Shade tree engineered P11 steering damper install

I've had a steering damper in a Norton spare parts box since sometime in the 1990's. It is a used steering damper I got at Raber's Parts Mart. I got it because I was getting a little head shake starting around 87mph. I never got around to installing it before putting the P11 in the corner of the garage and kind of forgetting about it. I was also riding modern sporty bikes at the time, and was always the last guy to the breakfast stop on the P11. That gets old, so I quit riding it. I'd kick it over once in a while to make sure the pistons still went up and down, but that was it. Anyway, I got a notion to install the damper. Dan Kyle with his fancy Ohlins damper talk was my inspiration.

I had the damper, the damper body mount, and a 35mm fork tube clamp with offset mount for the end of the damper shaft. I had to make a bracket to mount the damper body mount to. The clamp didn't really have a large enough offset, and I ran out of damper at both ends. So I reduced the full swing of the forks lock to lock first and then determined where I could mount the damper body without hitting the head when the front end was turned all the way to the left lock. In my usual under engineering style, I made the bracket with some cheap aluminum flat stock, spacers I made or had laying around, a hack saw, a hand drill, and some files.

The damper bracket is mounted to the front of the head steady and the left hand front tank mount. It sticks out about .25 inches too far, but this is a prototype and will get corrected eventually.

It's not real pretty. Kind of looks like I put an automotive hatch back damper on the side of the bike, but it works lock to lock. It's drizzling today so have not had a chance to see if it helps with the head shake. Fair weather only rider in my golden years.








The steering damper is adjustable and rebuildable. I have no idea who made it though. Has a D and a 3 stamped into the end cap at the adjustable end of the damper body.

Nice bike, but I have to ask, what is the adaptor and pipe for on the end of the exhaust rocker spindle?.

Oil pressure gauge.

Nice, obviously more to your bike than meets the eye. Are the pipes ceramic coated? and talking to a mate today who has a P11, he tells me the head gets it oil from the return to the tank, does running a pressure gauge mean you have converted it to pressure fed?

Please tell us more.

There is noting unusual about how the oil travels through the motor. I think your mate misread something or got his info from a Norton forum.

Oil is under full pressure at the rockers from a small circuit off the main pressurized supply. On my motor the oil pressure read from that exhaust rocker is 57 psi at cold startup, and pressure reduces to around 40 psi when warmed up. Oil pressure falls off from the rockers as oil exits the valve train. In the case of the exhaust side, oil dribbles or flows down the push rod tunnels, and in the case of the inlet side down through holes in the barrels. That oil lubricates the cam followers, and the remaining oil collects in the sump where it is picked up by the scavenge section of the pump, and returned to the oil tank. I just read that and paraphrased it. Caveat emptor

Pressure at the oil tank return is very low. If the rockers were fed with return pressure the spindles probably wouldn't last long. I also have a spin on oil filter in the gravity fed circuit out of the oil tank. Oil gets sucked out of the filter by the oil pump. People say that's wrong, but that's how it was done when I did it, and I have over 7K miles on it, so maybe it works.

There is more to my motor than many P11 motors, but nothing unusual for a healthy Combat Commando with a Fred Barlow ported head and 34mm Mikuni carburetors on it. It is not a P11 restoration by any stretch of the imagination, but it is a frame and engine numbers matching 1967 P11. The engine as built is overkill for the brakes. It's kind of sketchy to ride around on in traffic with the tall gearing and dinky front brake after riding dual disc brake bikes for the last 37 years. I need to get some real brakes on it one of these days.

The header pipes need to be ceramic coated. They have a little bit of underlying rattle can ceramic header paint, and BBQ stove pipe satin paint on them right now. It does not hold up to the heat like commercial ceramic coating does.

Ah, I believe that some Norton engines did use the oil return to provide oil to the head, I think they had scrolled rocker spindles to allow the low pressure oil to get where it was needed, I thought this method was used as late as the Atlas motors but it was common to convert them to pressure fed and use plain spindles, then the scrolled spindles found there way into pressure fed rockers engines and caused low oil pressure, probably would have been a good idea to make them a different diameter to stop that happening.

I take an oil pressure feed from my rocker feed on my road Commando with similar pressures to yours but it does drop to around 20psi at tick over.

I have often wondered if it really mattered which pipe the oil filter was fitted to and whilst mine is on the return, I think you have found it isn't that important, I wonder if it helps with controlling wet sumping your way.

I am with you on good brakes, but I have found it is easy to overwhelm older forks so there is a balance to be found and it is the same with the gearing, I tend to over gear because I like the bike to feel good on fairly fast bendy roads but like you say it makes them unpleasant in traffic, If I gear for traffic then it is unpleasant on the open road, I think we expect too much from our bikes re universal use.

Anyway no matter, P11s haven't been on my radar before my mate turned up on his and its mint, same colour as yours, both very nice.

I'm pretty sure all Norton twins prior to the Commando had the valve gear lubricated by a bleed from the oil return to the tank. No idea about the P11.

Nortoniggy said:

I'm pretty sure all Norton twins prior to the Commando had the valve gear lubricated by a bleed from the oil return to the tank. No idea about the P11.

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Maybe so. I have no first hand knowledge about the older Nortons myself. The Norton manual I have says the bleed-off is on the main supply for many Norton models prior to the Commando. Kind of vague.

Right or wrong... on my hot rod P11, the oil line to the head for the valve gear is connected to the same location on the timing cover (below the pressure release valve) as it is on Commando engines. I have a Commando timing cover on it to support the 2S cam and electronic ignition. (The timing side crank case needs to be modified a little to put a 2S cam and change the ignition in a Atlas engine. All of which was done correctly years ago.) The original timing cover was setup the same way for oiling the valve gear, but can't be used for the 2S cam, and does not support points in the timing cover. The valve gear is fed oil from the top on the stock P11 head. On the Commando head I have on the shelf, the valve gear is fed on both sides.

That being said, my limited knowledge of Norton engineering really begins and ends with the P11 in my garage. I only know enough to keep it running, or if the fecal matter hits the fan, rebuild it.

Well it obviously works. Worse case scenario is you'll get more oil in the head cavity than needed but unlikely to do anything bad. I had a 650SS which I converted to full pressure head oil feed, Paul Dunstall used to sell a feed pipe kit. Rode it hard for several years without any problems.

It definitely works the way it is setup.

Storm42,
The spin on oil filter on the feed side doesn't stop oil from draining into the sump when the motor is not run and the bike sits for a week. Wet sumping doesn't bother me. My motor breaths well enough and the sump clears out quick.

The auto white balance on the camera I took those pics with is way off. The ole horse is closer to candy apple red with fine metalflake.

It didn't bother me until I managed to blow the crank oil seal the other month never happened before but now I am looking at making sure It won't happen again. It is a 920 and it did rev a bit quick on startup after being left for a few months, so I know why it happened, it just over whelmed the breather and seal, but it was very inconvenient when it did it.

The colour looks good on my Mac and looks very close to my mates one.

storm42 said:

It didn't bother me until I managed to blow the crank oil seal the other month never happened before but now I am looking at making sure It won't happen again. It is a 920 and it did rev a bit quick on startup after being left for a few months, so I know why it happened, it just over whelmed the breather and seal, but it was very inconvenient when it did it.

The colour looks good on my Mac and looks very close to my mates one.

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I was thinking about this the other day, and wondered if electric start bikes might be prone to having issues with that crank seal if they weren't started frequently and the sump had a liter of oil in it. With a kick start bike and an old kicking leg, it's not as big a deal. I can't spin the crank as fast with my leg as a electric starter can. I do try to start my little 750 every 4 days to reduce oil in the sump. That's why I don't worry about wet sumping anymore. Today is day 5, so I got to get er done.

My Mikuni chokes do rev the motor up quicker than I like on cold starts, but no problems as long as I don't let it sit long and get a bunch of oil in the sump. I did replace the crank seal recently and it is a very tight fit in my case, so I doubt it would blow out. The one I replaced was in there tight as well and the sump used to get a lot more oil in it 27 years ago than it does today. It didn't blow out back then, and I rode the bike a lot harder when I had a full tank of testosterone.

The vent I installed in the intake valve cover helps a lot at getting pressure out of the crank case. I'm not suggesting anyone do it. I do because if I plug it, my motor won't idle very well, is harder to start, and performance falls off. Stupid solid 2S camshaft. The stock camshaft with the timed breather was doing the crank case breathing job really well when I had lower compression pistons in the motor, and the head was stock. Good lesson in leaving things alone. But I cant help myself.

Good luck with the work to keep the crank seal in place.

Not the late Atlas, N15, G15, P11 etc.

Nortoniggy said:

I'm pretty sure all Norton twins prior to the Commando had the valve gear lubricated by a bleed from the oil return to the tank. No idea about the P11.

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Can we clear this up once and for all?
Prior to the middle of 1966 the Norton rocker oil feed came off a T pipe on the return oil pipe. These bikes had a 3 start worm on the oil pump.
From the middle of 1966 norton fitted the 6 start worm to the oil pump, which pumped the oil twice as fast on the inlet and output.
Here's the complication, the 6 start worm was available to replace the 3 start one over the counter to anyone who wanted to buy one, who wanted to upgrade. The oil block on the crankcase on the upgraded 1966 was bigger holes, and the crankcase was drilled with bigger holes to suit. All that information is available in Norton's own post , note I said post , 1966 workshop manuals ( the green one)

Bernhard,
I wasn't real worried about the off topic oil feed facts myself, because I knew everything was all good on my P11, but it's nice that you filled in the blanks for those seeking the truth according to Norton. thanks

Schwany said:

.. I also have a spin on oil filter in the gravity fed circuit out of the oil tank. Oil gets sucked out of the filter by the oil pump. People say that's wrong, but that's how it was done when I did it, and I have over 7K miles on it, so maybe it works.

Click to expand...

It still is a mistake.
Hot oil should go through the filter.
Cold starting an engine every 4 days is probably the worst possible solution for wet sumping.
The weakest link in your lubrication system is the oil pressure gauge and the plastic line to it.
( nice bike though ..)

LOL

Everything I've done to my P11 is a mistake according to members here. I am not caring.

And now, back to the steering damper.

The way it is presently installed, the effective range of damping is very narrow at the angle the fork tube clamp is mounted, as compared to the pivot point of the damper at it's mounting point. So, the effectiveness of the damper is not optimal.

NOT THAT IT IS WRONG, just that it is not optimal.

If you rotate the fork tube clamp to where the rod end mount point is further outboard, it will result in a longer damper stroke distance through the range of steering lock, instead of the current very short stroke. That way, the damping adjustment can be much better set to the best feel for the rider.

...or not!

(as you say, it works)\

...and, I concur with those who have commented on how very nice your bike looks...

Could be "It works" was premature. I'm not sure it's doing anything yet, but I mounted it where I could move the steering lock to lock and not hit the engine. The geometry could easily be total crap. Head shake on the (my) P11 isn't that big a deal anyway. I just threw the damper on there because I had it

Going for a ride in a few minutes to see if the damper install does anything other than permit me to move the steering lock to lock. I'm not sure I have enough nads to ride it hard enough to produce head shake anymore anyway.

Thanks for the thought provoking comments.

Afternoon edit: Test ride says the steering damper does work. Front end feels better all around.

My P11 is a 50/50 bike. It looks good from 50 feet and going past at 50 miles an hour. I live with it, so I know where the ugly stuff is.

Thanks for the nice bike comments gents.