Helicoil

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Model T Ford Forum: Forum 2012: Helicoil
Top of pagePrevious messageNext messageBottom of page Link to this message  By John Aldrich Orting Wa on Saturday, November 10, 2012 - 06:37 pm:

Oh boy. Putting a Z head on my '27 Touring and have 2 stripped head bolts. Torque wrench was set on 30 lbs. DANG! Hope I do not find any more.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Blancard on Saturday, November 10, 2012 - 07:25 pm:

They were either waiting to let go or your torque wrench is way off. Had it calibrated lately?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Wolf on Saturday, November 10, 2012 - 08:13 pm:

Helicoils work great. Have 3 in my '14.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, November 10, 2012 - 10:09 pm:

You did clean out all the holes with a bottoming tap, didn't you? An old head bolt with four grooves ground lengthwise will do it.

You probably could have all avoided that trauma if you had used studs instead.

If you can't drop the head straight down with the studs installed first, set it in place, then snug each dry stud in with a pair of jam nuts: hand snug, not torqued. It's a little more work than bolts, but does not compare to repairing stripped threads.

Studs are self-adjusting for length: they always use all the threads available, without fear of a bolt bottoming out or being too short. There's no tricky stuff to do when holding a horn bracket or something.

There is pull only on the block's threads, no tearing as a bolt does as it is torqued down.

The fine threads on a stud's upper end give 28% more squeeze for the same torque.

Ford changed over to studs on the A, for some reason.

Two of the A studs are long, which are just the right length for a Frontenac head. I used to lose a head gasket every couple of years until converting to studs in about 2003, and none since.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, November 11, 2012 - 07:29 am:

Studs would not have changed the results.
Studs make it impossible to remove or install a Model T cylinder head without first removing the engine from the car. Not a sound idea for most of us.

You stripped out the holes in the block for a reason. Fix that. Likely the bolts bottomed out in the holes either because they were too long or there is debris in the holes.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, November 11, 2012 - 08:10 am:

"Studs make it impossible to remove or install a Model T cylinder head without first removing the engine from the car."

Huh?


I wrote: "If you can't drop the head straight down with the studs installed first, set it in place, then snug each dry stud in with a pair of jam nuts: hand snug, not torqued. It's a little more work than bolts, but does not compare to repairing stripped threads."

Do I need to make it more clear than that? Tighten a pair of jam nuts (or a normal nut and jam nut) on the top of the stud, and treat it just like a bolt, until you have the stud bottomed in the hole - by hand. Then remove the jam nuts and put on the normal nut and torque them all down in sequence. To remove the studs later, use jam nuts.

I won't even ask if you already knew how to use jam nuts to install and remove studs.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, November 11, 2012 - 08:39 am:

Ralph,

Studs make it impossible to remove or install the cylinder head with the engine in the assembled car, provided the car has a body.

You could remove the steering column and firewall to allow the head to be removed / installed with studs but that is sort of silly (and a lot of work!) considering studs are of zero benefit.

Clearly you don't have any experience working on Model T's or you would know this.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, November 11, 2012 - 11:49 am:

I can't see any advantage to threading each stud in with jamb nuts if they have to be removed again to remove the head. Might as well use the bolts. Not only that, if anyone has tried to remove a head from a Model A he can attest to the fact that is much harder with studs than with bolts. Helicoils are really not hard to install and they will hold just fine. I even used one to hold the spindle bolt on one end of the axle and have no problem with it. If the holes where you need to place the helicoils are the last ones against the back of the engine, you might need to either pull off the firewall or slide the engine forward when drilling for them, but once they are installed, they work just like original threads and you can remove or replace the head. in the usual manner.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, November 11, 2012 - 01:26 pm:

"Studs make it impossible to remove or install the cylinder head with the engine in the assembled car, provided the car has a body."

Reading is a skill some people never master, I guess. Installing studs is same procedure as installing bolts, just a couple of extra steps. She gave us two eyes, two ears and one mouth for good reason.

"Clearly you don't have any experience working" with head studs "or you would know" the advantages of using studs.







Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Sunday, November 11, 2012 - 07:07 pm:

I would rather use the KeenSert type threaded sleeves than Heli-coils.
You can put Lock-tite on the outside of them, screw them in and you're set for life even if you have to remove that bolts a few hundred times.
They are also not as likely to leak.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Schrope - Upland, IN on Sunday, November 11, 2012 - 08:38 pm:

......much as it pains me, I'll have to agree with Ralph on this one. That is, you can use studs and remove them to remove the head with the engine in the car. You won't strip the threads in the block in a dead pull on a stud as easy as you will twisting a bolt in the same hole. Of course, Heli-Coils are great if the threads strip. Once they're in there, I doubt you can get an accurate torque reading though. They bind to much. How many of them were torqued down with a torque wrench back in their day?

My opinion: If I were doing a high dollar overhaul, I'd use studs.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel D. Chicoine, MD, Pierre, SD on Sunday, November 11, 2012 - 09:31 pm:

I have found that in order to put the head on my 23 and 26, I have to put the rear 2 bolts in the holes and hold them part way up with wire wrapped around them, then slide the head back to position and lower the bolts. I can't get the full length bolts to clear the firewall so I have to put them in first. They also cannot be removed completely until all other head bolts are removed, the rear bolts elevated 2 inches, and the head slid forward. I believe I'd need to do the same with studs, double nutted or whatever. Since I couldn't slide the head forward until all the other studs are removed, I don't see the advantage aside from less fear of stripping. Helicoils eliminate much of that fear.
Noel


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Sunday, November 11, 2012 - 10:47 pm:

As you know Helicoils are the cheapest way to fix anything. I never use them in anything I like. There are so many good thread repair products out there why would you put in the junk. I use Time-Serts as they are stronger, have a step on top so they pull up tight and then the driver spreads the bottom threads for a very tight fit. Anything is better than a wire coiled around. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Sunday, November 11, 2012 - 11:09 pm:

I think Robert owens is correct. There are much better devices on the market besides Heli Coil. There is one on the market the is like a cup with threads on both the inside and outside. I have to think that they are much stronger. I don't trust heli coils as all they are is a coil of fine wire. I would think that any machinist that does much work on cars would be able to install them for you.

A91


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Sunday, November 11, 2012 - 11:55 pm:

Ralf is right, I use rubber bands to hold the two rear head bolts up just enough to clear the fire wall. then I can slid the head back into the proper place. You can also use clothes pins to hold the head bolts up until you get the head in place. I learned to use rubber bands from Mark Hutchinson at Ford and More

A952


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Monday, November 12, 2012 - 12:49 pm:

"There are much better devices on the market besides Heli Coil."

"I never use them in anything I like."

Well, think about that if you're ever flying in a plane with Pratt & Whitney turbo prop engine. Our shop made the magnesium engine housings for those for many years. Every threaded hole in those housings had Heli-Coils installed in them from new. We better let the FAA know.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Monday, November 12, 2012 - 01:32 pm:

Jerry, Think about your statement. As most everyone knows Mag is very weak.Its light and thats why it is used. Threads will pull out of Mag in a hurry so something need to be done with it. Heli-coils are the cheapest thread fix you can buy. So it looks like Pratt & Whitney is trying to keep within a budget and they have picked the cheapest way out. I will give up a beer or two and buy better parts. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Monday, November 12, 2012 - 01:35 pm:

Robert,

A Heli-Coiled thread in cast iron will be stronger than the original thread. Even if you don't believe it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Monday, November 12, 2012 - 03:07 pm:

Jerry, That may be so but everything else is way better than a Heli-coil. Iam not trying to put you down just expressing that there is a much better way to fix things. The Heli-coil is just larger than the damaged thread. And in some cases the only way to fix something. But if you use the solid walled inserts they are larger in diameter and have more holding power than a Heli-coil. And as we all know the head studs are a weak point. They are shallow and could use some help. So a larger repair insert will do a better job. Thats all Iam saying. Get more bang for your buck. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Monday, November 12, 2012 - 04:34 pm:

"I am not trying to put you down..."

I know, it's just discussion. Have a good day and enjoy your T!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Monday, November 12, 2012 - 04:48 pm:

The problem that can arise from using a "Keensert" or other solid walled repair insert is you run the risk of breaking into the water jacket, if you are attempting a thread repair in close proximity of the water jacket as the size of drill needed to install the solid type insert is quite larger than the drill size needed for a standard HeliCoil type insert.


Top of pagePrevious messageNext messageBottom of page Link to this message  By keith g barrier on Monday, November 12, 2012 - 07:32 pm:

I agree with Steve, seen to many problems with these type inserts. You are just enlarging the hole more and more. Helicoils are not just fine wire, they are hardened steel in a shape to match the threads. I have used them for years with no issues. KB


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Monday, November 12, 2012 - 08:54 pm:

Heli Coils saved my bacon more than once. I like um.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Aldrich Orting Wa on Monday, November 12, 2012 - 09:46 pm:

I appreciate everyone's input.

Everything I touched today turned to s--t so I decided against any T repairs.

Live for a chance to be stupid again... :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Gruber- Spanaway, Wash. on Monday, November 12, 2012 - 11:15 pm:

I've had days like that....best go sit in front of the TV and crack a beer.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Renea Aldrich in Orting,WA on Monday, November 12, 2012 - 11:34 pm:

Hey Bob, I put him in time out with a book with his lap warmers


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Gruber- Spanaway, Wash. on Monday, November 12, 2012 - 11:55 pm:

Renea...nice that you're looking after the ol' man!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Tuesday, November 13, 2012 - 02:11 am:

When working on a T, if anything CAN go wrong, it will. If you modify something "to make it better" there'll be a hundred other things that either won't work or won't fit. ITNOTB (Its the nature of the beast.)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Tuesday, November 13, 2012 - 07:00 am:

If you have ever worked much on Model A Fords then you know that the head studs are a real pain in the rear when the head rusts solid to the studs. Again I see zero reason to make this modification, any reasonably talented mechanic will not find the head bolts to be any issue worthy of note.

I have installed dozens of helicoilds in Model T (and other brand of car) engines to repair stripped head bolt and manifold bolt holes. Never had a problem with a helicoil yet.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Killecut on Tuesday, November 13, 2012 - 07:41 am:

If you use studs on a T or replace an A head coat the studs with anti-seize and you will have no problem removing the head the next time.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould on Tuesday, November 13, 2012 - 10:19 am:

Two observations.
Helicoils take less space so IMHO are the best first repair. If something goes wrong you can enlarge the hole and use a solid insert.
Second, the key to any thread repair is alignment. If you can make a jig to hold the drill and tap perpendicular to the hole, you will minimize wander. We've all done it by eye and wound up with a loose or angled fit.
Best job I did was on a 12 block where I mounted the block on a mill drill bed and located and aligned the drill and tap using collects.
Another time I needed a longer thread than 3/4" the longest helicoil in that size. I found you can stack helicoils IF things are perfectly aligned. Of course you increase the risk of wander, but if you're careful it can be done successfully, giving a close fit between the bolt and thread.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Wednesday, November 14, 2012 - 06:48 am:

Regarding Helicoils. If you've ever seen a Space Shuttle fly or seen its robotic arm in use, or the Robotic Arm on the JEM (Japanese Engineering Module) on the Space Station, then you've witnessed three very advanced devices whose RHC and THC (Rotation Hand Controllers and Translation Hand Controllers) had every single threaded hole use helicoils. Both devices were magnificently machined, highly complex devices. I personally built those controllers over a 12 year period and can state that helicoils create far stronger threads in aluminum than the aluminum itself. No cost was saved...nor shortcut taken in design...it just makes more sense that where possible, to launch aluminum and other lighweight materials into space than Cast Iron. I would not and do not hesitate to use them where and when appropriate in a model T. Keenserts and other thread repair devices also have a place in repair, but in all instances, those parts are a good deal larger than a Helicoil or tangless insert, and cannot always be used due to space constraints.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Wednesday, November 14, 2012 - 02:08 pm:

Standard Helicoils are excellent. Locking helicoils(dyed red)are bolt digesters and generally should be avoided. They are ok with hard high strength bolts but usually not needed in automotive work.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Wednesday, November 14, 2012 - 03:46 pm:

Scott Conger, As you said it makes more sense to put light weight materials into space. Heli-coil is the lightest thread repair going. And the strength needed in space is very low. If you have a clearance problem the Heli-coil is the thing to use. But I dont like eating at MacDonalds and thinking that I got a meal. If you are happy using the poorest repair and are happy go for it. There are better ways to fix things and a place for them. Heli-coil is not a premium repair and should not be confused with one. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Wednesday, November 14, 2012 - 11:36 pm:

On my thread repairs I have used Helicoils. At McDonalds, I get a McChicken and a senior coffee for less than $2. I spend the money I save on Model T's, tractors, and cows.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Thursday, November 15, 2012 - 06:31 am:

Robert

Years ago, I worked on the Space Shuttle as mentioned above. I am now on a program which mounts electronics on a howitzer. The chassis is an aluminum casting of significant size and all threaded holes use helicoils. This device sees thousands of g's of impact at each firing, for thousands and thousands of rounds. Frankly I do not understand your point that helicoils are inferior. I'm certain that this point is falling on deaf ears, and that's OK, but want to be sure that other readers come away with seeing examples of successful product use and come to their own conclusions. Also, don't mistake "light" with lack of strength. Items sent into space have to be very strong, indeed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tex Holtby on Thursday, November 15, 2012 - 07:01 am:

Even though this is my first (or second) post I have been a club member for a little over two years and have gained a great deal of knowledge from this forum (Thank you). I am currently bringing back to life two 1925 model t's (a runabout and a roadster - both asleep for over 40 years)! Thread repair is a matter of personal choice. Many times the repair is determined by what is most readily available. Helicoil was designed to actually strengthen threads in lightweight parent materials. The insert is actually made from 18-8 stainless steel wire. The assembly strength is derived from the fact that the insert, due to its spring like nature, actually balances the bolt load much more evenly over all the threads in the parent material when a bolt is tightened up. When tightening a bolt, the top 2 or 3 threads normally distribute the majority of the bolt load into the parent material. If (for example) a bolt has 8 threads, the bottom 5 threads do very little in the assembly allowing a bolt to easily strip out the parent material. You can take a 1/4-20 grade 5 carbon steel bolt and tighten it in a bar of 6061-T6 aluminum (hole properly drilled and tapped) and quickly strip out the aluminum threads in the bar. If you install a 1/4-20 helicoil insert in a bar of 6061-T6 aluminum and tighten a grade 5 carbon steel bolt you will break the bolt and not damage the helicoil or any of the threads in the aluminum bar (even though the bolt is much harder than the aluminum). You can then actually remove the broken bolt from the helicoil using just your finger (no galling between the bolt and helicoil). You can then install another bolt in the undamaged helicoil. Just remember to use the proper sized drill and STI tap when preparing the damaged thread for the insert. Never use any locking agent when installing the helicoil (the insert must remain flexible). If the damaged threads are really bad and past the tolerances for using the helicoil you can use a twinsert to return to the original thread size. This being said, I would not hesitate to use a solid bushing if I didn't have the proper helicoil - FIX IT AND GET IT BACK ON THE ROAD! Just my 2 cents Tex


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, November 15, 2012 - 07:04 am:

I wish the AC factory had put a helicoil in the single bolt hole that held the filter on the fuel pump on the Franklin engine on my Bellanca. I put on a new pump, because the old one was old. The new one leaked due to stripped threads in the aluminum casting, causing a lot of angst and an emergency landing. My mech fixed it with a helicoil.

Yes, a stud would have been better than the 1/4-28 bolt it had.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Thursday, November 15, 2012 - 11:23 am:

Tex,

Some very good information, thanks.

One other feature of a HeliCoil that is beneficial is that, due to its coiled construction, (i.e. not solid), it can actually expand somewhat into the hole. As the bolt/stud is tightened, there will be an outward force exerted on the coil, due to the angled threads. The outward force will make the HeliCoil expand tightly in its hole and more substantially "grab" the threads in the parent material. A solid thread insert will engage the parent threads no better than ony other bolt might.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Thursday, November 15, 2012 - 01:19 pm:

RD

Studs in an aluminum case don't fare that well either. The cylinder hold down nuts in Continentals often pull the stud out way before reaching torque. Of course the fix is a helicoil or in the case of a thru stud send the case to Divco for repair. Been there, done that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Aldrich Orting Wa on Monday, November 19, 2012 - 06:45 pm:

Got her all put back together without finding any more bad holes.

Helicoils worked for me!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Monday, November 19, 2012 - 11:53 pm:

Congratulations John! Been wondering how that all turned out,.....sounds like a huge success. I've known about helicoils for many years but for some reason (my good fortune I guess) I've never had the opportunity to use one!

I will say that thanks to you (and your "misfortune" X 2) this thread developed that enabled me and I'm sure, a few others, to learn more about helicoils. For one thing, ACCEPT NO SUBSTITUTES, helicoils are best, and, it's nice to know that this is one repair you can make that in many cases, is better than the original! Just be careful of yer' spinal column there ol' man,......harold


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