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Author Topic: Augusta progress  (Read 7876 times)
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Mikenoangelo
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Posts: 195


« Reply #90 on: 13 July, 2020, 08:47:51 PM »

I take no credit for the design of the adapter which I think originated in Australia, and as I said I made mine from drawings by Dale Hicks. It does make a neat job and with that spin off filter which is only 50mm deep, fits into the space previously occupied by the Autoclean filter leaving enough clearance to the front structure of the car to allow the canister to be easily replaced, although I imagine a bit of an oil slick will be released. The filter is used on many cars, particularly Renault and its derivatives like Dacia. The version W75/3 from Mann has a 20mm x 1.5 mm thread for which I fortunately had the correct die. The W75 version has a similar size but Imperial thread and is used on other makes.

Today I looked at the idler sprocket which adjusts the tension of the camshaft drive chain. The sprocket is sprung loaded and rides on a spigot in the timing case at the front of the block - guess what? The spigot shaft was worn which creates an extra means of escape for the oil which is supposed to be going up to the camshaft and rockers. The spigot is made integral with its supporting bush but that can be bored out to remove the old spigot and a new one machined to fit - done today, and the spigot is in the freezer overnight ready to press into the bush tomorrow.

I've also fitted the cylinder head using Blue Hylomar on the gasket an both faces and then torquing the nuts to the studs. The studs are 12mm and will take more torque than is needed, although I was surprised how much pulling on my 10inch  torque wrench is needed to get to 62lbs/ft (85N/m). I tightend the bolts in 5N/m stages and have got up to 52 Lbs/ft and will leave it at that for now and do the last tweak when I'm ready to start the engine.

I made a discovery today when looking at the block. Within the timing case there are two small lugs obviously intended to carry something which was not present on my car. The parts book does show a small curved widget but what is it for? Turns out from the Italian part number lists that it is a support to hang the camshaft sprocket on when the cyliinder head is removed. i just used a bit of wire!


Mike
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Mikenoangelo
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Posts: 195


« Reply #91 on: 15 July, 2020, 09:04:35 PM »

I finished the timing chain tensioning sprocket mounting and am ready to fit the chain and set the valve timing. One question - is there a recommended way of adjusting the spring loading on the tensioning sprocket? It can rotate eccentrically on its mounting, restrained by a helical spring which is adjusted by rotating the mounting on the three studs which hold it to the block. I assume it is just set to the tightest position, relying on the natural tension of the spring, unless anybody knows different.

The gearbox input shaft returned today - late but beautifully done and fitted perfectly.

I'm now battling with the dreaded freewheel. The usual advice is to put a zip tie around the 9 little rollers to keep them in place as it is assembled - does not work easily as they are spring loaded up the ramp cam and so expand to a greater diameter than the bore of the drum in which they work.  All of this goes on inside the back compartment of the gearbox while trying to hold the outer splined engaging/disengaging sleeve out of the way and pushing the  tailshaft and driven drum in through the back of the box and then sliding the engaging sleeve over the outside of the drum. The fit of the engaging sleeve is very tight on the drum too. Just wishing for a nice simple Bugatti to work on!! Oh and yes I forgot - the three rollers in each set of three are of three diameters and have to be in the right order.

I imagine Lancia must have had some form of clamp to hold the rollers so tomorrow's challenge will be to re-invent it.

Mike
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Kari
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« Reply #92 on: 16 July, 2020, 04:04:03 PM »

For installing the free wheel rollers I have been using strong rubber bands or a hose clamp.

I have never seen an instruction as how tight the chain tensioner must be adjusted. From memory I have been turning it about 1/4 turn or a bit more. Perhaps other Augusta boys out there know better?

Regards   Karl



* IMG_0310a.jpg (265.1 KB, 1128x752 - viewed 41 times.)
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Mikenoangelo
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Posts: 195


« Reply #93 on: 16 July, 2020, 09:08:55 PM »

Success with the rollers - a friend loaned a cable tie tightening tool which made it possible to progressively tighten the ties with one hand while using a screwdriver to compress the springs and guide the rollers to the lower part of the cam.

The next problem Karl is one you will recognise - as I mentioned some time ago the driving dogs on the output shaft were a bit tapered, which I was able to correct. There seemed to be no sign of overheating. although the selector fork needed building up. However the sliding splined sleeve which engages and disengages the free wheel was tight on the output shaft makng it impossible to assemble, a very fiddly job at the best of times. The sequence is to fit the freewheel unit to the tailshaft of the main gearbox (this is within a second compartment at the back of the gearbox), offer the sliding sleeve down through the top of the gearbox, push the output shaft in through the back of the box, slide the sleeve onto the output shaft then push the shaft fully forward onto the rollers and lastly heat the casing and press the back ballrace onto the output shaft and into the casing. If the sliding sleeve is tight, the task is impossible!

It seems that the sliding sleeve is slightly distorted oval by about 0.04mm (1.5 thou), just enough to be a problem. The previous owner had commented that the Augusta freewheel was a problem and it was locked out of action when I bought the car - perhaps this is why. So as the point of contact between the sliding sleeve and the output shaft is the peak of the splines inside the sleeve I plan to just grind away the very minimum to allow free sliding rather than risk trying to de-ovalise the whole unit in the vice! Although not obvious at a glance I could just see some signs of blueing of the bore of the sleeve so the distortion must have been caused by overheating due to friction in the selector fork.

Mike
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Mikenoangelo
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Posts: 195


« Reply #94 on: 10 August, 2020, 09:05:07 PM »

Augusta freewheel thoughts and ideas.

Iíve spent much time on the Augustaís freewheel which has delayed putting the gearbox back together but the subject is interesting enough to merit a detailed discussion so here goes!

I had thought all along that  using the  freewheel was probably not a good idea when driving an old car in current traffic, particularly on the hills around here. Discussions with fellow Augusta owners confirm that few of them use the freewheel and that some even disconnect the Bowden cable and wire the actuating lever in the permanent drive position, as had been done to our car. The previous owner in Italy had commented on YouTube that the freewheel can cause problems, so I expected the worst and never even tried the freewheel on the road, expecting to leave it disabled.

The freewheel is very similar to that used on Rovers from the 1930ís to the 50ís, with a three lobed driven cam which expands three sets of rollers outwards with a wedging action into a surrounding drum which takes the drive to the output shaft of the gearbox. When driving the rollers expand, assisted by a spring, but on the over-run they are rolled back down the cam allowing the drum to turn faster than the input shaft. A sliding internally splined sleeve, permanently engaged with six teeth on the outside of the driven drum is moved forward by a gear selector fork to engage with a six toothed dog on the input shaft, giving permanent drive, or backward, out of engagement with the input dogs to activate the freewheel. All the parts are superbly machined and surprisingly small and delicate, the drum being only 50mm bore and the rollers approximately 7.5, 8.0 and 8.5mm diameter and 20 mm long. At the front of the unit, running within the drum, and on a short length of 32mm diameter shaft between the front driving dog and the cam, is a set of three rollers 9mm diameter and 6mm wide, which act as the front bearing of the output shaft. These are static relative to both shaft and drum when the freewheel is locked, but rotate when the car is freewheeling.

Lots of wear was evident, both cam and the bore of the drum had axial ridges where the rollers took the drive and the rollers themselves had flats. The brass cage surrounding the rollers was quite worn where the ends of the rollers impacted the cage and it looked as though the rollers were trying to adopt a skewed angle to the cam rather than lying parallel. The 7.5 and 8mm rollers had at least two flats each whereas the largest 8.5 mm rollers had none. One obvious cause of the wear was that the bolt which holds the roller cage against the cam had sheared off, and lay loose inside the drum of the freewheel. This bolt is famously known to be a weak feature as despite the 12mm thread size, it has a 27mm hexagon which encourages  over tightening.

I think that Lancia  intended that the freewheel mode would be the normal way of driving as the freewheel selector is spring loaded towards the freewheel mode and is pulled into lockup mode by the cable. The three rollers which carry the front of the freewheel drum are I suspect too few and too small for the job they are expected to do when in lockup.   This may not have been a problem when the free wheel was mostly engaged as the rollers turn and even up any wear. However if always driven in lockup mode the rollers may develop flats, eventually allowing the drum and the front end of the output shaft a small degree of wobble. Permanently locking the free wheel by disabling the actuating cable must be a bad idea and even if the owner has no interest in using the freewheel it should at least be allowed to work once per trip so as to rotate the bearing and discourage flatting of the rollers.

Driving constantly in the lockup mode also takes its toll on the driving dog teeth at the input end of the freewheel which, as we know tend to become tapered, putting a load on the selector fork, assisted by the coil spring trying to disengage the dog from the sliding sleeve and only restrained by the Bowden cable. My freewheel had suffered this and showed signs of overheating due to pressure of the sliding sleeve on the arms of the selector fork.

Having seen all this I decided that, rather than relying on disabling the freewheel and ignoring its worn out state, or going to significant expense and hassle to regrind the worn surfaces and replace the rollers for  a freewheel I did not wish to use, I would eliminate it altogether.

This turned out to be quite simple as an idea but needed accurate machining of a split collar to clamp onto the input shaft between the driving dog and the cam to act as a supporting bush for the front end of the driven drum in place of the three small rollers. Since the bush does not rotate relative to either drum or input shaft it can be a tight fit on the shaft and a push fit in the drum, just loose enough that the drum can be slid over the bush during  assembly. The brass cage with the freewheel rollers was removed and replaced with a washer drilled to take the locating peg on the end of the cam and for the tag washer for the cam retaining bolt. This all worked out well and there is now no detectable slop between input and  output shafts and it all rotates freely and true.

I was concerned about the lubrication of the driving dog and the splined sleeve which is achieved by oil flowing through the shaft between the main gearbox and the freewheel and emerging from holes in the splines to escape through the front (three roller) bearing into the drum and out to the driving dogs. To allow this to continue I grooved the bore of the new bush and its front face and also machined an annular groove in the bore in line with the holes in the splined shaft to help spread the oil.

Following a suggestion by Karl Sšnger, an idea which originated with Kees Jan Boosman, I reversed the sliding engagement sleeve. This increases the area of engagement between the splines of the sleeve and the driving dog. In the normal orientation of the sleeve, alternate splines at the front are cut away to facilitate the lining up of dog teeth and splines as lockup is engaged. As mentioned earlier, the splined sleeve was a tight fit on the outside of the driven drum and needed a very small amount grinding from the peaks of the splines, done with air powered grinding wheel mounted on the toolpost of the lathe. The selector fork has to be reversed to suit the repositioned sleeve and this involved drilling a new hole in the selector shaft for the locking screw of the selector fork to locate the fork in its new position. The hardened shaft cannot be drilled with a normal High Speed Steel drill bit but a carbide slot mill worked well. I also replaced the helical spring on the selector shaft with spacer sleeves to front and rear to keep the selector and sleeve in position, taking care to preserve a 3mm gap between the forward face of the driving dog and the dividing partition in the centre of the gearbox. This is a point at which wear can occur if the freewheel Bowden cable is too tightly adjusted. With the 3mm gap, the splined sleeve engages fully with the driving dog teeth, even allowing for some wear between selector fork and sleeve. Finally I removed the freewheel operating lever and blanked off its bearing in the side of the gearbox.

With all new bearings in the gearbox, reconditioned spigot bearings and the removal of the freewheel, the gearbox feels very smooth and free turning, although no doubt first and second gear will still growl away as before. Weíll see once I get the car back on the road.

Iíll add some pictures shortly Ė Iíve been a bit held up recently as the lawnmower and sundry gardening kit were given notice to quit their habitat in the potting shed which is now required for its proper function by the chief gardener. Iíve had to build a new shed as such mundane functional kit is not allowed to invade the car department!!

Mike
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Raahauge
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« Reply #95 on: 11 August, 2020, 08:37:14 PM »

Mike,
Many thanks for all your posts and for this most interesting and detailed obsevation on the free-wheel.
I just resolved not to use mine believing that it would be reliable if not used, it seems I should worry a little.
Mike

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Mikenoangelo
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Posts: 195


« Reply #96 on: 11 August, 2020, 09:24:48 PM »

Mike - I'm just doing what seems to make sense from info from real Augustinians - before you tear yours apart to make the same changes I'd wait to see how mine works!!

Making the split collar was interesting - I started with a disc oversize on diameter and small in bore, sawed it in two, milled both sawn faces flat and drilled, threaded and countersunk for 4mm screws with heads reduced to 5mm. The two haves were bolted together and 4 holes made so that the unit could be attached to a disc to be held in the lathe and finally machined to size. The O/D was easy enough as the driven drum of the freewheel could be tried for size with the workpiece still in the lathe. the bore was more challenging as being smaller in diameter than the cam the size could only be determined by calipers etc.

Here are some pictures.

Mike


« Last Edit: 11 August, 2020, 09:26:50 PM by Mikenoangelo » Logged
Mikenoangelo
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Posts: 195


« Reply #97 on: 12 August, 2020, 08:34:27 PM »

Back to the engine.

Timing the valve gear is a fiddly process even with the engine on the bench - it must be a real pain when in the car.

I found that there had been a bodge when some previous fettler had failed to make the massive spring washer (which retains the cam wheel bolt and vernier adjustment washer to the end of the camshaft) seat properly as the bolt was tightened. In desperation the spring had been hammered and the washer distorted so a little remachining was needed. The recess at the camshaft side of the camwheel needed a few thou skimmed off to sit square on the end of the camshaft and the spring washer, an ugly very strong object, needed the ends of the coil ground to the right radius so it would fit into the recess in the vernier washer. The locating peg which does the vernier setting would not go far enough into the blind holes in the adjusting washer so the washer could not sit flat on the face of the cam wheel.

Anyway all came right with a little machining and after a few attempts I was able to get the timing right. I found the circlip which holds the vernier washer to the bolt is a pest as it prevented me from rotating the washer to align the peg while trying to engage the bolt with the thread in the end of the camshaft so I omitted the circlip - just needing a bit more care not to drop the vernier washer down into the timing case.

I've set the timing chain tensioner rotated by two bolt holes from the the neutral point of the spring. This feels about right and the free movement of the chain is about 8mm at the midpoint of the chain, observing this through the front timing cover. If anyone knows different I'd like to hear!

Mike
« Last Edit: 13 August, 2020, 08:15:18 AM by Mikenoangelo » Logged
Raahauge
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« Reply #98 on: 13 August, 2020, 08:46:47 PM »

Thanks, the questions for me perhaps are, what symptoms might present if it is about to fail, what will happen if it fails and will it do any damage beyond the freewheel mechanism?
Re cam chain tension, I think I initially set mine to much the same but have just tightened it up another couple of holes as I could hear it. Now cured.
The most irritating current noise is the door latch rods rattling, I have wrapped the rods on two of the doors but not had a chance use it since.  There must have been some felt or something when new though no evidence of any.
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Mikenoangelo
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Posts: 195


« Reply #99 on: 14 August, 2020, 08:56:02 AM »

I can't say what the symptoms of worn out freewheel are although no doubt wear in the three small rollers at the front of the unit will allow a certain amount of wobble at the end of the gearbox output - I could detect that when disconnecting the propshaft. If you recall I started this saga in search of the cause of annoying vibrations which seemed more speed related than RPM related. Of course I found more than one ( the lopsided clutvh spring being the main suspect) and am resolving all I find, hoping that when it is back together I don't have to go through it again to get the engine balanced! So my experiment is a lousy one having changed more than one variable. Reminds me of an academic I once knew who spoke of testing shampoo on one side of his hair and soap on the other - result - went bald in the middle!

Mike

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Raahauge
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« Reply #100 on: 14 August, 2020, 09:04:08 PM »

They say that there is "No advice like the advice you want"  I am reassured by your comments.
I changed the fibre coupling at the gearbox end last week and there was no detectable play in the output shaft.
On another matter I am working on a casting for the tank mounted petrol gauge mechanism. Progress is a bit slow but do you want one when available and is anyone else interested? 
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Mikenoangelo
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Posts: 195


« Reply #101 on: 15 August, 2020, 08:14:50 AM »

Tank casting - yes please Mike. I started on that but other more urgent problem arose!!
My new clutch spring turned out to be slightly too deep when fully compressed so had to go back to be ground down - only 5mm off the length but as the clutch travel is little more than that, the clutch could not be disengaged. Now I find it is about 1mm too small at one end to fit onto the clutch centre - today's task is to grind that out - interesting problem to grind a wobbly spring but I think I have a method.

Mike
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Mikenoangelo
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Posts: 195


« Reply #102 on: 15 August, 2020, 08:19:38 PM »

Yes I did. Made a block of ply sandwiched together with a central hole into which the spring is a good fit then set the job up in the lathe with the die grinder to take a smidgen off the bore at one end of the spring. Turned out that it was just the last coil which was slightly undersize.

Finally the spring is a good fit onto the boss of the clutch plate - just tight enough to hold in place - and fits nicely around the inner lip of the clutch cover plate. The spring is now true enough that with the spring uncompressed, the three corners of the cover plate are equidistant from the flywheel face to within 2mm.

If the previously fitted distorted spring was the cause of the elusive vibration, the new one should solve that issue. I'm hopeful that this will be the case as the vibration definately related to the clutch as a quick jab of the clutch pedal would temporarily reduce vibration.

Mike


* 83a.Trueing up the spring.jpg (150.75 KB, 640x480 - viewed 90 times.)

* 84. Spring should fit snugly on the clutch centre.jpg (108.81 KB, 640x480 - viewed 91 times.)

* 85. Against the rivets like this.jpg (121.19 KB, 640x480 - viewed 89 times.)

* 86. Also needs to fitinto the (flimsy!) clutch cover plale.jpg (117.5 KB, 640x480 - viewed 88 times.)
« Last Edit: 15 August, 2020, 08:21:44 PM by Mikenoangelo » Logged
DavidLaver
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« Reply #103 on: 16 August, 2020, 01:38:55 PM »


Love the block of ply and die grinder photo. 

My brother in law wouldn't let either into the same room as his lathe.
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David Laver, Lewisham.
Mikenoangelo
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Posts: 195


« Reply #104 on: 16 August, 2020, 03:43:35 PM »

His is probably less than 60 years old - I give mine a good clean up afterwards but it has to do whatever is needed including wood - just make sure sawdust doesn't get into the suds pump.

Mike
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