TR4/4A Clutch hydraullics question

[Zimmycobra]

I have a late 1965 TR4A that I have restored mechanically and am still working on the cosmetics.

I am sitting here at work thinking about the newest problem with the car (who isn't doing that?) and wondered what the group thinks. Car has been driving for 1 1/2 years and has been running fairly well - no clutch problems. I rebuilt the clutch master cylinder with the Moss rebuild kit and I replaced the slave cylinder when I did the restoration. All worked fine. The car has been parked since Mother's Day (something in the gas tank causing blockage and I haven't had the time to replace the tank yet - a whole other story :wink-new. Went to move the car the other day and found that I couldn't get into any gear. Clutch just wouldn't allow it. Master cylinder is still full, but the fluid is a very dark almost black color.

My guess is that the replaced seal has disintegrated, coloring the fluid and allowing fluid to flow around it preventing pressure for the clutch. Using Castrol LMA Dot 4 fluid.

Plan is to replace the master cylinder (just to be sure going forward) and to replace the plastic tube that connects the pipe to the slave cylinder with a new stainless braided hose.

Thoughts, anyone? Curious as to what you all may think. Thanks.

 

[Geo Hahn]

Dark fluid does usually suggest a deteriorated 'rubber' part though it is unusual to see that right after all the seals have been replaced.

OTOH, there may be more than one problem here...

Does the pedal feel normal yet the clutch stays engaged? You might look to see it the slave is indeed operating and the clutch arm moving. It is possible that the clutch disc has rusted to the flywheel & pressure plate - this can happen when a car has been parked for quite awhile (you say 3 months) especially in humid weather. Usually pretty easy to free it up if this is the case.

But of course that does not account for the dark fluid. Assuming the fluid was not dark before the rebuild and was thoroughly bled after the rebuild then I agree new rubber is called for.

 

[Zimmycobra]

Geo: Thanks for the quick reply. While it has been inside the garage all this time, it may have had enough humidity to rust stuck. How do you suggest trying to free it up, if so? The bad fluid makes me want to change the parts out for sure, but I will check slave operation, etc. as soon as I can get it up on the lift. Currently my other toy (427 Shelby Cobra replica) is on the lift getting the intake gasket replaced. I hope to finish that this weekend and then get started on the TR. The pedal did feel normal, so maybe the plate is frozen to the flywheel.

Thanks, again.

 

[Geo Hahn]

Getting it unstuck might be as simple as depressing the clutch and bumping the starter with your foot on the brake. But that didn't work for me.

Others have push-started in gear, then once underway depress the clutch and abruptly apply the brake. I did not try that.

Extreme cases (mine had sat in a church basement for a year) involve jacking up the rear end, starting the engine with the gearbox in a forward gear, revving the engine & having an assistant abruptly release the jack. Piece of wood or such on the jack to assure quick total release, check twice that you are in a forward gear. This is how I finally got mine loose.

Obviously you want some open driveway or road in front of you if you try either of the rolling methods.

 

[Zimmycobra]

Thanks again, Geo. I may try the first method, as it is fairly simple and safe, after I verify that the clutch is physically operating. I'll let you know how I make out after I can get a chance to work on it this weekend. Thanks again.

 

[TR3driver]

Rather than trying to apply excess force, I just started driving the car with the pedal held down. The heat and vibration from the engine popped it loose before I had gone 10 feet.

Driving without a clutch is one of those skills I consider essential for driving an old British sports car. It's gotten me home more than once. Ironically not always with an LBC; my Chevy had a cable-operated clutch and the cable tended to snap without warning.

 

[Deleted member 8987]

I have a late 1965 TR4A that I have restored mechanically
Went to move the car the other day and found that I couldn't get into any gear. Clutch just wouldn't allow it. Master cylinder is still full, but the fluid is a very dark almost black color.

My guess is that the replaced seal has disintegrated, coloring the fluid and allowing fluid to flow around it preventing pressure for the clutch. Using Castrol LMA Dot 4 fluid.

Plan is to replace the master cylinder (just to be sure going forward) and to replace the plastic tube that connects the pipe to the slave cylinder with a new stainless braided hose.

I have a question just to clarify. At what point in the replacement of clutch hydraulic bits did you shift to DOT5?

 

[Zimmycobra]

I didn't. I use DOT 4 as I said.

 

[Deleted member 8987]

I didn't. I use DOT 4 as I said.

Never 5? You get black stuff in the fluid, first thing one thinks of is mixing 3/4 and 5.
If the PO had used 5, and you replaced the master and slave, used 4, and didn't change the hose and flush the snot out of the lines.....that's where I'd look.
Since a 65 TR4A has an integral reservoir, if you didn't flush the snot out of the reservoir and there was residual 5 in it, plus the back-and-forth of any in the lines, you could very well have eaten the seals.
Personally, I've never seen new seals just go "bad" in that time frame unless some contamination is present.
The question of the presence of any 5 in the system still is...a question.

The other possibility is that the reservoir was not cleaned at all when you rebuilt the master (and all we have to go on is your commentary)......and it's just almost 50 years of crud coming loose.

Suck it all out, re-fill, and bleed at the outlet of the master until clean, see how it works.

You may need a NEW master, another NEW slave, NEW flex hose, and a full alcohol flush of the steel piping.

Because, nobody knows what's in there.

 

[Geo Hahn]

..and to replace the plastic tube that connects the pipe to the slave cylinder with a new stainless braided hose...

I had about forgotten that tr4As use a plastic tube there (3s and 4s use a short version of a brake hose). It will be interesting to note, once you open things up, which seal (or whatever) appears to have failed.

I don't think choice of brake fluid would be an issue in any case (I have used DOT5 for 15 years w/o such a problem), certainly DOT4 is 'as designed'.

 

[Zimmycobra]

I will almost guarantee that there has never been any DOT 5 fluid anywhere near this car. I know the previous owner and it was stored for almost 25 years (not drive-able - before I got it and it never had DOT 5 in it before that I am sure. I personally rebuilt the Master cylinder and it was completely cleaned and refurbished. The slave is new (a year ago) and has never had anything in it except Dot 4. The lines were completely cleaned and blown out with brake cleaner and high pressure air. I do not believe that there are any fluid issues. The new seals, if they went bad, were installed about 2 years ago. Thank you for your thoughts.

 

[Deleted member 8987]

I had about forgotten that tr4As use a plastic tube there (3s and 4s use a short version of a brake hose). It will be interesting to note, once you open things up, which seal (or whatever) appears to have failed.

I don't think choice of brake fluid would be an issue in any case (I have used DOT5 for 15 years w/o such a problem), certainly DOT4 is 'as designed'.

The question is MIXING the two fluids, not dedicated one or the other. If you don't flush it, you get black.
The masters I have seen for a 4A have integral reservoirs. Maybe they are replacement units?
If remote reservoir, and any DOT5 left when you add 4, we have a problem.
Especially since he did the slave, and bled, any contamination is now throughout the whole system.
DOT5.1 WILL mix, but we have no idea what was in it.

 

[RJS]

Here's my thought based on personal experience. I suspect the flywheel is rusted to clutch. Inspect that the slave cylinder is actuating when pedal is depressed. If so, fix as noted above. Essentially, start car in gear and drive with a nice open road in front of you - clutch pedal depressed. Give it some gas, it should break free pretty quickly.

As for the black clutch fluid, I replaced my slave cylinder this summer and bled/flushed the entire system with fresh, clean, new DOT 4 Castrol LMA. Two weeks later the fluid was squid ink black. I flushed completely again and now completely fine. I suspect the new slave had some "sluff" still inside from the manufacturing process.

Good luck

Bob

 

[Zimmycobra]

Bob:

Thanks for the feedback - especially the thoughts about the black fluid. I will try to break the pressure plate free this weekend. I may try the flush and refill approach before replacing the master cylinder as planned. Might be able to save a few bucks that I am sure that I can spend on some other TR requirement . I'll post results after the weekend. Thanks again.

 

[TR3driver]

Just a thought : "Back when", the fluid would turn black if you used non-Castrol DOT 3 or DOT 4. The legend was that the old Girling seals were made from natural rubber, and some brake fluids would attack the seals. I didn't believe that when I first heard it, but proved to my satisfaction that it was true, back in 1979 or so. Brand new, genuine Girling seals ruined in a matter of months.

But that doesn't seem to be true any more, no one else has reported a similar experience (that I know of) for at least 20 years or so. And of course Corey did use Castrol fluid.

What I'm wondering is if, perhaps, Castrol changed their formula (they've merged several times since then, and I believe are currently part of BP, not one of my favorite companies) since it was no longer needed. And then, maybe, someone got hold of the old Girling formula for brake seals and started using that again.

That's a lot of ifs and maybes strung together and I have no idea if it is true. I'm just curious what others think.

Oh, BTW, DOT 5 never turns black in my experience. Any DOT 3/4/5.1 left in the system will vacuum up the wear particles and eventually turn black, but the DOT 5 stays clear. With a really clean system, you may find some black wear particles floating in the DOT 5 but that's all. There's an amusing article at https://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm that shows how the DOT 3/4/5.1 will also suck the purple color out of the DOT 5.

 

[Geo Hahn]

Interesting theory on the Girling rubber formulation.

I, too, have never known the DOT% to turn black -- what will happen if there is some DOT3 or 4 still in the system is the DOT5 fluid will turn clear as the DOT3/4 seems to suck the purple dye out of the DOT5. Actually a useful trait as eventually (several bleeds) the DOT5 retains its purple color suggesting to me that the last remnants of DOT3/4 are gone.

Oh, heck - I didn't read all the way to the end of your post. I'm not telling you anything new.

 

[Deleted member 8987]

Funny. We used to get cars and trucks in the shop that the customer had put 5 into a 4 system, and the stuff in the reservoir was black, black, black.
Unless he or she had bled the system, sucking the reservoir out and adding correct stuff usually fixed it.However, once it went through the process (squeezing through ports, compression and decompression, back and forth) it homogenized and then it was really bad.

 

[TR3driver]

Sure sounds strange to me. I've converted several cars to DOT 5 now by just emptying the reservoir as much as possible; filling the reservoir with DOT 5; and bleeding until I got clear purple at each bleed valve. On the Chevy, I never did open the system again, but the fluid in the reservoir was still clear some 17 years later when I finally junked the car. Never had another leak either; it was still wearing original hoses and seals all round (except for the leaking caliper that was replaced when I did the conversion) at 250,000 miles.

On the TR, the (probably original) rear hose failed some years later, and I mistakenly rebuilt both rear wheel cylinders (thinking they were the problem). I found some black tarry gunk in both cylinders, in the dead area under the piston, which I took to be old DOT 4. But the DOT 5 was clear.

Makes me wonder if your customers weren't adding something else; like perhaps that mineral oil fluid that some English and French cars use. DOT 5 has never been easy to find in stores, and the price is usually high enough to discourage the average Joe from buying it. But lots of folks don't know the difference between say, DOT 5.1 and DOT 5; or "Synthetic". And my FLAPS used to keep the mineral oil stuff on the shelf right next to the DOT 3. I've also seen people put everything from power steering fluid to windshield solvent into the brake reservoir by mistake.
https://www.independent.co.uk/life-...id-drivers-fail-underbonnet-test-9697696.html

 

[Zimmycobra]

Guys: Thanks again for all of the suggestions and help. My available time being what it is, I am still working this out. I was able to get some clutch pedal help and it does look like the clutch is working, in that the arm is moving when the pedal is pressed. I am back to assuming that the pressure plate has rusted to the flywheel. I have been unable to free it by using the starter with the clutch pedal and brake pedal depressed. (I knew it wouldn't be that easy!)

Several of you have mentioned getting it running in gear and then lightly punching it with the clutch depressed to break it loose. I have a couple of dumb questions for you. Right now it is in the garage nose first so I would have to back it out. I do have a very long driveway (900 feet) so I have room to play. Can I start it in Reverse to do what you all suggest or do I need to roll it out and turn it around to use a forward gear (which gear is recommended?)? Now the dumb question - how do I start it in gear? Will the starter be able to turn it over fast enough to actually start the car?

I guess it has been very fortunate that with a lifetime of playing with sports cars (I'm 62 now) that I have never had to start or drive a car without a working clutch before. Please take pity on an old car guy and explain how I safely do this using small words where necessary. Thanks.

 

[TR3driver]

Yup, just stick it in reverse and start cranking. Wouldn't hurt to have the engine warmed up a bit first, just so it's easier to start. When you are ready to stop, just turn the key off and hit the brakes. It may lurch a bit as you come to a stop, but that won't hurt anything (and may jar the clutch loose). Then if you are ready to drive forward, shift to first (with the engine still off), and start the engine again. Since you want the engine to start, I'd stick to using first and reverse.

In my case, I only made it about 10 feet backwards down the driveway before the clutch came loose. But you can potentially drive long distances without a working clutch. Shifting up through the gears is a bit trickier, but all you really have to do is match the engine rpm to the gear you are trying to engage and then pull the lever into gear. When it's time to stop, feather the throttle and shift to neutral, then turn the ignition off while you use the brakes to stop. Believe it or not, most big trucks do this for every shift! (no synchromesh)