Technical Which flywheel?

[SPA]

Hi
The ring gear is shot on the flywheel for our 650 engine. I am planning to get a new flywheel rather than just the ring-gear. According to Axel Gerstl website there is one spec for the 600 and another for the 650. The one fitted to our 650 compares to the images of the 600.
Are these interchangeable? I have read elsewhere about the pro's and cons of different weights; that all makes sense. The one fitted to ours weighs 5.4kg which from a separate thread suggests it might actually be a 500 flywheel?
All opinions valued...!

 

[fiat500]

https://www.fiatforum.com/500-classic/441161-flywheel-weight-s.html?p=4188640

 

[the hobbler]

At 5.4kg your flywheel most probably IS a 500 item---they weigh in at about 5.3kg----a standard '126' weighs 7.3kg. The 500 flywheel will bolt straight onto a 126 engine, BUT it does not stand away from the engine as much as the 126 flywheel does, so is further from the starter. The result is that the starter will occasionally 'miss'. I know this because I fitted a standard 500 flywheel onto my tuned 126 engine and that is what I suffer. When it does happen, I just let the starter settle and then try again---very occasionally it will require 2 or 3 attempts. In the light of that experience, one of my 'over-the-winter' jobs was to change the flywheel for a lightened 126 flywheel--my new flywheel has been lightened to 4.5kg. This is the lightest flywheel weight that I think is sensible for road use; you need a bit of weight to help smooth out the engine.

 

[gordinir8]

The result is that the starter will occasionally 'miss'. I know this because I fitted a standard 500 flywheel onto my tuned 126 engine and that is what I suffer.

In my 126/500 flywheel combo as per Tom's suggestion when i was setting up my engine, starter miss happens very rarely. All i want to say is that i recommend the 500 installation f/w on a 126 engine although just the half of starter gear engages. I remember that i mιχ components from 3 starters in order to make it work properly but i don't remember what parts exactly. Tom please remember to post some pics from your flywheel when you do the mod.

 

[fiat500]

All i want to say is that i recommend the 500 installation f/w on a 126 engine although just the half of starter gear engages.

...just like the gearbox where one of thes staright-cut cogs only partlially aligns and jumps out of first gear when worn past a certain amount.

 

[Bigvtwin996]

.................................................. All i want to say is that i recommend the 500 installation f/w on a 126 engine although just the half of starter gear engages. ...............................................

I have seen many alternative engine swaps.. say a Ford engine onto a VW beetle gearbox etc...
I'd swear I have seen situations where a spacer is placed between the flywheel and crank... ) obviously longer bolts too (they may have had a couple of extra location dowels....

whilst not desirable these such conversions were chucking out well more than a Fiat lump.......

A possibility??

 

[F123C]

^^^ Or you could heat the flywheel ring gear and reposition it so that more of the starter motor pinion engages. If you're worried about the ring gear coming loose, just run a couple of tack welds to lock it to the flywheel.

Depending on the workshop facilities available, you could remove some metal from either/both the starter motor mounting flange and the area of the bellhousing where the starter motor fits - this would move the starter motor pinion closer to the flywheel.

Alternatively, you could remove some material from the bellhousing face where it attaches to the engine, but there can be consequences for clutch adjustment/operation, clearance for the gearbox input shaft in the crankshaft spigot shaft bush etc.

Fitting a spacer between the flywheel and crankshaft is certainly theoretically possible but it will also shift the position of the clutch in relation to the clutch release bearing/fork and may cause an issue.
And if you use such a spacer, best hope and pray that the flywheel doesn't become detached - I've only seen one flywheel do so (on an engine being run without a gearbox attached) and the distance travelled and the damage done by the errant flywheel was incredible.
On some types of front engine/rear wheel drive race cars in the U.S., they used to fit a heavy steel cage around the bellhousing in case the flywheel came off or disintegrated. (the flywheel would be in line with the driver's feet/lower legs.....)

Best/easiest solution is probably to do as 'gordinir8' (post #4 ) suggests i.e. mix and match components from different starter motors to achieve better meshing of the pinion gear with the flywheel ring gear.

Al.

 

[fiat500]

Anyone know? Is the 594 flywheel different from the other two?

 

[SPA]

Ok.. Interesting replies! I have never noticed the starter not engaging on the first attempt; however the starter teeth are very much worn only half way along. I now understand what's probably causing this. I don't yet understand how to fix but I will take a good look. Be prepared for me coming back on this thread!

 

[the hobbler]

May I suggest that you (a) you check that the starter bendix is able to fully extend and then, (b) you check that when you fully pull the starter cable (from inside the car) you are not able to move the operating lever on the starter any more (you will need a 2nd pair of hands for this check). If you CAN move the operating lever more, try altering the position of the cable where it attaches to the operating lever---you might (if my thinking is correct--anybody feel free to tell me if I am wrong) try moving the cable to the furthest out hole on the lever, in order that you take up any slack in the cable. The fact that the gear-teeth on the starter-ring are worn on only 1/2 the teeth's depth may indicate that the bendix is not going fully into the starter-ring teeth. Does that make sense?

 

[SPA]

You absolutely may suggest! I think that makes sense. Going to be some time before I can go through that as the engine is in component form - and it may not be back together for some time. Will be referring back to this thread tho. Separate thread seeking camshaft advice... ;-)