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500 (Classic) 1963 'D' resto with 126

Introduction

Hi all, I have learned a huge amount from threads on this site, so now my own resto is underway I thought I should start my own thread. I don't guarantee I can add an insight, but hopefully I can offer some inspiration!

I've never restored a car before, but have done a few old vespas and recently completed a nut and bolt restoration on an old moto guzzi, so am pretty confident I can have fun with this car and hopefully do a good job.

I bought the car in about October last year through an online auction. It was in a different city so I didn't view it first. A friend had a quick look and I took a bit of a leap of faith. I's a 1963 D model, which has had the rear roof unbolted to make it a "Transformable" of sorts. The existing roof just used the standard roof frame and some extra cross bars. You had to fold it back by hand but it worked well enough. The car ran well and I had a blast driving around for 3 months of summer.

It was pretty obvious the car had rust but I ignored this while I had fun. Earlier this year the car failed its warrant of fitness test so it was time to go and see my mate Dan, who's a panel beater, and figure how bad the rust really was. The pics here show some of what was in the sills and floor. The car had a "makeover" in about 1990, and was probably quite god then, but 22 more years on the road and the rust had slowly done its job. Front panel, battery ray, drivers door, floor, inner and outer sills all needed replacing...

Faced with either a full resto or a trip to the dump I decided to save the car. And so the learning curve stated! I'll post up soon with some pics on whee the panel work has got to so far, some details of the fiat 126 donor I found and some of the work I've done on the rest of the car while the panel gets done.

Cheers Roger
Thanks guys. Some of my friends have less flattering ways of referring to my obsession with the small details of my car!
Glad my posts are giving enjoyment.
 
Hi all, well, here's an update of sorts. Panel work is going very slow as my panel beater is only working on the car in his spare time. Meanwhile I can't get on with the engine as pistons, rod, valves etc are on back order. Seems there is a shortage of 695 kits out there (maybe you've inspired too many people Chris!?). 500Ricambi could only offer me the 80mm kit with forged pistons so I bit the bullet and paid the extra 150 euro or so! Should be here in a few weeks.

Meanwhile the panel beater has got the floor in on one side, and I've asked him to reinforce the engine mount towers. A local expert here tells me the extra power of a good engine can cause these to tear away from the body on a D. I wouldn't have thought is possible myself, but my panelbeater readily agreed and showed my a late model BMW in his workshop on which he was about to replace the entire rear sub-frame. Looking underneath you could see how the entire frame had ripped free of the body. If it can happen on a new vehicle I guess it can happen to a 50 year old micro-car!

I've been getting on with a huge number of small jobs, none of which are worthy of photos. But, have also had he engine casings and gearbox/diff casings wet glass blasted (water and glass bead - they call it Vapour Blasting). Creates a nice finish which cleans easily if you get grubby fingers on it while assembling. I've attched a few pics here, including a before/after shot of the gearbox housing. Despite having only 40,000 km on tghe clock my gearbox needed new synchro's and 1st/reverse gear kit. I'm no good with gearboxes and looking at the pic here of all the parts all I can think is "The work of the devil"! Lucky I have a good friend who's a mechanic and not scared of these things!

To cheer myself up and make it feel like I am making progress I have bought a nice Nardi steering wheel and also had my seats recovered. I stripped them down and powdercoated the frames, and the used a standard cover kit and new foam, which I had fitted by a professional upholsterer. They look great.

Oh yeah, and I've also rebuilt two steering boxes (one D and one F), I'll put up a separate post about that as there is a big difference in the seals used on each and someone may oneday find the info useful.

Cheers Roger
 

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OK, a note on steering boxes. This may be pure trainspotting, but as I have never seen this discussed before it may actually be useful to someone someday...

When I bought my car one of the first things I noticed was that the steering box had been leaking for a long time and the box was completely covered it a thick black sludge. Not long afterward a bunch of old 500 steering parts which included 3 steering boxes was listed on a local online auction site. I got the lot for $20. Two of the boxes were covered in gunk like mine, one was clean as a whistle - more on that later...

When I stripped my car I took apart the steering box out and started to strip it. First job was to take off the steering arm. This is on a tapered spline and was a tight fit to say the least. The various manuals don't mention it, but it can be VERY hard to remove. I took mine to an engineer friend who was amazed at how bound up it was. It eventually took a blow torch and a real blacksmith with a real blacksmith's hammer to separte the arm from the spline.

I ordered a new seal kit, stripped the box and after rezincing parts and vibro-polishing the body I went to reassemble. It was only then that I realised the seals in the new kit did not fit the spline layout. Digging out another steering box from my stash it appears that after the D model fiat decided to change the seal. The D has a seal that has a serated rubber section that actually seals against the spline. (photos one and two) This is clearly expensive to make and not that effective. F model boxes change to a standard type seal that seals on the shaft before the spline (photo 3). Other than that the boxes have the same internals (photos 4 and 5).

None of the parts suppliers I know could supply a D type seal, and several seemed to not know they exist. I found a crusty old one in with some parts of a local collector, but if anyone knows where new ones can be found I would be glad to hear from them.

Anyway, I have now rebuilt two boxes, one D and one F. I'll be using the F model version I think as the seal clearly is a lot better.

Now what oil to fill it with? A local mechanic who has worked on these cars for 40 years tells me all the boxes leak. "It's a good sign if it's leaking" he says "At least if it's leaking you know it's got oil in it!" Seems many ran dry in the first years of life and have run a long time since with no oil at all. And the clean one I mentioned earlier? Well when I openned it up it was packed full of thick bearing grease! Seems someone figured at least that wouldn't leak out. Mind you, if it's not packed in properly such thick grease will also form a cavity around moving parts and therefore not lubricate them.

I think the grease idea is OK, but I'll be looking to use a good semi-liquid gearbox grease.

Cheers Roger

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Fiat 500F and 500D steering boxes.JPG
 
At last my engine stuff has arrived. I’d been waiting while the barrel and piston kit was on back order. The valves are now with the engineer who is reworking the head, as are the new barrels so he can overbore the engine case to fit their larger spigot size, so in the meantime I thought I’d share some pics of the pistons and con rods. I bought these from 500 Ricambi and I’m really happy with them. From the crown markings it seems the pistons are made by ‘CP’ – otherwise known as CP Carrillo, which is a good firm. They are considerably shorter than standard pistons, have a stronger mount for the wrist pin and very much thinner rings. The skirts are coated to improve oil retention. The wrist pin is closer to the crown than standard, requiring the use of longer (130mm) conrods.

The rods themselves are also very good quality. At 400 euro they weren’t cheap though! They are not marked but look very well made and could also be by CP Carrillo. They’re “H” beam rods as opposed to the standard “I” beam versions.

All parts are lighter than the originals. A single 126 piston and pin weighs in at 427 grams. The new piston and pin weighs 325 grams. The standard 126 conrod weighs 425 grams. The new one weighs 391 grams. All up it looks like I am saving 16% of the original weight of the piston/pin/rod combination. I only weighed one of each, but I am guessing manufacturing tolerances on these will be pretty close. I’ll find out when it comes time for balancing – as soon as I’ve pulled the plugs from the crank and cleaned it out.

I can’t wait to put this thing together!

Cheers Roger
 

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The great thing about shiny metal though is:- you can't get nicked for viewing pretty young bits of metal--unless the missus catches looking at pictures of it!!:)
 
More automotive porno... I just got my head back from the engineer. It's awesome. I went for 36mm inlet and 29mm exhaust. As you can see from the pic that's as big as you can go without really major work. As it stand's he's had to open up the side of the combustion chamber around the inlet valve so the fuel can flow properly.
He's done a very nice job of blending the valve guides perfectly flush with the port so they don't interfere with gas or fuel flow.
One thing that is hard to see here is that he's used very deep valve seats (about 6mm) and used these to achieve a venturi effect around the inlet valves. This means the port narrows as it approaches the valve seat, creating a restriction, and then opens up again where the valve sits. In practice this will make the head suck more fuel. This will be felt when you first put your foot on the gas, and also when it gets into its sweet spot at higher revs.
The crank etc is now all away being balanced, so hopefully I'll be putting this baby back together soon.
Cheers Roger
 

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haha! So long as it's just the engine Chris. No way do you want to keep up with me on panel work... Some pics below of latest progress. Floor, inner sill and other patches now complete on one side, and have started on the other. We're leaving the work on outer sills and front guards etc until both sides are more metal than rust...
One thing I have done is add brace points underneath the car so it can be lifted in future in a four post hoist. Should make any future maintenance easier. The brackets came readymade and don't cost much.

Cheers Roger
 

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Hi all,

I've just got my crank and flywhel back from being balanced, so thought I'd share my experience of an area that seems to come up in questions often on this and other fiat forums.

The issue with balancing a paralell twin crank is that you cannot simply do a basic rotational balance job. This is because you need to take into account the forces on the crank created by the reciprocating weight of the piston/rods etc. Because these are always on "one side" of the crank, you can't compensate for them fully, so you have to take a percentage of their weight - effectively splitting the difference across the rev range. This percentage is called the "factor of balance". If you know an engine's factor of balance you simply add bob weights of the correct weight to the crank when you balance it. Trouble is, Fiat never published this percentage, so you have to guess.

In my case, the engineer was able to tell me that with standard pistons my crank was balanced from factory at about 37%. Now, that is crazy. Balance factors for parallel twins tend to range from 50% to 80%, so 37% was very low. Allowing for my new, lighter pistons and rods the crabk would have been at about 50%, still low in my opinion. Around 60% is very common, and this is what I have used, based on published data for 650cc parallel twin triumph motorcycle engines which also rev out to about 6000-6500 rpm.

To achieve this the engineer had to add quite a lot of weight to the crank counterweight, which he does by drilling out the steel and replacing with slugs made from a tungsten alloy which weighs 2x steel. Three of these were needed on my crank. Pic 1 shows a close up of one, including the grub screw used to make sure the slug stays in place.

The engineer also balanced the ends of the crank, which meant taking some weight out. That's done my shaving some steel off. (Pic 2) On one end it wasn't possible to take quite enough off without reducing the strength of the crank, so, in an opposite method to that used on the counterweight, the crank steel was drilled out and a lightweight alloy slug was added. (Pic 3).

Oh yeah, and before you do this make sure you"ve cleaned out the sludge trap on the crank, and put a few dabs of weld on the new cover plugs so they don't come out. (Pic 4).

As well as balancing the flywheel with the crank I also chose to lighten the flywheel a little. (pic 5) I can't recall the standard weight, but the new weight is approx 5.8 kilograms. As I recall that's about a 30% reduction over standard. I know there are mixed views over the need for this on a road car, but I felt a mild drop in weight would help the engine rev up a little faster and reduce load on the gearbox when changing gear - both good things in my view. A heavier flywheel obviously helps mask the inherient "lumpiness" of a parallel twin, but with the better crank balancing a mild reduction in flywheel weight should be noticed only for good reasons and not bad... ?!

All that's left to do is to tap into the oil gallery on the engine block to allow the adding of an oil filter/cooler at a later date and I can finally start the engine build. Can't wait!

Cheers Roger
 

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The issue with balancing a paralell twin crank is that you cannot simply do a basic rotational balance job. This is because you need to take into account the forces on the crank created by the reciprocating weight of the piston/rods etc. Because these are always on "one side" of the crank, you can't compensate for them fully, so you have to take a percentage of their weight - effectively splitting the difference across the rev range. This percentage is called the "factor of balance". If you know an engine's factor of balance you simply add bob weights of the correct weight to the crank when you balance it. Trouble is, Fiat never published this percentage, so you have to guess.


So this is why the engineering firm that did mine were constantly mumbling and swearing under their collective breaths. I new it might be tricky, but I didn't think it would be quite this complex.
I hope you kept all of the final specifications somewhere safe.

My engine is still a bit jiggly at idle (~800rpm) but once off idle it's very smooth.

Chris
 
Hi John. The 37% figure was my engineer's best guess at the crank's unmodified factor of balance, estimated using weight of standard pistons, rods, bearings. He shifted that to 60% of the weight of my new pistons, rods, bearings. Figures around this 60% mark are common on similar parallel twin engines, such as triumph motorcycles.
I have no idea what factor of balance fiat were aiming for, it is even possible that they did not use this balance method at all and simply did a rough rotational balance job. I suspect wide manufacturing tolerances mean different engines will show different results from factory. Fiat could get away with poor balance because the engine is in a car, mounted on a big spongy spring, and effectively de-tuned to give robust (if lacklustre) performance at a cheap price. Motorcycle manufacturers though had to do a better balance job as they were most often hard mounting engines in frames and riders were looking for better performance. Poor balance on a motorbike can rattle your fillings out of your teeth! Not to mention destabilising he whole bike at speed.
Cheers Roger
 
Hi all. Slow but steady progress on my panel work continues. Quite a big milestone reached this week though, with the car actually looking like a 500 again after a long time missing a lot of panels. Looks are deceiving in this case however, as the front guards, front panel and outer sills are not actually welded on at this stage, just screwed in place. The floors and inner sills are all done though, along with a lot of smaller work on the lower rear quarters etc. Just some work to do bridging from the rear of the inner front guards/door frame down to the new sills.

I've asked the panel beater to do his best to get nice even door gaps and he's working hard to convince the replacement panels to obey. Once he's happy he will weld on the outer sills while the front guards and panel will be screwed off before the car makes it's first trip to the paint shop where just the inside front will be painted. It may sound over the top, but I want to get good paint inside the front of the car - outside of the inner guards, into all the seams etc - and that can only be done with the outer front guards and panel off. No-one will ever see it, but I'll know it is there, and I won't worry about damp getting into unprotected inner seams etc. (The front panel you see here is late 'F' model, it's not the one I'll be using, but was the one to hand when the panel beater was looking to get on with this part of the job).

If I've got the new steering rack brackets fitted by then then the car will also get seam sealant along all the under floor seams and welds and a coat of textured stone chip seal across the whole bottom. I've been doing a lot of measuring for the steering rack conversion. It seems straightforward enough. I hope to be able to post some pics of this in the early new year.

Engine-wise I've stalled a bit while I investigate oil coolers, but have got the gearbox back together and will do the differential and axles etc later this week.

Oh, and I've got the alternator back from the auto electrician. I stripped and cleaned it all up and he checked it over and added new bearings. I like getting all these little sub-assemblies sorted because I know each one means the car will go back together so much faster once the panel and paint is done.

Currently also searching out good tyres for my nice new campanolo rims.

Cheers Roger
 

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Hi all, Over the past few weeks I've been making steady progress with a number of small jobs which aren't really that interesting to post about here. Today though was a bit of a breakthrough. I had a full half day with the panel beater and as well as making up some new curved pieces to join the new sills to the front of the door frame we were able to install the brackets for the 126 steering rack, cut the hole in the firewall for the pinion and mount the rack in place. Pretty damn happy I can tell you! Tomorrow I'll be looking at how to cut the old steering column and match it up with the 126 lower column. The 126 pinion is not in a straight line from the wheel like the steering box used to be, so you need to use the 126 lower column which uses two universal joints to make a "dog leg" in the column.

I used the brackets from the donor car. It was a bit of a mission for the panel beater to salvage them, but as they cost something like 80 euros each to buy new I think the time was worth it.

Cheers Roger
 

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