Put my car on a lift- found disturbing news

[leakyfaucet]

I put my car on a lift to see what was causing my steering wheel to pull randomly when I go over bumps. I found 3 problems:

1. Steering rack is leaking. It's a slow leak, so I'm not worried about that, but could this indicate that the rack is worn, and loose? Could this cause the steering to jump when going over bumps? The tie-rod ends were perfect.

2. Outer driver's side axle boot was freshly torn. The boot that is right where to axle goes into the hub. Does anyone know where to buy just the boot? The axle is okay, I'm just going to replace the boot.

3. Clutch slave cylinder leaking. Anyone know the cheapest place to get a clutch slave cylinder? Is it a bi*** to put in?

I will be doing all of the work myself, not taking it to a shop. I've never done any of this before so any tips or advice would be appreciated!

 

[laserspeeddemon]

OK keep in mind, that I'm not questioning your explaination. I'm just not fully understanding the operation of the system.

My appologies if I came off as 'attacking' in my previous post, I mearly wanted to get my point across.

No problem. My point is that many have used the extended rod with no immediate side affects, however, I would only do this as a temporary solution.

I can't speak to the tolerance of the pedal assembly, dash panel and master cylinder (MC), but I personally have 4 DSM's here that if you adjust them to that point, the MC is in cut-off. I venture to say the system (if new-no pedal assy slop) wasn't designed to go out that far (even though it can, doesn't mean it can be 'used' at that point)

I need further explaination of this. I, initially, had the clip adjusted about a little more then
half way out. Would not go into gear. I spent the whole day adjusting it out until it pretty much came all the way out. I adjusted the top side adjustment, to ensure maximum pedal travel, it was working, but was grinding going to every gear. Thats when I ordered the SS line and the Extended rod. Which problem improved GREATLY, but was short lived. The pedal got worse and worse.

The hydraulic clutch system is self adjusting. People need to realize this. As your clutch wears, the release fork moves more towards the engine. The slave cylinder (SC) needs to compensate. So, as a result the piston in the SC gradually, over time, moves more and more into the body of the SC.

Wouldn't this caust the piston to move AWAY (or further out of) from the body of the slave cylinder. The clutch fork works on lever. As the far side moves towards the engine, the near side should move away from it, this would cause the the rod to move out, which, in turn, would move the piston away from it as well. Was this a mistake or did you mean to say in moves into the body, if so, I need a explainatoin of this too.

Now, also recall why the slave is called the slave. It's reacting to actions at the MC. The MC is pushing fluid to it. It can ONLY move the amount induced by the amount of fluid sent it's direction. Now, the way the MC moves that fluid is by a piston and a compensation port. The port seals itself in the first 3-8mm of travel of the clutch pedal. Then, the fluid you are displacing at the MC can't be pushed into the reservior, it's sent to the slave.

I agree on this statement, but where I don't understand is if the there is 3-8mm of travel on a (guessing) 32mm rod, the total maximum travel is 40mm. However the Pedal bushings are letting the pedal move upon function and only allows 2-5mm of travel upon full compression of the pedal, then the total maxium travel is 37mm. If you get a extended slave rod that is 35mm (instead of 32mm) then you make up that missing 3mm. To return to the 40mm of maxium travel. Now I'm not saying that the pedal rod moves 40mm, I'm just using rough numbers to easier show my point about how an extended rod would improve some probelms based on the numbers you put out. I'm using rough numbers to keep things clean, instead of rations of the piston of the MC vs SC, which would include fractions of fractions.

Ok now for the bad. Since you are applying more pressure to the same existing location. You apply un-needed stress on the rest of the moving assembly to included; the PP, SC, MC, TOB, etc. However the longer the rod, the more accerlerated the wear will be. In my case, it REALLY bad. as I have a nut AND a extended rod, but is temporary. And 3 of the parts that could fail have lifetimes warranties.

There is no adjustment on the slave. The only way to increase the travel of the SC is by changing hydraulic ratios (MC/SC diameters) or changing the actutation point of the MC on the pedal itself (ie where it attaches).

There is no manual adjustment, but it is adjustable. The point of the longer rod is not to change the amount of travel from the SC, but the amount of travel over all.[/QUOTE]

There are only two reasons why the extended slave can work. One, misadjustment of the MC. If you adjust the pedal too far up (it deadstops), then you start to push on the MC rod and it puts the MC into cutoff (remember it only takes 1-2mm of pedal travel to induce this which is fraction of that at the MC(say .5 - 1mm) SO, if you've deadstopped the pedal and continued to adjust the MC rod out further, you will put it into cut-off. Then, you can't push the SC rod into the body. It's dead headed. Then, by adding any extra length of SC rod, you offset the release fork.

I still don't understand what cut-off is.

The second, would be making the extended slave rod too long. Long enough that when it is installed, it's constantly putting pressure on the release fork. (adding the nut can do this) I'd have to go measure the slave, but for discussions sake, say the bore is 40mm long. The piston (at nominal) is located in the middle of the SC body. Stroking the pedal (when adjusted correctly to provide maximum stroke) moves the slave piston 15mm. Release, and it returns to the middle. Over the life of the clutch, the disk wears, resulting in the release fork riding closer and closer to the SC. From the nominal point (center), the slave bore, because it's 40mm long, has 20mm of travel deeper that the piston can ride. This is more than likley within the bounds of a totally worn clutch.

Continuing the previous paragraph, Now remembering that the SC piston has +/- 20mm it can move. If you install an extended slave rod in that is say, 22mm longer, that means the piston will be pushed into the SC body 20mm (now bottomed out) and the slave rod now has to push the release fork 2mm in the opposite direction. (Yes, I can see how for some of you it works and you seem to have no symptons, yet) This is sketchy at best. It is guess work on whether you have the right length to where the release fork it not riding constantly on the pressure plate (PP), because now you've taken out all the self-adjustment of the hydraulic system. The downside of this approach is, as your clutch disk wears, the slave rod can't move deeper in the SC body and adjust. The result is a slipping clutch over time. It can also mean excessive wear on the PP fingers, TOB damage or early failure.

Have you seen the extended rod, it is only several mm longer then the factory one. Or at least the one I ordered was. I guess I can only wait and see. As soon as I get the DD running, I putting in a new tranny anway, so I will be able see the wear on the PP fingers.

Anywho, good post.

 

[Morphius]

I need further explaination of this. I, initially, had the clip adjusted about a little more then half way out. Would not go into gear. I spent the whole day adjusting it out until it pretty much came all the way out. I adjusted the top side adjustment, to ensure maximum pedal travel, it was working, but was grinding going to every gear. Thats when I ordered the SS line and the Extended rod. Which problem improved GREATLY, but was short lived. The pedal got worse and worse.

The pedal has a limited amount of swing, defined by the assembly or box it's attached to. Adjusting the MC rod moves the pedal up and down. If you crank the MC out far enough, it'll push the pedal up and bottom it out against the bracketry. Once it's hit that point, then it starts pushing the MC pushrod in. Recall, it only takes a few MM to put the internal MC valve into cut-off.

Wouldn't this caust the piston to move AWAY (or further out of) from the body of the slave cylinder. The clutch fork works on lever. As the far side moves towards the engine, the near side should move away from it, this would cause the the rod to move out, which, in turn, would move the piston away from it as well. Was this a mistake or did you mean to say in moves into the body, if so, I need a explainatoin of this too.

I meant as I said, the SC piston, over time, moves deeper into the slave body. As the clutch disk wears, the thickness decreases. This causes the PP fingers to then move outward. (imagine if you had installed no disk in your clutch on an install, what would be there to push on the PP fingers to flatten them out?) This results in moving the TOB away from the clutch, which makes the release fork, at the slave rod end, move towards the slave.

I agree on this statement, but where I don't understand is if the there is 3-8mm of travel on a (guessing) 32mm rod, the total maximum travel is 40mm. However the Pedal bushings are letting the pedal move upon function and only allows 2-5mm of travel upon full compression of the pedal, then the total maxium travel is 37mm. If you get a extended slave rod that is 35mm (instead of 32mm) then you make up that missing 3mm. To return to the 40mm of maxium travel. Now I'm not saying that the pedal rod moves 40mm, I'm just using rough numbers to easier show my point about how an extended rod would improve some probelms based on the numbers you put out. I'm using rough numbers to keep things clean, instead of rations of the piston of the MC vs SC, which would include fractions of fractions.

I can see where you are coming from. However, it still comes back to the self-adjusting aspect of the system. Even if you add a longer pushrod, it'll just push the SC piston deeper into the bore. The system will try to fine equilibrium. It takes less force to move the piston deeper in the bore, than move the release fork.

Now, this also leads into a situation where the SC rod is too long. Again, keeping in mind that as you add more length to the rod, the SC piston moves deeper in the bore. Say you hit a point where the piston is now bottomed out? Then it'll start to push and displace the release fork. For an instance like this, yes it works, even with a properly adjusted pedal. However, it's not a good idea because the self-adjustment feature is now gone. The result is a clutch which can start slipping more progressively over time along with accelerated TOB and PP finger wear. Very, very temporary. I might do it to get myself down the road, or get the car to the shop, but I wouldn't drive this way for any amount of time. It's just not a good idea, and will cost you more money in the long run.

Ok now for the bad. Since you are applying more pressure to the same existing location. You apply un-needed stress on the rest of the moving assembly to included; the PP, SC, MC, TOB, etc. However the longer the rod, the more accerlerated the wear will be. In my case, it REALLY bad. as I have a nut AND a extended rod, but is temporary. And 3 of the parts that could fail have lifetimes warranties.

True and not a good idea as you are aware. But how can the PP and TOB be covered under warrenty, when it'll be an obvious misadjustment problem? I think there are alot of people having this issue, accelerated wear. I've seen quite a few ACT 2600 PP with worn grooves in the fingers lately. I'd suspect, they don't have 50, 100, or 150K on them either. A pp shouldn't wear like that in a short amount of time.

There is no manual adjustment, but it is adjustable. The point of the longer rod is not to change the amount of travel from the SC, but the amount of travel over all.

Still though, it doesn't. You are mearly offsetting the slave rod, which will only work if the MC is in cut-off or you've bottomed out the SC piston, as discussed above. Remember, if the MC is adjusted properly, the slave will self-adjust, based on where the release fork is. Between pushing on the SC piston and the release fork, the SC piston moves first with less resistance. If you install a longer rod, it just pushes the SC piston deeper in the body.

I still don't understand what cut-off is.

The MC piston consists of two plungers, the main plunger and a smaller one on the end of it. The MC cylinder bore is usually stepped, with the larger one for the main plunger and a smaller one mating up to smaller the comp port plunger. In the end of the large bore there are holes leading out (or down) to the fittings for the clutch lines. In the end of the small bore there is a hole that leads to the reservior. So, with the pedal not pressed, fluid can move (in a sense it doesn't actually move) from the reservior to the MC bore to the lines. Nothing is sealing any of those off from each other. As you actuate the MC, in the first 1-2mm of travel, the smaller plunger seals off the smaller bore. Now, no fluid can travel to the reservior. At this point, all the fluid moves out the larger bore hole to the clutch lines. Without the comp valve, as you acuated the clutch, all the fluid would just be pushed into the reservior. This is cut-off. When the comp port is shut.

I'll see if I can find a good pic.

Have you seen the extended rod, it is only several mm longer then the factory one. Or at least the one I ordered was. I guess I can only wait and see. As soon as I get the DD running, I putting in a new tranny anway, so I will be able see the wear on the PP fingers.

I don't have one. I've seen them listed on the internet, so I can't speak to how much added length they have.

 

[laserspeeddemon]

So to sum it up
-Cut-off is when the the Master cylinder is sealed off from the Resvoir so that upon compression, fluid can only move through the lines.
-Maxing out the adjustment will cause the MC internals to mash into each other (over compression)
-To long of a extension cause damage on the PP.
-My problem is indeed the pedal (I was 100% sure of)


Good Deal, man. This all makes more sense now that you explain it further. I forgot the PP actually is a levering system itself, so it makes sense that the SC pistons moves into the bore an not out of. I need to get a new MC (again).

How far should I adjust the U-clip upon installation?

 

[black turbo gsx]

give rockauto.com a shot 4 parts

 

[Morphius]

So to sum it up
-Cut-off is when the the Master cylinder is sealed off from the Resvoir so that upon compression, fluid can only move through the lines.

Yes.

-Maxing out the adjustment will cause the MC internals to mash into each other (over compression)

It's more of.... maxing it out will close off one valve too soon. It'll be closed before you even press the pedal. The ideal is it's closed after you start to press the pedal.

-To long of a extension cause damage on the PP.

Yes.

-My problem is indeed the pedal (I was 100% sure of)

Sounds like a high potential.

Good Deal, man. This all makes more sense now that you explain it further. I forgot the PP actually is a levering system itself, so it makes sense that the SC pistons moves into the bore an not out of. I need to get a new MC (again).

How far should I adjust the U-clip upon installation?

Adjust it per the sevice manual, so with in the first 1/2" of actuation, you start to feel resistance. Check the system for cut-off by pushing the slave rod into the body of the SC. If you can't, it's in cut-off.