Just replaced (last summer/fall) clutch, pressure plate, through-out bearing, master and slave clutch cylinders, pilot bearing…in short the whole clutch assembly on my 1988 F-150, 4.9L, 5-speed Mazda manual tran., [10” clutch].This past winter I “smoked” the clutch in all the snow we got here in Maryland. The truck seems to be pulling alright but I know it has lost some of the useful life on the clutch.

Question: The clutch, even when the truck was new, under heavy load slips. Is this normal for this truck?

There are two sizes of clutches for this truck..10” and 11”. Would the larger(11”) clutch solve this problem? What will I need to do to upgrade to the larger clutch?

 

When I did my '01 rebuild, I asked around and was told that the flywheel is pre-drilled to accept several clutch sizes. "They" were right - in my case. I bought a Heavy Duty 11'' clutch(complete) and it bolted right up! You probably need to have the flywheel resurfaced, as "smoking it" causes hot spots which will definitely shorten the life of a new clutch if this isn't done. (New throw-out bearing is common practice too, while you're at it).

Check it out when you get the flywheel out for resurfacing - then buy the biggest clutch you can bolt on. I think mine was about $150 -$175 ( I did the work). I'm not sure why the smaller clutchs are even an option for 4.9's, they're not THAT much less$$. When you consider the overall labor and materials for installation...give me the "BEEF".

'not sure about the heavy load slippage. Are you in granny when it slips or does it occur in 2nd, 3rd...? How heavy a load? I don't know what clutch slippage feels like, so you must have something wrong....

 

I was told when I was replacing the clutch assembly the first time (1998/97) that the flywheel was designed for both sizes. Are the bolts the same size and thread? I know there are additional holes in the flywheel.

I probably used the wrong term “heavy load” probably should have said under strain... i.e. pulling up vegetation (bushes) as an example. I believe the engine should die instead of the clutch slipping.

 

Well, regardless of the load, slippage is no good and almost has to be the clutch package. I'm not "up" on the newer hydraulic clutches and your problem COULD be of that nature. I'd hope for a post in that regard from someone more in the know. Mechanically, the 11'' should bolt right up with the same bolts (mine did).

 

All Fords post 1985 have flywheels drilled for either the 10" or 11" clutch. Everything is the same as if replacing with the original 10". You should not be having any clutch slippage at all. As mentioned be sure to surface the flywheel. Be careful as to where you buy a replacement clutch. Many of the local parts stores have rebuilt or offshore made components. From past experience you will tend to have slippage and or chatter with a cheap clutch. Some reputible names include Luk and Valeo. Both of these companies are OE in Fords. Most folks do not realize Borg Warner, Ram, Centerforce, ect are not clutch manufacturers, they are repackagers. Look in the box of many of these companies and you will find various manufacturers components inside, sometimes good components and sometimes not so good. Let me know if you have any questions.

 

My 11'' HD clutch from NAPA was a LUK, now that you mention it. No problems to date... 20k + miles, no REAL HEAVY loads, but a few good ones... Did hear it COULD be a hydraulics problem...

 

The clutch assembly (clutch disk, pressure plate and throw-out bearing) I put in last summer/fall was Borg Warner. The clutch I installed in ‘97/’98 failed because the slave cylinder was failing and not fully releasing.

Right after the snow event I could feel the clutch slip a little and smell it burn at high acceleration but now it seems to be OK, however I haven’t had a real load or towed anything yet. My truck will still spin the 31’s at take off.

 

Take a ride in the truck. Get into 3rd gear and chug the motor, then nail the accelerator. Keeping an eye on the tach, if the rpm's jump but the truck is not responding the clutch is probably toast.

 

Take a ride in the truck. Get into 3rd gear and chug the motor, then nail the accelerator. Keeping an eye on the tach, if the rpm's jump but the truck is not responding the clutch is probably toast.



Tried your check.....flo0red it in third.......responded fine...kinda "pissed-off" this guy in a Chevy V-8 though!! Funny stuff!