91 f250 slave cyl

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  #1  
Old 09-29-03, 03:32 PM
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91 f250 slave cyl

My truck has the concentric (internal clutch slave cyl) there is an inspection port and the manual shows travel specs but is still kind of vague. Does this throwout bearing ride on the clutch fingers all the time unlike an old clutch or should there be visable clearance?
 
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  #2  
Old 09-29-03, 05:28 PM
Joe_F
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Sberry:

I recognize you from somewhere. I think you are in with WGoodrich in the electrical forum? I remember you jumping in and answering my question (that problem was licked a while ago).

I forget if this has a Borg and Beck clutch that's finger style or not. What are you trying to ascertain?

I can send you the printouts and test procedures from my Alldata at work if you tell me what you're doing/going with this.
 
  #3  
Old 09-29-03, 06:31 PM
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Well right now I am thinking I need a master cyl. I turned the flywheel twice and added 50 thou shim between it and the crank. I mic ed the flywheel and measured it from the Ford serv manual and thats what it came out to but it needs to push way to the floor to disengage, so I was adding 25 thou more, still doesnt seem to return all the way properly, like there is too much free play, similar to clutches in the old days. I couldnt find a drawing to see if there is also a return spring in the master to finsh returning the pedal all the way. I was wondering if this system was designed for the throwout to be constantly running on the clutch fingers unlike the old ones. It says there is no adjustment and the fluid level will rise as wear occurs, this tells me there is preload on it.
 
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Old 09-29-03, 09:46 PM
Joe_F
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Sberry:

Drop me a line at [email protected]

I'll look in Somedata, I mean Alldata to see if anything is there, and I'll check the OEM parts catalogs I have for Ford.
 
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Old 09-30-03, 12:46 AM
mike from nj
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most all cars and trucks nowadays have the throwout bearing riding right on the pressure plate fingers, i'm not positive about fords though, so don't quote me.

some slave cylinder have a bleeder screw on it. even without opening the hydraulic system, replacing the clutch can introduce a small pocket of air into the system, which will cause what you have.

try this, i can't explain how it works, but it does sometimes. pump the pedal 10-15 times quickly(in 10seconds) with full pedal travel, all the way up and down, then on the last pump, hold it down for 10 seconds, then slowly release it. it has seriously worked for me at least a dozen times and i discovered it one day from pure frustration, i bled that thing forever, still a low pedal, until i pumped it like that.


i've found it's MUCH cheaper to rebuild clutch master and externally mounted slave cylinders than replacing them, the seal or usually the garter springs behind the seal fails and lets air into the system when letting the pedal up(when under a vacuum). also very easy to rebuild too.

is there a rubber hose somewhere in the system that you can lightly pinch off with vise-grips, this will tell you if the problem is in your master cylinder or a slave cylinder travel problem(divide and conquer)

let us know
 
  #6  
Old 09-30-03, 09:42 AM
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Well in theory over shimming it by 025 shouldnt hurt anything then? As the spring from the slave is what sets the pre load pressure and takes up for wear it should be a non issue and I can probably leave it in then.
 
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Old 09-30-03, 10:27 AM
Joe_F
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Thumbs up Ding, ding, ding...we have some bulletins

SBerry:

See the attached. There are some bulletins that at least vaguely talk about your problem and I think they are worth investigating:

http://alldata.com/TSB/20/91201801.html

If you e-mail me a fax # and the bulletin # you want, I'll try and dig it up.
 
  #8  
Old 09-30-03, 02:54 PM
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Thanks for the help Joe, I looked thru the listings and there are a couple bullitens I might be interested in, will get you the numbers later this evening. I didnt spot anything particular to the clutch though. I think I have a grip on it now, seems like it wont hurt to be overshimmed slightly.
 
  #9  
Old 09-30-03, 09:37 PM
mike from nj
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as the friction disc wears out, the (release) fingers on the pressure plate rise up towards the slave cylinder, compressing it further and adding fluid to the resevoir as you already know. shimming it is just pushing the piston down that much further, i wouldn't be concerned about this
 
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Old 10-01-03, 08:03 AM
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Thanks Mike, your opinion helps reinforece the conclusion I have been coming to that adding 025 to that big spring isnt going to hurt anything. I am not past the point of no return yet so it wouldnt be a prob to remove it but then if it needed it again its a deal. I should have looked in the insp port to start with to see that it was actually riding properly. I didnt mind removing the trans anyway as I wanted to grind a bit off the casting that was causing a tick but it would have been nice to see the brg to start with.
 
  #11  
Old 10-01-03, 08:23 AM
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I think I found the original problem as I somewhat had suspected after the fact is a broken return spring in the master cyl. I opened the box to the new one this morn and there is a world of difference. A new one should make the pedel return to the top properly. I had intended to replace it earlier and as usual ,, should have, would have saved some greif. Thanks guys for the help.
 
  #12  
Old 10-01-03, 09:25 AM
Joe_F
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Thumbs up

Good for you and good job.
 
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