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-   -   Torqueing down the flywheel nut ? (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/torqueing-down-flywheel-nut-877076/)

J's fc 12-07-09 05:45 PM

Torqueing down the flywheel nut ?
 
I have a snap on XT7100 1/2 Magnesium Impact Wrench, and was woundering if i could torque the flywheel nut with this, to around 350ft lb. Thanks guys...

Gurew 12-07-09 05:51 PM

300 divided by your body weight = distance to stand on a breaker bar from center of nut, stand on the outside of that number btw

J's fc 12-07-09 06:53 PM


Originally Posted by rereme (Post 9664470)
300 divided by your body weight = distance to stand on a breaker bar from center of nut, stand on the outside of that number btw

But im going to use my gun, and i just wanted to know if my gun could torque that nut to spec?

Gurew 12-07-09 06:56 PM

im sure yes, but i dont think i would risk over torquing it...do it by hand

SirCygnus 12-07-09 07:00 PM


Originally Posted by rereme (Post 9664631)
im sure yes, but i dont think i would risk over torquing it...do it by hand

+1. it would behoove you to do it properly.

ForsakenRX7 12-07-09 08:07 PM

As long as the gun will go high enough in torque it will be fine. I've always used them for my flywheels. I've never encountered a problem. Just make sure you can set the gun correctly as well. My old gun (non name brand) had very clear adjustment. When it was stolen I went to a buddy of mine and borrowed his. It had the vaguest settings I swear. It just had 1-5. Asked him what was what and he didn't even know. So I just used the manual method. Both will work and both methods held fine. I just preferred that gun way more. Damn thieves, I hope it broke their wrist.

Gurew 12-07-09 08:09 PM

his gun specs are 700lbs torque...bit overkill and you risk overtightening it

therotaryrocket 12-08-09 01:36 AM

What would happen if you overtightened it? Does anyone know of a specific account where someone has done this? I recently torqued my counterweight on (have an aftermarket flywheel that bolts to auto counterweight), I used a 3/4" impact gun and a 52 mm socket, I turned the gun on the strongest setting and used the shop's pressure (95psi), I kept gunning it until the speed of the socket/nut spinning started to slow down to the speed of the eccentric shaft spinning. I also used the blue medium strength lock tight on the threads. I haven't had any problems, but I've only driven the car about 20 miles since then.

Aaron Cake 12-08-09 09:46 AM

The torque spec on the flywheel is kind of non-critical as long as it is tight enough. My method, which I got from the Rotary Aviation rebuild video, will work with most impacts of 250 ft-lbs or greater. Just manually tighten to 150 ft-lbs with a torque wrench, then make a mark on the flywheel at one point of the nut. Mark the point of the nut one behind the flywheel mark (to the right one point) and then tighten until the marks line up. That's about 400 ft-lbs. My electric impact can do this without too much trouble.

Gurew 12-08-09 11:25 AM

impact seems hokey to me...esp since it will be turning the engine backwards which could damage side seals depending on the porting done if im not mistaken.

just dont be lazy...book requests that you torque it to a certain spec...if they wanted you to torque bolts to a higher spec they would have put it in there....350lbs is the max i personally would go...and you can do this by hand easily

stevensimon 12-08-09 11:29 AM

crank the shit down and forget about it. ive never "properly" torqued a flywheel nut and ive never had an issue. also, ive never had an issue with spinning the motor backwards either. Mr. October 2009 is putting too much thought into this.

Gurew 12-08-09 11:31 AM

+1 on that...way too much thought, think about it..the engine works by turning counterclockwise, the flywheel nut tightens clockwise..it tightens on its own


put a little blue loctite on the threads, tighten to 150 then tighten by hand with a cheater bar 250+ should be find..it will tighten more as the engine runs

mikeric 12-08-09 12:53 PM

Maybe it is my Aviation training, but I always torque to spec. It just give you peace of mind that it is right and one less thing to worry about. Invest in a good set of torque wrenches and use them whenever you do anything on your car. Just do it right. My two cents.

therotaryrocket 12-08-09 01:56 PM

So that's 150 ft-lbs plus 60* more right? I think I get what your saying and I like this method, I'll do that next time because I know you've done more than a few Aaron Cake, well it also seems relatively fool proof.


Originally Posted by Aaron Cake (Post 9665771)
The torque spec on the flywheel is kind of non-critical as long as it is tight enough. My method, which I got from the Rotary Aviation rebuild video, will work with most impacts of 250 ft-lbs or greater. Just manually tighten to 150 ft-lbs with a torque wrench, then make a mark on the flywheel at one point of the nut. Mark the point of the nut one behind the flywheel mark (to the right one point) and then tighten until the marks line up. That's about 400 ft-lbs. My electric impact can do this without too much trouble.


Aaron Cake 12-08-09 02:50 PM


Originally Posted by rereme (Post 9665930)
impact seems hokey to me...esp since it will be turning the engine backwards which could damage side seals depending on the porting done if im not mistaken.
just dont be lazy...book requests that you torque it to a certain spec...if they wanted you to torque bolts to a higher spec they would have put it in there....350lbs is the max i personally would go...and you can do this by hand easily


Originally Posted by rereme (Post 9665939)
+1 on that...way too much thought, think about it..the engine works by turning counterclockwise, the flywheel nut tightens clockwise..it tightens on its own
put a little blue loctite on the threads, tighten to 150 then tighten by hand with a cheater bar 250+ should be find..it will tighten more as the engine runs

No to your first post that I quoted, and doubly no to your second post that I quoted. :)

First, turning the engine backwards cannot and will not damage the side seals, no matter how it is ported. If you are for some odd reason really worried about turning the engine backwards, simply hold the flywheel with your other hand. But in no way should you ever be worried about spinning the engine backwards. Additionally, the torque spec on the flywheel is largely irrelevant. The only purpose of that nut is to press fit the flywheel onto the taper of the eccentric shaft. As long as you have pounded it down enough (and Mazda has decided that about 350 FT-LBs is enough to accomplish this), then you are fine. No disaster if it goes to 450 FT-LBs, or no great crisis if it is only 300 FT-LBs.

Regarding your second post, the eccentric shaft is tapered where the flywheel presses on, and there is a Woodruff key locating the flywheel on the shaft. With the considerable force of the flywheel pressed onto the eccentric taper and the key, the flywheel cannot and does not rotate on the shaft.

I always recommend red Loctite on the flywheel nut. You just have to remember that it is on there and heat it up before you try and take it off.


Originally Posted by mikeric (Post 9666070)
Maybe it is my Aviation training, but I always torque to spec. It just give you peace of mind that it is right and one less thing to worry about. Invest in a good set of torque wrenches and use them whenever you do anything on your car. Just do it right. My two cents.

A torque wrench that goes to 350+ FT-LBs is a pretty hefty investment. And very difficult to use under the car. Even on an engine stand, unless that stand is bolted to the floor or held by several people, it is very hard to torque down the nut manually. Mazda has a special torque multiplier tool for this job, but again, it comes down to price. There are very few (if any?) engine builders that torque the flywheel nut to exactly the torque spec. It's just not required.


Originally Posted by therotaryrocket (Post 9666187)
So that's 150 ft-lbs plus 60* more right? I think I get what your saying and I like this method, I'll do that next time because I know you've done more than a few Aaron Cake, well it also seems relatively fool proof.

Yep, 150 FT-LBs (which is a common torque wrench) and then 60 degrees. You don't need a massive impact wrench to do this, even my 250 FT-LBs electric impact can do this in about 20 seconds. This is the method I learned from the Bruce Torrentine video many years ago, and I've used it on every engine I have built since.

alexdimen 12-08-09 05:37 PM

torque multiplier.

Ted Webster 12-08-09 05:47 PM

If you really want to torque it down using a standard torque wrench, there is a device out there that can be rented called a torque multiplier. I'm sort of annal about torque specs, but thats just me. I always use the multiplier and a new flywheel nut, and blue thread lock too--I know--annal, but what can I say. I've broken too many bolts, or stretched too many threads in the past.

As far as arresting the flywheel while all this is happening, I bought the tool for it that mazda trix or RB sells---works good, and I can do it without help.

fc3s22585 12-08-09 06:06 PM

both ways are fine it makes no diffrence ive rebuilt atleast 25 rotary and never had a problem either way, you should have no problem with impact gun

ForsakenRX7 12-08-09 06:48 PM

Wow...this becoming ridiculous. Its a nut. It has a torque spec. You tighten it to that spec by whatever means you feel necessary. That's it. There's really no more to it than that.

J's fc 12-08-09 07:20 PM

cool... Im going to torque it in setting 4 on my gun i got a flywheel stoper from mazdatrix and ready to get my baby runnig... thanks guys... :))

rootsgroup 12-08-09 08:30 PM

Here's how I do it-

I made this piece, but you could have it made as well.

Got the info for it from this website

http://www.specialpatrolgroup.co.uk/...ue/torque.html

rootsgroup 12-08-09 08:33 PM

Here's how I do it-

I made this piece, but you could have it made as well.

Got the info for it from this website

http://www.specialpatrolgroup.co.uk/spooky/torque/torque.html

rootsgroup 12-08-09 08:37 PM

2 Attachment(s)

Originally Posted by rootsgroup (Post 9667063)
Here's how I do it-

I made this piece, but you could have it made as well.

Got the info for it from this website

http://www.specialpatrolgroup.co.uk/...ue/torque.html

Let me try it again with the pictures

rx-7 obsessed 12-09-09 10:35 PM

wow wayyy to much thought going into this

take the impact and your socket
put the impact on the nut
pull trigger untill hammeraction cannot turn it anymore
make sure your 4 or higher if ur gun goes to 5

i am a transmission mechanic at a shop that has been around for 50 years. it dont matter if its 255 or 450 ft lbs if it dont crack it dont matter an impact thats rated for 700max will be fine.

i use a snap on impact thats rated 810 foward 1190 reverse never had a problem in 5 years

wackaloo13 12-11-09 01:48 AM


Originally Posted by Aaron Cake (Post 9665771)
The torque spec on the flywheel is kind of non-critical as long as it is tight enough. My method, which I got from the Rotary Aviation rebuild video, will work with most impacts of 250 ft-lbs or greater. Just manually tighten to 150 ft-lbs with a torque wrench, then make a mark on the flywheel at one point of the nut. Mark the point of the nut one behind the flywheel mark (to the right one point) and then tighten until the marks line up. That's about 400 ft-lbs. My electric impact can do this without too much trouble.

^ I use this method. Based on the thread pitch, torquing to 150 and tightening an extra 1/6 of a turn will get you to 300-330.

arghx 12-11-09 10:57 AM

blasted that bitch with the impact gun on full and called it a day

DriveFast7 12-11-09 12:42 PM

Every time I torqued that nut I had my 120lb girlfriend do chin-ups on a 3 foot cheater bar slid over the breaker bar. Until the cheater bar stopped moving downward.

Always owed her lunch after that.

wackaloo13 12-12-09 04:03 PM


Originally Posted by DriveFast7 (Post 9672942)
Every time I torqued that nut I had my 120lb girlfriend do chin-ups on a 3 foot cheater bar slid over the breaker bar. Until the cheater bar stopped moving downward.

Always owed her lunch after that.

pics or it didnt happen

solareon 12-12-09 04:37 PM

impact is much easier. I have a huge blue-point torque wrench that goes to 600 ft-lbs. Getting the stupid flywheel to hold still for that thing and then when the wrench clicks good luck

GeTCrAzYKiD 12-13-09 08:26 AM

Here's the show stopper. I USED A 1" Impact gun. Good for 1200 ft lbs AND IT STILL CAME LOOSE @ 90psi of shop air. (we have 1/2" air fittings, I work at a CAT equipment dealer.) I knew it came loose cuz I removed the inspection plate and pryed back on the flywheel and man was it loose. Did it all again and did ir properly with a snap-on 600 ft lb torque wrench and no more problems. I'll never guess it again. Ive rebuild a number of motors since then and always torqued it. None came loose yet. Do it right.

Puck 12-13-09 05:03 PM


Originally Posted by GeTCrAzYKiD (Post 9675918)
Here's the show stopper. I USED A 1" Impact gun. Good for 1200 ft lbs AND IT STILL CAME LOOSE @ 90psi of shop air. (we have 1/2" air fittings, I work at a CAT equipment dealer.) I knew it came loose cuz I removed the inspection plate and pryed back on the flywheel and man was it loose. Did it all again and did ir properly with a snap-on 600 ft lb torque wrench and no more problems. I'll never guess it again. Ive rebuild a number of motors since then and always torqued it. None came loose yet. Do it right.

Just because you did all that, does not mean that the flywheel was seated properly, when you tightened it. Although, with a taper fit, it is hard, near impossible, to misalign it. Maybe the key was holding it from seating all the way. If that was the case though, you would have had trouble bolting up the transmission.

How do you know you were getting 1200 ftlbs from your gun? Is that the rating for tightening, or loosening? You do make a good point though, if you do it with an impact gun, you don't know exactly how much torque you are putting on it.

I like to mark the flywheel and nut before I remove them, and then reinstall to the same mark, or a little more.


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