Boxer Clutch Replacement.

So it’s time.
The clutch in my car has started slipping, mostly at freeway speeds, when you punch it in either 4th or 5th gear.
So what to do? In the San Diego area, Bobileff’s or any of the shops here in town can handle this repair quickly and easily. But I enjoy working on my car, and after some deliberation on what it would take to do the job, decided to do it myself.
So one morning last month I started, and in less than 5 hours, had everything apart including the flywheel off the engine.
And it really wasn’t all that difficult.
So for any other DIYers, here’s a few pictures and a description of the job, and what it took to do it.

I had planned to post the pictures in with the text, but I guess that can’t be done?
So, all the pics are way down at the bottom.

Only a handful of tools are required. Wrenches and sockets in sizes, 11mm, 13mm, 18mm, 19mm, and a Good Quality 6mm allen wrench or allen socket to remove the pressure plate nuts. A small hard rubber mallet was handy to help loosen the bellhousing and flywheel after removing the bolts.

The first picture shows the engine with the heat shielding still in place, and the second with the mufflers in place and connected to the headers.
Pic 1 and 2.

The third picture shows all the parts that need to be removed, in order to gain access to the bellhousing. I thought about removing the rear clip (engine cover) just to make working access easier, but that’s a PITA, so decided against it.
Pic 3.

Between the mufflers, the aluminum heat shielding between the engine and mufflers, and the rear valance, the valance is the biggest pain to remove. After unbolting, you need to pull the front edges out and away from the fiberglass wheel well liners, as the front lip of the valance fits over the rear bottom section of the wheelwell liner. As I was doing this by myself, (Yeah, where were all my buddies when I needed them!) I had to do one side, then the other. Even though the valance is fiberglass, you still have to pull hard, cuss a little, and pull some more to get it out from around the wheelwell liner.

The heat shielding is made in two pieces, and comes loose with just removing a handful of bolts. The large piece just behind the engine has five bolts on the top, and one bolt in the bottom. Needless to say, you can’t remove the shielding without removing the bottom bolt.....

The mufflers just simply un-bolt. Some of the bolts are a little hard to get too, but all can be reached with patience. Depending when and if the bolts have been previously removed, they’re going to be tight, sort of rusted, but a couple shots of WD-40 will ease the task. New nuts, bolts and gaskets were purchased to use when re-installing.


Once the valance, mufflers and heat shielding is off, the bell housing is readily accessible.
The first thing to do here is to remove the lube oil drain plug on the bottom of the bell housing to drain the oil out of it. You could also drain the main gearbox oil now as well, but I opted to do that later. My thought was that if any small pieces of foreign material made their way into the gearbox during the work, it would likely drain out with the oil after the clutch replacement.
Pic 4 and 4a.

While the bellhousing oil is draining, I disconnected the hose going to the hydraulic slave cylinder that operates the clutch throw out bearing. This is a simple banjo fitting, so just loosen the 18mm bolt at the end of the hose, and remove it from the banjo fitting. Remember there are two copper washers on the bolt, one on either side of the banjo fitting.
Once the hose is loose and free, tie it off to something suitable, as high as possible, to keep the remaining clutch oil from draining out, and to keep the hose out of the way.
I’ll change out all the clutch oil while bleeding the system, after the clutch is replaced.

To remove the bellhousing, first slip some plastic baggies over the exhaust pipes to keep any nuts, bolts, whatever, from falling into them, then just simply remove all the nuts and bolts that hold the bellhousing in place.
Three long bolts hold the starter in place, and this is a good place to start. Once these bolts are out, slide the starter ahead a little to get the nose of the bendix away from the flywheel.
The remaining fasteners, nine of them, are nuts and washers. When removing them, remember there are two nuts on the lower part of the bellhousing, hidden under the transfer gear case.
Once the fasteners are off, the bellhousing is still held in place by the nine studs, and the tubes for the gear oil, and the propeller shaft. Just pulling back on the bellhousing didn’t seem to have any effect, so I used a piece of one inch wooden dowel to pry it back by putting the dowel into the vent slots around the circumference of the housing.
Once it slides free of the studs, it’ll still be held by the oil and propeller shaft tubes, so be prepared to hold the weight of the bellhousing so as not to damage the tubes. If the propeller shaft wants to slide out with the bellhousing, like it did with me, just wiggle it loose from the splines of the lower transfer gear, and push it back into the gearbox for now.
When the bellhousing is free and clear of the tubes and the propeller shaft, just ease it down to the ground and slide it out of the way. It’ll need a good cleaning inside and out before re-installing.
Pic 5

So now you can see the pressure plate in all its glory, as well as some greasy oily crud mixed with clutch dust making an unsightly mess!
Pic 6

Also note this is a clutch made by AP Racing that I believe came stock with a BB. I think a BBi has a pressure plate made of pressed steel as opposed to machined aluminum, but would guess the procedure to be pretty much the same.
The pressure plate is held on with six allen head nuts, and the suckers are fairly tight! Trying to loosen them as is, just results in the flywheel turning, so as you can see in the picture, I used the same wooden dowel with a wedge cut on the end, and tapped the wedge part in between the teeth of the flywheel and the starter area of the engine casing.
To crack the nuts loose, I slipped a piece small diameter pipe about eight inches long over the allen wrench to give a little extra leverage.
Pic 7.

Once they’re cracked loose, remove the piece of pipe. There will still be considerable pressure on the nuts from the springs inside the pressure plate, so with just the allen wrench, loosen all the nuts using a crosswise pattern, to relieve the pressure evenly.
Once all the nuts are off, like the bellhousing, the pressure plate will still be held in place by the six studs, and also three small locating pins that slip into the intermediate plate between the two discs. And like the bellhousing, just tugging back on the pressure plate had no effect, so I used the wooden dowel to pry it back far enough to come free. This prying took some effort, and it has to be done evenly using a crosswise pattern, as the studs are a tight fit inside the pressure plate.

The next picture shows the pressure plate and one disc on the garage floor. It’s easy enough to see the wear and burn marks in the pressure plate friction surface, but the picture doesn’t readily show that the friction material on the disc was worn right down to the rivets that hold it in place. Not many more miles on this clutch could have resulted in much more serious damage to the flywheel and pressure plate friction surfaces! As it was, they just had burn marks, but luckily no gouging or scoring.
I didn’t take the pressure plate apart any further to get to the second disc, as there wasn’t much point.
Pic 8

In the next picture, notice the same wear and burn pattern on the flywheel. Also note the six studs and three locating pins for the pressure plate attachment.
At this point the propeller shaft is still in place, but it probably would have been better to have already removed it, and stuffed rags into the gear oil and propeller shaft tubes to keep crud out.
Pic 9.

Next pic is with the flywheel off, the pilot bearing in the center of the crankshaft removed, and most of the greasy oily crud cleaned up. I was concerned that the mess was due to a leaking rear main seal, but a close inspection showed that it was still sound, and not leaking. I suspect the mess was made during the last engine out service, by too much grease being slathered onto the splines of the clutch input shaft, getting flung off and mixing with clutch dust during the past two years. At any rate, I didn’t change the main seal, but probably should have, as this would have been the perfect time to do it.
Pic 10
The last of the tear-down pictures shows the flywheel, and the infamous and god awful expensive propeller shaft! God awful expensive as it is, I still looked the shaft over carefully with thoughts of replacing it. But it showed only extremely minor wear on the splines on both ends in the form of a few shinny spots, but nothing to indicate that it was any more prone to failure than a new one. I thought about having it magna-fluxed, but couldn’t find a shop handy to do it, so didn’t.
Pic 11

At this point, the entire clutch, and the flywheel were sent to Clutch-Masters for a rebuild. I did this through a third party, but assume you could send it to them directly as well.
The rebuild included re-surfacing the flywheel, the pressure plate and the intermittent plate. The old worn out disc friction material was replaced with new Kevlar linings.
Cost for the rebuild was $950, or about half the cost of a new AP unit. The rebuilding was supposed to have taken about a week, but turnaround time was closer to two weeks.
During the wait I cleaned up more of the mess, painted the mufflers with some high temp paint, cleaned out the interior of the bellhousing, and closely inspected the throw-out bearing, which proved to still be in perfectly fine condition. I also had a shop inspect the transfer gears and bearings in the bellhousing for excessive wear, but nothing needed replacing.

The next picture shows the surfaced and rebuilt clutch and flywheel, with everything looking like new. Again, the second disc is already in place between the pressure plate and intermediate plate.
In this picture, note the three small pins located between every other stud on the flywheel, and the corresponding pin holes in the intermediate plate of the clutch.
Also note the shoulders on the outer edges of each of the six feet of the pressure plate.
Pic 12

Putting things back together would have been difficult doing it alone, so I enlisted the aide of my antique rifle collecting buddy. He’s not the F-car type, more the comfy cruiser type, but he did have a hotrodded 40 Ford once upon a time so knows the difference between a hammer and a wrench!

Next pic is with the flywheel back on the engine, and the new pilot bearing in place.
The flywheel only goes on one way due to a locating pin on the crankshaft that fits into a corresponding hole in the flywheel. The bolts were threaded in with a little dab of Lock-tite on the threads, then snugged down evenly, and finally torqued to spec’s with a ½” drive torque wrench. By the way, torque spec’s for any metric bolt can be found by Googling ‘Metric Bolt torque’.
The pilot bearing was pushed into place using a suitably sized socket to fit the outer race of the bearing, then tapped into the crankshaft recess with a hammer. Just tap evenly, holding the socket exactly in place over the bearing, eyeballing the bearing to be sure it’s going in straight, and you’ll hear, as well as feel a difference in the hammer taps when it’s fully seated.
Pic 13

The next pic shows the pressure plate with the alignment shaft in place through both of the disc’s, ready to go back on the flywheel.
Pic 14

Note there is a stamping on the disc that goes next to the flywheel that says ‘Flywheel Side’, so be sure it’s oriented correctly.
The pressure plate doesn’t have any particular orientation to the flywheel, other than alignment to the studs of course, but you also have to align it with the three small pins on the flywheel that fit into the holes in the intermediate clutch plate.
Once you have the stud holes and the small pins holes of the pressure plate lined up with those on the flywheel, push the pressure plate onto the studs of the flywheel, and at the same time push the nose of the alignment shaft into the pilot bearing hole. Don’t be surprised when it doesn’t push all the way on, because just like coming off, it’s a tight fit going back on too. Some whacks from side to side around the parameter of the pressure plate with a hard rubber mallet, not real hard, but not gentle either, helped it to start sliding onto the flywheel studs.
But, be sure to stop pounding just before the small pins start sliding into their holes in the intermediate plate. I’m not sure of their purpose, but captured inside each of the holes are two small C-clips. I say not sure of their purpose because there is no corresponding groove on the pin for them to clip too, but they’re in there and need to be aligned with the pins as you slide the pressure plate the rest of the way on. It wasn’t hard, just go easy and align the clips to the pins with a dental pick while your buddy taps the pressure plate into place. When the first disc is up against the flywheel, that’s as far as you can go by tapping with the mallet.
At this point I wiggled the alignment shaft around to center the disc as closely as possible, then whacked the end of the shaft to push the nose further into the pilot bearing.
Remember that once the pressure plate is bolted up tight to the flywheel, the disc’s will not move at all, and if they’re too far off center you’ll play hell getting the bellhousing back on!
So once you have the first disc up against the flywheel, and well centered with the alignment shaft, thread the pressure plate nuts back onto the studs. Then start tightening the nuts with the allen wrench in a crosswise pattern, just as when loosening them. As you tighten, you’ll see the center fingers in the pressure plate depress as the springs come under tension. As the pressure plate comes closer and closer to the flywheel, the last thing to check is to be sure the shoulder on each of the six feet on the pressure plate slip correctly over the corresponding edge on the flywheel.
Once everything looks good, use the same wooden dowel you used to hold the flywheel when loosening, and tap in back in between the flywheel and the engine case, except in the opposite direction to keep the flywheel from turning while tightening, then tighten the pressure plate down tight with the allen wrench, again using a crosswise tightening pattern.
Go around two or three times just to be sure all the nuts are tightened tight, and evenly. I’m sure there’s a torque spec for these nuts, but I couldn’t find it. They were really tight when I loosened them, so I just tightened them down really tight using the allen wrench, but without the cheater bar.
The next picture is with the clutch assembly back on the flywheel, with a little info added just for fun!
Pic 15

At this point it’s time to re-install the bellhousing, but there’s a couple things to do first.
Your buddy is going to need to be able to turn the flywheel from the top of the engine, so find a suitable wide bladed screwdriver, small crowbar, whatever, that will fit the teeth on the flywheel.
Thread a piece of thin rope through one of the starter bolt holes and tie it in a loop, so the buddy can help with lifting the bellhousing up into place.
Put a thin coat of grease on the bellhousing shaft splines, and on the tip that slides onto the pilot bearing.
Then a little grease on the throw out bearing surface that contacts the fingers on the pressure plate.
Be sure the threads on the studs for the bellhousing are clean, then slip the new O-rings onto the oil and propeller shaft tubes. I bought the O-rings at the local auto parts store, just take the old ones and match them for size. Put a thin film of silicon sealant on both the oil tube O-ring, and the propeller shaft tube O-ring. This will help seal the O-rings and also help them to slide easily into the recesses in the bellhousing.
Don’t forget the put the propeller shaft back in! Just push it into the tube, then twist it a little until the splines align with those in the transmission, and push it the rest of the way in.
To get the bellhousing in place, you need to align the splines of the clutch disc’s with the splines on the clutch shaft (the one in the bellhousing), so just eyeball the orientation of the disc splines then turn the shaft to match them.
There’s no need to try to align the splines of the propeller shaft to the ones on the lower transfer gear. These splines are small and it would be somewhere between difficult and impossible to align them accurately.
So now heave-ho the bellhousing up into place. I was under the car, my buddy leaning over the engine so he could help pull up with the rope. It’s not all that heavy, less than 50 pounds I’d guess, but as you get it up into place, you need to direct the propeller shaft into the hole in the bellhousing, and direct the clutch shaft into the center of the pressure plate, so it helps to have some lifting power from the top of the engine.
Once you have the propeller shaft directed into the correct hole, the splines of the clutch shaft might slip into the splines of the first clutch disc, if you’ve eyeballed them closely enough for alignment. But if they don’t, have your buddy turn the flywheel with the aforementioned turning tool (wide bladed screwdriver, crowbar, whatever). We used the engine timing slot as the fulcrum point. While he turns the engine, you just push the bellhousing toward the engine. Once the splines line up, the shaft will slip into the disc’s, and the bellhousing will slip closer to the engine. However, your still a long way from the studs slipping onto the bellhousing holes, so maintain lifting force and don’t let the weight of the bellhousing just hang on the clutch shaft.
If by some miracle the splines on the propeller shaft are aligned with the splines on the lower drop gear they’ll slide into place as well. But if not, have your buddy continue to turn the engine until they do. Having the transmission in gear will keep the propeller shaft from turning freely and making alignment difficult.
As the splines align, you’ll be able to slide the bellhousing forward more. Check to be sure the oil and propeller tubes are sliding into the openings in the bellhousing, then slide the bellhousing all the way up onto the studs. Again, as with coming off, this is a tight fit going back on, so will likely take some tapping with the rubber mallet to get the studs all the way through the bellhousing holes, and to seat the end of the clutch shaft into the pilot bearing.
I pushed, my buddy tapped, then we checked to be sure it was going on straight and even, then pushed and tapped some more, checking straightness and evenness, until the bellhousing was all the way up against the engine.
All that’s left now is to put the washers and nuts on the studs, and tighten the bellhousing down tight. Then put the starter back in place and bolt it down.

The remainder of the job is simply to replace all the things you’ve removed.
Re-install the clutch slave cylinder hydraulic line, then bleed the air out of the system.
Drain the remainder of the transmission oil, then refill with new gear oil.
Re-install the exhaust, the rear valance, and the heat shields, then clean up any unsightly greasy fingerprints, and you’re ready to take her for a blast!

The total working time to complete the job was about 20/22 hours. Not quick, but then I wasn’t paying someone a hundred bucks an hour to do it either.
And by doing it, gained another degree of intimacy with my favorite car.
John

 

Thanks for the nice words, , and yeah, I think it took longer to write than it did to do the job!

Ron, No spacers to be found with the AP unit. Maybe that's with the stamped steel BBi pressure plates? Besides, the disc were already worn down to the rivits.

Parker, List price on the AP clutch is $1850. With tax, that'll leave you with about 2 bucks for labor. Also the main reason I did it is because I like working on my car. The greasy fingernails cleaned right up with a little soap and water.

Hawaii, I would guess the procedure would be the same or similar with the TR. It's the same basic design after all.

And thank you Boxer guys for helping me, and answering questions about my car during the past couple years. When I thought of doing the clutch, it was also with thoughts of posting it here, and being able to maybe give a little back in return.

John

 

Thanks again guys!
It was an interesting project, and fun to do.
As for the questions, it looks like Paul and Peter have answered most of them, but for Big red, yes, I cleaned and scrubbed, then painted whatever I could, mufflers included, to make things look nicer.
I borrowed the clutch input shaft from the shop that sent the clutch to Clutch Masters. I could have used mine, as Paul replied as well.
Sam, the relay is for the fans where the resonators would have been. I'm not sure that do much good, but,,
The chunk of iron on the back is from the dot work and is welded on solid, with no easy way to remove it. I believe there's a similar one on the front also.
I actually don't have the car back on the road yet, as work got in the way of finishing her. The heat shield behind the engine has some nasty scratches in it from a previous removal, and I still need to buff those out as best as possible. And I want to do a little more detailing and painting before I button things up.
But I have taken it for a drive, even if just up and down my street, to be sure the clutch was operating okay. And yeah, minus mufflers, exhaust straight out of the headers!
And what a treat that was to hear her totally uncorked!
When I return home in a couple weeks, I think I'll venture a little further up to the parkway early one morning, and give her a really good blast!
Anyone want to ride along
John