Author Topic: Augusta progress (Read 131277 times)

GG · « **Reply #255 on:** 02 May, 2021, 12:38:39 PM »

In general, you are right. One thought tho - in the Aurelia (particularly the earlier smaller shafts), the ends of the machined splined fittings are held in the tubes. Over time, there is a slight "tweaking" that happens (from torque) and they get slightly cocked off axis. Its not noticeable until you get a full drive shaft on a bench, and see the out-of-alignment over the entire length. The guy who balanced them (a marine driveshaft specialist with interest in the similar GTV6 shafts on Alfas) sweated the connections, and realigned them... that plus careful fitting of the alum paddles (also can get out of perfect alignment) reduced the alignment issues to very small levels, and thus the balancing requirements were extremely modest. Too often people use balancing to correct for problems that stem from alignment.

I don't know if any of this is relevant for the Augusta, but it might be - at the ends of the main shaft. Although it looks rather robust, and the forces aren't so great.

Mikenoangelo · « **Reply #256 on:** 02 May, 2021, 04:53:16 PM »

More fiddling around showed that the jubilee clip alone is too much of an imbalance to counteract the balance weights fitted so I was able to dispense with the second jubilee clip and just use one with a piece of lead at 180 degrees to reduce the effect of the clip. With this I was able to make the shaft roll evenly on the knife edges This made little difference to the remaining slight vibration. I then turned the propshaft end for end, thinking that perhaps the engine and gearbox might be a greater transmitter of propshaft imbalance than the axle, the jubilee clip and weights are now at the axle end. Again some improvement such that vibration is now rarely noticed, mainly with a light throttle on a downhill stretch at 3000 rpm plus.

Karl your observations make sense as usual, however I have checked the propshaft very carefully and it is straight and when turned by hand in place on the car there is no more than 0.5mm measurable eccentricity in the middle or at either end. Your thoughts on the fabric discs are very logical. I have to say that there was only a small improvement when new discs were fitted although one of the old discs was in poor condition and the new discs, which were made to Morris Parry’s dimensions are very accurate and fitted perfectly to the driving spider couplings using real 8mm bolts not the 7.8mm ones which are usually supplied.

Certainly the diameter and the mass of the discs makes them suspect even if they appear to run true so I will have a go at them, sandwiching the disc between the two centering spiders even if, dammit, that means taking the propshaft off for the umpteenth time!

In fact the car is very driveable now and the vibration only happened a couple of times today on a 40km run. In fact it is as you know completely brilliant fun on a winding road and puts a big smile on my face

Yesterday the oil pressure seemed a bit low but cleaning the pressure regulating valve resolved that.

Mike

Charles · « **Reply #257 on:** 03 May, 2021, 10:05:19 AM »

It must be true that my propshaft was balanced by the factory and there is no reason to believe that it could have become "unbalanced". I think that it maybe slightly bent, it does have a little dent in it near the middle, also when I bought the car the centralising spider was missing at the gearbox end and the shaft was only held to the coupling by one bolt (Morris Parry very kindly supplied a new spider). Over the weekend I removed the shaft and "trued up" one of the tripod arms which fitting close tolerance bolts had revealed was not a perfect match with the centralising spider - probably because that was the one that had been bolted up when I got it. The photo shows the secondary gearbox mounting that I fitted. So then I rolled the shaft on knife edges and added a jubilee clip to neutralise what appeared to be a bit of out of balance. Having reinstalled it, the vibration was worse which didn't really surprise me as I hadn't been very scientific. So I have removed it for now while I ponder taking it to a specialist. Driving the car is quite pleasant, especially in 3rd and 4th so long as I don't try to go over 45mph whereupon the vibration suddenly cuts in and then persists until I slow down to about 35mph when is disappears again. Perhaps it's a special mod to stop speeding!

Mikenoangelo · « **Reply #258 on:** 05 May, 2021, 08:14:58 PM »

Another day of tweaking propshaft issues yesterday!

I checked the gearbox output shaft and the pinion shaft spigots on the which the centering spiders of the propshaft run - they both run true.

I tested the balance of the Hardy discs by fitting centering spiders to both sides of a disc and then rolling it on the knife edges. I must congratulate the supplier of the discs which were not only dimensionally very correct but very close to being perfectly balanced so no problem there. The discs weigh 490gms and needed no more than 2-3 gms added to one of the bolts to make them roll evenly. To give you an idea how small this is, an 8mm washer weighs about 2 gms.

I retested the propshaft with the discs fitted but they still were a little bit off balance whether they rolled on the bosses of the centering spiders or on the tube itself.

I then turned to the bolts, 10 of which are original with castle nut and split pin and two non original with self-locking nuts (these were mounted opposite to one another so should have been in balance). It turned out that the original bolts weigh 22gms and the castle nut 8 gms, a total of 30gms. The spurious bolts weighed 24 gms and 26 gms apiece including the nut - these are 7.8mm diameter and 1.25 mm pitch rather than the correct precise 8mm and 1mm pitch of the original bolts, the lighter of the two spurious bolts also has a 13mm head rather than 14mm. I added two washers to one of the miscreants and three to the other and put them opposite to one another on the disc. The whole propshaft with discs would now roll pretty uniformly on the knife edges, whether riding on the tube of the shaft or on the bosses of the centering spiders. This also confirms that the centering spiders are in true alignment with the rest of the shaft

I was a little sceptical as to whether such small variation matters, but nevertheless put it back on the car and this morning in brilliant sunshine had a test run. Amazingly even such a small balance correction on the bolts does have an effect as the vibration is now hardly noticeable just around 3100 rpm but then fading away up to my personal 3500 rpm limit. I’ll machine two new bolts to the proper size and weight, starting with a standard 10mm bolt, and leaving the head a bit deep so I can make a final weight adjustment. Too cold in the garage this evening and it's snowing!

I still find it hard to believe such a small weight difference could make a difference, but it evidently does.

This leads me on to a more general question - why is it that Lancias seem so sensitive to a slight imbalance which by all accounts is not confined to Augustas?

Kari · « **Reply #259 on:** 06 May, 2021, 08:49:21 AM »

Brilliant! I think we should nominate Mike for the "Golden Drive Shaft Award".

The findings of Mike confirm that small amouts of mass at the wrong place can upset balance.

Yesterday I jacked up the car at the rear and run the the drive train up to 4000 rpm. All was fine, no undue vibrations noted. Then I have removed the drive shaft and the flex couplings.

I installed the couplings on a spare spider and together with a spare output shaft installed it in a handheld electric drill. There were no vibrations up to 2900 rpm. So far so good.

I have bought the flex couplings in Italy early this year, and when they arrived, I noticed that they are made from very stiff material, much more stiff than those I have been using before. They are stiff enough that the disk supports the drive shaft with little deflection as in the photo. Now my concern is, that the stiff material imposes exessive loads onto the arms of the spiders and bending loads onto the dive shaft at every turn of the shaft, leading to metal fatigue. For the time being I will install my old couplings.

Most probably there is no specification avaliable, but I would be interested in a possibility to compare the materials.
And I am open to any info where to get flex couplings in the UK.
May I send a PM, Mike?

Karl

Mikenoangelo · « **Reply #260 on:** 06 May, 2021, 10:54:45 AM »

Karl I have sent you an email with the details of the suppliers of the fabric discs but here they are in case anyone else is interested.

http://www.gmspolymer.co.uk/flexible-couplings.htm

I am very please with the discs they supplied.

Charles · « **Reply #261 on:** 06 May, 2021, 07:27:30 PM »

Very encouraging news about the balancing - I will renew my efforts. I got the Blockleys fitted - no trouble - and they don't rub on the sliding pillars - phew!

Mikenoangelo · « **Reply #262 on:** 07 May, 2021, 01:27:01 PM »

Just curious - does anyone know why Augustas so often carry two spare wheels? It seems odd when the car was otherwise designed to save weight.
Mike

Mikenoangelo · « **Reply #263 on:** 10 May, 2021, 08:25:47 PM »

She thinks I’m a nut case - I wonder why?

It’s a fiddly job making nuts and bolts but as all but two of the original propshaft joint bolts and nuts are present and correct (meaning a true 8mm with 1mm pitch and 14mm heads) I thought it worth the effort. In any case, they could not be bought, even 8mm x 1mm all metal self locking nuts are hard to find and the 14mm hexagon is obsolete.

The bolts were machined from stock 12mm bolts, milling the flats and cutting the split pin slots worked out well with the milling machine and dividing head. The nuts were milled to 14mm hexagon from a 20mm round bar.

Mike

Kari · « **Reply #264 on:** 11 May, 2021, 04:36:31 PM »

Augusta spare wheels: I think that was one of few options when ordering an Augusta, besides exterior paint colour and upholstery colour. At that time many cars had 2 spare wheels, probably the quality of the tyres was less than to-day and there were still many horses around, loosing their irons and nails. Dirt roads too.

I was wondering how my car would look with one spare wheel, so I made a short attachment to find out. I think it looks a bit stubby with one spare wheel....

The difference in weight is about 17 kg, which is about 2% of the empty weight.

Regards Karl

brian · « **Reply #265 on:** 11 May, 2021, 06:46:33 PM »

I hate - and am somewhat frightened - to disagree with Karl on anything to do with Augustas but I like the less heavy look of the single spare wheel. I agree modern tyres are probably miles better than in the 30s so it seems rather silly to carry 2 spares! I have luckily never had a puncture on the Augusta. Now there is temping fate!!

Kari · « **Reply #266 on:** 12 May, 2021, 08:39:19 AM »

No worries Brian, your opinion is accepted! It's for the looks. My car always had 2 spares. And I did have punctures. Decades back, in my juvenile ignorance, I have fitted 2 imperial size tyres onto the metric rims, which within a short time, slipped on the rims, shearing off the valve stems of the inner tubes in the progress. With spectacular flats within seconds.
Karl

DavidLaver · « **Reply #267 on:** 14 May, 2021, 01:32:34 PM »

I wonder if two spare wheels is like having two water bottles on a peddle bike?

Mikenoangelo · « **Reply #268 on:** 14 May, 2021, 02:46:00 PM »

Just don't ask me to wear Lycra
Mike

Mikenoangelo · « **Reply #269 on:** 15 May, 2021, 07:50:13 PM »

A final (hopefully) tweak to the propshaft balance. Continuing from my previous knife edge balancing method I felt an improvement could be made if I made a pair of short stubs of 1 inch steel which could be machined down a few thou to give a tight fit into the middle of the centring spiders. This would allow the propshaft to be rolled on the knife edges with a very accurate simulation of the shaft in place on the gearbox output and axle input shafts.
With the discs in place, attached with the now equal weight bolts, nuts and washers and the stubs in the centring spiders, I made a small adjustment to the jubilee clip such that the shaft would roll evenly. I still noted the tendency of the shaft to stop with two of the attachment arms down and one up, but this seems inevitable with an odd number of arms but it would stop with any pair of arms down. Back on the car it now feels even better and runs happily up to 3500rpm in top without vibrating. So success - eventually!

So now on with some minor jobs including sorting out the driver’s door latch. On the Augusta when you open the door a tiny spring loaded sliding stop moves into place to hold the tongue of the latch in the retracted position. When the door is closed the sliding stop is pushed across releasing the tongue to latch the door. This is obviously safer than giving the tongue a radiused face as per a household door but is a bit complicated. On our car the small bowed spring had broken, requiring the door handle to be held down when closing the door which was definitely a handicap when the owner boastfully tried to show off how the doors close with one finger!

To make a new spring I used a strip of steel cut from a length of pallet strapping band. This, as it comes, can be cut with tin snips and bent to shape. Being spring steel at a low level of hardness, it can be made into a proper spring by heating red hot and dropping it into water. It cools very quickly in the air and must still be red hot as it hits the water. It feels properly springy with no need for further tempering. The most fiddly job is to refit the catch to the door without dropping any bits.

More thoughts on the two spare wheels. I'd like to see how it looks with one spare so had a look at the mounting on the boot lid to see whether it is adaptable but could not see any way of doing this. I have seen a picture of an Augusta with the mount reversed although such an arrangement compromises the boot space. Does anyone know about this?

Mike