1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Changing Clutch need info

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Old Oct 19, 2014 | 01:32 PM
  #1  
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Changing Clutch need info

I finally got my transmission out today to change my clutch. My car is a little bit of a Frankenstein, I think the drive train is all 81. But I know they made different size flywheels so I want to make sure that I am ordering the right one. I measured from the mounting bolt for the pressure plate across to the other mounting bolt and got 10.5 inches and then I measured from the tooth of the ring gear across and got 11 3/4 inches. Do I still have the original small flywheel?

Also is the pilot bearing mounted in the flywheel or in the back of the crank? My flywheel has to be cut and I was hoping I could save on buying the tool to pull the pilot bearing.

A long cotter pin fell out from somewhere while taking out the trans where does that go?

Also Ive never dealt with this before, is this an RX7 thing? I couldn't get the trans out with out removing the pressure plate bolts through the starter hole. Once I did I slid the trans right off. I found about 2 or 3 inches of mud, clay, and sand behind the flywheel, is there somewhere it comes in from? Everything was very rusted so Im glad I was changing it. I had to pry the clutch fork back to make it launch the clutch and pressure plate out of the bell housing.

Last thing I just wanted to make sure the nut securing the fly wheel is 2 1/8 inches? Im going to go buy a socket tonight. Will an average impact gun get it off of should I borrow my friends 600ftlb Ingersol?
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Old Oct 19, 2014 | 01:51 PM
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From: KC
Since your pulling the flywheel, just validate the flywheel number for the clutch size. A 1981 flywheel should have a "21" on the engine side and be a 215mm clutch.

The pilot bearing is in the end of the eccentric shaft.

The flywheel nut is 2 1/8 == 54mm.

Flywheels
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Old Oct 19, 2014 | 02:22 PM
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Borrow your friend's impact wrench for the flywheel nut, it is torqued to 350 ft.lbs. If you can't for some reason, here's a clever trick I used on my car. Get the proper socket, a breaker bar, come-along and a big tree. Make sure the flywheel is locked in place, then crank the come-along so it pulls the breaker bar counter-clockwise. Instant 2000 ft.lbs of torque this way.

You can find a 54mm or 2 1/8" socket at Sears or Tractor Supply Co for ~$20.

As for the pilot bearing, these are a real PITA without a puller tool. The Mazda tool is basically a slide hammer with mandrel type jaws to hook onto the bearing. As I dislike this approach (I think it's clumsy and inefficient), mine is a modified Harbor Freight one with the jaws ground down to fit. Crank the bolt on it for 10 seconds and it pops the bearing right out every time.

The clutch/pressure plate issue is definitely abnormal. On my FC, once the crossmember and bellhousing bolts are out (and the clutch slave unbolted), it just took a firm tug to get the transmission out. Sounds like clutch disc wasn't aligned when the pressure plate was bolted on before. This puts excess load on the transmission input shaft, making it a bear to remove or install. Been through that a couple times too, not very fun.

The cotter pin has me baffled though, never heard of such but 79-85 isn't my area of expertise though. Any experts with a first gen? Bueller? Bueller?
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Old Oct 19, 2014 | 06:12 PM
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Removing the flywheel nut with a Sears 54mm socket, breaker bar & 5 feet of iron plumbing pipe.
The blue tape mark is for hanging 102 lbs of concrete block and steel bar to produce the 350 ft lbs to get the nut back on.

350 / 102 = 3.431 ft. or 3' 51/4"
Attached Thumbnails Changing Clutch need info-dscn1224.jpg   Changing Clutch need info-dscn1019.jpg   Changing Clutch need info-dscn1014.jpg  

Last edited by TimWilbers; Oct 19, 2014 at 06:20 PM. Reason: Wrong math
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Old Oct 19, 2014 | 06:43 PM
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I got the idea of using a long pipe from this forum.
I'm not that clever.
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Old Oct 19, 2014 | 07:18 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by TimWilbers
I got the idea of using a long pipe from this forum.
I'm not that clever.
lol, me too. someone pointed out that its pounds FEET, i suppose, give me a long enough lever and i can move the world.

hmm, i want a 10 foot bar now, it would probably self torque!
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Old Oct 19, 2014 | 09:31 PM
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I just saw that your loading the bar clockwise. Is the but left hand thread or were you just trying to tighten it?
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Old Oct 20, 2014 | 10:39 AM
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Originally Posted by RX7TR7
I just saw that your loading the bar clockwise. Is the but left hand thread or were you just trying to tighten it?
First image - counter-clockwise to remove. I'm 160 so leaning on the end of the pipe un-torqued the nut without issue.

Second image - clockwise to assemble. Using the concrete blocks with known weight to achieve the correct spec. I could not find any shop in town with a 350 ft/lb torque wrench.

The first time to remove the nut I took the stack to our local mechanic. He popped it off in 2 seconds. Having since purchased the socket, breaker bar (Sears listed it as a sliding gear wrench and to fit into the pipe the one end ball stop was removed) and the iron pipe, I gave it a go which was much quicker and easier than transporting the stack again.

Sears.com
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Old Oct 21, 2014 | 05:44 AM
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Apologies to the OP.
Using a long bar to remove the flywheel nut with the engine on an engine stand is highly NOT recommended.

That is why I have a steel bar stuck in the horizontal section of the stand, and wedged at the other end (red arrows). Otherwise the downward force (blue) could cause the stand to flip (yellow).
Attached Thumbnails Changing Clutch need info-dscn1224-no-flip-nut-removal.jpg  

Last edited by TimWilbers; Oct 21, 2014 at 05:46 AM. Reason: error
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Old Oct 21, 2014 | 07:10 AM
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Since your engine is still in the car the impact gun is the best choice, long bars get cumbersome underneath the car. The last one I did I had the Ingersol Rand 600 and it wouldn't quite get it. I had to go to the 1400 lb version. Some of these are really stuck.
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Old Oct 21, 2014 | 07:22 AM
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Waffles - hmmm good
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Also applying heat from a torch can help in getting the nut off. A 600lb gun should be more than
enough.
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Old Oct 21, 2014 | 08:07 AM
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^^^^ +1. Same process as you would do to a stubborn crankshaft bolt during a timing belt change out. With the pilot bearing, i use a porting bit, it only takes a minute to grind out the bearing
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Old Oct 30, 2014 | 05:36 PM
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I took the flywheel off it was surprisingly easy. I used the impact and a chrome sears socket. I had to put a breaker bar and a pipe on the crank bolt to keep it from spinning. I tightened the but on the flywheel sprayed of with pb then lossened it and it came right off. I screwed it back on one turn by hand and hit the edges where the pressure plate mounts with a hammer and it fell off second blow. The only thing is I don't see a 21 on the back I have either 78 or BL stamped on the back. What flywheel do I have?
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Old Oct 30, 2014 | 06:13 PM
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Old Oct 30, 2014 | 09:31 PM
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Looks like 81-82.

Weigh it.
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Old Nov 1, 2014 | 05:14 PM
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I dont know why I didnt try it earlier I measured the pieces of disc then the face of the old pressure plate both were 8.5 inches which is the same as 215mm. So I think Im good to go. The flywheel just came back from being cut and is all set.
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Old Nov 5, 2014 | 08:28 PM
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What kind of impact gun did you end up using?
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Old Nov 14, 2014 | 08:14 AM
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I used the Ingersoll 600ft lb impact gun. With my compressor set at 120psi. The socket is a chrome one from sears with a 3/4 to 1/2 inch adapter so it would fit on the gun. At first it wouldn't loosen the nut turns out the motor was turning slowly. So I put a ratchet on the crank bolt and held that while using the impact to remove the big nut on the flywheel and it came off like nothing. By the way to get the flywheel off screw the nut on like 2 turns then hit the area where the pressure plate attaches with a hammer a couple times and it will fall off.
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