Hydraulic Release Bearing Problem

[Tim Terry]

Drove the car to be inspected Friday. The car was running and feeling great - no issues or warnings. I was feeling like all the waiting for title and registration was about to end.

After I found out the shop couldn't do the "ASE Certified Master Technician" work required by Texas, I hopped in to find another certified shop.

Started the car, then uh-oh. I couldn't get it into gear. Clutch pedal went soft. Shut it off, went to the rear, and noticed a puddle of brake fluid under where the hardline clutch lines connect to the braided stainless lines that go to the Quartermaster internal release bearing (721100 model).

I had the car towed home. Now to disassemble and pull the Quaife back to reveal the issue.

It's either the connections to the release bearing or the bearing itself leaking. All the hardlines look good.

I probably have 15 miles on the car, just around the block locally. Other than adjusting the shift cable linkage to be able to find reverse gear, there have been no other issues with bleeding the clutch or shifting all gears.

More to follow.

 

[Mark]

Tim,

If there is any salvation, that should have been my biggest problem. Look on the bright side, you did not have to totally build your car twice like I did. This is a real inconvenience but at least you were able to isolate the problem.

 

[Mark]

Thinking back now, the day I was supposed to pick up my car from HRE Motorcars, my clutch leaked as well to the extent that all the fluid poured out from one of the lines due to faulty fitting. This was discovered after all the auto parts stores were closed. I was pretty upset. Thinking back now, that was probably a key indicator of how the whole car was assembled. I forgot about that episode until now. Probably because it was just the tip of the iceberg.

 

[Tim Terry]

So sorry to hear that, Mark! Yes, this is nothing that a few hours of wrenching won't reveal! I was just getting anxious to get to the driving part of ownership.

 

[Mark]

The first time was a nine month build time which resulted in basically an unsafe mock up. I am extremely lucky that the car did not catch fire given how it was assembled. The parts that I took off that thing were so poorly made, it was enough to make you cry. Luckily that was evident before I used it.

The second time took 15 months and that was the real deal done by a real professional. Unfortunately, I have become so disenchanted and tired of the project, I have just parked it in my garage and covered it. I will look at it again in the spring of 2017. At that point, perhaps I will treat myself to some seat time.

 

[Mark]

Tim,

Once you work through the bugs, I am certain you will have a great experience.

 

[Markus]

Tim,

I made the same experience

Different release bearing, different gear box.

Do you have a soft pedal all the time? Or only when the engine is running?

Let me know.

Markus

 

[Tim Terry]

Markus,
The pedal was pretty firm, good feedback and easy to use. After the leak, the pedal is understandably soft and won't pump up. I'll let you know what I find, probably next week.

Tim

 

[Mike]

Tim, how much clearance did you have between the QM and the clutch diaphragm? How much travel did you need fully disengage clutch?

 

[Tim Kay]

I'm not familiar with QM so this may not apply here but in my experience with Tilton's "concentric hydraulic t\o bearings" a pedal stop is critical. If the pedal extends the t\o too much is blows past the seal, only talking an 1/8" tolerance.

 

[Mike]

Yup, that is what I was wondering. How are you holding the bearing stationary so it does not try and rotate when making contact with the pressure plate?

 

[Tim Terry]

This is a good photo of the setup. We measured twice (at least), did all the calculations for clearance and throw, then added shims. I believe we ended up adding 8 or 9 shims.

To answer Mike's question: There is a post you'll see in the photo. That came from Olthoff and is used (per Olthoff's installation instructions) to prevent rotation.

I'll look into the pedal stop. Great thinking on that one. Perhaps I blew it out. Good thing I already ordered a seal kit for the bearing.

https://www.flickr.com/gp/141675158@N03/m69S52

 

[Mike]

Tim, is that rust on the bearing housing? Was it new?

I won't second guess Dennis as he knows what works. That said I did weld on a flat plate on the back of the tab sticking down that fits in-between shift rod bosses so that the bearing holder would not be able to rock back and forth between the bosses. That to me seemed like it would allow a lot of flex back and forth on the hoses and fittings that I did not want.

There is no pedal stop other than contacting the back of the pedal box frame. I adjusted mine so that it had just enough throw to release the disk without drag. You will need to come down from the top access plate under the A/C to get at.

 

[Markus]

Tim,

just in case you need a pedal stop quick:

http://www.gt40s.com/forum/gt40-tech-powertrain-transaxles/23912-spf-gt-clutch-pedal-stop.html

There is even an easier way by deleting the spacer and use a nut on both sides > with this setup you can easily adjust the pedal stop to what you need.

Markus

 

[Markus]

Markus,
The pedal was pretty firm, good feedback and easy to use. After the leak, the pedal is understandably soft and won't pump up. I'll let you know what I find, probably next week.

Tim

Tim,

If you find an obvious leak disregard the following.

Did you try with the engine running and engine switched off?

At the end my issue turned out to be the following:

- I did not have a pedal backstop at the time
- obviously I overtravelled the throwout bearing
- this bent the diaphragm spring of the pressure plate
- in the engine turned off position the system somehow worked (no leak, clutch seemed to work fine)
- when the engine was running the release bearing started to wobble when touching the diaphragm springs > which was too much for the seal in the hydraulic throwout bearing and it started to leak - clutch did not work
- you guess, when I switched the engine off > everything was back to normal

So check if engine on / off makes a difference.
When you take the stuff apart check the pressure plate for perpendicularity (run out)

Good luck<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com<img src=" /><o></o>

Markus

P.S. jac mac, thanks once more for pointing me into right direction back then ......

 

[Tim Terry]

Tim, is that rust on the bearing housing? Was it new?

I won't second guess Dennis as he knows what works. That said I did weld on a flat plate on the back of the tab sticking down that fits in-between shift rod bosses so that the bearing holder would not be able to rock back and forth between the bosses. That to me seemed like it would allow a lot of flex back and forth on the hoses and fittings that I did not want.

There is no pedal stop other than contacting the back of the pedal box frame. I adjusted mine so that it had just enough throw to release the disk without drag. You will need to come down from the top access plate under the A/C to get at.

Mike,
Yes, that is rust. I found it odd for a brand new part from Olthoff, but I certainly made sure the surfaces that make contact were clean.

Regarding the rocking back and forth of the bearing: We thought that very odd as well. Do you have a photo of the flat plate you added? I want to do something like that when we get inside the bellhousing again.

We DID adjust the pedals - without moving the box. That may have contributed to the excessive throw condition, but I'll look much more carefully about adding a stop, as Markus and others have discussed here.

 

[Mike]

I had a similar issue, albeit several thousand miles later. 2307 has a an adjustable stop, not sure if it is factory installed or Olthoff installed, but I thought I would play with it. I have the same quartermaster and my clutch was engaging immediately upon coming off the stop. I wanted to adjust it up a little so I lowered the stop, increasing the throw. Soon after, I noticed a leak, I guess I over extended the piston. I put a new quartermaster in and put the stop back to the set point I originally had and all is good again, I just wish the clutch didn't engage so quick.

 

[Mike]

I know I am a little biased but that blue #11 car in the Superformance add above sure looks good

 

[Gus Meyjes]

Ive had poor experiences with throwout bearings in my Cobra. The seals don't seem to hold up. So I went back to the old fashioned clutch arm. My SPF has the throwout bearing... just waiting for it to fail...

 

[Mike]

My understanding is the QM units are more reliable than the units from McLeod. Mine has not been a problem knock on wood.