Stronger starter-bolts for 6.2d ?

[Fred_M1010]

I broke a starterbolt on my 2500 last week (the bolt between the brace and the block had gotten loose)
Luckily I got out the stump by just using a small screwdriver and a knife.

Now I noticed that it's a class9.8 M10 bolt.
I know I've heard that you should only use stock bolts for this,
but why not use a class12.9 bolt instead?
They are much stronger.

 

[4X4HIGH]

Starter bolts are a special bolt. They have a special centering shoulder on them.

 

[Slapperbar]

ARP probably has what you're looking for.

 

[Fred_M1010]

Starter bolts are a special bolt. They have a special centering shoulder on them.

Not these bolts, they have the same diameter (10mm) from the head to where the thread begins.
The last 18mm before the thread have some kind of strange knurling though
Whar purpose can that have?
I'll see if I can snap a picture of it later.

One concern I have about going 12.9 is that they might be designed to be the weak link...
So the starter or the block doesn't break instead

 

[Fred_M1010]

It looks like this:

If I swap to 12.9 I would take one with the same unthreaded length, and cut it to the same total length

 

[4X4HIGH]

I can't say for sure but i don't think that's a factory starter bolt. Every factory starter bolt i've seen has a washered head and the knurl pattern down by the threads. It's hard to tell from the pic but someone might have tried to make that "knurled pattern" themselves. That bolt looks more like a bunch of center punch marks rather than the typical knurl pattern i've seen.

 

[Fred_M1010]

The knurling-pattern looks symetrical, so it's probably machine made,
but it might be some half-assed Taiwan-made bolt.
(BTW The one that broke had a slightly better pattern)

I've realized now that the knurling makes the bolt about 0.1mm thicker at that point,
which makes it pretty tight against the hole in the starter.
And thats right at the place where the starter meets the block,
so I'm thinking it's for getting a better alignment...

 

[rob h]

When i had my 6.2 my starter brace did the same and snapped the bolts, i ordered a new brace, a grade 8 for the brace and new starter bolts right from gm...they were cheap and i never had a prob after that.....

 

[Wrench]

The 6.2's used washers under the head of the bolt, so if you're missing those that would be an issue. Make sure you use the correct brace on the end of the starter, and order your bolts from GM. Install them with a torque wrench, install the brace and tighten, and you're golden.

Any shortcuts will come back and bite you in the ass

 

[dieselponyexpress]

My 6.2 Starter bolts also have a washered head. The ones you pictured do not look like that. Does the bolt have a 15mm head? If not, then its not an original part. Here's a pic from my installed starter with the GM bolts:

It is strongly recommended to only use original GM starter bolts. No additional washer on the bolt head needed! I torque mine every oil change. And as stated earlier, keep an eye on the front bracket.

You did not write what caused your bolt to break, probably don't know it. So, why not use TWO original bolts for this time and have an eye on them. Just my 2 cents.

1982-99 starter bolt, GM # 15544950, recommended torque 40ft/lbs (55Nm)
1982-88 front support bracket GM # 14028931

Walter

 

[cegusman]

This one looks like the ones you get in the HELP section at the parts store.

 

[Slapperbar]

The name for the head is "Flange head".

 

[Fred_M1010]

Thanks guys!
Stock-bolts it is then.
And yes the bolts did have loose washers, and the brackets seems fine.

Just thought I could both save a buck and get a better bolt at the same time, by going 12.9
But I'll follow your advice

 

[AJMBLAZER]

Seems like it may be one of those cases where the design precludes using a stronger bolt.