BMS Crank.

[NY Twin Turbo]

I cleaned up and my list of crank codes is not where it has been for years. May have been put in a file or shredded.... I remember them though

Cranks codes start with an R, T, N or W. There were 8 codes given to me. There may be others, but doubt it.

From the picture, It looks to have an N. If this is so, the only N crank was N78 and the reason I remember this is it was the only 5140 crank they made. As a reference, the early power source books referenced 5140 material. The later books reference 4140.

The best and last design was the W15, the T92 is the next best, then T70 and all three are 4340. R57 is 4140, R75 is 4340. N78 is 5140. T65 is 4340 and T66 is 4140. These are from memory and I would say they are correct.

Well Dave, it appears we need a little more insight as to what the hell all these other numbers and letters mean. Looks like you just opened a can of worms!

So who do you recommend we hunt down and torture for the rest of this information?

Don't worry. Your safe. You have already done your part.

 

[rag231]

I finally removed a 3.400 stroke BMS crank from an off center motor that was in a building fire and it has a lot of bearing material on the journals. I am going to see if it can be salvaged, it has a lot of pitting on the counter weights also. It has T96 on it.

 

[TurboWh1]

I have a BMS crankshaft and building a motor currently. Is this a 4340 or 4140 piece? Curious as to what HP it can reasonably handle.

 

[Mr.Spool]

I have a BMS crankshaft and building a motor currently. Is this a 4340 or 4140 piece? Curious as to what HP it can reasonably handle.

A 4140 has been mid 8s,and a 4340 has 7s

 

[TurboWh1]

A 4140 has been mid 8s,and a 4340 has 7s

I did some more research, believe it is 4140 per the Buick Powersource manual. I agree, still a very durable crankshaft. I was curious to the code stamped on the crankshaft based on other information posted here. And hopeful it was 4340!

 

[David Husek]

I did some more research, believe it is 4140 per the Buick Powersource manual. I agree, still a very durable crankshaft. I was curious to the code stamped on the crankshaft based on other information posted here. And hopeful it was 4340!

T96 is a 4340 crankshaft, the list I posted years ago seems to be missing. Read all my previous posts. A 4140 crankshaft will not handle the power. The US 4140 couldn't handle the flex which all Buick crankshafts do, so they changed to 4340. They fracture when they flex and eventually will fail. All china cranks are throw away. Period. All run china cranks will have fractures, including 4340 ones. A 4140 has been really fast in a common journal configuration, but the Buick crank is a split pin and has a lot of flex. Not happening. Sure there are a few exceptions though. Kenny Duttweiler could not make more than 1700hp on his dyno. Any higher the crower would flex so bad, the crank trigger would lose signal. He switched to a common journal(odd fire) crank and made 2350hp. Any info give me a call as lots of miss information about material and crankshafts are out there. I have heard that others are making more power today, but crank design and machining processes have improved.

 

[TurboWh1]

T96 is a 4340 crankshaft, the list I posted years ago seems to be missing. Read all my previous posts. A 4140 crankshaft will not handle the power. The US 4140 couldn't handle the flex which all Buick crankshafts do, so they changed to 4340. They fracture when they flex and eventually will fail. All china cranks are throw away. Period. All run china cranks will have fractures, including 4340 ones. A 4140 has been really fast in a common journal configuration, but the Buick crank is a split pin and has a lot of flex. Not happening. Sure there are a few exceptions though. Kenny Duttweiler could not make more than 1700hp on his dyno. Any higher the crower would flex so bad, the crank trigger would lose signal. He switched to a common journal(odd fire) crank and made 2350hp. Any info give me a call as lots of miss information about material and crankshafts are out there. I have heard that others are making more power today, but crank design and machining processes have improved.

Thanks David. That helps to know that it should be a 4340. I probably won't be at that HP level. On the other hand, I'm building a motor and don't want to worry about the strength and longevity of it. This is from the Buick Powersource book. But that is dated information. Were all the BMS cranks made in China? Or did US step into the equation at some point?

 

[750H.P.V6]

Thanks David. That helps to know that it should be a 4340. I probably won't be at that HP level. On the other hand, I'm building a motor and don't want to worry about the strength and longevity of it. This is from the Buick Powersource book. But that is dated information. Were all the BMS cranks made in China? Or did US step into the equation at some point?

The BMS cranks were forged in the US and machined by a number of crankshaft companies. Dave is referring to the currently available forged cranks being forged and machined in China.

Neal

 

[David Husek]

Thanks David. That helps to know that it should be a 4340. I probably won't be at that HP level. On the other hand, I'm building a motor and don't want to worry about the strength and longevity of it. This is from the Buick Powersource book. But that is dated information. Were all the BMS cranks made in China? Or did US step into the equation at some point?

All BMS crankshafts are
MADE IN AMERICA.

 

[TurboWh1]

All BMS crankshafts are
MADE IN AMERICA.

Excellent!!!!

 

[chasmat2316]

All BMS crankshafts are
MADE IN AMERICA.

David do you have any info on A BJ coded crank?

 

[David Husek]

David do you have any info on A BJ coded crank?

See post 31, has my list of codes. Some race teams stamped there own codes and would not know anything about them. If they started with raw forging, it would have of those codes. Sorry.

 

[David Husek]

I cleaned up and my list of crank codes is not where it has been for years. May have been put in a file or shredded.... I remember them though

Cranks codes start with an R, T, N or W. There were 8 codes given to me. There may be others, but doubt it.

From the picture, It looks to have an N. If this is so, the only N crank was N78 and the reason I remember this is it was the only 5140 crank they made. As a reference, the early power source books referenced 5140 material. The later books reference 4140.

The best and last design was the W15, the T92 is the next best, then T70 and all three are 4340. R57 is 4140, R75 is 4340. N78 is 5140. T65 is 4340 and T66 is 4140. These are from memory and I would say they are correct.

Typo - T92 is really T96
Typo - R75 I believe was 4140, not 4340. I will confirm if I can locate my notes one day

 

[TexasT]

Could I aquire an early bms 4140 and expect it to be able to do 500hp? 600hp? 700hp? Not all of us are after four digit power. Is the 4140 bms stiff enough to spin up to 55-6000rpm in a stock block and not flex enough to run the main webs out of it?
Or am I just better off to do a Chinese 4340 and send that?

Thanks

 

[chasmat2316]

I would take 4140 made in USA over 4340 from china any day of the week!

 

[Mr.Spool]

Could I aquire an early bms 4140 and expect it to be able to do 500hp? 600hp? 700hp? Not all of us are after four digit power. Is the 4140 bms stiff enough to spin up to 55-6000rpm in a stock block and not flex enough to run the main webs out of it?
Or am I just better off to do a Chinese 4340 and send that?

Thanks

Run the stock crank.send that

 

[Chuck Leeper]

I had 5 shafts from Kings Cranks. They were all US forgings, AIRC.
He ground them to 2 stroke specs, and I ended up selling all 5.
Some may still be around. Should be identified with the ft cw inscription.

 

[TurboWh1]

Dave was spot on with his assessment T96 is 4340. The x-ray machine dont lie! The BMS crank is a very nice piece from all of my checks. Im very fortunate that Dad has some sweet tools. Everything is dead nuts. +/- .0003.