Technical Grinding from transmission while clutch is pressed and car is in motion

[RobertM]

Hi all, a little road trip update, unfortunately with some bad news. About 2 minutes from our hotel for the night I stoped at a traffic light and when I took off I heard a pretty awful grinding sound which seemed to go away when I shifted to second gear. When I stopped at the next light the grinding came back with an occasional loud thud coming from under the car.

This grinding sound persists when I try to move in first or second gear. It goes away when coasting, but if I push the clutch in and select any of the gears while rolling it comes back.

There’s a pretty consistent drip coming from what looks like the transmission. My hope is it’s just a little low on fluid, which I’m going to top off tomorrow morning, but my fear is that it’s a clutch or internal transmission issue. Both drive shafts appear to be fine.

If anyone has any thoughts on what to look out for hopefully I can get to the bottom of this. So long as I can coax this car another 850 miles swapping a clutch or even a transmission shouldn’t be too big of an issue as long as I can get parts.

 

[fiat500]

You're hardy Robert, (as we say in Scotland).
I could speculate about all sorts of internal gearbox issues, which I assume you have also done.
One likely candidate for this situation, which you can identify or eliminate fairly easily, is where the driveshaft splines enter the cast-iron, sliding boss that is bolted to the rubber coupling at the hub.
On most cars there will always be a bit of slop where splines on both the driveshaft and the driven coupling are worn. But it can develop to become a clunk and then finally, a lack of drive. It should be easy to check how bad this is with the car jacked up. As a stop-gap, it might be possible to save the day by just replacing the cast-iron component to get you home.
Whilst there, check that the rubber of the aluminium couplings is intact, as that is another wearable item.
A long shot is to find a stone trapped between the coupling and the swinging-arm.

 

[the hobbler]

You're hardy Robert, (as we say in Scotland).
I could speculate about all sorts of internal gearbox issues, which I assume you have also done.
One likely candidate for this situation, which you can identify or eliminate fairly easily, is where the driveshaft splines enter the cast-iron, sliding boss that is bolted to the rubber coupling at the hub.
On most cars there will always be a bit of slop where splines on both the driveshaft and the driven coupling are worn. But it can develop to become a clunk and then finally, a lack of drive. It should be easy to check how bad this is with the car jacked up. As a stop-gap, it might be possible to save the day by just replacing the cast-iron component to get you home.
Whilst there, check that the rubber of the aluminium couplings is intact, as that is another wearable item.
A long shot is to find a stone trapped between the coupling and the a swinging-arm.

To reassure you on one point----if the problem is one of the cast-iron sliding parts of the the drive-shaft coupling, normally it is only the sliding part that strips out its splines. Replacing these is an "in-situ" job--- a bit fiddly but it can be done. If one has gone, I would suggest that both are replaced. Toreplace these sliding couplings "in-situ", undo the 4 bolts that hold the sliding part to the main rubber/alloy coupling (13mmspanner), pull the drive-shaft far enough away/up from the suspension arm, remove the circlip on the end of the drive-shaft and slide off the coupling----reverse operation to fit new coupling. When you get the new coupling (if that is what you require) check toseeif there is any'bluing' around the splines area. If there IS, good, it will denote that the splines have been heat-treated---the cheap couplings usually don't have this faint blue colouring, but even a 'cheap' coupling should get you the rest of the way home. Don't forget to put the car ON STANDS when working underneath it.

 

[RobertM]

To reassure you on one point----if the problem is one of the cast-iron sliding parts of the the drive-shaft coupling, normally it is only the sliding part that strips out its splines. Replacing these is an "in-situ" job--- a bit fiddly but it can be done. If one has gone, I would suggest that both are replaced. Toreplace these sliding couplings "in-situ", undo the 4 bolts that hold the sliding part to the main rubber/alloy coupling (13mmspanner), pull the drive-shaft far enough away/up from the suspension arm, remove the circlip on the end of the drive-shaft and slide off the coupling----reverse operation to fit new coupling. When you get the new coupling (if that is what you require) check toseeif there is any'bluing' around the splines area. If there IS, good, it will denote that the splines have been heat-treated---the cheap couplings usually don't have this faint blue colouring, but even a 'cheap' coupling should get you the rest of the way home. Don't forget to put the car ON STANDS when working underneath it.

Those parts would make noise regardless if a gear was selected wouldn’t they? My noise gets louder if the car is in gear with the clutch pressed. I did try to move the drive shafts around by hand, they both have very little play, though the car was on the ground when I tried.

 

[Noah500]

Congratulations on getting underway, @RobertM! - have you got a 'travel log' type of thread anywhere so we can see where you've got to, how many miles, etc.?

On your specific issue, I hope it's not something that's going to set you back - let us know how you get on

 

[RobertM]

Congratulations on getting underway, @RobertM! - have you got a 'travel log' type of thread anywhere so we can see where you've got to, how many miles, etc.?

On your specific issue, I hope it's not something that's going to set you back - let us know how you get on

I usually make videos of all my trips. I plan on doing that and making a big post on here with a bunch of pictures once I make home regardless of how I get there.


On a happy note, I ran to the auto parts store, and had an hour long fight with the fill plug on the transmission. It took a pretty small amount of fluid before it was full… but it did take some fluid and sure enough on our 1.5 mile test drive back to the hotel the noise was gone. So hopefully it was just a case of being low on fluid and we didn’t cause any damage in the 3 or so miles we drove it while it was making noise.

Either way, a slight delay today, but back onto our plan of visiting national parks on our way to Florida (currently in VA with ~700 miles covered)

 

[fiat500]

Those parts would make noise regardless if a gear was selected wouldn’t they? My noise gets louder if the car is in gear with the clutch pressed. I did try to move the drive shafts around by hand, they both have very little play, though the car was on the ground when I tried.

They would make a noise when starting off and might go quiet when coasting out of gear. The sudden thrust when putting in gear whilst coasting would make worn shafts clunk.
But, as you say, "My noise gets louder if the car is in gear with the clutch pressed." That might implicate some internal damage in the gearbox such as a loose selector or a chipped cog.

 

[the hobbler]

Congratulations on getting underway, @RobertM! - have you got a 'travel log' type of thread anywhere so we can see where you've got to, how many miles, etc.?

On your specific issue, I hope it's not something that's going to set you back - let us know how you get on

If your noise is apparent with the car in gear and the clutch depressed,that would leave one to believe that it is NOT a drive-shaft problem. Is the noise apparent with the engine running, NOT in gear but with the clutch depresssed? If that is so, then I would say that the problem is with the clutch/release mechanisim because with the clutch depressed, the internals of the gearbox are not being driven, so should not be making a noise.

 

[RobertM]

It Made the noise loudest when taking off in first or reverse. After adding the fluid we’ve done over 100 miles today and have had no issues… well aside from the lead breaking off of the new condenser that I had installed which was very annoying and took a while to diagnose.

If your noise is apparent with the car in gear and the clutch depressed,that would leave one to believe that it is NOT a drive-shaft problem. Is the noise apparent with the engine running, NOT in gear but with the clutch depresssed? If that is so, then I would say that the problem is with the clutch/release mechanisim because with the clutch depressed, the internals of the gearbox are not being driven, so should not be making a noise.