Clutch master failure mode?

Pete Whitstone

Pete Whitstone

True Classic
Yesterday I went to move the 037 project out of the shop so I had more room to work around the car. Everything was fine, clutch felt normal. But when I went to pull it back in, the clutch stuck to the floor and was not disengaging. I'm surprised that it could go from working good to totally dead literally between 2 pedal presses. No fluid anywhere, no leaks. I tried vacuum bleeding it to see if I could pull any air out, but didn't get anywhere. Does this sound like a bad master?

I know in the past there was a situation where people were having to replace the clutch master about every year, which is probably close to how long this one's been in the car. Is that still going on?

Anyone have a recommendation for where I could get the best quality master?

Edit: A bunch of views on this but no comments. For you X1/9 guys that are saying "I don't know anything about Scorpion clutch masters", the X1/9 and the Scorpion share this part, so your input is needed as well.

Thanks!
 
Last edited:
Pete, when you say "the clutch stuck to the floor", do you mean the pedal went to the floor and won't return by itself? Or the actual clutch assembly is frozen in the engaged position?

The first situation (which I believe is what you mean) does sound like a faulty master to me. However I suppose it might be possible for a failed slave to do so. The second situation seems more like a clutch pressure plate failure.
 
From previous post on master cylinders.. IMO and based on observation, none of the current aftermarket replacements are any good. None are near oem Fiat/Lancia quality that once was.. Not just the cast iron housing, the piston design & materials are cost reduction_ed in the current aftermarket replacement master cylinders for both clutch & brakes.

Solution is to have a reasonable good oem Fiat/Lancia master cylinder sleeved in SST by Karps Brake service, then apply new known high quarry seals. This IS the more costly and involved way to replace the master cylinders, it does tend to produce better and lasting results..

Clutch pedal not returning oil dripping down

On a 60 deg day I took her around the neighborhood yesterday. Noticed the clutch wasn't returning to position. Today there wa an oil leak dripping down on the clutch. Having done a search, I hope it's not a master cylinder replacement. The clutch pedal is just not springing back up. Now I'm not...
xwebforums.com


Pay now or Pay later deal or Penny Wise_Pound Foolish...
Bernice
 
Dr.Jeff said:
Pete, when you say "the clutch stuck to the floor", do you mean the pedal went to the floor and won't return by itself? Or the actual clutch assembly is frozen in the engaged position?

The first situation (which I believe is what you mean) does sound like a faulty master to me. However I suppose it might be possible for a failed slave to do so. The second situation seems more like a clutch pressure plate failure.
Click to expand...

Yes, the clutch that was working fine a few hours before just went to the floor and stuck there the next time the pedal was pushed.

I am going to pull the slave and make sure it has not leaked dot3 into the clutch area, but I suspect it's the master.
 
Rupunzell said:
From previous post on master cylinders.. IMO and based on observation, none of the current aftermarket replacements are any good. None are near oem Fiat/Lancia quality that once was.. Not just the cast iron housing, the piston design & materials are cost reduction_ed in the current aftermarket replacement master cylinders for both clutch & brakes.

Solution is to have a reasonable good oem Fiat/Lancia master cylinder sleeved in SST by Karps Brake service, then apply new known high quarry seals. This IS the more costly and involved way to replace the master cylinders, it does tend to produce better and lasting results..

Clutch pedal not returning oil dripping down

On a 60 deg day I took her around the neighborhood yesterday. Noticed the clutch wasn't returning to position. Today there wa an oil leak dripping down on the clutch. Having done a search, I hope it's not a master cylinder replacement. The clutch pedal is just not springing back up. Now I'm not...
xwebforums.com


Pay now or Pay later deal or Penny Wise_Pound Foolish...
Bernice
Click to expand...

Thanks Bernice, I'll read through that thread. I don't really want to have the MC as a maintenance item, I will spend the money to make sure it's "one and done".

Speaking of money, what does the sleeving and quality parts add up to?

Also is there such a thing as bench bleeding this type of master?
 
When it comes to replacing master cylinders, not having a heater/AC box under the dash is worth not having heat or attempting to have AC.
 
Well, it wasn't the master or the slave, it was the 3rd option, the "something more sinister" option. Still not as bad as it could be. I found the line to be leaking in a totally inaccessible location. Right on the engine side of the firewall, there is a line union. On a Scorpion, there's loads of room to get in there and service that particular location. On my car, you have an evil confluence of chassis tubing, shift cables, emergency brake linkage, heater lines and fuel lines running through that area. So I basically had to cut the union out, and I am going to redo the clutch line so the union is on the passenger side of the firewall. So new clutch lines all the way back to the clutch from there. Difficult, but not impossible. Wish me luck.
 
Pete Whitstone said:
Thanks Bernice, I'll read through that thread. I don't really want to have the MC as a maintenance item, I will spend the money to make sure it's "one and done".

Speaking of money, what does the sleeving and quality parts add up to?

Also is there such a thing as bench bleeding this type of master?
Click to expand...
Think sleeving cost about $100, add seals, shipping and related. Call Karp, they can do it all from just sleeving to complete rebuild and beautifying like powder coating..

Important to use a good Fiat core.. pointless to sleeve-re-build an iffy aftermarket cylinder.

Bernice
 
On the subject of clutch master cylinders, I am on the fence between a simple rebuild and replacement with new. My present cylinder is only 2 years and a thousand miles old. I find that pressure (fluid) was escaping out the hole under the operating seal and back towards the reservoir. Put in one of my NOS seals and it works fine on the bench. Curious thing is, I'm measuring only a couple thousandths difference between new seal and old, and that on the inner diameter. No difference in OD or width. Can someone confirm this is enough to cause failure. The penny-pincher in me wants to use my NOS seals. However, it is a really nasty job to do over!
 
lgibson said:
On the subject of clutch master cylinders, I am on the fence between a simple rebuild and replacement with new. My present cylinder is only 2 years and a thousand miles old. I find that pressure (fluid) was escaping out the hole under the operating seal and back towards the reservoir. Put in one of my NOS seals and it works fine on the bench. Curious thing is, I'm measuring only a couple thousandths difference between new seal and old, and that on the inner diameter. No difference in OD or width. Can someone confirm this is enough to cause failure. The penny-pincher in me wants to use my NOS seals. However, it is a really nasty job to do over!
Click to expand...
"Penny wise, Pound foolish"...
Such is the reality of current aftermarket master cylinders, they are of Meh quality.

How were the cylinder bores and piston measured? What is the condition of the cylinders, pistons and related. If the cylinders are not happy (bore diameter, cross hatch and more) they will leak regardless of the seals condition.

OEM Fiat seals are flat with spherical edges, current aftermarket seals are the common cup style seals. They are not interchangeable as the piston designs are completely different.

IMO, due to the "not fun at all" job replacing hydro master cylinders in the exxe, is why good condition OEM Fiat master cylinders are sent out to be sleeved with stainless steel then rebuilt with the highest quality seals with proven good pistons. This is the most costly, involved and resource involved method to deal with the master cylinders.. rewards, master cylinders that last for years and years with no issues.


Bernice
 
Thank you for the perspective.
Is there any wisdom out there relative to quality of Metelli vs Cati master cylinders?
 
lgibson said:
The penny-pincher in me wants to use my NOS seals.
Click to expand...
I can relate to your inclination. Which makes me think you may be rather surprised at the steep cost to have one resleeved...I know I was. However it would be a great option if money is no object.

Since new replacement units use a rather basic style seal, I've given thought to installing a high quality replacement seal from a known seal maker into a new cylinder. Naturally if the cylinder itself is out of spec then the new seal won't last long. But it is more likely the seals in the new replacement units are the major issue. So installing a better quality seal may offer a cost effective solution.
 
You must log in or register to reply here.
Back
Top