Slickshift 50 gearbox oil additive

[Alistair F]

The gear change action on my 1958 350 NH is far from smooth and before I remove the gearbox and dismantle same it has been suggested that I try using Slickshift 50 gearbox oil additive to see if this improves things first. Has anyone had any experience of using this and is there any known reason why I shouldn’t try this? Any advice gratefully received!

[Paul Slootheer]

I suggest before you make use of a oil additive, first check if your clutch is freeing properly.

[nevhunter]

Any oils should be yellow metal friendly for the Ariel gearbox (or similar) The thicker the Better for gear changing. Cushioning. BAP and CP boxes are snicky when changing gears. Racing type use knocks them around with the dog engagement suffering. A sympathetic rider can get better life from them. A Magnet in the gearboc is a goodidea. BAP's generally have no drain plug for some reason that eludes me. A mixture of a GL4 oil Plus tacky Mill grease is what I use.The grease doesn't fling or channel. Use the Later seal Modification... Matchless 500s only used a CP type box. and it was a factory option on the Round base VCH Trials/Scrambler. It's a considerable weight saving. Nev

[Simon.Gardiner]

It's pretty unusual for these gearboxes to have a problem with the gearchange action itself unless there is a mechanical problem. The mechanism is behind the outer cover and doesn't need the box taking out of the frame to check over.
If you're having trouble with graunching gear changes then (as Paul says) check the clutch isn't dragging, and also that the chains are correctly tensioned!

SG

[MarkPhillips]

Hi Alistair I agree your problem will 99% be clutch drag. I got my 1959 NH 350 this time last year very ropey gearbox and clutch, with Geoff Browns advice and club spares I rebuilt my gearbox in situ it’s the best and recommend way to do it. Covered 1800 miles with little issue then I to started getting graunchy changes. Found my clutch plates dragging slightly but all my adjustment used up, to cut a long story short I found the clutch cable had frayed where it was soldered into the nipple at the handle bar leaver and was stretching.
New cable and properly adjusted using the adjuster on the gearbox cover and were the cable goes into the gearbox, all good again.
It’s really important with the chrome clutch cover of, pull the clutch lever in everything should be loose and free to spin and the spring plate moves squarely and evenly no drag whatsoever. I set my clutch so its bite is right at the end so I get maximum plate separation.
I think Slick whatever will be a complete waste of money.
Personally I found 90w Castrol classic gear oil a lot better than engine oil.
I’ve also found if you get a little graunch or rumble selecting 1st at stand still roll the bike forwards or backwards a few inch’s as you engage it will snick in super smooth if your clutch is good.
Cheers Mark.

[nevhunter]

Technique has a lot to do with downshifting Nicely. A dry cork clutch has one of the best actions you are likely to get. Nev