Ariel Owners Motorcycle Club

JohnLay wrote: ↑Sun Feb 18, 2024 5:31 pm As an aside the gearbox and clutch centre nuts once the tab washers bent were back proved both to be loose, despite or maybe because of the previous hammer and chisel treatment.

Dodgy splines?

Interested to see the clutch springs, mine, for what it's worth, has the shorter
springs. It must have been fun balancing the pressure plate with your
collection of springs.

Three springs 1/2" OD x 1.4" wound right hand plus one also 1/2" OD but 1" long wound left hand. Which one is correct if either ?

A quick and not especially accurate measure of my clutch springs gives 6 turns wound left-hand
with 16swg wire with an OD of 1/2" and a length of 15/16". My springs may well have settled
over time but are more-or-less the same as your shorter spring.

The Burman part number is 92-R which doesn't seem to be used elsewhere but my stock of
Burman literature is far from complete.

I wonder what stock the club's gearbox spares scheme has?

To NOT unwind with a RH thread you need LH wound springs' Put strong opposite strong and weak also opposite weak then adjust so plates come apart ( disengage) evenly. Check no springs coil bind with clutch released Don't run a lot of excess pressure and the action will be lighter and smoother. Nev

The 'R' in the part number denotes that it is a part only used on the 'R' gearbox, when it is used on multiple gearboxes the suffix used is 'X'. However, because Burman's were not as clever as Ariel if a part is used on another model later the number will change from being specific to a model to universal. No cross reference or supersession list available. When the GB box arrived any part that was carried over from earlier boxes was given a new number, in spite of it being the same part. Mad.

There are any amount of clutch springs on line but listed mostly by stock number or by machine (modern) which make searching by size difficult. The best I have found are for a BSA bantam, but as bantam clutches have 6 springs I wonder if the compression rate would suit as the Ariel has only 4. What do the panel think?

Refitted the clutch with the original springs for the time being, they can be looked at in the future as the clutch can be accessed without having to remove the primary drive cover.
At the same time a new primary chain was fitted, the original even with the gearbox as far back as it go was still slack. The box needed to be pushed forward by a little over ½" for the new chain to fit. To make access to the box adjuster easer I removed the offside root rest – the nearside having already been removed in order to take the chain cover off. However it would seem the the bike had “been down the road” at some point. Both the cross rod and the tapered sleeve the rest mounts on were somewhat bent. Not much of a task to straighten, just another thing to do.

Back on the subject of clutch springs I've had a try at comparing my 92-R spring with a
brand-new Draganfly 3405-54. These latter are significantly stronger than the Burman
cork clutch spring 3405-36.

5mm compression on the Draganfly spring produced 3mm compression on the 92-R
spring with 10mm producing 7mm.

This I found somewhat surprising as I'd expected the 92-R to be far the weaker based
on its appearance.

Next, reassemble and refit the clutch using a couple of the original springs for now, plus fitting new front and rear chains. But before that I gave the whole area a good clean up. The crankcase, bottom frame tubes, and front chain cover e.t.c were all covered in black oily muck, none of which can be seen when the cover is in place. It is however easier to work on something clean rather that dirty. Note, the chain cover is just that, a cover, there's no back to it.
Needed to push the gearbox forward by about ½" to get the front chain on. The original back chain was fitted with a half or cranked link which I thought I might not need having pushed the rear wheel forward as well. However, with the gearbox also pushed forward it seemed that I did need it after all.