1 Fly wheel 2 PP thread bad

[AnthonyG]

Hi guys, went to reinstall PP on flywheel & Murphy showed up on last bolt! Per 17-20’lb torque spec last bolt stripped thread in flywheel! I know all the options. 1 Different flywheel w/o prob. 2 Helicoil. 3 weld redrilled retap. Or my solution as I have a lathe I went to a 3/8”-16 tap/thread & drilled a concentric hole in the 3/8”-16 bolt to remove weight till same weight as 5/16-18 bolt using balance scale to achieve same weight so it should still be balanced. I don’t like Helicoils. Didn’t wanna heat up flywheel w weld! Don’t think I need new flywheel! So that’s what I did. Engine still out of car. Don’t beat me too much but what do u think of my solution?

[drolston]

Shade tree approach:

Line the stripped hole with a tube of tinfoil and put the original bolt in just tight enough that the lock washer is copressed so it will not come loose. The balance is preserved and the pressure plate could care less that it is fastened with five and a half bolts instead of six.

Alternatively, fill the hole with JB Weld, drill it, tap it, and torque it to about half recommended value.

[tubman]

I am not enamored with any of the above approaches. I would use a quality thread insert (Keen-Sert, etc.) and be sure.

[Ronnie]

Hope you don't fly,aircraft are one of the largest users you can find with heli coil approved repair scheme. On a side note welding cast iron and drilling and tapping will be another venture you should eliminate from your offerings.It becomes almost non machinable at best. "Tub" has also given sound advice


R

[supereal]

Try a metric threaded bolt. Sometimes it will grab damaged threads and allow careful tightening when the SAE threads are worn or cross threaded.

[cmbrucew]

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Make a template and rotate it 60 degrees, redrill and tap. Good as new.
Bruce

[tubman]

Originally Posted by supereal

Try a metric threaded bolt. Sometimes it will grab damaged threads and allow careful tightening when the SAE threads are worn or cross threaded.

Really? On a clutch assembly?

[cadillac512]

I think your fix will work just fine. If your "new" bolt made torque and felt solid doing so, I don't see any reason to worry.


Terry

[AnthonyG]

Thx all, I do agree welding cast & trying to reaching is a poor option. Keensert I agree is a good fix but don’t think significantly different than my fix which eliminates the extra piece of metal. No way on the drilling tapping a new pattern without a precision mill & turn table, have a horror story w a flywheel I had originally gotten w the vehicle that after several engine pulls & detective work realized it was .090 out of ci centricity causing major vibration due to out of balance condition! I did a test run & used another 3/8-16 bolt like the one I’m using in a junk flywheel I put same thread in & torqued to 30 ‘lbs w no problem. I will use the 3/8-16 bolt I modified to correct weight. 1 out of 5 of u agrees thx Terry, u & me makes 2 outa 5, that’s 40% LOL! Thx all for comments & not spanking me too hard! Being a machinist & having experience in dynamic balancing I believe it’ll b fine.
Best all
A

[V8COOPMAN]

It SEEMS pretty evident that some of y'all have never witnessed what's left after a clutch explosion. I remember two different occasions specifically back in the latter '60s, and it ain't nice! One guy lost a leg over it. That's one area that you couldn't make me cut ANY corners. You DO realize that those six bolts have specially-sized shoulders and lengths? Do yourself a huge favor and if you can't afford a new flywheel, at least round-up a good used one. At the very least do as suggested above and re-drill and tap (PRECISELY) at the 60 degree offset...…..did I say PRECISELY? And don't just go to Lowes and buy six grade 8 bolts.....get the proper, dedicated pressure plate bolts. But WTF do I know? DD

[Jack E/NJ]

C512>>>I think your fix will work just fine.>>>
AG>>>thx Terry, u & me makes 2 outa 5,>>>


Ditto. Probably makes it at least 3 outta 6 oops 7 now. 8^) Jack E/NJ

[Kube]

Originally Posted by V8COOPMAN

It SEEMS pretty evident that some of y'all have never witnessed what's left after a clutch explosion. I remember two different occasions specifically back in the latter '60s, and it ain't nice! One guy lost a leg over it. That's one area that you couldn't make me cut ANY corners. You DO realize that those six bolts have specially-sized shoulders and lengths? Do yourself a huge favor and if you can't afford a new flywheel, at least round-up a good used one. At the very least do as suggested above and re-drill and tap (PRECISELY) at the 60 degree offset...…..did I say PRECISELY? And don't just go to Lowes and buy six grade 8 bolts.....get the proper, dedicated pressure plate bolts. But WTF do I know? DD

I've witnessed it up close and personal. Hurt like heck as I recall. Both bones in my right leg, well, they turned in to four bones if ya know what I mean.
Scatter shield was installed soon thereafter.

[Kube]

Originally Posted by cmbrucew

Make a template and rotate it 60 degrees, redrill and tap. Good as new.
Bruce

A template? Really?

[Kube]

Originally Posted by drolston

Shade tree approach:

Line the stripped hole with a tube of tinfoil and put the original bolt in just tight enough that the lock washer is copressed so it will not come loose. The balance is preserved and the pressure plate could care less that it is fastened with five and a half bolts instead of six.

Alternatively, fill the hole with JB Weld, drill it, tap it, and torque it to about half recommended value.

Yikes!

[KGS]

Originally Posted by V8COOPMAN

It SEEMS pretty evident that some of y'all have never witnessed what's left after a clutch explosion. I remember two different occasions specifically back in the latter '60s, and it ain't nice! One guy lost a leg over it. That's one area that you couldn't make me cut ANY corners. You DO realize that those six bolts have specially-sized shoulders and lengths? Do yourself a huge favor and if you can't afford a new flywheel, at least round-up a good used one. At the very least do as suggested above and re-drill and tap (PRECISELY) at the 60 degree offset...…..did I say PRECISELY? And don't just go to Lowes and buy six grade 8 bolts.....get the proper, dedicated pressure plate bolts. But WTF do I know? DD

The man knows from whence he speaks, as do I. Fortunately for me, unlike Kube's experience, every piece missed me completely. Do yourself and the next owner of your car a favor and get another flywheel...
Ken

[tubman]

OK. You can make that 3 1/2 out of 9, because I think what the O/P suggested is the best of the bad ideas.

But it's still a bad idea. I used to drag race too.

[Kube]

Ya know, this is yet another of those threads that perplexes me.
Man oh man, I pray some of you guys are never near me on the highway. Some guys should simply put the wrench down, shut the lights off and leave the garage...

[AnthonyG]

Wow! There’s the ass kicking I expected! While I still think my plan was viable considering the almost 20% larger hardware, I’ll go w a Helicoil fix staying w original 5/16-18 PP hardware. I asked for ur opinion so. As Ronnie indicated Helicoils r certified repair for threads in aircraft & aerospace industry so gotta b good for old fords

[deuce_roadster]

And as stated above, always use the correct shoulder bolts on the flywheels designed for them. Personally those flywheels are not difficult to obtain and are not rare. I would junk the flywheel with stripped hole and get another off the shelf.

[V8COOPMAN]

Originally Posted by cmbrucew

Make a template and rotate it 60 degrees, redrill and tap. Good as new.
Bruce

Now that's funny! Is a cardboard template good enough? I guess using the pressure plate itself would complicate matters?

Originally Posted by AnthonyG

As Ronnie indicated Helicoils r certified repair for threads in aircraft & aerospace industry so gotta b good for old fords

Now there's a perfect example of some good ol' MSM-like obfuscation. What Ronnie "indicates" ain't necessarily the WHOLE story for ALL parts in flyin' flivvers and space ships. With your mind seemingly made-up, I'm not sure why you even wasted your time asking for advice here to begin with. Just try VERY hard to imagine the scary stuff going-on inside that clutch housing with that flywheel/clutch spinnin' at even 2,500 RPMs. THEN try to imagine the tremendous multi-directional forces and loads imposed on those six, lousy 5/16" bolts screwed-into Helicoils when ya raise the RPMs to four grand and enthusiastically engage the clutch! GOOD LUCK, ol' buddy! I wish ya the best!! Just remember what deuce_roadster indicated....used flywheels are NOT hard to round-up. DD

[40 Deluxe]

Isn't there an identical bolt diametrically opposite? Just drill and tap it to 3/8" and use identical 3/8" bolts in each. Balance problem solved! You will still have 4 shouldered 5/16" to locate the pressure plate. Or check a GM pressure plate bolt. I believe they are 3/8" bolts with the required shoulder.

Oh boy, did I goof! Never type a response late at night! Apparently I was thinking of a '50-'51 Merc with a Borg and Beck diaphragm clutch. At least, that's my (lame) excuse!
Sorry about that!

[Mart]

^^ Actually there isn't. because of the 3 sets of holes offset by 32 degrees there are not two holes opposite each other.

I think I would have helicoiled the original hole, but that's me.

Actually the make a template comment isn't a bad one. You could rotate the PP 32 degrees so three bolt holes are still in use and drill and tap three new ones to the original spec.

Many ways to do this job, some better than others.

Some threads go like this where I bet the Op wishes he had just not mentioned it.

But the bottom line is the car is now capable of being driven. Balance was taken into consideration so I would say that it is an okay repair. There might have been better ways, but that way is okay.

Mart.

[cadillac512]

Once again, Mart is a voice of reason. Well said. Carry on...
Terry

[Kube]

Originally Posted by Mart

^^ Actually there isn't. because of the 3 sets of holes offset by 32 degrees there are not two holes opposite each other.

I think I would have helicoiled the original hole, but that's me.

Actually the make a template comment isn't a bad one. You could rotate the PP 32 degrees so three bolt holes are still in use and drill and tap three new ones to the original spec.

Many ways to do this job, some better than others.

Some threads go like this where I bet the Op wishes he had just not mentioned it.

But the bottom line is the car is now capable of being driven. Balance was taken into consideration so I would say that it is an okay repair. There might have been better ways, but that way is okay.

Mart.

Perhaps it's my (former) career as a tool maker that makes me cringe when I see suggestions to "make a template" to properly and (necessarily) precisely locate threaded holes.
And perhaps it's simply my decades of mechanical experience that screams "ARGHHH, NO, don't do it that way".

Yes, there are many ways to preverbally "skin a cat". However, while some of those methods will get the job done, many will surely turn out quite ugly.

[AnthonyG]

six, lousy 5/16" bolts screwed-into Helicoils

Just 4 the record it’s 1 lousy 5/16” bolt that would b screwed into 1 Helicoil not 6. It’s 1 threaded hole that’s bad 5 are fine. But point taken!

[Jack E/NJ]

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Your one lousy, probably stronger than original, 3/8" fix should be fine if you try to keep revs under 10K. 8^) Jack E/NJ

[V8COOPMAN]

Originally Posted by AnthonyG

Just 4 the record it’s 1 lousy 5/16” bolt that would b screwed into 1 Helicoil not 6. It’s 1 threaded hole that’s bad 5 are fine. But point taken!

Hey Anthony....NOW I get it! Only ONE lousy bolt out'a six. Of course, we all know how stingy and frugal the auto makers are. Hell, if they can POSSIBLY save 10 cents per car, they WILL! That adds up to a remarkable $100K savings for every million cars produced. The corporate bean counters love that thinking. Ya reckon that if they figured they could get by with only five GOOD pressure plate bolts, they WOULD?


The picture below is the result of a clutch explosion in what appears to be a '37-'41 Willys coupe, which ironically is close in configuration and size to a '35 Ford. DD

[AnthonyG]

Several have indicated shoulder bolts? As supplied from MAC’s they’re not, they’re hardened 5/16-16 X 1” long full thread no shoulder?

[GOSFAST]

Originally Posted by AnthonyG

Several have indicated shoulder bolts? As supplied from MAC’s they’re not, they’re hardened 5/16-16 X 1” long full thread no shoulder?

ALL pressure plate bolts MUST have the shoulder to "center" the cover on the wheel, if not you run a very high risk of a vibration!!

The bolt shoulders MUST reach into the counterbored section of the flywheel!

Thanks, Gary in N.Y.

P.S. Just went down this road with a member here on his "blown" unit, Here's a a couple shots of how the bolt should be and some asst'd ones! The third bolt over shouldn't be used! Maybe even the last one as well.

[AnthonyG]

Thinking MAC’s sent wrong hardware? Will call them today!

[V8COOPMAN]

Originally Posted by AnthonyG

Several have indicated shoulder bolts? As supplied from MAC’s they’re not, they’re hardened 5/16-16 X 1” long full thread no shoulder?

Funny, that's the grade-8 bolt I warned about using from Lowes in lieu of the correct parts, and one more reason I keep trying to warn folks about THAT outfit in general! Below picture is an example of some precision, shouldered "pressure plate" bolts. I don't believe I've ever seen a plated pressure plate fastener like depicted in your picture. DD

[AnthonyG]

Thx, will buy a set of ARP’s

[Bored&Stroked]

Originally Posted by AnthonyG

Thx, will buy a set of ARP’s

Now you're talking . . . why the heck scrimp on something so cheap as flywheel or pressure plate bolts - makes no sense. This is absolutely the last place I try to save a few dollars - on any engine.

Along the same line, I know quite a few guys that have no problem putting their cast iron flathead flywheel on a lathe and carving the crap out of it to get it down to 22 - 24 lbs. Been done lots of times . . . and every time I hear about it, it scares the heck out of me. Who can possibly know how much carving is "safe" on their specific cast flywheel - before it explodes that one BAD day???

Here is an example of how I get to a 24 lb steel flywheel . . . via a custom billet steel version. Yes, it costs $440 for a custom machine and profile cut version (to get to my weight) - but I know it won't explode and take out my thin cast iron integral bell housing - on the way to my legs. I run my engines hard (at times) - have had my 284 up to 6200 in 1st and 2nd . . .

IMG_8369 copy.jpg

IMG_8371 copy.jpg

[Kube]

Originally Posted by Bored&Stroked

Now you're talking . . . why the heck scrimp on something so cheap as flywheel or pressure plate bolts - makes no sense. This is absolutely the last place I try to save a few dollars - on any engine.

Along the same line, I know quite a few guys that have no problem putting their cast iron flathead flywheel on a lathe and carving the crap out of it to get it down to 22 - 24 lbs. Been done lots of times . . . and every time I hear about it, it scares the heck out of me. Who can possibly know how much carving is "safe" on their specific cast flywheel - before it explodes that one BAD day???

Here is an example of how I get to a 24 lb steel flywheel . . . via a custom billet steel version. Yes, it costs $440 for a custom machine and profile cut version (to get to my weight) - but I know it won't explode and take out my thin cast iron integral bell housing - on the way to my legs. I run my engines hard (at times) - have had my 284 up to 6200 in 1st and 2nd . . .

Attachment 429959

Attachment 429960

You make a good point.
I have removed the bell from nearly every flywheel I've installed. However, I grind them off and always well bathed in coolant while doing so.
They are then balanced and checked for cracks.
Perhaps I've simply been lucky, but I have never found a bad flywheel after grinding.
I have tossed a few that were heat cracked - seen upon visual inspection prior to grinding.

[AnthonyG]

It appears the ARP bolts required r used from 1949-to modern small block Fords. Looks like ARP# is 150-2201? Is this the preferred replacement for originals?
Also does anyone have a reasonably priced flywheel ready to go in?

[bobH]

Regarding the part of this discussion that has to do with the correct, shouldered, pressure plate bolts.... This all becomes a little 'fuzzy' to me, as my local clutch rebuilder ALWAYS supplies a fresh/new set of correct, shouldered, PP bolts with the pressure plate he sells. It's automatic, and part of the package. I'm wondering if some of the folks here are not getting the same service.

[Kube]

[QUOTE=AnthonyG;
Also does anyone have a reasonably priced flywheel ready to go in?[/QUOTE]

What size clutch ?

[AnthonyG]

10”, also trying to verify ARP pressure plate mount hardware, wanna buy new. Think it’s Arp#150-2201? Any insight?

[V8COOPMAN]

Anthony.....I want you to understand that I have NOT been trying to bust your chops in this thread. I just don't want to see you damaging your stuff, or end-up injured in any way. I've just spent better than an hour trying to verify that ARP part number, although that 150-2201 is the one that I tentatively jumped on initially. The problem is that ARP doesn't seem to list specific application info as far back as our flatheads. Those 150-2201 bolts "look" about the right size, BUT...…….! Those -2201 ARP bolts' actual dimensions are 5/16"-18 thread, with an overall length of shank UNDER the head (shoulder AND threads) of 0.780". So, how long are the shanks on your current bolts...UNDER the head?


I see where it looks like Kube may be attempting to find you a GOOD flywheel. Isn't your engine an 8BA-type ('49-'53) engine? If so, the replacement flywheel MUST be a matching 8BA-type. DON'T let anyone tell you differently!! 8BA f'wheels can be identified by the six bolt holes being drilled all the way through the flywheel. Earlier f'wheels have "blind" holes….NOT drilled all the way through to the opposite side. You need to stipulate WHICH type of flywheel you need.


If I had a spare wheel layin'-around, I'd send it your way for the freight. Unfortunately, I DON'T have one layin'-around, but I'll bet half a dozen guys reading this thread have a decent one layin' in a corner, never to be used again, that could sell or donate to your cause for the freight cost. So, what type of flywheel you got, and what is bolt shank length of your six original bolts? And just to be sure, will a common 5/16" "coarse"-threaded bolt thread into one of the undamaged, threaded holes? DD

[Gene1949]

Originally Posted by AnthonyG

Also does anyone have a reasonably priced flywheel ready to go in?

Last year I bought a Centerforce II [10" PP, duel friction disk] and flywheel from J*gs using their discount.

Instillation was a breeze and smooth as silk. AND really easy on old knees

[AnthonyG]

Originally Posted by V8COOPMAN

Anthony.....I want you to understand that I have NOT been trying to bust your chops in this thread. I just don't want to see you damaging your stuff, or end-up injured in any way. I've just spent better than an hour trying to verify that ARP part number, although that 150-2201 is the one that I tentatively jumped on initially. The problem is that ARP doesn't seem to list specific application info as far back as our flatheads. Those 150-2201 bolts "look" about the right size, BUT...…….! Those -2201 ARP bolts' actual dimensions are 5/16"-18 thread, with an overall length of shank UNDER the head (shoulder AND threads) of 0.780". So, how long are the shanks on your current bolts...UNDER the head?


I see where it looks like Kube may be attempting to find you a GOOD flywheel. Isn't your engine an 8BA-type ('49-'53) engine? If so, the replacement flywheel MUST be a matching 8BA-type. DON'T let anyone tell you differently!! 8BA f'wheels can be identified by the six bolt holes being drilled all the way through the flywheel. Earlier f'wheels have "blind" holes….NOT drilled all the way through to the opposite side. You need to stipulate WHICH type of flywheel you need.


If I had a spare wheel layin'-around, I'd send it your way for the freight. Unfortunately, I DON'T have one layin'-around, but I'll bet half a dozen guys reading this thread have a decent one layin' in a corner, never to be used again, that could sell or donate to your cause for the freight cost. So, what type of flywheel you got, and what is bolt shank length of your six original bolts? And just to be sure, will a common 5/16" "coarse"-threaded bolt thread into one of the undamaged, threaded holes? DD

DD, I’m an old fart w very thick skin & been around a long time mostly in groups where if u can’t take the heat get outa the kitchen. U’ve been very helpful on quite a few of my posts! I know ur style & personality at least from many of ur posts replies! Really didn’t take it wrong & understood u points & tried to add a bit of humor to indicate I was fine w the busting chops, I do it all the time. I call it “Telling them to go to hell but trying to make them enjoy the trip”! Obviously info from reply’s heeded on my part. While I do consider myself frugal while researching solutions regardless of my reply’s I add the collective info to the ole computer.

Now, the info Yes engine is an 8BA, shank length r 1”, threads r 5/16”-18
No harm no foul!

[Bored&Stroked]

Hey Anthony - so you're looking for a 49-53 flywheel with a 10" LONG style clutch pattern? If so, I will look out in my shop and I'm sure I have one or more.

Be happy to send you one for the price of shipping . . . or you can drive to Columbus, OH and I'll hand it to yah. We're not that far apart - though the "time factor" always comes into play. Let me know - happy to help out.

Note: It should be resurfaced and balanced with your clutch plate (is what I'd do).

[tubman]

All's well that ends well!

[AnthonyG]

Thx Bored&Stroked & much appreciated but I started networking during the thread & found one locally thru a Mechanic friend, guy in a his Car Club & is donating . I’ll join the club as thx to him! But Big Thx for ur very generous offer! As networking typically works another guy in the club owns a local automotive Machine & Fab shop who can do the surfacing, probably balancing too, but that I have to check. Thx again for the offer!!

[V8COOPMAN]

Well Sheeeit! Is this place cool, or what? Ain't that B&S guy about as righteous as it gets? Damn straight! DD

[V8COOPMAN]

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…...and they all lived happily ever after! DD

[AnthonyG]

DD just to close on the bolts, I found NOS Ford PP bolts on EBay from I guy I’ve bought from before & trust!-NOS Ford flathead 1932-56 V8 special clutch pressure plate bolt set (6)

[ford38v8]

Anthony, I've never installed a clutch, so I'm out of my league, but from info I've picked up here on the Barn, the balancing should be done on the complete assembly of flywheel/clutch disc/pressure plate.
Beyond that, I'm glad you've decided to heed advice to not modify your flywheel with Helicoil or Keensert. They are used in Aerospace Gov spec applications, however I'm not sure of those products certified usage with shoulder bolts.

[Bored&Stroked]

Originally Posted by AnthonyG

Thx Bored&Stroked & much appreciated but I started networking during the thread & found one locally thru a Mechanic friend, guy in a his Car Club & is donating . I’ll join the club as thx to him! But Big Thx for ur very generous offer! As networking typically works another guy in the club owns a local automotive Machine & Fab shop who can do the surfacing, probably balancing too, but that I have to check. Thx again for the offer!!

Glad you found a local solution . . . best of luck!

[AnthonyG]

All good! Thx all! FB’rs Great! Great source for all ole Ford knowledge! Even @ 70 I continue to grow! While I renewed many clutches I never had a stripped mounting hole in a flywheel. Will always opt in the future for a replacement w a flywheel w all good threads! I’ll keep the frugal Tool & Die maker under control !

[rich b]

I believe the hole is now too big to repair using a 5/16" heli-coil, anyway.

[AnthonyG]

Not that it matters for this post as a fresh flywheel is being used but for general knowledge a 21/64” drill is needed for a 5/16-18 Helicoil. The Major thread diameter of a 5/16-18 bolt is 5/16. So even if thread is stripped of thread completely a 21/64 drill would remove 1/64 more than 5/16 & all stripped condition in preparation for the 5/16-18 Helicoil tap.

[AnthonyG]

Installing fresh FW balanced w PP. Does anybody use Loctite on PP to FW Bolts?

[Mart]

Originally Posted by AnthonyG

Installing fresh FW balanced w PP. Does anybody use Loctite on PP to FW Bolts?

I don't. Why would you? Just use the stock spring washers and torque to the correct value. You (or someone else) will want to undo them some time in the future.

[AnthonyG]

Hey Mart, I was pretty much there w lock washers & torque only & beings it put me through a little bit of hell thought can’t hurt to check