Technical fiat 500f 69' - engine swap 126/650cc

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Technical fiat 500f 69' - engine swap 126/650cc

Phiat500

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Hi Guys... New member and tons of questions. I've purchased a fiat 500f/69 but the engine was a little smokey. I decided to purchase a fully restored fiat 126/650cc engine. The gentleman that sold me the engine said it would fit right in with no problems. He gave me a new clutch, bell housing and starter. Will this fit in as he said? Will the old transmission work? Thanks
 
I know it's advisable to upgrade your half-shafts to later half-shafts from a 500r to handle the extra torque.
 
Not only is it advisable to fit 500R (25mm) drive-shafts in order to handle the extra power (!), but the 126 drive shafts are too long--the rear track of the 126 is slightly greater than the 500---if you hunt through the various sites, there is one showing how to strip the front end of the gear-box, fit new drive-shafts and refit the bell-housing. I would suggest that an evening going through the sites would be well spent, as the range of advice is quite amazing. All the best--welcome to a gathering of slightly, but wonderfully barmy people(y):)
 
Not only is it advisable to fit 500R (25mm) drive-shafts in order to handle the extra power (!), but the 126 drive shafts are too long--the rear track of the 126 is slightly greater than the 500---if you hunt through the various sites, there is one showing how to strip the front end of the gear-box, fit new drive-shafts and refit the bell-housing. I would suggest that an evening going through the sites would be well spent, as the range of advice is quite amazing. All the best--welcome to a gathering of slightly, but wonderfully barmy people(y):)
Will my current drive shafts work? Or are you giving me the instructions if I upgrade the drive shaft to 126? Do you know of any good sites that explain this? Thanks
 
Phiat(500),

If you are putting a 126 gearbox into a 500, yes you'll have to change the halfshafts because the 126 ones are too long.

If you are keeping the 500 crashbox and just changing the bellhousing so it mates with a 126 engine, then no you don't have to change the halfshafts, but beware, the early thin halfshafts are prone to failure even with modest power increases.

From the R/L series on, the thicker halfshafts were standard. They are available and they are not difficult to fit.

See here http://www.flickr.com/photos/ricambifiat500/sets/72157615692546231/ for a nice pictorial tutorial and here http://www.fiat500clubsa.org.au/articles/swapping-niki-parts-into-your-bambino for extra things that you can do with your car.

Chris
 
To Bambino!!!

Thanks for the post. My car is a 1969 fiat 500f, are the half shafts the thicker ones?
My 650cc engine is on its way from Poland and should be here in the next few days. The gentleman that sold me the engine said he would include the bellhousing, starter and clutch set. He also told me it would be a straight swap. I think you confirmed this, Right?

Thanks for the great info.

Please anyone with any helpful advice, please post/reply!!
 
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To my knowledge, the 500Fs all had the thin shafts - mine certainly did. You may be OK using them, but just be aware that they do occasionally fail. If you've currently got the transmission out of the car, I'd be changing the halfshafts. Whilst it's not hard to pull it all out again if one of the shafts fails, it is a pain in the bum to have to do so. Once you get the car back together you'll want to drive it rather than repair it, again ...

I've never tried the bellhousing swap so I don't know for sure if the studs line up. When I rebuilt my car, I converted it using both a bored out 126 engine (695cc) and a synchromesh transmission.

If you are fitting a 650 engine, you will certainly need a 126 bellhousing as the starter motor setup and general shape of the bell end is very different from the standard 500 bellhousing.

The Polish engines are OK - we got them here in Oz as Niki 650s - but they are not quite as good as the Italian Fiat engines eg: they leak a bit of oil, the castings look a bit rough etc. Don't let me put you off though, they are still quite serviceable.

Chris
 
Found these two photos of the different bellhousings. The bolt pattern on the box case proper looks the same.

Is the ring gear on the flywheel the same between the two models, that is, are the starters interchangeable?

Chris
 

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500F to 500R / 126 starter motors are not interchangeable because of the flange mountings but you can get and swop the ally castings. The 126/500R has a different little cover plate where it mounts to the bell housing plus there should be a rear support bracket on the stater motor that connects to the gearbox . Sounds like you will have the right bits to do the job and if you use the original box you will have to split the diff housing to swop the bell housing so you in a great position to fit the 500L/R drive shafts . Starter ring gear is not a problem I am running a bored out 500D crankcase , 500 flywheel , starter motor , 500 bell housing and a 126 synchro box and I know of others who have done the opposite by matching up a crash 500 box to a 126. You can mix & match (y)
 
I found that the 500 bellhousing won't fit the 650p engine. There is no cut-out in the 650 engine block to accept the 500's top mounted starter motor so the starter can't be installed since it fouls on the block. I'm pretty sure the bellhousings are interchangeable although one has studs whereas the other has bolts but it's simply a matter of extracting the studs and using the bolts - or vice versa?
 
Hi Folks;
Another mix 'n match is to obtain a 126 BIS (the watercooled version) gearbox, put 25mm 500 drive-shafts into it and an AIR-cooled 126 bell housing (or 500 bell housing if you are using a 500 engine, it also fits onto the front of the 126 gearbox) This way, you end up with a slightly higher final-drive ratio--which a tuned engine will pull and makes for more relaxed cruising. This is the way that I am going with my 695 engine, which will be based on a 126 '650'.(y)
 
This is where the starter motor clashes - so you can't use a 500 bellhousing on a 650 engine (or a 650 bellhousing on a 500 engine). The gearbox will fit either bellhousing.
My '71 500L has the thicker driveshafts so I think the 500F might be the same.

image001a_zpse6da2463.jpg
 
Found these two photos of the different bellhousings. The bolt pattern on the box case proper looks the same.

Is the ring gear on the flywheel the same between the two models, that is, are the starters interchangeable?

Chris
Thanks for the photos. I will post some photos tonight..... i just received the engine and parts yesterday.
 
500F to 500R / 126 starter motors are not interchangeable because of the flange mountings but you can get and swop the ally castings. The 126/500R has a different little cover plate where it mounts to the bell housing plus there should be a rear support bracket on the stater motor that connects to the gearbox . Sounds like you will have the right bits to do the job and if you use the original box you will have to split the diff housing to swop the bell housing so you in a great position to fit the 500L/R drive shafts . Starter ring gear is not a problem I am running a bored out 500D crankcase , 500 flywheel , starter motor , 500 bell housing and a 126 synchro box and I know of others who have done the opposite by matching up a crash 500 box to a 126. You can mix & match (y)
thanks, this explains alot and assures me of the questions i had.
 
I found that the 500 bellhousing won't fit the 650p engine. There is no cut-out in the 650 engine block to accept the 500's top mounted starter motor so the starter can't be installed since it fouls on the block. I'm pretty sure the bellhousings are interchangeable although one has studs whereas the other has bolts but it's simply a matter of extracting the studs and using the bolts - or vice versa?
thanks, As long as it's doable!
 
This is where the starter motor clashes - so you can't use a 500 bellhousing on a 650 engine (or a 650 bellhousing on a 500 engine). The gearbox will fit either bellhousing.
My '71 500L has the thicker driveshafts so I think the 500F might be the same.

image001a_zpse6da2463.jpg
Thanks this helps alot. I with post some pictures later on tonight.
 
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