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  #1 (permalink)  
Old 12-02-2001, 07:37 PM
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Default Slave Cylinder Snapped

Gang,

Taking a leisurely drive today when I enagaged the clutch to shift into third. I heard this little tink under my clutch pedal, and suddendly had no clutch. Not far from home, I gently drove my car home and let it cool. After jacking up the car to check the clutch arm adjustment, I discovered that the slave cylinder mounting arm had snapped leaving the assembly semi-functional until I physically touched the rod arm and had the slave cylinder fall free. Have any of you experienced this situation? I have a top loader and the cylinder is a Wagner-Lockheed. I think it stamped FD 48909. Do you think that this was a weak or slightly fractured part, or does this possibly indicate that the positioning of the drive arm is out of plumb to the extent that it is placing undue stress agianst the bracket. The reason that I say this, is because the casing on the tranny has been notched out by the manufacturer so that the drive arm has clearance to engage the slave cylinder. However, I noticed that the arm has been rubbed worn a little bit against the casing. This is what leads me to believe that the casing needs to be notched out a little more since the flex boot sits slightly at an angle, thus changing the angle that the drive arm takes to enage the cylinder. While I know that this part is warrantable form my builder, I'm wondering if the major parts houses might have it in stock. But more so, what should I do to keep this from happening again? Any suggestioms or comments?

Fred
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Old 12-03-2001, 08:51 AM
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Fred:

Do you use the slave kit bracket that Unique supplies or did you make your own?
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Old 12-03-2001, 05:04 PM
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Cal,

I used the factory cast Wagner/Lockheed slave cylinder with the bracket cast as part of the assembly. I checked with Unique this morning, and Alan had never heard of this happening, since the cast metal is about 3/8ths in thickness. I went to NAPA this morning (they too were surprised to see the break), and they were able to cross reference their number with Lockheed's number. Surprisingly, they had one in stock. More interestingly, was the fact that the bracket arm of this new unit had a slight jog in it, which centered the drive arm more precisely to the middle of the fork. The Lockheed cylinder had a straight arm bracket which is why Unique had to notch the bell housing. Anyway, maybe a casting weakness, or possibly dropped somewhere in the distribution stream, causing a slight fracture at the weakest point on the cylinder, the mounting hole. All's well, that ends well!! Installed the new one today, and headed off into the 70 degree, blue sky day. Thanks for responding.

Fred
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Old 12-03-2001, 07:36 PM
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Exclamation Crap!

Fred,

Dang, that's not good to hear. I'm just now installing that slave assy. on my car, as I'm getting tired of dropping the trans just to service the slave cylinder.
Now I start hearing of problems with this setup.

I bought the bracket and cylinder from Unique and got the fork from the local Ford dealer. I hope it works.

Later,
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Old 12-03-2001, 07:57 PM
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Fred,
Could you post the NAPA and/or Lockheed part numbers? Just in case.......
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Old 12-03-2001, 08:18 PM
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Default Slave Cylinder #'s

Jim and David,

The Wagner/Lockheed # FD48909 and the NAPA crossover #33721 (United Brake Parts). Here they are JUST in case. However, I think this may have been just a fluke.

Fred
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Old 12-03-2001, 08:32 PM
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Jim & David;
In 16 years of being around Uniques cars this is the first time I have heard of the casting of the slave cyl breaking.

Poorbboy
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Old 12-03-2001, 08:44 PM
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I have to agree with Poorboy, we have installed eight of these with 'nary' a problem.

Dave: Why do you have to drop the transmission to remove the slave cylinder? It is externally mounted in front of the transmission.
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Old 12-03-2001, 08:45 PM
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Default YOU ARE ALIVE

Don,

I was checking the obituaries..felt sure you kicked!! I agree the slave cylinder breaking was just a strange test of fate, to further familiarize me with the underside of my car. Having a ***** of a time getting my speedo cable in. Okiesnake said that I am going to need some type of adaptor from Unique for my guage, due to my top loader(to change rotation). Do you have any idea if I do need such an adaptor? Also, could get the cable to slide into the tranny opening, although a very snug fit! However, the cable will not go into the guage far enough for me get the collar nut to thread. The stop on the cable goes all the way to the guage opening, but the bell fitting still lacks about a 1/4" of beig snug against the housing, thus not allowing the collar nut to reach thread. Got any ideas?

Fred
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Old 12-03-2001, 09:30 PM
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Fred;
Unless you have a reverse sweep speedo you don't need any kind of adapter. What did you buy the cable to fit? Other than length any speedo cable for most Fords in the 60s will work. Sounds like you don't have the cable in the gear. Try turning the cable at the speedo end while pushing in on it. It should not turn.

Poorboy
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Old 12-03-2001, 11:16 PM
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Cal,

I originally used the McLeod hydraulic T/O bearing, which eliminates the clutch fork, pivot, and all external linkage.
This setup is functionally identical to that which Ford uses on many of their late model vehicles. (My Explorer has a similar setup and no problems in almost 200,000 miles.)

When it works, it is exceptionally smooth and has a relatively light pedal feel, considering the monster pressure plate I have.
However, the McLeod unit has failed twice in 1,300 miles. Th efirst time an internal seal got rolled out of its groove and cut. This time, an o-ring on a banjo fitting deteriorated and leaked.

Since the slave is mounted concentric to the input shaft, the trans has to be dropped to get to it.

That's why I decided to go to the more conventional setup. At least if it leaks, I can fix it in a few minutes.
The biggest hassle is the external slave is right where I originally mounted a torque limiting chain, so I had to design a new mount for that. (There's always something.)

I should have it back together tomorrow. I'll let y'all know how my clutch feels then.

Later,
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Old 12-04-2001, 08:59 PM
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Default It works...sort of.

Well, I got everything back together today.
I fired her up on the lift, and stuck it in gear.
The clutch won't quite release completely, it drags just enough to keep the trans spinning, making reverse grind a bit.

I adjusted the slave pushrod for about .100" clearance, and lengthened the pedal pushrod to maximum, but it still drags.
However, the pedal pressure is very light, heck I can push it down easily with one hand now.

I just ordered a 1" bore master cylinder to replace the 3/4" unit.
I hope that will firm up the pedal and shorten the throw back to where it was before.

Later,
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Old 12-05-2001, 06:02 AM
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David,
A couple things to check first.... if you haven't already done it.
First would be a compatability issue between the present master and slave. If the present master is moving enough fluid to move the slave to its maximum travel, your not going to gain a thing by changing masters, except maybe to change pedal feel.
If the slave is moving as far as it can before blowing out the seals, than your going to have to look at the leverage issue at the clutch fork/slave rod junction. Can you attach the rod closer to the bell housing? This would provide less leverage equaling more travel at the throw out bearing, and will also increase pedal feel.
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Old 12-05-2001, 08:09 AM
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Default grinds into rev...

hope you dont have the problem a neighbor had on his s-10 (since we build cars we're the neighborhood final solve on car problems). after he had replaced lines, mc, slave, clutch/presspl, pin, trans.......he brought it by. the stock gm unit only travels 7/8"-1 1/8" and no more, it auto adjusts off of an internal spring/sliding valve when it first contacts the arm, thereby starting the travel. this one traveled only 1", still not enough, ground going into gear. bleeding didnt solve it. it was the thickness of the throwout bearing face that did him in. number same (rebuilt) with a hydraulic unit/arm/tbearing it's still static as to the dimensions, actually an easy problem to solve. the hydraulic fluid/line merely replaces the linkage.
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Old 12-05-2001, 07:27 PM
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Jim and Sonny,

Thanks for the suggestions. I already checked the travel and I'm only getting .550" at the slave with the max stroke possible at the master.
The slave looks to have over 1" of total travel, and the 1" bore master should give me about ..900", (I did the calculations last night, but I left it at home) which should allow me to lower the pedal back down and still have plenty of travel.

I'll post back next week when I have a chance to swap it.

Thanks,
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Old 12-06-2001, 09:05 AM
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Default SONNY: CLUTCH ADJUSTMENT?

Sonny,

While I have you in this thread, let me ask you a question about my clutch adjustment. I have a top loader, with a hydraulic clutch. I have adjusted the clutch to the point where it shifts fine and works seemingly quite well. However, after I have run the car for 20-30 miles, or otherwise to the point where it is warm from travel, the clutch seems to loose some adjustment and want to grind to gear. Physically, the adjustment arm has not deviated, as I have the locking nut securely in place. It seems to only do this after the system has been run for a while. Also, I notice that the clutch pedal will sometimes not have any initial resistance, but a quick pump of the pedal immediately regains pressure. I bled out the system ( I thought, thoroughly), when I installed the new slave on Monday. Also have rechecked and topped off the master with fluid. While it doesn't seem to be a problem, I'm just gaining info on the characteristics of what to expect on my car operation. Do you have any thoughts on these two questions? Thanks!!

FIAFRED

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Old 12-06-2001, 01:03 PM
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Fred,
Something to check....
Does your clutch pedal return ALL the way back when you take your foot off of it?
Might need a return spring to help it out.
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Old 12-06-2001, 01:30 PM
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Default Clutch Spring

Jim,

Thanks for the reply. Yes, the clutch pedal does return all the way, as I have got a spring on the tranny to keep pressure from the fork to the drive arm, so that it does not drop out.

Fred
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Old 12-06-2001, 07:22 PM
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Fred,
I meant a spring on the 'pedal' itself. I remember reading somewhere that one may be necessary if the master cylinder rod does not return all the way in order to uncover an internal valve. Was susposed to affect the way the pedal felt...... like you were explaining above.
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Old 12-06-2001, 09:23 PM
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Default Pedal Spring

Jim,

You raise an interesting question. I was trying to think my way through the idea that the spring on the drive arm had the same effect as a spring on the pedal, in as much as, the spring on the drive arm is placing a positive pressure on the rod arm in the direction of the cylinder return. Is my thinking skewed on this line? I will note the travel on the pedal now that you raise this question, because I can also visualize that if the pedal does not fully retract that it would create the situation that you suggest by not fully activating the internal valve, which creates a resetting type motion for the slave. I do not know how the slave works to this end, as I thought it was a simple motion of the plunger traveling through the cylinder with the application of pressure from the pedal and returning as pressure is relieved. Can you sort through my reasoning and set me straight?

Fred
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