Augusta progress

[Mikenoangelo]

Oh B*gg*r!

Sorry to hear that Mike. It's that oilway so close to the journal. I can see a crack above and below the oilway going vertically in the picture.

Maybe a two main bearing crank is the answer   - the Austin 7 racers all prefer two bearings to three. The Twin Cam Salmson can be either two or three bearings with, on the three bearing version a split disc for the centre main just like the Augusta. Three bearing Salmson cranks have been known to break but not the two bearing.

How much undersize are the crank journals? I do think the Augusta crank webs are very slim and wonder if there could be benefit (if making a new crank) in shortening the centre main and the big end bearings to thicken the webs?

Mike

[JohnMillham]

Commiserations, Mike. When I had a new crank made, Phoenix made the centre main the same size as the rear one, rather than the same as the front, which is a bit smaller. So far, it has proved OK and nice and smooth, apart from having little oil pressure, which might well be to do with the shell bearings used for the centre main.

[JohnMillham]

It might pay to get together with Peter Renou, who recently had a similar problem, to see about getting some new crankshafts made.

[Raahauge]

Thanks for the commiserations.
The centre main is 48.25 and the big end is 41.2. The crack looks to me to have propagated from the oil drilling to the centre main where there is only 2mm of material. I would be interested to know what the standard journal sizes are.
I will mail Peter about a possible collective effort, if anyone else is interested please come forward.
I do have a another crank in a wreck of an engine I bought last year but even if it looks good when I get it out it may have the same flaws.

[Mikenoangelo]

According to the English version of the instruction book the big end would have been 42mm, the front and centre main 50mm and the rear main 60mm. The actual diameters are not shown but they do show undersize measurements to fit no 1 and no 2 undersize bearings. The no 2 undersize diameters are, for the big end 41.582 - 41.600mm, for the front and centre mains 49.182 - 49.200mm and the rear main 59.180 - 59.200.

The big end which I measured on my engine was 41.66, or about 13.4 thou undersize in pre Napoleonic measurement. I'm no expert but suspect that the undersizes to suit replacment bearings are pretty cautious and would think that the  bigend could tolerate a 20thou regind but an expert such as Ian Burlingham of JBL near York should be consulted.

John's oversize centre main is intended to give more clearance for the oilway as well as providing support a little further out radially along the crank web. I still feel the centre webs look too thin but the saying that "if it looks right it is right" is considered twaddle by real engineers.

Mike

[Mikenoangelo]

Spring cleaning this week!

New serrated bushes and bolts were made for the front end of the springs, both out of En24T, over-size on diameter to suit the now reamed holes in the chassis bracket and the 14.3mm bore  of the metalastic bushes. I hardened the serrated bushes - red hot then quench in 50/50 engine oil and kerosene, polish then warm until straw/ blue and cool slowly. They are hard enough to be pretty resistant to filing.

I replaced the bearings at the rear (shackle) end of the springs. These look like metalastic bushes but include small rollers in place of the rubber in metalastic bushes. I replaced them with a steel inner sleeve clamped by the original 9mm through bolt, surrounded with a bush made of nylon which is a press fit into the eye of the spring and a running fit on the inner sleeve. I thought that the nylon bushes would end up with a smaller bore after pressing  into the spring eye so bored them first and then made the inner sleeve to fit. In fact the reduction in bore was very slight but I’d still do it the same way. Googly research suggested that Vaseline (petroleum jelly) is the best lubricant for nylon so the medicine cupboard was raided. The lower bearings on the shackles were replaced but I left the top ones undisturbed as they turned smoothly and had little detectable play.

Next job was to clean the spring leaves, grease and re-assemble them, taking care not to mix the leaves, and to put the springs back on the correct sides of the car, which a previous fettler had failed to do so that the serrated bushes were not engaged. Castrol advised that a molybdenum disulphide grease was appropriate between the leaves, readily available as it is used for CV joints. Assembly of the springs involves a pair of large “G” clamps to compress the two top rebound leaves which are of the opposite curvature to the main leaves, and a length of 6mm rod to align the holes for the centre clamping bolt. Once the leaves are fully compressed the clamping bolt can be tapped in, displacing the 6mm rod and holding the spring together so the clamps can be removed.  A slightly fraught process as the greasy leaves are very slippery but trivial compared with the frightening task of fitting an Aprilia spring.

I then wrapped the springs with Denso waterproof tape which keeps the mud and wet out and refitted them to the car, nor forgetting the red fibre pads between spring and axle and between spring and U bolt plate. The U bolts were slightly spread and needed squeezing in a vice to  match the holes in the plate. They are a very hard grade of steel and I found that I had to re-tighten them several times, presumably as the red fibre pads get compressed. There is no means of locking them on our car, although I see from Karl’s photo that  a second locking nut could be fitted if there were enough thread projecting. Ours would need to be a half nut.

All back together for a test run this afternoon. All seems fine and the car improves each time and goes really well. There is still a small vibration of unidentified origin but I am becoming more and more sure that it is not engine related as it continues even if the clutch is disengaged and the revs allowed to drop. I thought I had found a cause as two of the (Michelin rim) wheels are a bit out of shape so although the whole is balanced, the tyres run slightly  eccentric, but swapping them with the spares which do run true had no effect. I wondered if the fabric U/J at the rear of the propshaft might be off centre but it does not seem to be. My only idea now is that the fabric may distort under load as that disc does look a bit skinny compared with the front one and the bolt holes are a fairly free fit.

Mike
 

[frankxhv773t]

A jar of Vaseline has been a standard part of my tool kit for forty years, if I need any for medical purposes I have to go and find it in the garage! It was always the thing to put on battery terminals and I generally apply it to any electrical connectors in exposed places, horn connections being a typical use.

[Kari]

Always interesting to read of the progress of Mike's car. One of the issues are vibrations of the drive shaft. I did have unpleasant vibrations on my car, which could be repeated when casting down on my favorite stretch of road where I could reach nearly 100 kph with the engine off.

I did replace the hardware store "8" mm bolts by close tolerance 8 mm bolts and that cured the problem. I think the flex couplings are very sensitive to out of alignment, considering the drive shaft turns at engine speed in top gear.

If the original roller bearings at the shackles are still fine, they should be greased now and then. Once it was suggested that removing the nut and filling it with grease before replacing would be a way to lubricate the bearings. When I still used the (hollow) 9 mm bolts, I did cut a tread in the bolt head and installed a grease nipple. Now I have Nylon bushes at the shackles.

The recent breaking of an Augusta crankshaft has prompted me to have my spare crankshaft crack tested, especially as the big-end journals are almost 1 mm less than the original 42 mm.
I'll let you know the findings, I hope none.

Regards   Karl

[Raahauge]

Vibrations. When I rebuilt the car I reused a fibre coupling that was not very good but I was keen to get the to project on the road.
In service it was fine but when I looked at it recently it looked to be deteriorating quite quickly so I decided I had to replace it.
I obtained one and installed it without close examination but it vibrated badly. Upon inspection the bore of the cup was 0.5 larger than the nose on the rear of the gearbox. Some clearance is obviously acceptable but unsurprisingly half a mm is not.
I have made another from conveyor belt using the original fittings and it is very smooth.
Crankshafts. I am gathering information and will start another thread shortly.
 

[Mikenoangelo]

I reckon from what has been said that the fabric disc joint at the back of the propshaft is the problem. The front joint appears to be a period replacement with the trademark CAP. (Photo 117). It is 11mm thick but as you can see (photo 116) is somewhat distorted as if being pulled back by the propshaft. The rear joint is different, with no marking (photo 114) and is only 8mm thick (photo115) and also slightly pulled forwards by the propshaft. The bolts are a poor fit in the disc whereas the bolts for the front disc are a fairly tight fit.

Perhaps the 3mm lesser thickness of the rear disc is causing distortion, and who knows what happens at speed. Can someone confirm the correct thickness of the discs and also has anyone experience of the discs sold by Cavalitto?

I resolved another minor issue today. It surprised me that the water outlet tap by the pump has no provision for a drain pipe to direct draining water through the hole in the chassis side plate, resulting in water running all over the frame side plate and needing bowls and buckets to catch it. I had tapped the underside outlet of the tap when the engine was out, made a brass fitting to connect a thin plastic pipe, but then stupidly forgot to fit it before refitting the tap (it‘s an age thing). Having got the tap and the aluminium elbow fitted and leak free I was reluctant to remove them so had to attack the problem from benath the car. Access is really difficult but with the plastic pipe pushed onto the brass fitting, and guided by a stiffening wire I managed to feed it up through the hole in the side plate and engage the fitting with the thread in the tap.

Finally here (photo 113) is the road spring refitted and wrapped with Denso tape. There is an assisting spring hooked onto the hand brake lever on the back plate to encourage the handbrake to free off. The other end of the assisting spring was hooked to a rather flimsy bracket clamped around the leaves of the suspension spring so I made a 90mm link to allow the assisting spring to be hooked to the clamp holding the main spring leaves in line.

Mike

[Mikenoangelo]

I did wonder whether settling of the rear springs might tend to move the axle back a fraction but the springs are more or less parallel with the chassis in the horizontal plane so any movement would be minimal and. although the rear shackles are inclined rather than vertical, the chassis is absolutely parallel with the ground so I doubt they have settled much. They do seem to have been reset by the traditional blacksmith's hammer whose imprints are visible, however the leaves all follow the same even curve so apart from one leaf which has a sideways curve, the job seems to have been done well.

Mike

[Kari]

The flexible couplings are 11 mm more or less. The rear one looks a bit thin, and depending on the stiffness of the material, can warp like the one on the picture. The trained eye will note that the spider with the centering bush is installed at the wrong position.
It might sound a bit picky, but I think the masses of the bolts, nuts and washers attaching the flex couplings, should be the same at every position. I am not ashamed to use self locking nuts.
The shackles are inclined about 30 to 40 degrees from vertical. The distance between the forward egde of the boot and the centre of the label on the diff is 115 mm on my car.

Regards  Karl

[Mikenoangelo]

Thanks Karl. The material of your dodgy disc looks just like mine, although the plates are slightly different but I suspect they are from the same source. I agree re self locking nuts - particularly as I have run out of the correct thickness split pins. The original bolts are in good condition but are of finer pitch than the readily available 8mm self locking nuts. Two had been replaced with non matching. I will have to change the bolts and somehow organise a new disc.

Mike

[Mikenoangelo]

Good vibrations!

A flash of inspiration hit yesterday - if one or both of the fabric U/Js were defective, swapping them from end to end of the propshaft should produce a change in vibrations and confirm my suspicions.

I think that the joint at the back of the propshaft is more likely to be able to set off vibrations as it is connected to the axle which, as well as bouncing with the springs and twisting with torque effects, is also a much smaller mass than the engine and gearbox and less able to contain vibrations.. The suspect 8mm thin joint was at the back so more crawling underneath today to swap them and a test run today proved the point - I need new fabric joints.

The vibrations are much less than before, seem to start at higher speeds (50 mph upwards)  and quite unrelated to the engine as they continue when coasting. 

I did check the height of the rear end as suggested by Karl and the mesurement was 90mm so my car is 25mm lower at the back than yours Karl. It is level relative to the ground so the back and front match.

Mike

[simonandjuliet]

Sorry to go back half a conversation , but I only came across these today ..... 3 NOS bushes and nuts, if they are of interest to anybody

Plus, I found 2 other bearings that aren't Aprilia, does anyone know if they are Augusta ??

Thanks