Slipping clutch

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Vintageant
Posts: 24
Joined: Wed Aug 28, 2019 6:00 pm
Your car is a: 1973 Fiat 124 Spider

Slipping clutch

Post by Vintageant »

I've read all the clutch adjustment posts and also watched this:

https://www.youtube.com/watch?v=MUk_KrZglV0

If I understand correctly, tightening the clutch cable adjustment will stop grinding (particularly in reverse), and loosening the adjustment will reduce the clutch slipping.

Looking for confirmation that I have this correct.

Thanks!
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Slipping clutch

Post by 18Fiatsandcounting »

Vintageant wrote:If I understand correctly, tightening the clutch cable adjustment will stop grinding (particularly in reverse), and loosening the adjustment will reduce the clutch slipping.
This is correct, but only if your clutch adjustment is really out of whack. If you tighten up the adjustment, it can allow the clutch to disengage more completely when shifting, which can reduce grinding. There are other causes of grinding though, such as worn synchronizer rings, and that requires a transmission rebuild to fix. Trying to shift too fast on a decades-old transmission can also cause a slight "chirp" as the gears grind a bit.

If your clutch adjustment is too tight, the clutch could be partially disengaged even when the pedal is all the way up, and that would cause slipping. However, there are other likely causes for clutch slippage, most often a worn clutch or pressure plate or oil on the clutch face (likely from a leaking rear crankshaft oil seal or transmission input shaft seal).

I think the standard technique (for pretty much any car) is to adjust the clutch so that there is about a 1/2" or 1" of pedal travel before the clutch starts to disengage. In other words, if you press on the clutch pedal by hand and it moves about this amount before it suddenly gets much harder to push, then it's adjusted correctly.

-Bryan
Vintageant
Posts: 24
Joined: Wed Aug 28, 2019 6:00 pm
Your car is a: 1973 Fiat 124 Spider

Re: Slipping clutch

Post by Vintageant »

Thanks Bryan!

I have minimal clutch slip, particularly in higher gears, so I'm going to measure the current pedal travel and then probably loosen the adjusting nut a turn or two to observe any difference. Plus, the grinding is only upon selecting reverse, never during shifting/driving.
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Slipping clutch

Post by 18Fiatsandcounting »

Note that the reverse gear does not have a synchronizer, so it will almost always chirp when shifting into reverse unless the car is fully stopped and the clutch has been depressed for a second or so. If you try to shift too fast into reverse, things are still spinning in the transmission, and without a synchronizer, you'll get that "crunch". If your transmission oil is thinner than it should be, it might take longer for things to stop spinning before you can shift into reverse.

-Bryan
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