500 (Classic) F/L engine in an R chassis and clutch issues

[Marvin 1973 500]

Hello -- first time posting. I have a 1973 Fiat 500 that has an R model chassis, but an older F/L engine and non-synchro trans. Starter on top of bell housing. The car was brought over from Italy many years ago. It has the round instrument cluster -- like the earlier cars. I am told that the VIN 110 F 5112103 is a 1973. The ID plate also says Motore 126 A6 000.

Question #1 : Will the older half shafts be of the correct length and fit to this R chassis? Would the original engine and trans have been different? The starter in the car is the traditional cable pull. The unique "spring and plate" rear engine mount of the R chassis does fit onto this older engine. The car basically seems to run well.







Question #2 : I am getting clutch chatter when starting out, so I have to really baby it. I did not buy a new clutch assembly, as the car came with some new parts - the clutch being one of them. It is the diaphragm type. Unfortunately, I did not have the flywheel surfaced (just cleaned it up with Scotchbrite). It seemed to have a little corrosion. I cleaned all contact areas of plate and flywheel with acetone before assembling. I do see an oil leak that I think is from the crank seal, but also probably the trans input shaft seal as well (90 wt. oil). The clutch plates do not appear to be wet, but I sprayed them a lot with cleaner to make sure. But the chatter is still there. If I have to replace the crank seal, can it be done with the crankshaft in place? Just remove and reinstall the bearing assembly using a new seal? Are new flywheels available? Need advice / help on what to do next. Thanks for any and all helpful input.

 

[varesecrazy]

Hi , and welcome to FF,

it's well before my Era of FIAT knowledge,

but as you've tagged it Classic 500 , you should get a wealth of experience replying in the coming days ( it's a national holiday weekend in the UK)

Charlie - Oxford - UK

 

[Luxe]

Are you sure you have an R transmission? The starter being on too is indicative of an R transmission bell housing. Like you said 126 is an R vs 110F for an L or F. The shaft lengths are correct. They were changed for the Fiat 126.

Clutch chatter is normal for the 500, but it sounds like yours might be excessive. Also main bearings would be difficult to change in situ.

Regarding parts, you can purchase new flywheels through Mr. Fiat in Georgia.

 

[Marvin 1973 500]

Are you sure you have an R transmission? The starter being on too is indicative of an R transmission bell housing. Like you said 126 is an R vs 110F for an L or F. The shaft lengths are correct. They were changed for the Fiat 126.

Clutch chatter is normal for the 500, but it sounds like yours might be excessive. Also main bearings would be difficult to change in situ.

Regarding parts, you can purchase new flywheels through Mr. Fiat in Georgia.

Thank you for the info. It is good to know that the half shafts are of the proper length, since they were not changed until the 126 model. One mystery solved. When I bought the car, the engine (with trans connected) was sitting inside the car in place of the front seats. I have attached a picture. The stamp on the engine says 110F 000 *1625804*, but the ID plate on the car says Motore 126 A6 000 *5111108*. So I do not think that I have the same engine that the car was built with. Somehow I thought that the R model cars only came with 600 or 650 engines?


I have rebuilt the entire car in the past 5 years. The parts I bought for the engine and trans were for a 500 F/L model, and everything works well. I had the crankshaft checked and the machine shop said the surface finish was good. All new seals of course, and I was careful when reinstalling. If I take the engine out, and IF the flywheel side crank seal is leaking, can I replace it by removing just the bearing assembly? I don't want to take everything apart if I can help it.


With regard to the clutch shuddering, I looked at the pictures I took of the engine when I took it apart. That flywheel does not look that great. Unfortunately I only cleaned it up and did not get it resurfaced. I am attaching the sad picture. If one is not careful, the car really shakes and vibrates. Have to very gently let out the clutch and feather the gas.


So I think that I am going to have to remove the engine and trans and fix this clutch issue, and look closely for the oil leak. There are always a number of drops on the floor after driving it. I am also wondering about obtaining a synchro transmission. I will have the half shafts and bell housing from my current trans to move to it.


Thanks to all in advance for replies.

 

[Marvin 1973 500]

Hi , and welcome to FF,

it's well before my Era of FIAT knowledge,

but as you've tagged it Classic 500 , you should get a wealth of experience replying in the coming days ( it's a national holiday weekend in the UK)

Charlie - Oxford - UK

Thank you very much. Greetings from across the pond in California! This forum is all new to me, but looks like a nice bunch of people, and a wealth of information. I am confident to get my car operating at 100%.


Yes, I have an "old school" 500. Definitely a little slower than modern day cars, but I am use to it. My wife and I also drive an Isetta, so the "power" of the Fiat 500 is amazing!


"Cheers" -- as they say in the UK.

 

[fiat500]

Hi Marvin. There could be loads of reasons for the clutch judder and I wouldn't say that it is a feature that you should expect with this car. You're probably onto it most accurately with yours suspicions as you know the thing best.
But on that photo of the flywheel the pilot bush in the centre looks either really worn or possiby missing. As it guides the input shaft of the gearbox, that would have an effect on the smoothness of take-up.
Although I think you possibly could replace the rear seal of the engine the way you describe, you might affect the front bearing and seal and put a strain on other components.

 

[Marvin 1973 500]

Hi Marvin. There could be loads of reasons for the clutch judder and I wouldn't say that it is a feature that you should expect with this car. You're probably onto it most accurately with yours suspicions as you know the thing best.
But on that photo of the flywheel the pilot bush in the centre looks either really worn or possiby missing. As it guides the input shaft of the gearbox, that would have an effect on the smoothness of take-up.
Although I think you possibly could replace the rear seal of the engine the way you describe, you might affect the front bearing and seal and put a strain on other components.

Yes, that picture shows the condition of the engine when I took it apart. I replaced almost everything in it with new parts -- including the pilot bushing. The Haynes manual written in the UK called it the "spigot bearing", and the "quill shaft" that passes through the clutch fits into it. I think that the shaft itself was not worn, but when I take it apart I will need to check it and verify the fit. When I put the clutch assembly on, I made a tool to line everything up. I think I used a socket that fit snug into that bearing, and built up the other end of the tool to just fit the hole in the plate. I remember that the transmission went it without a problem.

From the condition of the flywheel, I am not going to mess around, but will buy a new one. I have heard that if an old one is machined, it must be done perfectly. Why take the risk? When I do get it off, I can then carefully examine the end of the crankshaft to see if there is oil there. I would think that would tell me if the seal is OK or not.

I looked at my disassembly pictures to see how I got the crank bearing out -- see photo. I don't know if I would be successful in getting it back in with the new seal mounted inside. Beforehand would have to double check the crank for burrs or irregularities. Probably freezing the bearing would help installation, but I would not wish to put a strain on the other end like you said.

Looking at the photo again, I am amazed at how much oil and dirt was there behind that flywheel!! Where did it come from? The only sources I can think off would be: the crank seal, the transmission input shaft seal, and the dust from the clutch plates. Perhaps these engines all leaked a little? And that explains why the cover underneath the flywheel and clutch has a hole in it? Any thoughts? Thanks

 

[fiat500]

I think you're probably correct to suspect that Fiat made that hole in anticipation of oil leaks, but equally, it could have been to allow dust to exit or to reduce condensation.

 

[Marvin 1973 500]

Are you sure you have an R transmission? The starter being on too is indicative of an R transmission bell housing. Like you said 126 is an R vs 110F for an L or F. The shaft lengths are correct. They were changed for the Fiat 126.

Clutch chatter is normal for the 500, but it sounds like yours might be excessive. Also main bearings would be difficult to change in situ.

Regarding parts, you can purchase new flywheels through Mr. Fiat in Georgia.

Thank you Luxe. I see that they offer a lightened flywheel and also one made of stainless steel. I assume that the lightened one is for "performance" -- so that the RPMs will increase more quickly?


I also assume that the stainless steel one is so that it will not rust if the car sits for a period of time. Is this a problem with the old 500s? I do know that disc brakes on a car will get surface rust if not driven for a bit, and you can hear it being scraped off the first couple of times that they are applied. Would a rusty flywheel lead to clutch shuddering? Has anyone had this problem, or installed the SS flywheel? Perhaps it is not a bad idea, as why would a SS flywheel even be manufactured as a replacement? Are there other reasons?


Thanks.
Marvin

 

[Luxe]

Yes the lightened flywheel is for performance.

So SS or cast iron. The standard cast iron flywheel is not prone to rust that bad. The SS flywheel obviously is almost impervious to rust, but the main difference being it is a much stronger material than cast iron. Unless you are going for a hot engine, the old flywheel will work just fine.

Anyone have any experience with changing flywheels?

 

[AndrewHarvey]

I was warned of lightening my flywheel too much when building my engine
Apparently the car can be horrid to drive at motorway speeds as the lightened flywheel means it runs out of inertia
I built mine with the 500 flywheel rather than the 126 version and lightened it to 4kg as specified in kit instructions