Augusta progress

[JohnMillham]

 I suspect the original method was to use some sort of cross bar clamp as there are two 8mm holes diametrically opposite in the crankcase flange although oddly there is not enough room on the back of the flange for the head of a standard bolt.

That's the way I do it, with a length of angle iron between the two holes, held in place with tapered nuts on studding. I also make sure the spring goes in the same way round each time, as well as everything else. A spiggot is also needed to centre the clutch plate. Please keep up the reporting, as it's very interesting.

[Mikenoangelo]

Clutch removed last night without difficulty. As I suspected the spring is out of line. I’ll put some pictures on here tomorrow so you will understand how the clutch works - it’s very ingenious and very lightly built, the clutch plate weighing almost nothing which no doubt contributes to the extraordinary ease of changing gear despite the absence of synchromesh.

The spring is not original, but of heavier wire, 8mm x 9mm rather than 8 x 8, perhaps to discourage slip. The clutch cover plate is a very thin pressing and it looks like the stronger spring is right on the limit of loading for the cover plate as it is a bit distorted.

The problem is that the spring is not very accurate and the coils which should seat in a lipped recess in the thin steel cover plate are too tight a fit so that the spring is canted over a couple of mm to one side. This does not affect the clutch plate, which rides independently on the gearbox input shaft between the box and the flywheel  but because the clutch thrust race is carried on a tripod of thin spring steel there seems to be a possibility that the thrust race housing is pushed more on one side than on the other. This in turn might cause the clutch plate to be squeezed more at one side of the axis at the instant of engagement which would put an asymmetric load on the front spigot of the input shaft. This could explain the wear on the spigot and perhaps allow the clutch plate to move a little off line before being trapped as the clutch finally engages so contributing to an imbalance and vibration. It could also explain why the vibration I am chasing is affected by pressing the clutch pedal. Just a theory!

In fact the clutch behaves perfectly as a clutch, taking up smoothly, never slipping and permitting easy reversing up hills. I can’t fault it and the faces of the flywheel and the pressure plate are perfect and the lining absolutely unworn, flat and even.

Unless I can grind the existing spring to sit properly in the recess I’ll have to seek a new one from the supplier used by Dale Hicks a while ago.

Mike

[JohnMillham]

I modified my Augusta's clutch by adding three small springs - a copy of Mike Wheeler's system because I found there was a tendency to slip after I fitted the blower.

[Mikenoangelo]

Here is the Augusta clutch. Top centre is the pressure plate (the disc) with the central boss which carries the clutch release bearing. Inside the bearing is the clutch release dog, mounted on a  hollow shaft with a nut on the inner end which is pulled back by the action of the clutch pedal and via the thrust bearing pushes the pressure plate back away from the lining to disengage the clutch. The pressure plate unit is fixed to the flywheel by the three spring steel arms which flex to allow the plate to move away from the flywheel.

The spigot shaft, not shown, goes through the hollow centre shaft, is splined to the clutch plate and aligned by the gearbox input shaft between flywheel and box.

Top left is the cover plate, a very thin steel pressing, attached to the flywheel by three bolts, which compresses the spring against the central boss of the pressure plate unit.

The flywheel, most unusually does not fit to a taper on the crankshaft but is held in place and driven by four bolts which screw into the end of the crank - they are strong! I’ve seen that many of the components have a small round indent, showing that they were routinely tested for hardness, and this includes the four bolts.

Today I have made a fixture to prevent the flywheel from rotating while I undo the four flywheel bolts to replace the centre spigot ball race. I work on my own, often for a couple of hours in the evening so I don’t have a handy assistant.

Mike

[Kari]

On the last photo, I note that the friction plate is of a different construction as the original, which is made from aluminium, slotted and wavy. The linings are attached alternating to the front or rear of the plate. The original assembly has a weak point, that are the rivets who attach the plate to the splined hub. They can become loose allowing the hub to move on the plate, resulting in elongating the holes. The one of Mike's Augusta seems to have those rivets spaced on a greater radius.

Karl

[Mikenoangelo]

My clutch plate is certainly different to Karl’s as the disc is steel rather than aluminium. It all looks fairly new and the riveting is really tidy, so perhaps having found that aluminium is a bit weak the previous owner substituted a steel version, or did the later cars use a steel plate (mine is 1936)?  With the cut out holes just inward of the lining it looks like a very professional job. See photo 16 above. The part behind the lining is wavy as it should be. . The more I look at this the more I suspect that it is a clutch plate from some other source rather than a specially made replacement but as I said it works perfectly.

There are other differences - the rivets attaching the linings are all on 133mm, not alternating diameters as in Karl’s photo. The centre boss of mine does not have the cylindrical flange seen on yours Karl. The rivets fixing the centre boss are on 43 mm diameter.

[Mikenoangelo]

Decision time - new clutch spring ordered from Tested Spring Co, who previously made a batch for Dale Hicks. The spring is slightly stronger than the standard Lancia version but very similar to the rather inaccurately made spring on my car. Not cheap as a one-off at £98 plus carriage.

If anyone else would like to have one please let me know by Dec 16th and I will see if a better price can be negotiated.

Having looked into all the likely sources of vibration I could imagine in clutch, gearbox and transmission there remained the possibility that the problem might originate in the engine. So today I started the engine which is still in place in the car, but shorn of clutch and gearbox. The engine is now supported just by the two leaf springs which connect the crankcase to the chassis which appear to be more or less at the midpoint of balance as it stays level with no assistance apart from than the two radiator hoses. However I supported the sump at both ends just to be safe.

I let it warm up and then cautiously let it rev up to 3800 rpm. It’s bad for an engine to rev free of load so the test was very brief but nothing untoward happened - no obvious vibration periods so that’s a relief. The flywheel runs absolutely true both in rotation and wobble. I did note that the starter pinion just occasionally tinkled against the flywheel teeth at tickover. A good result!

[Raahauge]

Mike. Thanks for the detail on the dust cover and all the other posts. I am following it all with interest so please keep at it .
I didn't drive our Augusta before I repaired everything so I don't know what noise, if any, my broken drive spring would have made but from my (limited) experience with Ardea and Aprilia the clonking could be from the bottom bush, particularly if it was only lubricated with grease.
The Ardea also had similar clonking from play in the bearing housing fixed with locktite.

[JohnMillham]

The flywheel runs absolutely true both in rotation and wobble. I did note that the starter pinion just occasionally tinkled against the flywheel teeth at tickover.
 I'll see if I can find a spare pinion return spring for you.

[Mikenoangelo]

John thanks re starter spring. I'm not in there yet but will let you know if I need one, and if you find it!

Not much progress - precedence given to domestic decorating last weekend - we moved house a couple of years ago and there are still some projects in hand. House is 110 years older than the Augusta but perhaps not as well made.

I've ordered a new clutch spring and have silver soldered the parts for the front suspension tools. This evening I removed the front brake drums which it seems have been skimmed. It has had new moulded linings fitted and the rubbing contact is uniform all around and across each shoe - no wonder it stops well - the brakes are massive for the size of car. I'll change the wheel bearings to sealed  ones as a precaution although the shielding of the brakes from escaping grease looks very thorough. It was very satisfying to find that the stub axle threads and the nuts are pristine with no brutal burring or monkey wrench marks as are the slotted screws holding the backplates to the pillar housings. This seem to be the case with every part seen so far.

Mike

[Mikenoangelo]

Dismantled the front suspension today. All the tooling made to Morris Parry's Newsletter drawings worked fine. The hardest task is to remove the lower cap retaining the main  spring, a two man task, using a jack to hold the tool in place to free the thread and then the monster "G" glamp to take the load of the spring as the cap is unscrewed. It takes two to do this as heaving on one end of a 5ft lever is not enough and makes the car on its tall axle stands seem very unstable. However with the bar (a 1 metre length of 25mm steel bar)  extended through the box spanner with a pipe on the the other end we each had about 800mm of leverage, symmetrically applied, and the cap was soon freed.

No broken springs and so far nothing seems unduly worn, however it was filled with grease which just does not allow the shockabsorber valves to work, as noted when  using the car. More investigation needed and perhaps (Christmas preparations permitting) tomorrow when I'm a bit less greasy, some pictures.

Mike

[Mikenoangelo]

Getting very grubby today cleaning up front suspension parts. Lots of springs (five per side!), numerous tiny spring and ball or plunger flow valves and unfortunately masses of grease. On the off side spring unit several of these flow valves were tightened to the point where no flow could occur, and the brass head of the cylinder was mounted upside down so that the rebound shock absorber action was lacking as I had noted.

The operating piston has a thin steel disc non return valve which I replaced, and the face of the piston was worn and renovated by lapping with a diamond lap plate.

All these parts are tiny as the bore of the shock absorber cylinder is only 24mm and the threads on some of the bits are of minute 0.75mm pitch. Beautifully made though.

Mike

[Mikenoangelo]

Progress between crackers and Christmas cake.

I finished dismantling the sliding pillars. The nearside main spring is distorted at the lower end so that the coils do not sit flat on the thrust bearing when not under load. The track of the bottom race shows evidence of this in the wear marking although the bearing seem to turn smoothly. I can see no reason why the spring is distorted as unlike the clutch spring, it seems to be original, not a dodgy replacement but I’ll have to sort that out.

At this point I checked the sliding pillars for wear by cleaning all the grease off the pivot and bushes then replacing the bottom (spring retaining) cover without the springs so that free play can be felt. With the spring in place, the spring pressure masks any play. There was nothing detectable in the top bush but a small amount could be felt in the bottom pivot.

I disconnected the brake pipes and removed the complete stub axle, brake and swivel unit so I shall have to refill and bleed the brakes later. Not a problem though as I have to replace the brake fluid reservoir which is corroded, There is a Girling replacement which is used on the Series 1 Land Rover from 1954-58 and readily available - it is very similar to the original Lockheed part, just needing a change of mounting strap and the correct flared pipe fitting (UNF 7/16 x 20tpi ) to the outlet pipe.

Now I had to remove the lower spring pivot (effectively the bottom end of what on lesser cars would be called the kingpin), the bush for which is the bore of the lower spring retaining cover  The most difficult part of the job is to remove the small circlip which retains the pivot. The circlip is inside the bore of the pivot and can only be attacked from beneath the axle end while grovelling on the floor. With this removed the pivot is easily unscrewed for inspection.

Both pivots showed some wear, which is as expected more pronounced on the side towards the centre line of the car. Checking the clearance between pivot and bush with a narrow feeler gauge showed about 4 thou on the most worn area (0.1mm) and 3 thou on the least worn area (0.08mm). The pivots which are slightly barrel shaped show a wider band of wear on the loaded side. The “bush” seems unworn with no marking or measurable departure from its 35mm bore.
I’d like to rectify the wear on the bottom pivots but how? Others have built them up with braze or white metal or I suppose they could be hard chromed and reground. I’m reluctant to use any heat on this rather critical component which must be made of high quality heat treated steel. It is also a very difficult thing to reproduce should anything go wrong!

I wonder whether I could nickel plate to build up the worn area and then hand fettle to size. I’d copper plate first to give both a base and a “guide coat” for the fettling then nickel the worn area. I’d get a home nickel plating kit and experiment before committing to the job but also need to find out whether plating can by hydrogen embrittlement damage the steel. Nickel or maybe cupronickel should have sufficient wear resistance for the task.

Now back to the Christmas cake.

Mike

[Mikenoangelo]

I took the flywheel off to replace the 10x30x9mm spigot bearing which carries the nose of the gearbox input shaft - my clamp to prevent rotation while undoing the four bolts worked perfectly and also held the flywheel in place until I was ready to take it off. There was very little oil leaking from the rear main bearing. There is a large oil scroll on a fitting on the engine side of the flywheel and very well designed channels for leakage to be returned to the sump. The spigot bearing seems OK but I’ll replace it with a sealed version.

Back to the sliding pillars and shock absorbers. I’d already spotted that the tiny spring loaded non return valve at the bottom end of the shock absorber spindle on the offside (R/H) had been screwed up tight, completely stopping oil flow and I now see the consequence of this. The cap closing the lower end of the bore of the lower spring pivot, within which the shock absorber spindle slides had been forced off its seat by hydraulic pressure of oil which had no other escape route. The non return valve is just a ball and spring in the end of the tubular spindle with a tiny spider further up the tube for the spring to seat on. The screw which provides a seat for the ball screws into the end of the spindle but there seems to be nothing to stop it from being screwed right in and locking the ball between cap and coil bound spring, and nothing to stop it from unscrewing. Perhaps it was originally retained by solder - maybe a job for Locktite.

In view of this, and all the grease, it's no surprise that the shockabsorber function was poor  on that side.

Mike

[Jaydub]

Mike ,could you not drill 2 holes diametrically opposite each other and put a small splitpin in when the screw is in the correct position, or is there no room?
Excellent article by the way. Even though I have zero knowledge of Augustas and that type of suspension, I find any engineering problems/solutions interesting, as we learn something new everyday.