Can someone explain "Offset Ground Crank" to me?
Thread Starter
Joined: Nov 2001
Posts: 32,987
Likes: 58
From: Houston, TX
Re: Can someone explain "Offset Ground Crank" to me? Here is a nice LS1Tech.com exclusive graphic that I whipped up via Photoshop that should explain this clearly:
<img src="gr_grin.gif" border="0">
Tony
<img src="gr_grin.gif" border="0">
Tony
Re: Can someone explain "Offset Ground Crank" to me? WOW! An exclusive LS1tech graphic! I feel very special Tony <img src="gr_grin.gif" border="0">
Thanks for the replies. That's what I was thinking it was. Seems like a lot of extra machining $$$. I know ARE does this. Wonder how much for an extra 5 or 6 cid?
Todd
Thanks for the replies. That's what I was thinking it was. Seems like a lot of extra machining $$$. I know ARE does this. Wonder how much for an extra 5 or 6 cid?
Todd
Re: Can someone explain "Offset Ground Crank" to me? [quote]Originally posted by onfire:
<strong>It takes a lot to impress me....but that photoshot post did it. Good job Tony! <img src="gr_grin.gif" border="0"> </strong><hr></blockquote>
LOL
Now if it was an animated GIF, i'd be impressed <img src="gr_images/icons/wink.gif" border="0"> <img src="gr_grin.gif" border="0">
<img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />
<strong>It takes a lot to impress me....but that photoshot post did it. Good job Tony! <img src="gr_grin.gif" border="0"> </strong><hr></blockquote>
LOL
Now if it was an animated GIF, i'd be impressed <img src="gr_images/icons/wink.gif" border="0"> <img src="gr_grin.gif" border="0">
<img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />
Re: Can someone explain "Offset Ground Crank" to me? I ground crankshafts for 7 years while in college and graduate school. We charged about an extra $100 over a standard crank grind. That was 10 years ago so Im sure it is a little more now.
Make sure you have a competent shop do your crank grinding beecause maintaining the proper radius on the journal is SUPER important to maintain the stength of the crank. I used to do this all the time to small block chevys and then small journal rods were used or the major bearing manufacturers actually made thicker bearings so you could use your stock rod.
Make sure you have a competent shop do your crank grinding beecause maintaining the proper radius on the journal is SUPER important to maintain the stength of the crank. I used to do this all the time to small block chevys and then small journal rods were used or the major bearing manufacturers actually made thicker bearings so you could use your stock rod.
Thread Starter
Joined: Nov 2001
Posts: 32,987
Likes: 58
From: Houston, TX
Re: Can someone explain "Offset Ground Crank" to me? I like pictures. Makes the explanation much easier to understand in most cases.
Even the village idiot would know what offset grinding is after seeing that picture <img src="gr_stretch.gif" border="0">
Tony
Even the village idiot would know what offset grinding is after seeing that picture <img src="gr_stretch.gif" border="0">
Tony
TECH Addict
Joined: Nov 2001
Posts: 2,556
Likes: 0
From: Nawf Carolina
Re: Can someone explain "Offset Ground Crank" to me? Tony, you should whip up a whole series of technical drawings, we could put em in the FAQ when it gets done <img src="gr_stretch.gif" border="0">
J.
J.
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Verdad Gallardo Thread Starter
Joined: Nov 2001
Posts: 32,987
Likes: 58
From: Houston, TX
Re: Can someone explain "Offset Ground Crank" to me? Each rod journal on the crank is ground to a slightly smaller diameter, but off-center from the original centerline. This moves the rod journal centerline effectively outwards, and you just end up with a slightly smaller journal.
Then, you need some custom rods/bearings to fit on those new journal sizes.
It takes a special type of grinder, and there are shops out there that specialize in only grinding and restoring cranks (for engines and industrial engines). I've seen a 10 foot long crank be offset ground before! <img src="gr_eek2.gif" border="0">
Tony
Then, you need some custom rods/bearings to fit on those new journal sizes.
It takes a special type of grinder, and there are shops out there that specialize in only grinding and restoring cranks (for engines and industrial engines). I've seen a 10 foot long crank be offset ground before! <img src="gr_eek2.gif" border="0">
Tony
Re: Can someone explain "Offset Ground Crank" to me? My understanding is that the crank is welded on one side of the crank journals.
Then the bearing surface is reground with reference to a different centerline than the original journal. The added weld material allows this to happen, otherwise there would be nothing to grind.
This allows the journal centerline to move in or out, thus decreasing or increasing the stroke.
Then the bearing surface is reground with reference to a different centerline than the original journal. The added weld material allows this to happen, otherwise there would be nothing to grind.
This allows the journal centerline to move in or out, thus decreasing or increasing the stroke.
Re: Can someone explain "Offset Ground Crank" to me? It can be done either way but I would highly recommend not welding a crank for a performance application. Welding of cranks is generally only done to rare pieces that cant be replaced by a new one economically or because of obscurity.
