Grinding a crank with Dads portable crank grinder

[George Miller]

Here are some pictures of grinding a crank with a portable crank grinder. I had not used it to grind a crank for almost 50 years. We use to grind cranks in the car back in the day. Most of the time it was just one rod journal. We had a big crankgrinder we used when the crank was out of the car.

This is not the best way to grind, but I wanted my mains with no run out. Most of the cranks that I have had ground by some one else, run out at the flywheel, and crank gear.

The mains are done, but forgot to take a picture of that setup.
Just another way of doing things.

A picture of rod piston and crankshaft that let go a 5000 rpms at the hill climb.

 

[40 Deluxe]

Very interesting! On that broken crank, does the crack show signs of gradual failure (beachmarks) or was it an instaneous failure (from overload like detonation, maybe)? Also, I've often wondered: how accurate is that in-car crankshaft grinder? How long did the average job last? Thanks, Allan

 

[Artiki]

Hey...I bust my crank just like that! Here's what the other end looked like...

 

[Blessyouboys]

Who ground the crankshaft that let go on the hill climb?

 

[George Miller]

Very interesting! On that broken crank, does the crack show signs of gradual failure (beachmarks) or was it an instaneous failure (from overload like detonation, maybe)? Also, I've often wondered: how accurate is that in-car crankshaft grinder? How long did the average job last? Thanks, Allan

Part of the crack started where I had drill it. It was very close to the radius. The radius had a sharp edge where the crank grinder used a wheel with no radius. That is where the crack started. But I also used that engine for hill climbs many times. Another reason I wanted to grind my own, was because they did not use a radius on the wheel. I also changed how I drill my cranks.

Grinding cranks in the car is only as accurate as the operator. It does take more skill than a stationary grinder. As far as how long they last, if done right they will last.

 

[George Miller]

Who ground the crankshaft that let go on the hill climb?

It was not me. That one was ground about 8 years ago.

 

[George Miller]

Hey...I bust my crank just like that! Here's what the other end looked like...

Looks like you did not have much radius, like mine. Plus it looks like it started at the drilled hole, but can't tell for sure from the picture.

 

[Artiki]

I had thrashed that engine around for several years, running a best of 17.3 @ 77mph on the quarter mile in a T Touring. Used to think nothing of dropping the clutch at 2,000rpm and shifting at 4,000. Ran great. The crank went bang as I was tootling along, quietly shifting from 2nd to 3rd, doing about 25mph, on the way to the local hardware store. Broke my heart.

 

[Russ/40]

I'd sure like an explanation on how that crank grinder works.

 

[TechNova]

My Dad and uncle have talked about my grandfather grinding cranks in the car. He did it back when they were everyday driver cars.
They do not know where the equipment went, he musta got rid of it before he passed in 1971.
I'd be interested in any pics of in car grinding or the equipment.

 

[George Miller]

My Dad and uncle have talked about my grandfather grinding cranks in the car. He did it back when they were everyday driver cars.
They do not know where the equipment went, he musta got rid of it before he passed in 1971.
I'd be interested in any pics of in car grinding or the equipment.

I will scan a picture from the manual later today.

 

[Richard in NC]

My Uncle Bill said the in-car journal grinders did pretty good so long as you pulled the head and replaced the connecting rod. He said some people tried to get buy using the old rod which was usually out of round from the knocking. You just can't cut corners when it comes to engine bearings.

 

[Jim Brierley]

Those crank grinders did a fine job if the operator was good. We had a couple of big rigs repaired that way years ago, one was on a 1080 cubic inch Hall Scott. It went back to work and did great!

 

[George Miller]

My Dad and uncle have talked about my grandfather grinding cranks in the car. He did it back when they were everyday driver cars.
They do not know where the equipment went, he musta got rid of it before he passed in 1971.
I'd be interested in any pics of in car grinding or the equipment.

My Uncle Bill said the in-car journal grinders did pretty good so long as you pulled the head and replaced the connecting rod. He said some people tried to get buy using the old rod which was usually out of round from the knocking. You just can't cut corners when it comes to engine bearings.

What he said was true, you also needed to make sure you got all the grinding grit out of the engine.

 

[George Miller]

My Dad and uncle have talked about my grandfather grinding cranks in the car. He did it back when they were everyday driver cars.
They do not know where the equipment went, he musta got rid of it before he passed in 1971.
I'd be interested in any pics of in car grinding or the equipment.

For some reason I can not upload pictures, will try later.

 

[George Miller]

I'd sure like an explanation on how that crank grinder works.

When and if I can post pictures again, you will be able to see how it works. You turn the engine with a motor that turns the flywheel. The grinder goes over crank journal, with a hook that has a flat spring to hold it in place. You adjust the grinder for no tapper and size with 3 screws on the bottom. You have to hold the grinder as the crank turns, and move it from back and forth slowly.

 

[Jim Brierley]

When we had the Hall Scott done I had to remove the piston from the offending hole, re-install the head so when the engine was rotated the cam drive chain would not get tangled up, then reverse the procedure after the crank was done, whatta pain! When I got it running again I found that the oil needed to be checked with the engine running, it made about 1 gallon difference on the dip stick and if not done that way the oil pressure was down.

 

[Russ/40]

When and if I can post pictures again, you will be able to see how it works. You turn the engine with a motor that turns the flywheel. The grinder goes over crank journal, with a hook that has a flat spring to hold it in place. You adjust the grinder for no tapper and size with 3 screws on the bottom. You have to hold the grinder as the crank turns, and move it from back and forth slowly.

So with the lathe setup, you manually move the grinder. How is the journal size determined?

 

[George Miller]

So with the lathe setup, you manually move the grinder. How is the journal size determined?

You have to mike it before you start, then you can go by the big dial at the end. But you have to stop and check for taper and size as you are grinding. That is where the skill comes in, getting the taper out and stopping at the right time. On the rods I ground on this crank 3 are the same size and one is .0003 smaller. no taper

Still can not get the pictures to post

 

[40 Deluxe]

Plus, I imagine you did not always grind to a specific undersize, but could stop whenever the journal cleaned up and then just bore the rebabbited rod to any size needed, right? Is this where semi-finished inserts came in, also?