Sunday, April 24, 2011

1999 3.8L Mustang Clutch

This is a huge job, not for the faint of heart.

I had several problems with the original clutch on a car with ~113k miles.  Hard shifting, chattering clutch, and the throwout bearing would whine when the clutch was disengaged.

I decided to go with the SPEC stage 1 clutch from American Muscle.  To put this much work and money into a car, I wanted good quality American parts.

DISCLAIMER:  I am not a professional mechanic.  This post is for entertainment purposes only.  I will not be responsible for anything you do to yourself or your car. 

Obviously, all the standard car safety rules apply here;  block the wheels, use jack stands, use the jack as a backup safety, wear eye protection, etc.

  1. An entire weekend.  I needed 24 hours of work time.
  2. Clean and secure work area to leave the transmission out of the car overnight.
  3. A buddy
  4. A good jack with at least 20" of lift.  A set of 20" jack stands.  A second set of shorter jack stands to support the transmission once lowered.
  5. A comprehensive set of tools:  Socket set with extensions, u-joint, torque wrench.  A 15MM socket is necessary to remove the transmission from the bell housing--most socket sets do not have a 15MM socket.
  6. New clutch kit; clutch plate, pressure plate, throwout bearing, pilot bearing, and alignment tool
  7. New seals.  Consider replacing the rear main seal and the output shaft seal on the transmission.  These are easy to do during this job but very difficult to do later.
  8. New ATF.  I went with Royal Purple Synchromax also available from American Muscle (best price I've found).  OEM fluid is commonly available in any auto parts store.

There will also be some miscellaneous items that are necessary...

Not pictured is blue locktite and moly lube to pack the pilot bearing and lightly grease the throwout bearing.

Having a second vehicle to run for parts and get the flywheel turned is a must.  Having the buddy do these things while you can work on the car would save a lot of time.

Remove Shifter

Remove the shift knob, outer boot (pulls right off with trim piece), inner boot, and shifter.  The shifter may be difficult to remove.  I had to use a hammer to pry the shifter plate up while pulling on the shifter itself.

Pack with paper towel/shop cloth to prevent dirt and debris from getting into the transmission.

The shifter box seal has been cleaned up to get it ready for a silicon gasket I also bought from American Muscle.  RTV silicon can also be used--I would still cleanup this seal.

Remove the Y-Pipe

The y-pipe is deceptively heavy.  DO NOT LET IT FALL ON YOU!!!

Unclip all four of the O2 sensors from the catalytic converters and exhaust pipe first.  Then remove the bolts from the header.  After that remove the bolts from the pipe going to the muffler.

A few hits from a hammer may be necessary to free up the pipe.

Drain the Transmission

Since the shifter has been removed, the only thing to do here is removing the drain plug.  A 3/4" socket is all that is necessary.  The drain plug is the lower plug.

This is where a funnel and gloves come in handy.  Old ATF is smelly, messy, and can burn skin.

Drop the Driveshaft

The driveshaft is attached to the differential by four 12MM bolts.  These bolts, and the position of the driveshaft should be marked prior to removal.  This is what the Crayons are for.  Failure to reattach the driveshaft in the same position could lead to noise, vibration, and more wear on the car.  You will know if you mess this part up!

Although a 12 point socket can be used here, I found a wrench to be better.  I used the tire as leverage and put my whole body into breaking these bolts free.  A cheater bar would have been nice!

One of the rear tires needs to be lifted to allow you to spin the driveshaft to access each of the bolts.  The parking brake can be applied to lock the wheels for torquing--have a buddy do this.

Remove Transmission

With the driveshaft removed, it is now time to remove the transmission.

First, unplug all sensors from the transmission.

Then, support the transmission with the floor jack and position a jack stand under the output.  This will help balance the transmission on the jack once removed.  The transmission is heavy at around 90 pounds.  DO NOT LET IT FALL ON YOU!!!

The transmission will unbolt from the bell housing with four 15MM bolts.

Once unbolted from the bell housing, carefully remove the transmission mount.  During this time, you should be able to tell if the transmission is well supported by the jack.

The transmission, in theory, should slide straight back at this point.  In fact, this was the hardest part of disassembly for me.  It helped to have a buddy engage and disengage the clutch to free up the input shaft while I worked the transmission backward.

Eventually it came out and I was able to lower the jack a little to get the transmission back out of the way.

The output has some paper towel held on by rubber bands to prevent dripping while I am under the car.

Remove Bell Housing

First, disconnect the battery, remove the starter, and disconnect the clutch cable.  The clutch cable will have a piece of metal protecting the connection to the shift fork--this is easily removed.

Then remove all bell housing bolts.  Most of them will be facing rear, but some will be facing front towards the bottom.

Remove Old Pressure Plate, Clutch Plate

This is easy--can't mess it up.

Remove Flywheel

The flywheel is also heavy.  DO NOT IT FALL ON YOU!!!

Replace Rear Main Seal

I preferred to replace the rear main seal prior to pulling the pilot bearing because the pilot bearing removal got messy.

The seal is easy to remove with a screw driver, just be careful not to scratch the flywheel or the block.  Scratches will cause oil leaks.  There will be a small amount of oil that comes out with the seal, but it is not necessary to drain the engine oil to do this.

The new seal should be lubed with a light coating of new engine oil and can be gently pounded in.  I used an old toothbrush (soft plastic) to buffer between the hammer and the seal.  Make sure the new seal is fully seated.

The rear main seal is $20 from Ford and there's no reason to not do this.

Pull Pilot Bearing

This is where things went south for me and I have little pictures.  I rented a puller tool from Advance Auto...

This tool shredded the old bearing.

There is a hydraulic trick that I should have tried but the shredded bearing wouldn't give me a good seal.

I ended up buying a Dremmel and cutting the bearing out.  This is the only part of the process I regret.  I ended up cutting two very small channels in the crankshaft as it was hard to tell when the bearing was cut.  I should have stopped to check with a chisel and a hammer more often.

When this was done I had a major mess.  I had to make sure the crankshaft was completely clean of all the metal bits or the new pilot bearing may seize up.  I used new motor oil to help get the metallic dust out of the crankshaft and clean up--it seemed to work well.

Install Pilot Bearing

The new pilot bearing should be packed in grease.  I used moly lube for this.  You do not want an excessive amount of grease in the crankshaft or it could push back out on the flywheel and cause the clutch to slip.

This is why the bearing should be packed prior to installation.

Install Flywheel

The flywheel was resurfaced by a local shop that I've been taking work to for years--I trust them and they always check their work.  They pulled and replaced the original dowels for me so there was no need to use new ones.

I had purchased a Ford Racing bolt and dowel kit but found out the kit was incorrect for the 3.8L Mustang.  So I re-used the old bolts after a careful inspection.

Two things are critical on the flywheel; 1.  Blue locktite and correct torque.  2.  Clean the flywheel with brake cleaner to prevent slipping.  I cleaned the flywheel in place to make sure nothing from my hands ended up on the flywheel.  I had to be careful not to over spray or drip.  I also used shop towels instead of regular paper towels.

Install Clutch and Pressure Plate

Follow the manufacturer's instructions.  Again, blue locktite, proper torque, and cleaning the mating surface of the pressure plate are all critical.

A clutch plate alignment tool is also critical to keeping the clutch plate centered to get the transmission back in the car.


Reassembly is common sense. 

Don't forget to correctly install the new throwout bearing in the bell housing.  The throwout bearing will have a spine to prevent rotation which goes to the open side of the shifting fork.  A light coat of grease can be applied to the inside of the throwout bearing.  I also put some fresh grease on the shift fork pivot point.

Remember to blue locktite the bell housing bolts, transmission bolts, and driveshaft bolts.  Proper torque specs are key.

Getting the transmission back in the car was the second most difficult part of the job.  The transmission bolts should not be used to pull the transmission onto the bell housing.  Finally a combination of working the jack and fighting the transmission in worked.  I also had a buddy engage the clutch once I knew I had proper alignment (had 1.5" inches left).

On the transmission fluid, replace the output shaft seal prior to filling with ATF.  A trick to filling the transmission is to use the shifter box and fill inside the car.  This requires some care and patience but works well.  While filling, the top plug should be removed.  Once fluid starts to overflow, the transmission is full.

Most manufacturers include break-in instructions.  SPEC calls for a 500 miles break in period and it should be strictly observed.  My new clutch was uncertain and chattered until 30 miles.  At 100 miles it was smooth and consistent.

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