FH - wear in the valve train

 Last time we were here, I wrote about some wear I detected in the valve train through not being able to set up the valve clearances properly. What I've done now is remove the rocker box again to have a close look at the tappet adjusters and the push rods. 

Removing the push rods and measuring them revealed that the inlet pushrods are correct to the measurements shown in Draganfly's pages of information. Strangely enough the exhaust push rods are actually slightly too short, which is unexpected since I was able to set up these valve clearances easily.

I also measured up the tappet adjusters. I made some posts on the club Facebook page about both the tappet adjusters and the push rods which revealed some useful advice from fellow members. It appears that the tappet adjusters are more or less the correct length, however the later BSA or Triumph adjusters (which are the same length and thread, 5/16" CEI) are provided with hex socket heads and are consequently easier to use. Looking closely at my original Ariel adjusters showed that the square heads were deformed slightly and would not go into the lock nuts, limiting the adjustment available.

I resolved to take the club member's advice, and bought a new set of adjusters and lock nuts.

Further advice from a gentleman who races Ariels had me looking at the extent of the heat treatment of these adjusters. Some of the ones on the market are apparently prone to breaking around the hexagon socket due to over hardening in that area; it appears that the extent of heat treatment on the ones I bought is limited to the area that makes contact with the valve stem, so that should be all right. Hopefully...

Today I fitted the rocker box again, with a longer bolt inside the inlet end. This is a much better approach than the stud and nut that Ariel specified (you will lose the nut down the pushrod tunnel) and is actually a BSA approach to fixing the rocker box shown to me by Steve, a long distance Huntmaster rider. 

Unfortunately tightening the rocker box bolts revealed that the nuts in the two rear corners could not be fitted with the box fully down. I loosened the main bolts and jacked up the rocker box using the inlet valve adjusters high enough so that I could get the reduced hex nuts in place on the rear corners without losing the pushrod location in the rocker cups.

That done, it was time to pack up for the day but not before I had temporarily fitted the rocker box covers and one of the head steadies. One of the rocker box covers doesn't fit very well due to burring on the locating pins which I'll have to fix later.

Here's a wider view of the engine, with both exhaust pipes temporarily in place:

Next, we can finalise the valve clearances, which are 0.010" for both inlet and exhaust; these new Triumph adjusters need a 1/8" hex key, one of which will have to go in the toolkit. When that's done, we won't need to have the facility to turn the engine easily, so we can close up the gearbox. Before I do that I will fit the pear nipple on the clutch cable; I'll adjust the inner clutch cable length later as I want to replace the handlebar end nipple with a brass one. I'll do the air lever nipple at the same time.

Offline from all this I can replace the dynamo chain and fit the timing cover. Then we can seriously think about first start.

FH - rocker box

It's pouring with rain here today so badly that I can barely take the dogs out, so I've taken a little while to come and varnish an oak window sill and fit the rocker box to the Huntmaster. 

We start with Wellseal on the rocker box gasket faces and stick the gaskets in place. Next we'll put another coat on the cylinder head gasket faces and manoeuvre the rocker box into place over the pushrods.

I'm using a small USB camera connected to my phone to have a look in some of the small spaces around the top of the engine. The camera is small enough to go down towards the pushrod tunnels so that we can verify that the bottom end of the push rods are sitting in the tappets properly.

The camera fits through the inspection hole in the top of the rocker box and through the big spaces at the front and back to allow us to see whether the push rods are engaging with the rockers properly. You can get a small screwdriver in front or rear to nudge the pushrods into place.

With a bit of fiddling, I got the rocker box down and bolted. These bolts are actually supposed to have shakeproof washers so I shall have to change them later but the gaskets are pulled down properly. I've also fitted the rocker box oil lines.

So this all went pretty well except for one thing. Whilst the rocker box is down and I've managed to adjust the exhaust rockers to a reasonable clearance, there is no way that I can get the adjusters far enough into the rockers to bring the inlet rocker clearance to specification. I'm not sure what's wrong with this, it might be worn adjusters, it might be worn pushrods...

Wish I had had the foresight to measure the pushrods before I started...

FH - gearbox

 First off let me just say that I'm not going to rebuild the GB gearbox on the Huntmaster just yet. The gears select well, there's no play in the mainshaft, no lateral play in the gearbox as far as I can tell and whilst there's a little bit of movement in the sleeve gear it's no worse than other gearboxes I've looked at at the outset. Turning the shaft by hand doesn't reveal any strange noises so I think we'll just leave it be for the moment. 

However, there is something strange going on. When I assembled the clutch I discovered that I couldn't get the plates to touch, even when the screws were done up relatively tightly against the springs which made me think that perhaps there were two ball bearings within the main shaft. I fitted a new one when I replaced the push rod but now that the pushrod assembly is effectively over long I think there may be two. 

Of course I can't remove the ball bearings from the clutch side because they are right down at the other end of the mainshaft and I've no means of pulling them out. Therefore I've got to remove the kickstart case cover, have a look at the clutch mechanism and remove the balls from that end. This will give me a chance to polish the kickstart case cover to match the timing cover. Secondly it will give me a chance to look at the mainshaft end float and to learn a little bit about the gear selector mechanism on the GB, which I've never looked at before.

The kickstart quadrant is in lovely condition:

It looks very clean inside and it's immediately obvious that the design is a little more sophisticated than the BA/CP type that I'm used to. The mainshaft has no detectable end float that I can find. It's obvious that the gearbox has only had oil in it; though I will probably use the Morris K400EP grease in it as usual.

Moving the pushrod from the clutch side, having pulled the lifting mushroom out revealed something rather strange. There's a large lump of what appears to be oily rust sitting at the end of the main shaft:

I pushed this out and then ran a little roll of paper up and down the inside of the mainshaft swabbing out the remaining muck. It was at this point that I realised that the quarter inch push rod that I had made in a previous post is the wrong diameter for the GB gearbox. Speaking to the various members of the club, including the gearbox specialist, revealed that GB gearboxes use a 5/16" diameter push rod. 

While waiting for some new bits to arrive I'll polish the end cover:

FH - clutch pushrod

 I usually make clutch pushrods for the simple reason that by the time I find that I need one I don't usually have the time to order one from one of the main suppliers. You can make them very easily with material from eBay or somewhere like that: they're just a 1/4" round silver steel bar cut to an appropriate length. Most Ariel ones are around 12 1/2" for the CP & BA boxes; later models with GB gearboxes are around 9 1/2" or so and are 5/16" diameter. Don't take these figures as gospel since there are a number of different variations in length due to different mainshaft lengths, different numbers of clutch plates, and the presence of friction material in the clutch basket in the last machines.

When you obtain the steel it will be in normal condition and will require the ends to be hardened. This is very simple - All you need to do to harden the steel is to heat the end to cherry red and quench it in water. 

First, before hardening you want to cut the rod to the right length. It's easy to find the right length, because the wonderful people at Draganfly provide a parts list which has the lengths recorded. If you're feeling guilty about using their information but not buying the parts rest assured that you'll be buying lots of bits from them at some point or other!

Start by marking and cutting the steel to the right length.

Next you'll want to square up the ends and smooth them off. You can use a file for this but I usually use my bench linisher with the mitre attachment set to 90°. With the end squared off I like to put a tiny bevel on the edges just to soften them.

Next step is to heat the ends and harden them. Some while ago I took one of the mini beer kegs and turned it into a small furnace with some ceramic blanket and fire cement. It makes heating this kind of thing very much more efficient, because it contains the heat from the torch. You use a lot less gas and the whole job heats up a lot more quickly.

Next you just plunge the end into a cold water bath, and turn around and do the other end; the middle part of the bar doesn't need to be hardened. You can clean off the oxide colours if you want to but it's not necessary. 

Pop your push rod into the main shaft and you're ready to build the clutch. 

By the way, these pictures show a 1/4" pushrod in a 5/16" hole. You live and learn!

SQ4 Clutch Investigation

 After the Blakeney run, Tom reported that the SQ4 clutch was slipping when he got home - he couldn't get it to go over 50 mph without the clutch slipping. 

We rebuilt it using the new plates from the W/NG, which got it's old Ferodo plates back; middle grandson Felix helped with the job:

We made a little pointer to show the pressure plate was lifting squarely:

Oddly, it wouldn't function with the old pushrod - We had to add 1/8" to the pushrod length, having found the original 12 3/4" wasn't long enough but 13" was too long. We settled on 12 7/8".

A month later, we had the opposite problem where it wouldn't disengage - Tom took it apart again and adjusted it, and all was well. Sticky new plates, or some intermittent fault?

W/NG clutch repairs

July has been a month of tinkering with little bike jobs. I use the W/NG a lot, because it's an easy bike to ride around the little lanes and to thread through busy holiday traffic - unlike the Square Four, which is much heavier, less nippy but is also more suited to the open road - faster, more comfortable and with a much lighter clutch. 

Talking of clutches, the W/NG's clutch was starting to trouble me a bit - it felt notchy, gear changing was getting more difficult to perform quietly and it was obviously starting to drag. I knew the plates, basket and centre were in good condition because I had pulled them apart when I rebuilt the engine late in 2020, but the operating mechanism had not been touched.

Here's the first observation. See the pushrod? It's not supposed to be dished like that, so that was obviously knackered. The little bronze bush wasn't in too bad condition, but it was very loose in the gearbox cover:

Next - the arm is not supposed to pivot on an M5 bolt. This gave rise to a lot of lost lever movement as the larger of the two holes in the arm is threaded 1/4" CEI:

The pushrod was dished at the other end as well, as someone had fitted a ball in the pressure plate:

I looked around for a new pivot pin for a while. These came from AOMCC Gearbox spares:

The bush is held in place with Loctite 603 Retaining Compound:

All back together and feeling a lot better. I just need a road test now, though I think I may need a new set of clutch springs. It's been difficult to get the pressure plate level without one of the springs ridiculously loose....

Clutch

Having got the brake shoes back, I want to finish off a couple of cables that are cluttering up the workshop, before starting on the cylinder head. One of those is the clutch cable, and I would like to do a dry run of the clutch build. It's a dry run, beacause I want to spin the engine on the power drill using the crankshaft shock absorber nut, and I don't have the oil pump or any of the timing gear ready yet - because the head is not fitted.

So today I will fit the clutch temporarily, to have a look. First up is the basket, fitted over the cage & needle rollers. It's retained with new bolts and lock washer I bought from John Budgen.

Next up is the stack of plates and the clutch centre, preceeded by the final thrust washer. First problem appears - the new clutch centre nut is not happy on the gearbox mainshaft thread - though the old one still fits. This is the whole point of a dry build!

Push rod fitted!

The pressure plate comes next, followed by the cups, springs and the nuts. And the first outing for the clutch spring screwdriver I made a couple of years ago. Works fine!

The clutch operates very nicely using the arm on the other end of the gearbox, and the pushrod adjuster is screwed almost right in. Odd I think, the plates are in good shape but not wholly unworn. Most of them came from John Mitchell of the AOMCC. Maybe the pushrod is too short or there is a ball missing? The ball is certainly present in the adjuster cup...