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Old 09-14-2013, 11:42 AM   #1
Kurt in NJ
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Default My quest for vibration reduction

I know my car has a vibration problem, it moves in a circle going through about 1000 rpm, and buzes a little around 45 (so I drive faster) , way back in the mid 80s it was decided to attend the "world Meet" in Wisconsin ---the engine had about 3000 miles since a total rebuild ---time to adjust the babbitt ---the rear main was crumbs--guess that was why a thumping was felt when driving, we had collected some KRW tooling and it was decided to do our own babbitt, I had been playing with pouring some before this using the Restorer article from the 60s, and the KRW book, I had 1 month, this is when I first found crankshaft off center, mine is .003 ---so 2 other cranks were sent out--they came back at .004, .006 out (It's just an old car, it won't matter) ---this put the desire to grind my own crankshafts in my mind.

The babbitting went ok, took a couple of trys to get the pour to my satisfaction ---got it all together the night before, still had the circular movement though but most of the vibration was gone, I had weight matched the pistons, rods the best I could ---broke it in on the road, by Ohio it rocked on compression, by the middle of Ohio I knew it would go 67, much better than the 52 I had before --on the way home I tried to break it, rarely under 55, did 65 the whole length of the PA turnpike---passed a lot of cars.
Now it is 25 years later, over 20,000 miles(maybe more, I used to unhook the speedo ) and the flywheel balance issue is taking it's toll, and one of the rods I chose by weight didn't have the best babbitt--it came apart some 20 years ago and for a "tempoary repair I put in one with 10 grams more weight---more vibration, less top speed ---it is soon time to fix it properly, I can feel the thump starting to come back--

I had wanted to rebuild engines in the 80s, pour babbitt, had looked into getting my own crankshaft grinder -but they cost too much and I didn't have a place to put it---got discouraged after trying yet another place to gind crankshafts and having bad results--- I gave up

Knowing I had this problem coming, and that I had to make a engine for my brother ---and at work the job was changine to more computer work and away from engine work my need for making metal chips wasn't being satisfied I started looking for a place to grind crankshafts ---first I educated myself, I bought a crankshaft grinder instruction book off E-bay, looked at many you-tube videos, and searched the subject online (something I couldn't do in 85) ---then I started calling shops within 100 miles, asking what machine they had, and asking if they could do the model a crankshaft to original specs ---the conversation usually went like this----can you grind a model A Ford crankshaft to factory specs ---sure, no problem ---how much ---125$ ---so you can get the flywheel flange and timing gear flange to less than .001 runout, the stroke and index to within .005 ---oh, you want racecar crankshaft grinding --that will be 350$ ---ok, when it is done can you show me it meets the specs ----no, we can't really measure the stroke and index, why would you want to check that---it's just an old car.

In my searching I had found that crankshaft grinding machines have come down in price for used machines that need some work, and learned about shipping ---I made a deal on one delivered, it would need sme work, he damaged it some loading it and I got a further price reduction (it covered the cost of all the restoration parts) ---

I am grinding my first crankshaft ---I have found that getting within .001 isn't very hard, you just have to care and take the time to set it properly, I have started with a very rusty "junk" crankshaft that I never expected to be able to use, the first time I didn't try to set in in centered, purposly ground the stroke and index wrong ---it was to get round and taper good, and to learn how to correct centering and index ---make it wrong to make it right, this machine works on centers, to correct stroke and index I would need to know how it is off ---mark the places it is wrong and set it up there so it is ground straight----this is where much of the problem with regrinds start, the instructions say to center on the least worn journal and the journals don't wear evenly----this just grinds any errors round, after several regrinds like this the errors add up ---and most people buy by price, it takes time to plot the errors, time to set up to correct ----probably 5 ordinary regrinds can be done in the time it takes to "blueprint" and correct a single crank ---and it takes thought and caring about the results---something that seems to be less common today.

I still have a lot to learn, and the more I learn the more I learn I dont know.

I have a few cranks for learning---the rack was made years ago from junk and plans in a Ford rebuilding shop book, todays project is to plot out the rod journal positions and correct them ---and work on my list of questions to ask someone more experienced than me, hpoefully i can find a mentor to help shorten the process --I think I have the machine working properly, it runs quieter than a bench grinder
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Old 09-14-2013, 12:37 PM   #2
Pete
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Default Re: My quest for vibration reduction

Very nice looking machine restoration.
That is a very good machine for automotive cranks.
My cam grinder is built on the same base.
One short advice, clean the Arnold gauge and it's slide each time you finish a crank. It will maintain it's accuracy much better and longer.
It looks like you copied my crank rack design exactly...lol
Add a piece of plywood to the mid shelf and you can store cams there.
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Old 09-14-2013, 12:40 PM   #3
700rpm
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Default Re: My quest for vibration reduction

That is very cool, Kurt. I hope I can find someone on this side of the country, and I hope in Portland, who cares as much as you do.
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Old 09-14-2013, 02:16 PM   #4
BRENT in 10-uh-C
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Default Re: My quest for vibration reduction

Kurt, one of the best all around guys I have met who has plenty of experience rebuilding and running those machines is Joe Baker JR in Cincinnati. His company Joe Baker Sales is a huge building full of equipment they are restoring. They also have a room there with crank machines running that they grind cranks for shops all around Ohio. I would give him a call and at least talk with him.

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Old 09-15-2013, 01:09 PM   #5
Jim Brierley
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Default Re: My quest for vibration reduction

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You are on the right track, and very light pistons will also help the vibration problem.
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