Poor gearchange

Previously robert_tuck wrote:

The action of my 99 box has never been A1 so I'm going through it all, in the process I've come accross a new old stock primary chain made in Japan marked EK standard, I think it came from RGM, Anyone know if it is worth using?,The gearbox is part stripped ,I'm suspicious of a tight ball race in the inner cover and an earlier fitting of a roller bearing in the primary side that was done without checking end float,Do these normally need shimming?,I'm also thinking of using a lighter oil than ep90 to reduce drag.

Robert The answer may well be in the question. Gear change is not improved by clutch drag, which is what I assume you are referring to.

Previously robert_tuck wrote:

The action of my 99 box has never been A1 so I'm going through it all, in the process I've come accross a new old stock primary chain made in Japan marked EK standard, I think it came from RGM, Anyone know if it is worth using?,The gearbox is part stripped ,I'm suspicious of a tight ball race in the inner cover and an earlier fitting of a roller bearing in the primary side that was done without checking end float,Do these normally need shimming?,I'm also thinking of using a lighter oil than ep90 to reduce drag.

Hello if its the Clutch that'sDragging this will make it hard to change gears the oil I use is Lucas primary Clutch oilformulated to stop clutch drag or Clutch Slip and help with cooling , and the rightadjustment of the clutch centre Screw and Clutch cable is paramount there should be the minimum ofadjustment of the clutch cable that the gearbox end, and to seal the outer case I use Black hightemperatureSilicone sealer on the back of the Rubber band only , on the inner primary case .Then I use Morris waterproofGrease for theoutercasehas Not all grease iswaterproof. this then makes for a good seal and then you can poor your oil into the primarychain-case from the top filler hole but undo the drain plug and fill until it comes out of the drain plug then fit the drain plug and all is then OK Have you now got it, yours Anna J

I am pretty sure that the oil you refer to is in the gearbox, not the primary chaincase, Bob, and the drag to which you refer is that caused by the viscosity of the oil on the gears? I have a few Norton twin manuals, which are very slightly contradictory where gearbox oil is concerned. One specifies 90 grade gear oil or sae 50 engine oil, which I believe are of a similar viscosity. Another says sae 40 engine oil in the summer, sae 30 in the winter in both engine and gearbox, the 3rd simply specifies sae 50 engine oil; as does the Commando manual. The concensus then is sae 50. I believe one has to be careful with EP gear oils, as the additives which give it the extreme pressure rating can damage bronze bushes etc.

As these gearboxes when well set up are fine with sae 50 oil, I am not sure that thinning the oil is the answer. If there is no, or minimal, end float, that could cause the gearchange to be stiff, more so as it gets warm. Mine was the opposite; too much end float, which caused it to jump out of 1st. I used Commando Isolastic shims, rear ones if I remember, which did the job.

EK chains are good quality, provided it is the correct spec.

Ian

I can't imagine changing to 80/90 gear oil will do any harm. I think I have 75/90 in mine. ATF is very thin. I put it in my primary chaincase the other day, which resulted in the worst bout of incontinence I have ever seen; and that was at the Goodwood Revival! Bit embarrassing; soon got changed to engine oil again!

It sounds as though your 'box needs to come apart for a look-see. Fortunately all but mainshaft removal and inner layshaft bearing removal can be done in situ; just as well! Good luck!

Ian

If your kickstart is tending to go down on its own, your layshaft bearing needs urgent replacement. With a 99, just stick to a good quality ball bearing.

Lets hope the sleeve gear etc is all ok,don't want to take the motor and box out.

It is just possible to remove the gearbox without removing the engine. I have done it, but it still involves most of the work required to take the engine out, without actually doing so. The 'loose' engine is moved forward as far as possible, in a position which will allow the gearbox to be rotated to a point where it will slide out. Still a lot of work, though...

I did it because the gearchange was poor. Turned out the previous owner had bodged a repair to a crack in the casing around the camplate detent ball and spring retaining bolt using JB weld or similar. The repair didn't hold, causing hit or miss retention of the camplate. I don't know if that is a weak point, and whether others have suffered casing failure there, but it is worth a squint underneath to have a look. I had the case welded and re-machined to effect a permanent repair.

I can't imagine changing to 80/90 gear oil will do any harm. I think I have 75/90 in mine. ATF is very thin. I put it in my primary chaincase the other day, which resulted in the worst bout of incontinence I have ever seen; and that was at the Goodwood Revival! Bit embarrassing; soon got changed to engine oil again!

It sounds as though your 'box needs to come apart for a look-see. Fortunately all but mainshaft removal and inner layshaft bearing removal can be done in situ; just as well! Good luck!

Ian

Ian Do you know that ATF oil only make a nasty mess of your Clutch Rubbers,in time !!!

I didn't know that Anna, well not until now! However, as I said, it was only in there for a day, before being replaced with engine oil. I have noticed you mention the Lucas Primary Clutch oil before, so I will check with local suppliers. Thanks for the tip. Ian

Does the selector mechanism all look sound? Any wear on the selector plate, burrs etc? The selector rod not being tight could cause vagueness. As you have a roller inner layshaft bearing, you will need to check for end float. Apart from that, the bearing in the outer cover is cause for concern.

Hi Bob. Good work so far! My Norton manual covering 1959-67 states:-

Mainshaft diameter (clutch end) .8105"/.8095"

Mainshaft diameter (kickstart end) .6248"/.6244"

Mainshaft bearing SKF-RLS5 5/8" x 1 9/16" x 7/16"

Layshaft bearing SKF 6203 17mm x 40mm x 12mm

Layshaft diameter (Clutch end) .6692"/.6687"

Layshaft diameter Kickstart end) .6855"/.6845"

Sleeve gear bearing - situ (O/D) 1.2500"/1.2495"

Sleeve gear bush O/D .906"/.9055"

Sleeve gear bush - reamed in situ .81325"/.81200"

Layshaft bush - bare diameter .6875"/.6865"

Hope this helps.

CheersIan

I shimmed the k/s end, as shown here...

This should cover most questions; with luck!

Ian

Ian Do you know that ATF oil only make a nasty mess of your Clutch Rubbers,in time !!!

I didn't know that Anna, well not until now! However, as I said, it was only in there for a day, before being replaced with engine oil. I have noticed you mention the Lucas Primary Clutch oil before, so I will check with local suppliers. Thanks for the tip. Ian

Hi Bob. I get what you mean, but, the proof of the pudding, as they say.... it works, and it is much easier to shim the outer end than the inner.

Hello Robert,

It may not be of any use, but earlier in the year I moved over to EP 140 in my gearbox and EP 90 in the primary drive of my Mk.III Commando. Initial impressions are that it is much smoother and doesn't dribble everywhere. Previously I had been using EP 90 in the gearbox and ATF in the primary drive. The gear change is very smooth but I don't know what it will be like when the weather turns really cold (my machine is used all year).

Regards, Colin Cheney, Leicestershire [the home of the British Motorcycle Industry ]