Sheared a Flywheel bolt - what's the right torque?? (Gen3 Coyote)

[mmklaxer]

Following the manual installing the flywheel with bolts from Forte. Manual states 80 ftlbs. started hand tight around the 8 bolts, then walked them up in torque in a star pattern.

before I hit 80 ft lbs, i sheared a bolt off. Luckily it sheared at a point where I can remove easily, but now I'm back to square 1. will buy new bolts, but wondering if I either got a bad bolt or is the torque a lower value?

I'll call Mike Forte as well to get his thoughts, but curious if anyone else ran into this problem.

Thanks.

[michael everson]

80 is right. Maybe a bad bolt or bad wrench?
Mike

[edwardb]

From a Ford Service manual for a 2015 Mustang GT. That would be a Gen 2 Coyote but no reason to think a Gen 3 is any different:

Torque (in a star pattern):
Stage 1: 89 lb.in (10 Nm)
Stage 2: 177 lb.in (20 Nm)
Stage 3: 60°

Note: The flywheel bolts are torque to yield design and are not reusable. Remove and discard used bolts.

Note also since this is from a Ford service manual, a valid assumption would be only for Ford branded bolts. Which I've used successfully on a couple Coyote builds following the above instructions. Note also there's come confusion between 4.6 mod motor specs which have 8mm flywheel bolts and the Coyote which have 10mm flywheel bolts. The above specifically is for a Coyote as noted. The Ford bolts have a locking compound already on the threads so nothing additional is required. Can't say why FF doesn't provide this information vs. a straight ft.lbs. spec when they call out Ford bolts. Finally, note if using something other than Ford bolts, the above could be different. ARP, for example, specifies only a torque value but also say to use their lube when installing. Which makes a difference.

[weendoggy]

From a Ford Service manual for a 2015 Mustang GT. That would be a Gen 2 Coyote but no reason to think a Gen 3 is any different:

Torque (in a star pattern):
Stage 1: 89 lb.in (10 Nm)
Stage 2: 177 lb.in (20 Nm)
Stage 3: 60°

Note: The flywheel bolts are torque to yield design and are not reusable. Remove and discard used bolts.

Note also there's come confusion between 4.6 mod motor specs which have 8mm flywheel bolts and the Coyote which have 10mm flywheel bolts.

Strange..., my 4.6 had 10mm bolts, same as my Coyote. Difference can be either 6 or 8 bolt pattern flywheel on the 4.6 along with length of bolt. I use ARP with torque of 70 lb/ft.

[mmklaxer]

From a Ford Service manual for a 2015 Mustang GT. That would be a Gen 2 Coyote but no reason to think a Gen 3 is any different:

Torque (in a star pattern):
Stage 1: 89 lb.in (10 Nm)
Stage 2: 177 lb.in (20 Nm)
Stage 3: 60°

Note: The flywheel bolts are torque to yield design and are not reusable. Remove and discard used bolts.

Note also since this is from a Ford service manual, a valid assumption would be only for Ford branded bolts. Which I've used successfully on a couple Coyote builds following the above instructions. Note also there's come confusion between 4.6 mod motor specs which have 8mm flywheel bolts and the Coyote which have 10mm flywheel bolts. The above specifically is for a Coyote as noted. The Ford bolts have a locking compound already on the threads so nothing additional is required. Can't say why FF doesn't provide this information vs. a straight ft.lbs. spec when they call out Ford bolts. Finally, note if using something other than Ford bolts, the above could be different. ARP, for example, specifies only a torque value but also say to use their lube when installing. Which makes a difference.

Talked to Forte - he concurred. Will need new bolts, which he has, but back moving forward.

Double checked the torque wrench on the lug nuts; clicking properly. Thanks all.

[edwardb]

Strange..., my 4.6 had 10mm bolts, same as my Coyote. Difference can be either 6 or 8 bolt pattern flywheel on the 4.6 along with length of bolt. I use ARP with torque of 70 lb/ft.

I don't want to go down a 4.6 rabbit hole. I personally have no experience with them plus off topic from the OP's question. I only mentioned it because in my experience people have confused the torque settings between the 4.6 and the Coyote. Some have suggested they are different because of the different bolt size. But perhaps not all 4.6's are the same.

As for the original question, I'm a huge believer in following the mfg's recommendations, and in this case Ford is very specific with the Coyote when using their parts. They pay a lot of engineers and do a lot of testing. My recommendation is to torque their flywheel bolts exactly as they describe. Which I have done myself with two Coyote builds and no issues. I've also had great experience with ARP hardware and they certainly have a good reputation. Using their flywheel bolts and their instructions would be another very solid choice IMO. But at nearly three times the cost.

[mmklaxer]

I don't want to go down a 4.6 rabbit hole. I personally have no experience with them plus off topic from the OP's question. I only mentioned it because in my experience people have confused the torque settings between the 4.6 and the Coyote. Some have suggested they are different because of the different bolt size. But perhaps not all 4.6's are the same.

As for the original question, I'm a huge believer in following the mfg's recommendations, and in this case Ford is very specific with the Coyote when using their parts. They pay a lot of engineers and do a lot of testing. My recommendation is to torque their flywheel bolts exactly as they describe. Which I have done myself with two Coyote builds and no issues. I've also had great experience with ARP hardware and they certainly have a good reputation. Using their flywheel bolts and their instructions would be another very solid choice IMO. But at nearly three times the cost.

Agree. And this one is on me for not ready all the instructions and triangulating the right answer before proceeding. Lesson learned.

[CraigS]

You did note that the TQ specs are in lb.INCH right? You said "Manual states 80 ftlbs." and "Double checked the torque wrench on the lug nuts;" but edwardb's specs say;
Torque (in a star pattern):
Stage 1: 89 lb.in (10 Nm)
Stage 2: 177 lb.in (20 Nm)
Stage 3: 60°

[mmklaxer]

You did note that the TQ specs are in lb.INCH right? You said "Manual states 80 ftlbs." and "Double checked the torque wrench on the lug nuts;" but edwardb's specs say;
Torque (in a star pattern):
Stage 1: 89 lb.in (10 Nm)
Stage 2: 177 lb.in (20 Nm)
Stage 3: 60°

Good question. So the Gen 3 Coyote installation instructions clearly states 80 FT lbs in both the text and in the Table of Torque specs. I did the same thing - wondered if I glossed over that when reading and either missed that the 80 should be IN lbs or Nm. Nope - I did it by the manual, but the manual is inconsistent with the Ford Performance specs for torqueing their bolts. I should have checked with the ford specs first, but since the torque was specifically listed in the COyote instructions, I thought I'd be good following them. Wrong answer.

[Jeff Kleiner]

Good question. So the Gen 3 Coyote installation instructions clearly states 80 FT lbs in both the text and in the Table of Torque specs. I did the same thing - wondered if I glossed over that when reading and either missed that the 80 should be IN lbs or Nm. Nope - I did it by the manual, but the manual is inconsistent with the Ford Performance specs for torqueing their bolts. I should have checked with the ford specs first, but since the torque was specifically listed in the COyote instructions, I thought I'd be good following them. Wrong answer.

Ford bolts=Ford specs. My buddy used the FFR Coyote supplement specs when assembling his and pulled threads out of the flywheel while installing the pressure plate.

Jeff

[JohnK]

You know, there are a lot of things that could be revised for clarity in the FFR manuals but continuing to publish blatantly wrong torque specs is just inexcusable. It would take them all of 5 minutes to update the instructions with correct torque specs.

[Lickity-Split]

The tire department at Costco can calibrate your torque wrench to see if it's really clicking at 80 pound feet. I had to ask the guy nicely, but they checked mine for free.

[mmklaxer]

Ford bolts=Ford specs. My buddy used the FFR Coyote supplement specs when assembling his and pulled threads out of the flywheel while installing the pressure plate.

Jeff

good to know. Cause I totally would have gone with the 35ftlbs as called out. I'll be checking the ford specs, the ARP specs, and the pressure plate specs before doing anything.

[CraigS]

WOW, this is sad.
FFR are you reading this?
In the past I have often looked up generic specs by bolt size. You have to be careful about fine or coarse thread, bolt hardness (Grade 5 or 8 or...), type of lube etc. but they have been helpful in giving an expected range. But now, w/ so many OEs being torque + angle specs, generic charts don't work out.

[Hoooper]

Unfortunately I think the FFR torque specs for everything that is manufacturer equipment like axle nuts, flywheel bolts, driveshaft bolts, etc. should at least be verified against the OEM spec with a quick google search before torqueing down. Having read this kind of thing before starting my assembly I only relied on the FFR torque specs for things that were FFR designed like the IRS control arm to frame attachments, etc.

Also sometimes the OEM spec changes! Thats why its good to double check online. Like the 2015+ IRS axle nuts, the OEM Ford spec for that changed I think around 2018 so they could have a spec in there from when they designed it and it was right, but now its no longer right. And then even when you get it right theres no guarantee, Ford racing unofficially says to check the torque on the 2015+ rear axle nuts between each section at the track because the hub is known to be a bit weak!

[JeffP]

You guys have me a little concerned on this one, I setup my engine a year ago so can't specifically recall what torque I would have used for these bolts but I'm sure I would have followed FF's instructions. Just doing google searches I can find documentation that supports 75-85FTlb's.. and some even reference both Paul's inLB stage1&2 but then reference a FTlb stage3...

So, how concerned do I need to be if I did the 80ft lbs? Anyone venture a guess at what 177in lb's + 60* might end up in ft lbs? Any chance we're getting in the same neighborhood?

I found this ford doc that states 75-85ftlb, but can't tell which flywheel its for. I don't have the part number on my flywheel available to search it specifically, it was the one Mike provided.

"For a 5.0L/5.8L based engine, the flywheel to crankshaft bolts (FRPP # M-4216-A210) must be hand-torqued
to 75-85 ft. lbs. Use of an impact gun can cause crankshaft damage. Damage of this type can cause the rear
main seal to leak. Loctite thread lock should be used to keep the bolts tight and seal the threads from leaking oil
past the threads and onto the clutch. "

https://performanceparts.ford.com/do...-7560-A302.PDF

[edwardb]

You guys have me a little concerned on this one, I setup my engine a year ago so can't specifically recall what torque I would have used for these bolts but I'm sure I would have followed FF's instructions. Just doing google searches I can find documentation that supports 75-85FTlb's.. and some even reference both Paul's inLB stage1&2 but then reference a FTlb stage3...

So, how concerned do I need to be if I did the 80ft lbs? Anyone venture a guess at what 177in lb's + 60* might end up in ft lbs? Any chance we're getting in the same neighborhood?

I found this ford doc that states 75-85ftlb, but can't tell which flywheel its for. I don't have the part number on my flywheel available to search it specifically, it was the one Mike provided.

"For a 5.0L/5.8L based engine, the flywheel to crankshaft bolts (FRPP # M-4216-A210) must be hand-torqued
to 75-85 ft. lbs. Use of an impact gun can cause crankshaft damage. Damage of this type can cause the rear
main seal to leak. Loctite thread lock should be used to keep the bolts tight and seal the threads from leaking oil
past the threads and onto the clutch. "

https://performanceparts.ford.com/do...-7560-A302.PDF

The quote you found ("5.0L/5.8L") is likely the older SBF engine. The displacements match and seems to match with the link you provided. That's an old design and likely pre-dates the now more common use of torque-to-yield specifications. Especially given that in its original form was an iron block and heads, which is not as critical as the now very common aluminum engines. So no surprise it's specified as a torque value only. The quote I provided previously was specifically for the Coyote engine and you can take that to the bank. Don't try to correlate torque-to-yield settings to straight torque settings. One of the main points of torque-to-yield is that it removes the variables common with straight torque values, like friction, lubrication, etc.

As far as the torque values in the FF documentation, I have no issue with the general information they provide for the suspension components, the torque guides, etc. But when it comes to specific OE components (like this example) I always quickly check what the mfg's say. Almost always just a few minutes Google search. It's maybe a little unrealistic to think they could list every mfg spec since their products, by definition, can use so many different brands of parts. Having said that, can't think of a good excuse for listing Ford OE parts in the Coyote instructions and then providing torque specs that don't agree with the mfg recommendations. Buyer beware is the best I can come up with.

[JeffP]

The quote you found ("5.0L/5.8L") is likely the older SBF engine. The displacements match and seems to match with the link you provided. That's an old design and likely pre-dates the now more common use of torque-to-yield specifications. Especially given that in its original form was an iron block and heads, which is not as critical as the now very common aluminum engines. So no surprise it's specified as a torque value only. The quote I provided previously was specifically for the Coyote engine and you can take that to the bank. Don't try to correlate torque-to-yield settings to straight torque settings. One of the main points of torque-to-yield is that it removes the variables common with straight torque values, like friction, lubrication, etc.

As far as the torque values in the FF documentation, I have no issue with the general information they provide for the suspension components, the torque guides, etc. But when it comes to specific OE components (like this example) I always quickly check what the mfg's say. Almost always just a few minutes Google search. It's maybe a little unrealistic to think they could list every mfg spec since their products, by definition, can use so many different brands of parts. Having said that, can't think of a good excuse for listing Ford OE parts in the Coyote instructions and then providing torque specs that don't agree with the mfg recommendations. Buyer beware is the best I can come up with.

Thanks Paul, how bad off am I assuming I used the 80ft lb's? Obviously none of them broke, so it went on with out any issue. But is this something I need to remove and replace? The car is complete, so this would be a monumental task.

I can't find a manual specific to the M50C (G3, coyote, manual), closest I can find is the Aluminator which has the torque values you mention. https://performanceparts.ford.com/do...6007-A50NA.pdf

[edwardb]

Thanks Paul, how bad off am I assuming I used the 80ft lb's? Obviously none of them broke, so it went on with out any issue. But is this something I need to remove and replace? The car is complete, so this would be a monumental task.

I can't find a manual specific to the M50C (G3, coyote, manual), closest I can find is the Aluminator which has the torque values you mention. https://performanceparts.ford.com/do...6007-A50NA.pdf

Obviously there's no way for me to know for certain. But if it were mine, I'd leave it alone.

[CraigS]

JeffP, off top of my head 80# sounds reasonable for a 10mm 10.9 bolt so I am w/ edwardb, leave it as is. But maybe my old standby will help you make a decision. Do some searching for metric bolt torque specs by size. Were yours 8 or 10mm? We can assume fine thread. I can educated guess at a grade 10.9 but maybe someone can verify. You may remember whether you lubed them and what with. So, if generic charts come up w/ 70-90# I would forget it and drive on. Outside that range, let's get more opinions here.

[Andrew Davis]

Just a possibilty, I would measure the hole depth and endure the threads go deep enough. It could be a torsional failure.

[Kbl7td]

LS flywheel bolts are 11mm 74ft/lb

[Hoooper]

Even the ARP flywheel bolts for a coyote only call for 70 ft lbs and theyre always higher than OEM unless there is some kind of over-clamping flaw in the OEM design which would be extremely unusual. If I were you I would certainly be at least a little concerned, especially since others have broken bolts trying to get to the torque you think you might have used. The problem is its a major pain to check obviously, and if you just leave it and there is a problem you wont know there is a problem until there is a very big problem.

[Pat Landymore]

Apologies I’m late to this thread…

When I was assembling the flexplate to the big block in my ‘35 pickup, two of the bolts felt “mushy” as they started to tighten down. Removed all and checked…there was an insufficient chamfer on the flexplate to clear the generous radius under the bolt head of the ARP fasteners.

Is it possible that -mmklaxer has an insufficient chamfer to clear on a couple of his flywheel bolts. I’ve read that with rod bolts this situation is almost guaranteed breakage whether while assembling, or if you missed it, once engine hits some revs.

My 2 cents.

Cheers

[mmklaxer]

Wrapping this one up. For starters, great discussion and thanks to all for the input.

I'll be following the torque specs from ford performance for the flywheel bolts (10 Nm, 20 Nm, 60*)

contacted Mike Forte for the PP bolts, as they came in a bag without a part number. He confirmed the torque for those is 55-57 ftlbs. Glad I confirmed, as that aligned with some other threads I've seen but not the instructions. They are also NOT the ford performance PP bolts that appear metallic in color with threadlocker on the threads

For the tremec bellhousing, going with their torque specs for the bellhousing to engine and transmission to bellhousing. (looking them up now...)

[mmklaxer]

Closing this one out. Completed the 3 stage torque process described above. When i got to the angle-of-turn step, I marked the bolts and flywheel for 60 degrees and started turning with increasing torque settings on the wrench just to see what happens.

Clicked at 50 ftlbs before 60*
clicked at 70 ftlbs before 60*
set the wrench at 80 ftlbs and it didn't click before i achieved bolt stretch

[JeffP]

Closing this one out. Completed the 3 stage torque process described above. When i got to the angle-of-turn step, I marked the bolts and flywheel for 60 degrees and started turning with increasing torque settings on the wrench just to see what happens.

Clicked at 50 ftlbs before 60*
clicked at 70 ftlbs before 60*
set the wrench at 80 ftlbs and it didn't click before i achieved bolt stretch

I really appreciate this feedback, at the very least it gives me a little peace of mind i'm in the ball park.