67 austin healey 3000 clutch problem

Question or Comment::
> Please help I own a 1967 Austin Healey 3000 and this is the
> problem...35 miles ago the clutch worked perfect!! Now the clutch
> releases at the extreme very very top pedal travel. How do we adjust
> this down? The clutchsystemis hydralic there are no threaded rods to
> adjust. I have checked the resevoir, master cylinder, slave cylinder
> and all related lines. There are no leaks in the system. What sequence
> of check points would somone suggest for me to follow to correct this
> situation???? Car shifts, runs, drives fine. Just the clutch issue.
> Thanks for your help!

Hi Fraser,
When was the last time you changed the fluid in the brake/clutch system? If it has been more than a couple years, I'd start with replacing all the fluid and bleeding both systems.

How does one go about bleeding the clutch?

Depress the clutch pedal, open the bleed screw to allow air/fluid to escape, and close the bleed screw before releasing the pedal. Repeat numerous times, until no more air comes out (only fluid) and until you get clean fluid (this assumes you extacted the old/dirty fluid and filled the reservoir with clean fresh fluid before starting)

Brake fluid is hydroscopic, meaning that it will suck the moisture out of the surrounding air. Never use fluid from a container that is partially full and more than three (3) months old. Buy the pint containers, not the quart size, unless you're sure you'll use the whole container.

There are pressure bleeders on the market from various sources, but you'll need to know the fundementals before using any of them; better to have a willing assistant...

At the risk of sounding like the class nerd, the term is 'hygroscopic,' and of course silicone fluid isn't (but that's a discussion for another thread).

The clutch slave cylinder bleed screw is located at the top of the cylinder and hard to get to. It's actually easiest to unbolt the cylinder from the housing to bleed it.

Bob_Spidell said:

At the risk of sounding like the class nerd, the term is 'hygroscopic,' and of course silicone fluid isn't (but that's a discussion for another thread).

The clutch slave cylinder bleed screw is located at the top of the cylinder and hard to get to. It's actually easiest to unbolt the cylinder from the housing to bleed it.

Click to expand...

Nerd :wink:

Well, it rhymed with hygroscopic...

I'll take fluid changes every couple of years over a spongy silicone fluid pedal (in case we don't get another thread). There are other drawbacks as well, in my opinion, but that one alone is a deal-breaker for me.

Hello fraser,

If you bleed the slave cylinder off the transmission housing (where it usually lives)is probably the easiest for BJ8 cars remember to,

a) attach a hose from the bleed nipple into a glass (so you can see when the air stops coming through) jar with a small amount of fluid in the bottom.
b) fasten either a large hose clamp or "C" clamp around the cylinder to stop the piston from coming out when the pedal is depressed.

Best regards,

bundyrum.

I agree with all that have posted. Not sure of your experience but I'll assume you haven't done this before. You'll have to jack up the car, or put on a lift to reach the clutch cylinder. It's attached to the transmission. It's really easy if you remove, or at least set aside the transmission cover. If you're going to that much trouble I would highly reccomend you replace the clutch cylinder hose as they get spongy and soft over time and will cause the problems your having. After doing all that you should notice that the plunger will operate much further than before, thus the clutch will operate much better.

Randy Forbes said:

I'll take fluid changes every couple of years over a spongy silicone fluid pedal (in case we don't get another thread). There are other drawbacks as well, in my opinion, but that one alone is a deal-breaker for me.

Click to expand...

Is that from experience, or hearsay? I've used silicone brake fluid for years in my BJ8 and the pedal doesn't feel at all spongy to me. I haven't driven other BJ8s, but have driven older 3000s and the pedal feel on my car is only slightly softer, which I attribute mostly to the older cars not having a servo.

The common wisdom is that any sponginess is due to air in the fluid, most likely due to improper filling technique or handling of the fluid. No fluid, AFAIK, is compressible but air certainly is.

Another issue--relevant given Ford's recent massive recall on cruise control cutoff switches--is that 'organic' brake fluid is flammable. I haven't heard of it happening, but the brake light switch in Healeys is not unlike the cruise control switch in Fords (and probably other modern cars)--i.e. there is only a diaphragm separating the brake fluid from 'hot' electrical contacts--hence a fire is not inconceivable.

Well, with DOT 5, remember, anyone who quotes "hygroscopic" needs to also be aware of the design characteristic of DOT 5 absorbing AIR.
DOT 5 holds air bubbles in suspension, hence the "soft" pedal.

You can buy Root Beer and never have a can explode when you pop the top, but the delivery guy drops the case, some punk shakes the cans in the chill box up.....SIMILAR thing can happen with DOT 5.
Don't shake. Don't pour excessively (once, long ago, I read never to pour from a large container to a small container before installing, as more air bubbles could be created).

You're lucky.

Dave

If silicone brake fluid was that great, it would be standard in all our BMWs.

Several years ago, BMW decided to include free maintenance within the warranty period. At the same time, they extended the mileage interval between oil changes to 9000/15000 miles(depending on engine; the ///Ms have the lesser interval) undoubtedly to save money. Old-school me, I still adhere to 4500 miles or once per year if I drive less. But they still mandate that the hydraulic brake/clutch fluid be purged/replaced/bled every two (2) years from the in service date.

Takes longer to replace the hydraulic fluid than do an oil change, yes?

Maybe rapid-firing ABS solenoid valves don't like a spongy feel either?

My feelings against silicone fluid are from experience (beginning in the mid 80s), long before there were any BMWs in my garage. :wink:

Randy Forbes said:

If silicone brake fluid was that great, it would be standard in all our BMWs.

Click to expand...

Not if they have ABS. Silicone BF is not suitable for ABS, I believe due to viscosity issues (all ABS that I've owned/seen specify Dot 3). The rapid cycling of the valves may be problematic with DoT 5 as well.

TOC said:

Well, with DOT 5, remember, anyone who quotes "hygroscopic" needs to also be aware of the design characteristic of DOT 5 absorbing AIR.
DOT 5 holds air bubbles in suspension, hence the "soft" pedal.

...

You're lucky.

Click to expand...

Soooooooooooo ... you've used silicone BF and gotten a 'soft' pedal?

Johnny said:

....If you're going to that much trouble I would highly reccomend you replace the clutch cylinder hose as they get spongy and soft over time and will cause the problems your having. ...

Click to expand...

I agree with Johnny on this point. A soft rubber clutch line can cause the sudden change in the clutch release point and can get so bad that after a while, the clutch won't engage at all. The line swells up internally and blocks the flow of brake fluid bcak to the reservoir when you release the pedal.

Bob_Spidell said:

Not if they have ABS. Silicone BF is not suitable for ABS, I believe due to viscosity issues (all ABS that I've owned/seen specify Dot 3). The rapid cycling of the valves may be problematic with DoT 5 as well.

Click to expand...

Then how well does it stand up to cadence braking?

Cadence braking explained: https://www.madabout-kitcars.com/kitcar/kb.php?aid=448

I did a quick search to uncover some of the mystery of silicone brake fluid. I have used it for years for certian racing applications, but wont use it for others. Check out this link:

HERE

Here is some more information that may help better understand the DOT specifications.

And HERE

Thanks for that; I learned some things I didn't know (just took for granted) and reinforced some beliefs I already holdfast.

Randy Forbes said:

Then how well does it stand up to cadence braking?

Cadence braking explained: https://www.madabout-kitcars.com/kitcar/kb.php?aid=448

Click to expand...

I wouldn't expect a problem; ABS cycles much faster than anyone can pump a pedal. I don't have definitive info on silicone BF aerating in an ABS system, but I vaguely remember reading that somewhere.

Randy Forbes said:

Thanks for that; I learned some things I didn't know (just took for granted) and reinforced some beliefs I already holdfast.

Click to expand...

IOW, when someone writes what you already believe you're going to believe it even more. That's the point I'm trying to make: people have beliefs they are going to believe no matter what. The link cited does not cite any references--remember footnotes?--and I'm always leery when someone uses phrases like 'it would seem' (that's a strong clue they're simply offering up an opinion). That is not a definitive way to prove anything--just more opinion and hearsay. Now, if he cited actual data I might be swayed (he mentioned SAE but failed to cite specific references).

I've heard claims silicone BF causes a 'soft' or 'spongy' pedal. I've asked someone who made the claim if he installed silicone BF and got a 'soft' pedal. I'm not trying to pick a fight, I'm actually interested, but so far no one has come forward and stated unequivocally that they installed DoT 5 and had an unacceptably soft pedal. It appears this may be another instance of hearsay or previously determined opinion being passed off as fact.

I respect the opinions of many people on this site, many of whom have a lot more experience than me, but I take nothing on faith. I want to see data. I've used silicone BF for many years of hard driving--no, no racing--with absolutely no problems. That's a data point, for anyone looking who hasn't already decided what they're going to believe.

I made the mistake of trying silicone on a fully sealed brake system. Basically you fill the body with a gravity type bleeder, bleed, then seal up with a plug. When the system reached normal operating temp, fluid would have expanded, build up pressure, engange brakes, and get spongy pedal. Replace with DOT 3, 4 or 5.1 and didnt have any problems. On a different standard style brake system with a resevoir for same application, the silicone would work flawlessly. Now when I changed the sealed fluid displacement system to a resevoir, there were no problems and it worked same as with glycol based fluid. You could say I didnt pour or bleed it properly, but it always worked in one style and not the other. It should work in an automotive application if the fluid temp does not vary much or volume of fluid under pressure was at a minimum. But it is just my opinion.

My admittedly <span style="font-style: italic">bad experience</span> came by way of a 1958 XK140 Rdstr, sometime around 1985. The owner (Robert Hatcher) complained that he had a spongy pedal after just flushing the brake system and substituting silicone fluid. Claimed to have purged all the circuits with the then available brake parts cleaner.

Without the use of any type of pressure bleeder or suction device, we bled his system for several rounds and made no progress: unacceptable spongy pedal. The next day, I purchased rebuild kits for the master and wheel cylinders from Jaguar George (George Bentley, Lafayette, Louisiana) and procedded to rebuild them all.

Upon disassembly, there was nothing found to be out of the ordinary; no puddles of reluctant glycol brake fluid found hiding anywhere. The brake pipes and reservoir were purged with more chlorinated brake parts cleaner while the circuits were opened up. The silicone fluid was a reddish-purple color, but I do not remember the brand name.

After putting the works back together, Robert Hatcher (the car's owner) came back to my shop (1012 Emerante Drive, Breaux Bridge, Louisiana) and we once again embarked on bleeding the brakes. Prior to his arrival, I had let the system "gravity bleed" to expel as much of air that would be trapped in the pipes and cylinders as possible (the master cylinder was pre-bled on my workbench). Again, the results were a spongy pedal.

I had found nothing wrong with his brake system, so I condemned the silicone fluid. It was the first time either of us had tried it.

I once again tore down the master and wheel cylinders, cleaned them and the pipes with more brake parts cleaner and put everything back together. I filled the system with Castrol GT LMA brake fluid, allowing it to drip from each wheel cylinder prior to Robert coming back the following day to quickly and successfully bleed the circuit, test drive the car and take it home.

Job finished.

Now I don't know why we couldn't get the silicone fluid to act right in that Jaguar, and I really don't care.

I've done my best to give you the information as I remember it, so I'm sorry if I lack the documentation you desire.

I'll be damned if I'll ever put silicone fluid into another brake system as long as I live, nor will I recommend it to anyone that asks.

I use Castrol GT LMA exclusively in my Healey, and ATE Amber (ATE Blue can stain the reservoir) in BMW M Rdstrs/Coupes (of which I've probably refreshed the brake fluid in at least ten__10__examples just this year).

Nowadays, I do use a pressure bleeder, and in the case of the BMWs, a diagnostic computer that can cycle the ABS solenoid valves during the bleeding process. I like to be thorough, as I cannot allow a "come back" situation for my customers.

I, as well as the BMW owners that either drive or ship their cars across several states, some from as far away as Texas, Florida, California and most of the New England states, consider myself to be quite competent when it comes to working on British and German sportscars. I am located in Toledo, Ohio.

I will back that up <span style="font-weight: bold">with bonafide documentation</span> of my completed work. Please see: www.spcarsplus.com/gallery