BMS Crank.

[NY Twin Turbo]

So how does a well prepped BMS crank measure up against today's new offerings?

 

[bison]

A non wasted one if you can find one will go beyond just about what everyone's engine could make. Jimmy Morrison has been 8.0x @170 with one at tso weight


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[NY Twin Turbo]

A non wasted one if you can find one will go beyond just about what everyone's engine could make. Jimmy Morrison has been 8.0x @170 with one at tso weight


Sent from my iPhone using Tapatalk

So you believe it could handle as much or even more stress of any of the new mass produced forged offerings?
And to get a crank better than a BMS you would have to then order up a custom billet?

Of course, we mean a well prepped, NOS BMS crank.

 

[TURBOELKY]

I've seen some still in forged form for sale. That would probably be as good as it gets. I think Jeff Rand or Neil Stewart was selling one.

 

[robzombie]

I've seen some still in forged form for sale. That would probably be as good as it gets. I think Jeff Rand or Neil Stewart was selling one.

I have seen that also.

If you factor in the cost to machine a raw forging it will cost more than what most are willing to spend.

 

[David Husek]

So how does a well prepped BMS crank measure up against today's new offerings?

It depends on the vintage and grinder of the crankshaft. Buick made the mistake of making the early cranks in 4140 material and they were failing. BMS changed to 4340 soon after. Many were dumped on the Turbo Buick market in the early 90's. You hear a lot of horror stories about them breaking in Buick's and I will bet they were 4140 cranks. I have a list of the crank forging ID and material used from a BMS engineer. Many grinders though took the ID off. If you find one that is not fatigued and is 4340, they are much better than any of the china cranks available especially the 4140 stuff. The BMS crankshaft will be wide journal, but I have a new BMS narrow journal here and have seen a few others over the years. Very rare. I prefer a Moldex crankshaft if you can find one. Now compared to a Crower crankshaft, the Crower is the best you can get, but you will pay for it.

 

[NY Twin Turbo]

It depends on the vintage and grinder of the crankshaft. Buick made the mistake of making the early cranks in 4140 material and they were failing. BMS changed to 4340 soon after. Many were dumped on the Turbo Buick market in the early 90's. You hear a lot of horror stories about them breaking in Buick's and I will bet they were 4140 cranks. I have a list of the crank forging ID and material used from a BMS engineer. Many grinders though took the ID off. If you find one that is not fatigued and is 4340, they are much better than any of the china cranks available especially the 4140 stuff. The BMS crankshaft will be wide journal, but I have a new BMS narrow journal here and have seen a few others over the years. Very rare. I prefer a Moldex crankshaft if you can find one. Now compared to a Crower crankshaft, the Crower is the best you can get, but you will pay for it.

This is the kind of tech talk I was hoping to spark up. My motor was built with a virgin BMS crank. I'm obviously happy with all. But it's nice to have a little topic talk because you never know what the future holds.

Moldex is no longer?
Crower can still make one?

 

[750H.P.V6]

Crower makes Billet cranks which are the ones that TA sells. I have a BMS forged crank that was machined by Crower way back when and I have a Crower billet also. You can't go wrong with their stuff.

Neal

 

[NY Twin Turbo]

Crower makes Billet cranks which are the ones that TA sells. I have a BMS forged crank that was machined by Crower way back when and I have a Crower billet also. You can't go wrong with their stuff.

Neal

More questions then. Did BMS ever make non forged cranks also?

 

[rag231]

I still have 2 raw forgings and was planning on selling 1 to raise some roller money. I would hand deliver it to King's Crankshaft here in Denver, NC. to turn it to whatever stroke anyone wanted, it was going to be around 1600. Funny thing is the last 2 that were sold were turned down to sizes below 3.40.

 

[David Husek]

I still have 2 raw forgings and was planning on selling 1 to raise some roller money. I would hand deliver it to King's Crankshaft here in Denver, NC. to turn it to whatever stroke anyone wanted, it was going to be around 1600. Funny thing is the last 2 that were sold were turned down to sizes below 3.40.

What is the code on the forging. I may be interested in one.

 

[750H.P.V6]

More questions then. Did BMS ever make non forged cranks also?

BMS cranks were sold either semi finished or as raw forgings. The forging # on all the ones I've had was 25500008.

Neal

 

[NY Twin Turbo]

BMS cranks were sold either semi finished or as raw forgings. The forging # on all the ones I've had was 25500008.

Neal

OK thanks. I thought there may have been a few cast ones out there. I must have miss interpreted the previous posts above. It didn't seem to make sense.

 

[NY Twin Turbo]

I guess the guy who does the finishing makes the crank that much more special?
Example..... Crower = Good?

 

[NY Twin Turbo]

I guess the guy who does the finishing makes the crank that much more special?
Example..... Crower = Good?

You guys need to forgive me for these newbie type questions. My motor was built by RPE and I put my full trust in Boby's expertise. And thankfully, I got exactly what I wanted. And after more than 10 years, it still runs strong and it's getting better every day. But I kind of skipped engine tech 101. I got my masters degree in fabrication though. So, I like to play a little catch-up on some of this stuff because no motor lasts forever. And we all need to plan for the future.

 

[David Husek]

BMS cranks were sold either semi finished or as raw forgings. The forging # on all the ones I've had was 25500008.

Neal

25500008 is the part number of the raw forging. All BMS forgings have an ID code cast into them that gives you information about material and vintage. I am interested if the raw forging is a W15 or T96. I took a picture of a crank I have here for reference.

 

[750H.P.V6]

Dave,

That's good info. I've owned a bunch of BMS cranks finished by different places and never payed any attention to those numbers. It makes me want to drop my oil pan and see what's in my current motor.

Neal

 

[forcefed3.8's]

I had my pan off, and forgot to look.

 

[NY Twin Turbo]

Dave,

That's good info. I've owned a bunch of BMS cranks finished by different places and never payed any attention to those numbers. It makes me want to drop my oil pan and see what's in my current motor.

Neal

Well, I think I feel a little better. I'm almost certain mine has T-96 on it. For some reason I believe I noticed this number and never questioned it. My pan may be off in 2 weeks or so.

 

[V6sleeper]

Informative thread..