Ls2SilverBullet

Due to a broken flexplate my trans has to come down. When doing so I noticed one of my rear main bolts is stripped out. I am going to helio coil it, but wanted to get a little advice first..

How much bigger do I drill the hole?

How do I know what size coil I should install?

Once the new helio coil is installed, should it fit the same bolt threads as before?

Where can I buy these things? Online order or do they have them at auto parts stores like napa or advanced?

Thanks in advance

RARON455

iTrader: (35)

If you go to autozone they have complete kits, come wuth a bit, tap, and insert,,just make sure you get the right insert for your bolt size and pitch,,and yes you will be able to use the stock size bolt.

wssix99

iTrader: (5)

Local auto parts stores should sell some, but they won't have a wide selection. If they don't have the correct part, you may try Fastenal. These can be pricy, so if you have time, you may find better deals on eBay, etc.

You'll want to size the coil to your bolt and get the coil kit. The kit will come with a specially sized drill bit for the hole, a coil threading tool, and a coil insertion tool. (if needed)

As you search, you'll want to beware that Heli-Coil has lots of competitors. You may find equivalent parts under the Recoil brand name, etc.

I used a Heli-Coil kit for a stripped O2 sensor and it did a great job.

Ls2SilverBullet

Thanks for the help guys, it is appreciated. Looking into helicoil and other coil replacement brands now. Trans is comming down tonight so I hope I can find a kit at the auto parts store that fits my threads so I can fix it tomorrow

RedHotG8

iTrader: (1)

Threaded inserts are much stronger than Heli-Coils. They are solid metal instead of a thin metal band so they have more holding power.

Ls2SilverBullet

What is the difference between threaded inserts and heli coils? I am skeptical of the heli coils or anything that simply threads into a hole to have that much holding power. Torqing the rear main bolts to spec seems like it would pull them out. But I have been told they work by multiple ppl.

RedHotG8

iTrader: (1)

Here's a picture for comparison:

Ls2SilverBullet

The heli's are tiny compared to the others. Are they just lighter duty inserts? Do some hold certian torque loads or are they just different styles?

RedHotG8

iTrader: (1)

The heli-coils are a different design than threaded inserts. A heli-coil is like a wound up spring, a threaded insert is like a nut (solid) that screws into a re-threaded hole.

Ls2SilverBullet

Ok, knew heli coils looked like springs but I didnt think that could be possible. What is it that holds each in to the re-threaded hole?

RedHotG8

iTrader: (1)

A heli-coil is held in place by friction since it's wound slightly larger than the new threaded hole. An insert is held in place by hammering the 4 tabs down after its screwed into the new threaded hole. So not only is an insert stronger, there's no way it will back out like a heli-coil can.

wssix99

iTrader: (5)

You shouldn't get too hung up on the design. Go with what you can get. Neither is inherently "stronger" if properly installed and used - they are just different and each have their drawbacks.

Force in bolts is transferred through the threads, so there's no effective strength gain on the coil vs. the jacketed design when the bolt is properly torqued. The jacket certainly helps keep the threads spaced properly for installation and the coils are probably a little less forgiving and more work to install. The trade off is the size of the hole required to install them. The coils need a smaller hole, so you keep more of the base material in the part.

Acme has a close to fair comparison on their web site:
http://www.acmeindustrial.com/heli-coil_comparison.html The business Acme puts out there on strength is irrelevant if the repair is properly sized and installed. (If not, the Acme design will probably help.) You'll see that most of the benefits are installation-related. Of course, they don't point out the hole size thing.

RedHotG8

iTrader: (1)

I have used inserts and heli-coils over the past 30 years as a tool and die maker. I have never seen a threaded insert fail, but I have seen many hundreds of heli-coils fail. That to me says it all....now which one would you choose?

RARON455

iTrader: (35)

We use the helicoils here at work, they are better than helicoils by far, but harder to find. They work great and I have never seen one fail. They do require a bigger hole because they have much thicker walls than a helicoil. You will have to buy the insert, the correct size bit, and tap. It may get pricey. Taps arent cheap.

RedHotG8

iTrader: (1)

A tap is required to install helicoils too, so there really isn't much of a price difference. You have to use a special tap for the heli-coils, where as an insert uses standard size taps. SO if you have your own set of taps like I do the inserts cost less in the long run.

Ls2SilverBullet

Damn, Cant find any type of thread replacement that fits my m10x1.5 bolts at any auto parts stores around. Guess I'll be ordering

RedHotG8

iTrader: (1)

Ace Hardware should have heli-coils.

wssix99

iTrader: (5)

You can get that size at Grainger, but... that's a big bolt - so the kit with the bit, tap, etc. is going to be expensive. If you can wait a couple of days, you'll get a better deal online. The inserts themselves are inexpensive. The tools are not.

RedHotG8

iTrader: (1)

Most taps are around $10 so I'd hardly call that expensive.

wrencher

iTrader: (2)

Agreed inserts are stronger no question.
The OEM approved thread repair tools for the LS motors by kent Moore is an insert kit for a reason.