Need a good clutch

So, I'm tired of fighting with futile external fixes for my truck's clutch.  After the number of times things have been bled, the few different lubes I've tried thinking it was a synchro issue, the darn thing has just gotten worse and I have realized now that the clutch is dragging.  It's getting to the point where I sometimes have to shut it off at a stoplight to get it in gear.  The part that I don't get is that the clutch still acts "normal."  It always engages at the same distance away from the floor.

I have no idea why, but it's not something I can fix from outside.  I'm just going to re-do the whole bloody thing.  The frustrating part is that I know the PO did a clutch, master, and slave right before selling.  I know that because I saw the receipts and visual inspection showed all the tell-tale signs... as in, the master was the only thing under the hood that was perfectly clean, the bleeder for the slave was pristine, and the transmission case had all the fresh greasy fingerprints on it.  My only guess is that they cut the flywheel too much instead of using a new one.

At any rate, it all has to come apart, and given how cheap parts are for a 94 Fordzda Branger, I can do the whole thing for about $200 in parts.

I know nothing about good clutch brands, nor the materials used to make them.  In all honesty, the only thing I know about clutches is how to replace them.  I did a lot when I was working in repair shops.  Box of generic parts shows up, I install them, customer drives away.

Application 94 Mazda B4000 (Ford Ranger 4.0L/M5OD).  I frequently push the limits with the truck.  70% of it's life is driving around with a little lumber in the back.  The other 30% is towing 4000 lbs around town with lots of hills, lots of stop and go, and (with 160 hp) lots of shifting on the highway with a trailer to keep speed.  I truly use it like it is an F150.

I want something that will take the heat, but not be a leg-killer, and not be tough to engage smoothly.  I assume (since they're pretty similar in function to brake pads/rotors) that each composition has benefits and drawbacks in each category.  Much like how F1 brake pads don't work until they're hot, or metallic pads like to eat rotors.

Get me up to speed?  This should be an engaging conversation. Get it... engaging.  Clutch joke.

I don't have any suggestions on clutches, other than to make sure it's new and not reman. I've had bad luck in the past with reman pressure plates. 
 

I am interested to see what you find when you get it apart. I had one in the past where the PO put the disk in backwards and after a little bit of wear the hub was contacting the flywheel bolts causing problems. 

Double check the crank shaft thrust washers. Several times over the years I have run into cars that would not disengage because the crankshaft was moving forward when the pedal was depressed. Yeah, it sucks. I also agree with Notime about reman clutch parts, do not use them.

I'm half-tempted to just get a junkyard longblock and freshen it up and swap.  I have a lifter tick as well, which on the OHV 4.0L requires pulling the heads.

I will check for crank walk.  I've never noticed flecks in the oil, but when the trans is out it's a lot easier to pull the pan and look.

The partial list of little nitpicky things on this truck looks like this:

Did the PO change the pilot bearing?  
 

Your issues sound exactly like what happens when they are in the early stages of departing this world.

It could be a failing pilot, or a bent finger or two on the pressure plate, but forgive my prejudice that the problem is air in the hydraulics.  These are notoriously difficult to bleed due to the way the master cylinder is oriented, and people have made good money inventing tools to make it possible, like reverse bleeders.

It's a rare Ranger/B-series that doesn't have disengagement issues.

I have had the best luck removing the master cylinder, inverting it so the outlet is on top instead of on the bottom, and bleeding the system that way.  Still takes two people, one to push the master and one to open and close the bleeder.  (I always wanted to try a 6-8' length of hose on the bleeder screw, routed to the reservoir, but never got around to it)

I agree about the bleeding problems.  I have a rubber tipped blow gun for my bleeder to push the fluid up from the bottom. There should be no more than a quarter inch of free play at the footpad on the pedal.  The pushrod should allow the pedal to return all the way to the mechanical pedal stop.

Other possibilities involve hanging the trans from the disc while installing, causing a wobble, pilot bushing greased too much or tight, no machining of the flywheel so the edge of the disc is grabbing,(that should go away as it wears), leaky front trans seal, or a crap pressure plate.

I bled twice; once traditionally, once with vacuum.  One shop tried the inverting the master cylinder trick (former Ford tech) and another shop took a whack at it with the fancy reverse bleeder.  No change with any of them.

The pedal returns fully to the stop with no play at all.  If I try to lift on the pedal it goes nowhere.

PO did do a pilot bushing (if I'm remembering the receipt he showed me) but who knows if the input shaft got munched.

I agree... sounds like air in the system.  That makes the most sense.  But if there is air in the system, two shops and two attempts by me to get the air out have failed.  I also don't think that air would be something that slowly gets worse.

The most expensive clutch kit I found (with new flywheel, slave, master, bushing, even a rear main seal) is about $250, or I can get a cheapo clutch kit for $69 and a flywheel for $34.  The way I see it, even if I get in there and find something obvious like a bad pilot or a lot of crank walk, I can't see putting it all back together with a clutch that has 20k on it of unknown quality, especially when I can put all new premium stuff in there for about 2 bills.

Translated:  If I'm going to spend a weekend laying on my back in the driveway pulling a transfer case and transmission, I don't want to be cheap and save $200 hoping I fixed the problem.

I've had good luck with South Bend Clutch and can recommend them.  Poking around their site they show listings for Rangers.  
 

I've heard good things about Ram Clutch from the long tome Ford drag racers I bought my TKO-600 from D&D Performance (Don Walsh Sr and Jr).  This was backed up from the tech line guy I spoke with at Summit Racing recently.   

Back in the 70's my dad bought a new GMC.  He had problems with the clutch from the git go and after several trips back tot he dealer it ended up being the flywheel was messed up.  Hard to believe but I was told thatit was warped, from new.  I can not figure out how that would happen.   The flywheel was replaced with new and the problem was solved.  YRMV

Any ideas on what flavor to get?  I've heard of some good brands like Luk and Spec, but am I looking for Kevlar?  Metallic?  Ceramic?  Organic?

As I understand things from my research the materials are ranked in order of increasing torque capacity as organic, organic blends (Kevlar aka aramid, and metallics), Aramids, ceramic, and metallics.  Carbon fiber, from what I understand, offers the torque capacity and temperature capability of ceramics and metallics with the softer engagements of the fibrous materials (organic and aramids).  Note that torque capacity is not clamping force which is a function of the springs in the pressure plate.  
For your application I think an organic clutch with diaphragm pressure plate would be fine.

LUK makes a LOT of OEM clutches so they should have manufacturing processes down.  There are a lot of clutch makers out there like Spec, ACT, Zoom, Centerforce, Exedy, McLeod, Ram.  

Maybe poke around on Summit Racing to look at options and available brands for your truck?

As far as clutch kits go, I have had extremely good luck with Exedy.  Ive installed more than I can remember in customer cars and my own stuff over the years.  We even run a regular stock replacement Exedy in our Chumpcar. 

And I have had disappointments with Luk, OEM or not. I put one in a 240 Volvo that was wickedly out of balance.

logdog said:

As far as clutch kits go, I have had extremely good luck with Exedy.  Ive installed more than I can remember in customer cars and my own stuff over the years.  We even run a regular stock replacement Exedy in our Chumpcar. 

 

Came here to say this as well.

I use them in all my race cars and have never had any issue with them.  Ever.  Just the stock OEM equivalent clutch.

When you pull the tranny to replace the clutch, make sure that the rear main seal isn't leaking.  I had a vehicle once that had a rear main seal leak that was getting oil onto the clutch disk, and the oil was getting heated up and becoming a sticky tarry mess.  It didn't really feel that different during engagement but the tarry stuff would make it drag so bad with the clutch depressed that I would sometimes have to do as you said and turn it off --> put it into gear --> and restart it to take off from a stop.  

Curtis73 said:

Any ideas on what flavor to get?  I've heard of some good brands like Luk and Spec, but am I looking for Kevlar?  Metallic?  Ceramic?  Organic?

I would not recommend Spec. One of my co-workers has had two of these fatigue crack in exactly the same place, and they've refused to listen when he pointed out the sharp corner where the crack starts is a stress concentration. And I've heard some other reports of general lousiness with their clutches that I can't remember at this time. LUK is probably a better choice - they're an OEM German manufacturer, but I don't have any experience with them to report.

I've been happy with the luk flywheel in my spyder and the Exedy clutch. 

Ok.  So maybe a good organic, or organic blend might be the ticket... unless I can find a carbon fiber on sale?

I'm inferring from what I'm reading that (just like brake pads) the metallic and ceramic might be race-y or grabby, but the fiber offerings will feel more like stock engagement... just that the carbon fiber would offer more heat tolerance than organic for those road trips with the boat on the back.

All of the offerings I'm finding are diaphragm.  Am I correct in assuming that a weighted diaphragm adds clamp force from centrifugal weight without adding an pedal force?

JBinMD said:

When you pull the tranny to replace the clutch, make sure that the rear main seal isn't leaking.  I had a vehicle once that had a rear main seal leak that was getting oil onto the clutch disk, and the oil was getting heated up and becoming a sticky tarry mess.  It didn't really feel that different during engagement but the tarry stuff would make it drag so bad with the clutch depressed that I would sometimes have to do as you said and turn it off --> put it into gear --> and restart it to take off from a stop.  

If I'm going in, it's getting everything including a new flywheel.  They're only $44, and a RMS is $5.  Everything between the crank and the trans can be bought for this truck for about $250, so I see no reason to skimp.  It's like doing cam seals while you're doing a timing belt.  Easier to do it while you're in there.

+1 on Exedy for OE replacement.  Otherwise, I have always used SPEC for higher performance clutches.  

Can you enlist a helper to see how far the clutch fork is getting moved by the slave?  I'd start with a visual inspection that you're getting the full range of movement.  Could be a bad slave or master, even though they're new.

FWIW it was the pilot bushing on my '94 Ranger with the 3.0 Felt just like the throw out bearing starting to fail.

Tyler H said:

+1 on Exedy for OE replacement.  Otherwise, I have always used SPEC for higher performance clutches.  

Can you enlist a helper to see how far the clutch fork is getting moved by the slave?  I'd start with a visual inspection that you're getting the full range of movement.  Could be a bad slave or master, even though they're new.

Internal slave.  Can't see it.

The temptation is to tear it apart to diagnose, but then I have several days of downtime while I wait for parts to ship.  I suppose that isn't a terrible thing. I'm tempted to order all the parts, tear it apart, then fix what is wrong, and return what I don't need.

Upside is I will have all I need.  Downside to that is potentially paying shipping twice on the parts I don't need.