gearbox' ( the tach drive unit)...the engine had come with the drive case, but no guts inside it. Not wanting to drop $300.00 on a replacement, I managed to track down the drive worm, then decided to try making up a gear by hand. I had to take a couple of tries before I was successful, but in the end I got it right, installed the guts and fitted new end caps. After spinning it with a drill for about ten minutes, I declared it fit to use and bolted it to the outside of the timing cover. Now it's on with the big gearbox.

Oh by the way, Merry Christmas to one and all and best wished for a happy and prosperous 2020!
 

Attachments

#50 ·
bit more detail on how you made that driven gear would be interesting, a coarse helix thread cut on a lathe?
( my big thing at the mo; is lathes, i'm trying to hunt one down having not touched one since school. they say a lathe is the only tool that can self replicate it's own parts. maybe I should start a lathe thread 8o/ )
happy and healthy 2020 to all.
 
#51 ·
When I say I made it by hand, that's exactly what I mean. :) It's a 16 tooth unit...I used the lathe to cut the blank and index the cut locations, a piece of softwood tapped against the worm to get the approximate tooth angle, then used a hacksaw and a series of mill and jewelers files to carve it out.
 
#54 · (Edited)
Ok, on with the big gearbox. Despite the busy Yuletide season and a rotten cold, I managed to get it apart and back together. The first thing that caught my attention was a broken stud holding the inner cover in place. All the other internal studs were seriously necked down/ stretched from being over-torqued and in danger of breaking too...the worst one had been necked down by almost 0.040".
At first glance the gear cluster didn't look too bad, but on closer inspection, I discovered that the 2nd gear on the mainshaft was badly spalled on the thrust faces...something that I have often seen on the 1st gear in these machines. I'm going to blame this on a combination of abuse and the PO using ATF instead of proper gear oil. Gary from BCS was very helpful in replacing this, he even looked through the used stock in the basement (a gearhead's wonderland), but everything he found was also damaged, so I opted for a brand new one. While I waited for that to arrive, I got busy on the lathe and cut a new set of studs for the inner gearcase and replaced all those stretched out ones that were ready to break. There was also some damage to the clutch cable adjuster mount in the outer cover...it would still function properly, but since I wouldn't give something like this back to a client I figured, why not fix it. I spun up a small aluminum cover that is held firmly in place by the cable adjuster locknut and gave the inside a good smear of JB weld to fill in the crack and glue it permanently in place. A good solid repair with no ugly crack in the case to draw the eye.
 

Attachments

#56 ·
I haven't forgotten about this project, but I must confess to working on a couple of other things since my last posting...and dealing with helping out the 'boss of me' after she some got some hand surgery. Anyhoo, with the engine and transmission ready to go, I got the Norton up on the lift at the end of last week and started cleaning up the frame in preparation for paint. It's now black and shiny, will clearcoat it for a bit of added protection. There's a LOT of black paint on this bike, so this will keep me busy for a little while.
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top