Spongy clutch pedal

[deathsled]

After being on the road since 2012 and being reliable for the most part, problems are beginning to arise. This one involves the clutch pedal. It is not pulling far enough on the clutch to slip into gear as easy as before. And the pedal is spongy which suggests the return spring is losing its tensile strength? I attempted to adjust the pedal under the hood on the Z bar but it hasn't fully corrected the problem. Wondering if that rod is even correct for the setup. Also wondering if there is a secondary place under the dash for an adjustment or is something more insidious going on like loosened bracket(s)?

[Bob Gaines]

It looks like you are at the end of your adjustment from the picture. Make sure your Z bar is not twisted which can effect adjustment. If all in order then it may be time to replace your clutch and pressure plate which I would recommend replacing at the same time.

[s2ms]

After being on the road since 2012 and being reliable for the most part, problems are beginning to arise. This one involves the clutch pedal. It is not pulling far enough on the clutch to slip into gear as easy as before. And the pedal is spongy which suggests the return spring is losing its tensile strength? I attempted to adjust the pedal under the hood on the Z bar but it hasn't fully corrected the problem. Wondering if that rod is even correct for the setup. Also wondering if there is a secondary place under the dash for an adjustment or is something more insidious going on like loosened bracket(s)?

Looks like you also have a 65 z-bar and clutch rod...

[shelbydoug]

The most likely and most common cause of this situation is that the z-bar has twisted.


If you read through the original Ford specs, the original specs on the clutch rates it at 2,600 pounds.

To my knowledge, the Ford service part for the clutch pressure plate was a "Ford rebuilt" and rated at 2,800 pounds. Considering the general dependability of the original z-bars, those two must have been within the capacity of the original components?


If you read through the specs on seemingly every aftermarket pressure plate, they start at 3,200 pounds and some are as high as 3,400 pounds.It is very unlikely that your car has an original equipment pressure plate installed?

The original z-bar was never intended to work with the pressure of current aftermarket pressure plates.



If you attempt to use an original equipment z-bar, what will happen to it is the long leg, the one that curves around the steering column will also bend to the point that you can no longer move the throw out bearing/clutch pedal far enough to release the clutch.


The fix generally is simple. Replace the z-bar with a stronger z-bar. Sounds simple right? Typically the after market z-bars are not tempered enough to use without them also twisting like cooked spaghetti.

You are going to need a replacement that can handle the pressure of the current replacement clutches.That means that even if you found an original Ford Service part, which I doubt, you are going to need one that is reinforced in some way. In addition, there are at least two types.



The 289hp, because of it's unique cast iron exhaust manifolds uses a unique part to clear that driver side exhaust manifold.

My suggestion is that regardless whom or where you purchase it from, that it is certified for use with higher aftermarket pressure plate assemblies otherwise you will be in the same situation within a very short period of time?



You may also need to replace the plastic balls (bearings) on the z-bar mounting brackets with something better then the original brackets.

You need to be an educated consumer on this and make sure that you are dealing with someone who understands the issue and has the correct reinforced pats. You might want to ask the folks at Cobra Automotive for help on getting the necessary reinforced parts for this repair?

This is something that is very common for them to deal with and they can save you a lot of time in supplying the right parts the first time through?


You certainly can choose to go further in replacing or reinforcing other components in the clutch release system but what you are experiencing is a z-bar issue. You could find other components seriously worn when you disassemble and it would be a good time to consider upgrading them but that may not be absolutely necessary.

[Royce Peterson]

Scott Drake, Mustang Steve and others offer a Clutch Pedal / Brake pedal shaft rebuild kit which replaces the babbit bushings with caged needle bearings. That is a fantastic upgrade.

Like the others above mention the Z bar is likely worn out or twisted. Possibly the pivot points are worn out too which can only be solved by replacement. There is only one place to adjust the clutch.   

[Bob Gaines]

I thought I would mention that if replacing the Z bar that the 65 and 66 GT350 do not need the special hipo Z bar. The hipo Z bar is to provide clearance around the special hipo cast iron exhaust manifolds. The 65/66 GT350 used tri Y headers and consequently can use ether OE hipo Z bar or the non hipo Z bar. The non hipo Zbar actually fits better because it gives more clearance around the tri Y header tubes compared to the hipo Z bar. Just some information to provide you with alternatives if needed.

[SFM6S]

One other thought is to check the pivot arm that goes into the bell housing where the lower rod goes from the z-bar. That dimple may no longer be a dimple and is now becoming a hole.

Joe

[deathsled]

Thank you gentlemen.  I am overwhelmed with the great response.  Since 843 is a day two car I am going to go for upgrades.  The required work and replacement is over my head.  If I tried it I would screw it up somehow.  Cobra Automotive will charge to the rescue with their parts.  I have used them in the past and love the whole outfit.  I still dwell on those Trans Am lug nuts they sold me.  They look so choice on the Torqs.  I suppose when the term "twist" is used in reference to the Z bar it isn't some shifting of where it might be bolted to but an actual bending or distortion of the metal in the bar.  My best option is to get the Cobra Automotive parts and bring the car over to East Dundee's Mustang Restorations.  I will likely take the hit on labor but better that than trying a little science experiment in my garage.    The car was originally an automatic.  I cannot state where they pedal assembly came from.  Thank you all for your helpful input.

[JWH]

One more thing to check is the bracket that the pedals hang from up under the dash. I had this exact thing happen and it was gradual over time until I could not get the car in gear. The bushing in the bracket had worn out and every time I pushed in the clutch, it elongated the circular hole in the bracket more and more. It will be the bushing on the side of the bracket closest to the e-brake handle.
Jeff

[6s1640]

In the attached image are two Z-bars. The one on the left is a HiPo and the one on the right is a LoPo.  Both have been reinforced. The LoPo was still bending under load.

[Bob Gaines]

Thank you gentlemen.  I am overwhelmed with the great response.  Since 843 is a day two car I am going to go for upgrades.  The required work and replacement is over my head.  If I tried it I would screw it up somehow.  Cobra Automotive will charge to the rescue with their parts.  I have used them in the past and love the whole outfit.  I still dwell on those Trans Am lug nuts they sold me.  They look so choice on the Torqs.  I suppose when the term "twist" is used in reference to the Z bar it isn't some shifting of where it might be bolted to but an actual bending or distortion of the metal in the bar.  My best option is to get the Cobra Automotive parts and bring the car over to East Dundee's Mustang Restorations.  I will likely take the hit on labor but better that than trying a little science experiment in my garage.    The car was originally an automatic.  I cannot state where they pedal assembly came from.  Thank you all for your helpful input.

Cobra Automotive has many great products but I didn't see anything special about the Cobra Automotive Z bar online except the high price. I think your best and also most economical bet is to buy the inexpensive 65 66 Z bar and (take top pivot part off for 66) and have your Mustang Restoration shop weld some metal gussets on it like what was done in the previous picture of a modified bar. At least that is what I and others have done for many decades with positive results.Of course this is a typical day 2 mod . The concours crowd just replaces the bent original type Z bar with another unmodified Z bar every so often as needed .   

[Bob Gaines]

You do need to determine if the Z bar is twisted or not before you go and buy parts. If not the Z bar look at pedal support bracket for oblong or destroyed pivot (where pedal is secured) as has been mentioned . The clutch fork can also be a source if the rod has worn a hole into the fork allowing it to dig into the fork metal as has been mentioned . If all of those things are OK and intact it is time for a new or rebuilt clutch and pressure plate.Your go to Mustang restoration shop should be of help determine which course of action to take if all of this is over your head.   

[shelbydoug]

ASk Cobra Automotive what is different about their z-bar. They will tell you.

[TA Coupe]

Another thing to try is to have your Z bar cryogenicly treated to strengthen it.

      Roy

[deathsled]

I plan to take the car over to East Dundee.  It's going to cost but better to find out than me troubleshoot in the dark.  My mind tends to switch off when it comes to clutch forks and linkages.  It might as well be magic where I'm concerned.  I suppose I could take a deep dive into the subject matter but I'm taking the easy way this time.  Cobra Automotive said they would have to check for anything heavy duty manual because according to them, these days many are going with hydraulic clutches (even in their race cars) which surprised me.  I distinctly remember reading once that Cobra Automotive went with mechanical fuel pumps over electric fuel pumps in their race cars for reasons of greater reliability.  I would have thought that philosophy would have spilled over onto clutches.  Maybe not.