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How hard to change flywheel

Old 02-27-05, 02:57 PM
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How hard to change flywheel

Ok well that what i need know. I've been putting off fixing my car for 2 months now trying to find a place that will work on my car for less than an arm and a leg. So with moist of the estimates costing more than i can afford i'm back to thinking about doing it myself. I'f a pretty good mechanic but i've never changed a flywheel. What will i need to do it? i've also heard that an impact wrench on the flywheel nut is a big no no, is that true? and how high off the ground will the car need to be?
Old 02-27-05, 04:26 PM
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It's easy to do if you have the equipment. Remove the exhaust, driveshaft and tranny. That's fairly easy.

To remove the flywheel nut, you will need either a LARGE breaker bar (which doesn't work too well if the engine is still in the car) or an impact gun (only way to go). That nut is likely torqued to 300+ ft LBS, and is 54MM / 2 1/8 . So you need to find the special socket.

Then to remove the flywheel, you can normally just pry it while someone gives it a wack with a hammer (use wood to protect flywheel surface). Assembly is reverse of the removal, making sure to torque the flywheel nut to 300 ft-LBs.
Old 02-27-05, 04:31 PM
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When you loosen the nut, leave it on by just a couple threads. It will stop the flywheel from falling all the way off when it pops free.
Old 02-27-05, 06:16 PM
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Originally Posted by Project84
When you loosen the nut, leave it on by just a couple threads. It will stop the flywheel from falling all the way off when it pops free.
And onto your face, assuming you'll be UNDER the car. Considering that the damn thing weighs 28 pounds, that would be a very unpleasent experience.
Old 02-27-05, 07:59 PM
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yeah i almost caused some real damage when i tried to catch a falling flywheel. ouch bent my wrist back something fierce.
Old 02-27-05, 08:07 PM
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Just get out of the way...

Thats what you learn from working in a machine shop..
Just get out of the way.... doesn't matter what is falling, don't touch it.

Having said that, last time I changed my flywheel/tranny I dropped the tranny on me, kinda hurt. Pretty hard to move away from something under there... hehe
Old 02-28-05, 08:46 AM
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good to hear but i don't think i'll need to protect the old flywheel with wood since it's no good anyway (ring gear won't stay on it) and i have a lightwieght one that wieghs 14lbs, anyone know how much the counterwieght wieghs? also since aaron said it was ok i'm guessing a impact gun is ok on the flywheel nut? the shop that was going to do it said that they couldn't use one cause it would damage bearings in the engine what up with that?
Old 02-28-05, 09:15 AM
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Impact gun is the only way to work with that nut. In my mind, there is no other option. You'll never damage the bearings by tightening the nut. Exact torque isn't even that important, as long as you can get it over 250 Ft-lbs or thereabouts.
Old 02-28-05, 09:48 AM
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wont the flywheel free spin if you dont have a piece of wood or something keeping it from moving while you take the nut off?? I am curious as well as Im an going to be using an act clutcha nd flywheel setup soon. I have seen a few threads where people had a long 2X4 bolted to the flywheel but the engine was out of the car. Is that nec if the engine is still in the car?? thanks
Old 02-28-05, 09:51 AM
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Originally Posted by bigturbo
wont the flywheel free spin if you dont have a piece of wood or something keeping it from moving while you take the nut off?? I am curious as well as Im an going to be using an act clutcha nd flywheel setup soon. I have seen a few threads where people had a long 2X4 bolted to the flywheel but the engine was out of the car. Is that nec if the engine is still in the car?? thanks
With an impact gun it wont free spin, the impact will be putting down all the torque at once quickly and the flywheel wont be able to spin that fast.
Old 02-28-05, 12:54 PM
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when you say spin the flywheel would that mean the engine is turning over?
Old 02-28-05, 01:08 PM
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Originally Posted by totallimmortal
when you say spin the flywheel would that mean the engine is turning over?
Yes
Old 02-28-05, 01:33 PM
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nice since my poor engine hasn't been turned over in 2 months due to the damn ring gear on the flywheel not being on the flywheel.

Ohh yeah i've got the tools taken care of, but how high does the car need to be off the ground to have clearance to drop the tranny? and no one knows what the counterwieght wieghs? i don't have a scale here that will wiegh something like that so any help would be appreciated
Old 02-28-05, 02:37 PM
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Originally Posted by totallimmortal
nice since my poor engine hasn't been turned over in 2 months due to the damn ring gear on the flywheel not being on the flywheel.

Ohh yeah i've got the tools taken care of, but how high does the car need to be off the ground to have clearance to drop the tranny? and no one knows what the counterwieght wieghs? i don't have a scale here that will wiegh something like that so any help would be appreciated
I normally raise the car from the back only, I set the stands on the third tooth.

For the counter weight:
https://www.rx7club.com/showthread.p...counter+weight

basically:
Originally Posted by RotaryResurrection
There is no way to tell them apart once removed from the mazda factory box which is marked with the part number.

I've inspected all different years of auto ctwts and cant tell any physical difference, unlike front counterweights. I've even weighed them on a digital scale accurate to .01lb and can't find any consistent difference between s4 and s5/s6 weights. I've weighed both stock weights from engines I've parted out, and new in the box weights that came with customer flywheels.
Old 02-28-05, 03:01 PM
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Why do you want to know the weight of the counter weight??? Arw you calculating HP or just worried about lifting it??

Calc HP=?????

Lifting= Not very heavy at all 4lbs maybe?? If you are getting one from a junkyard make sure you get the large ring that the 6 bolts go threw...and the 6 bolts. A trick for Junkyard pulling. Once you take the 6 bolts out and take the stock Auto flyweel out of the way, you can use the 6 bolts as a counterwweight puller. Just put them back in the hole they came out of and start tightening them until they hit the stationary gear housing. Just keep tightening them and hit with a hammer and that thing will pop loose. tighten in a crisscross pattern to keep the pressure even.
B4 I get flamed, this happens 'after' you get the 2 1/8" nut loosened.

about the hight of the car: you need to buy a set of 4 jack stands. The car needs to be as high as those stands will go. my rocker panels are 15" off the ground. Remember your not going to take the tranny anywhere once you get it out. you just going to drop it down to the ground and move it back. The car does not have to be so high so that the tranny goes and sits in the corner some where.

Impact is the only way. Buy the electric one for $70-90 bux. If you try to use air you need a hefty compressor with a 500 lbs impact wrench to do the job. (ask me how I know) I was fortunate enough to have a way to take the whole engine over and have the thing taken off. My impact was 375 lbs with a compressor that went up to 120 lbs and they would not budge the nut. I believe it was Aaron that has an electric impact. ask him.
Old 02-28-05, 03:06 PM
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One more thing. Have you spent as much in tools as you would in labor??

Jack that will work on both the car and the transmission=$75
Jack stands=$40
Torque wrench (electric) $75
Torque wrench ( air ) $40 wrench $80 compressor


You just spent $190 in tools to do the job. My motto is "why buy one for $25 when you can build your own for $75!!! And build two for four times the price"
Old 02-28-05, 03:18 PM
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so what type of impact wrench can I use to get this thing off??? I am trying to gather the tools now that I will need as I am replaceing the clutch and flywheel together.
Old 02-28-05, 03:23 PM
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Originally Posted by bigturbo
so what type of impact wrench can I use to get this thing off??? I am trying to gather the tools now that I will need as I am replaceing the clutch and flywheel together.
i have a 450+lb rated impact and i couldn't get a flywheel nut of an S5 NA block until after i heated the nut up. according to sources here, it is locktighted on from the factory and heat is needed to break the locktite free. i didn't have a torch so i just got a cheapy torch nozzle and a disposable butane bottle from the local hardware store for like 20 bucks.
Old 02-28-05, 03:24 PM
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I heard a Bosch electric......seems that what I heard.

Somebody RENTED a Bosch Electric and said that it was killer. Took the nut right off.
Old 02-28-05, 05:32 PM
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well the impact gun i'm useing is rated at 900 lb, lol i'm borrowing it from a friend who works at a garage, it took of my rear axle nut without even bending out the tab after we tried for days with a 4 foot breaker bar. So i think i'll get the nut off. Do i need to take the driveshaft off the tranny or can in move enough to just sit it down? I've also heard that when i remove the driveshaft all the gear oil will come out there.

Ohh i'm concerned with the wieght of the counterwieght since it should also be included in the wieght of the flywheel since its attatched to it and i know the wieght of my flywheel as well as the stock one the only thing keeping me from knowing what difference there is gonna be is to know the wieght of the counterwieght which that thread didn't specifie only that all of em wieghed the same

Last edited by totallimmortal; 02-28-05 at 05:56 PM.
Old 02-28-05, 06:10 PM
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Originally Posted by jhammons01
I heard a Bosch electric......seems that what I heard.

Somebody RENTED a Bosch Electric and said that it was killer. Took the nut right off.
That was me

And I am about to rent it again
Old 02-28-05, 06:20 PM
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People have different experiences with their flywheels. I have a few friends engines that just popped off with minimal effort. However... my flywheel took 2 days to get off, 2 people, a blow hammer, impact wrench, torch, home made pry bars and home made breaker bars, large gear puller, blocks of wood, and a few more blunt objects. This was all with the engine out of the car. Granted this may have been a special case, but I have heard others having similar issues.

When I finally got the flywheel off, it was bent horribly bad from the gear puller. It was funny.
Old 03-01-05, 03:48 PM
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Originally Posted by KNONFS
That was me

And I am about to rent it again
See!!! There ya go. Now, I get a cookie for my substantiated answer.

I am not sure about this. But doesn't your flywheel incorporate a counter weight? Like I said I am not sure bu the incoporated counter weight in the flywheel is the same weight as the counter weight. So your not gaining more weight....... Just thinking out loud maybe somebody that knows something (unlike me) will know the correct answer.
Old 03-01-05, 04:14 PM
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you have to use a counterwieght from an automatic rx7 with an aftermarket flywheel like mine i'm wondering about the wieght of it
Old 03-02-05, 04:57 PM
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so when i pull the driveshaft off will the tranny fluid leak out there?

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