FastKat

iTrader: (10)

I am trying to get my crank pulley pinned while everything is apart. I have the Magnacharger crank pinning kit but no dowel pins. I called the machinist that is doing my heads and he suggested using a roll pin instead. A roll pin is a hollow pin with a slit going the length of the pin.

I know that waiting for solid a dowel pin is the "safe" thing to do, but I want to get this done now. Besides, a solid dowel might be overkill. Any suggestions? Would a roll pin work good enough?

slowride

iTrader: (3)

Take a hard bolt of the correct size with enough smooth surface and cut it to size.

Hank Peabody

iTrader: (2)

Or cut the solid end off the drill bit size you drilled the hole with, drill bits are pretty hard metal.

FastKat

iTrader: (10)

Yea, I was thinking about both of those things. The bolt is way undersized, and the drill bit is a little closer... though the drill bit is pretty brittle.

I might try the bolts after I drill, but before I use the reamer.

I really wanted the roll pins to work, but I'm not willing to be the first person to try it. I don't think roll pins were made to be loaded up parallel with the slit in the pin.

Pocket

iTrader: (22)

Use a 1/4" drill bit shaft, ts hardened tool steel. To fracture, it'd have to split down the length, which is incredibly difficult

killernoodle

drill bits are more brittle at the cutting end than the shank too. I'd use a drill bit.

FastKat

iTrader: (10)

Alright, thanks for the info. I think I am going to use whichever fits best. (drill bit or bolt shaft)

SilverSS

iTrader: (30)

NO! don't it! The strength and hardness of a dowel pin is much stronger than a drill bit piece or a roll pin. I tried using the drill bit method in desperation once (carbide bit) Sheared the bit in half in no time and marred my crank snout. Get some dowels from ATI to save yourself from a headache.

it was double pinned btw..

pwrtrip75

iTrader: (8)

X2 drill bits are so brittle and weak. Use a dowel pin... any hardware store will have them.

BadgeZ28

iTrader: (28)

Check with your local bearing specialist. See if they have any loose roller bearings the right size.

FastKat

iTrader: (10)

Gotcha, yea if you look at McMasterCarr's website, the shear strength of their alloy dowel pin is 10,000 lbs and the shear strength of the roll pin is about 7,000 lbs. The issue is how the roll pin is going to be loaded - that 7,000 lb number is probably the shear strength perpendicular to the slit, rather than parallel with the slit, which is how I would be using it.

The machinist I talked to said not to use a drill bit for that reason.

I am hoping I will be able to use the bolt - it'll be pretty strong. I mean really... a grade 5 or grade 8 bolt is going to be pretty darn tough!! If the bolt shaft has too much play, I'll just wait and order some dowel pins.

Alloy steel dowel pins are REALLY hard to find locally. None at Home Depot, Ace Hardware, Sears Hardware, True Value, etc. I checked them all... even those 50+ year old mom and pop places that stock everything. If you want them you need to order from McMaster, Fastenal, eBay, internet vendors, etc.

Pocket

iTrader: (22)

Pics or it didnt happen
What special type of steel do you think dowel pins are made of?

Do not use a dowel pin, they have empty space in the center which allows them to crush. A solid pin must be completely fractured horizontally to spin the balancer. Pins in general are rated for shear strength. You wont find info on fracturing along the axis, that number will be ridiculously high and impossible to calculate from your balancer. Also, do not use a butter bolt grade 5, that stuff is softer than common mild steel. Grade 8 is plenty strong, but keep in mind bolts are not machined to the same tolerance as drill bits/dowels so you will likely have some play in the hole which can lead to the balancer moving ever so slightly. If you want to get REALLY technical, get a taper dowel pin with an interference fit on the big end

SilverSS

iTrader: (30)

An ATI dowel pin is much stronger than a drill bit or a roll pin. Yes it happened to me. Sorry no pics. This happened about 7 years ago.
I was surprised myself. I would never thought you would be able to shear a carbide drill bit in half this way but it did it. This was with a stock crank and a D1SC maxed out.

FastKat

iTrader: (10)

A dowel pin is solid and a roll pin is hollow.

I actually had a shot at a tapered dowel pin but I passed on it. I wanted something that would fill the whole hole at the point where the crank pulley meets the crank snout. I tapered dowel pin would fill the whole hole on only one side of the pin. I don't know if I saw the same pins you are thinking of, but the ones I saw had quite a noticeable taper to them.

I think I am going to play it safe and just wait for a dowel pin. I am using a borrowed Magnacharger pinning kit, and one of the holes is egg-shaped a little from the previous install. Therefore, I am just going to use a single dowel pin and do it right.

BTW, my crank pulley is from a supercharged Cadillac CTS-V, and it looks like GM used a 3/16" key. If they're only using a 3/16" key, I am pretty sure my 1/4" dowel will be fine!

Pocket

iTrader: (22)

Tapered pins arent cones, they're a set diameter on one end and the small end is a few thousandths smaller, you have to put a set of calipers on it to see which end is which. Do a search on Mcmaster, you want .25" x .75" long

Dont try to reuse an old pin or keyway, eyeball the balancer on the snout as best you can and drill a new hole. You do NOT want to egg out or try to cram a round pin into a square hole when it comes to the balancer. Slop encourages pin failure because of the extra play

FastKat

iTrader: (10)

I think I am going to pass on the tapered pins. I want a uniform fit through the entire hole. The bolt shafts I measured are between .242" and .248", varying from bolt to bolt. The small end of that 3/4" taper pin at McMaster Carr is .243.

The ream is marked as .2495, but when I measure the cutting edges with my caliper, it comes out to more like .2515... not sure why.

I thought about it, but the edges of the keyway would be wider than the new hole. Reusing that spot would be a bad idea.

Pocket

iTrader: (22)

Take a scrap piece of metal and drill/ream it then measure the hole. Measuring the tool beforehand isnt an accurate way to know the results