J's fc

iTrader: (1)

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

iTrader: (4)

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

iTrader: (1)

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

Gurew

iTrader: (4)

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

SirCygnus

iTrader: (1)

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

ForsakenRX7

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

iTrader: (4)

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

therotaryrocket

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

iTrader: (1)

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

iTrader: (4)

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

iTrader: (11)

crank the **** 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

iTrader: (4)

+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

iTrader: (20)

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

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.

Aaron Cake

iTrader: (1)

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.

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.

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

iTrader: (13)

torque multiplier.

Ted Webster

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

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

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

iTrader: (1)

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

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

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

Let me try it again with the pictures

rx-7 obsessed

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

iTrader: (3)

^ 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.