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Mopar RB Crank Journal Spacing

General engine tech -- Drag Racing to Circle Track

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Rick!
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Mopar RB Crank Journal Spacing

Post by Rick! » Sun Nov 10, 2019 5:09 pm

Does anyone know if distance between main journals 4 and 5 is the same as between journals 1 and 2?
I've got a two piece crank and a vernier and it's not quite the right equipment to make the measurements so I can complete the CAD model of it.
Thanks.

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Re: Mopar RB Crank Journal Spacing

Post by BillK » Sun Nov 10, 2019 8:53 pm

Rick,
I have several cranks at the shop. I will try to remember to measure a couple of them in the morning.
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Re: Mopar RB Crank Journal Spacing

Post by SchmidtMotorWorks » Sun Nov 10, 2019 10:21 pm

Most Race cranks are.

The OEM stuff was all over the place.
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Re: Mopar RB Crank Journal Spacing

Post by Diodedog » Mon Nov 11, 2019 10:58 am

What is a two piece crank and why not just check the mains in the block, if the spacing is different on the crank the block will be spaced accordingly.

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Re: Mopar RB Crank Journal Spacing

Post by Rick! » Sat Nov 16, 2019 4:39 pm

BillK wrote:
Sun Nov 10, 2019 8:53 pm
Rick,
I have several cranks at the shop. I will try to remember to measure a couple of them in the morning.
Thanks for the measurements, Bill, much obliged.

Diodedog, "two-piece" is another way of saying broken crank. The block, along with a new Bryant billet crank, is in Immokalee this weekend.

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Re: Mopar RB Crank Journal Spacing

Post by SchmidtMotorWorks » Tue Nov 19, 2019 1:43 am

Rick! wrote:
Sat Nov 16, 2019 4:39 pm
BillK wrote:
Sun Nov 10, 2019 8:53 pm
Rick,
I have several cranks at the shop. I will try to remember to measure a couple of them in the morning.
Thanks for the measurements, Bill, much obliged.

Diodedog, "two-piece" is another way of saying broken crank. The block, along with a new Bryant billet crank, is in Immokalee this weekend.
What is your goal?
To make one?
http://www.schmidtmotorworks.com Prototypes, Tooling, Molds.

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Re: Mopar RB Crank Journal Spacing

Post by Rick! » Tue Nov 19, 2019 7:41 am

SchmidtMotorWorks wrote:
Tue Nov 19, 2019 1:43 am

What is your goal?
To make one?
My goal is to have a reasonably accurate CAD model so I can do a bunch of modals on it to understand what rpm the crank shouldn't be run. By reasonably accurate, I mean it will have the right physics but not be perfect enough to to send to CAM and make a crank. (It could be but there is minimal data I can find on the interwebs to place mains 1 and 5 perfectly and to mimic the angles of the cuts on the pork chops.)

Free-free modals are already done. Now I need to CAD up an ATI balancer and create a physically correct TC (inertia-wise) and simulate the mains and finish the analysis stuff. That will drop the torsional mode shown by a bit, I just need to know by how much as it's right at a shift point currently.

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Re: Mopar RB Crank Journal Spacing

Post by SchmidtMotorWorks » Wed Nov 20, 2019 10:07 pm

Rick! wrote:
Tue Nov 19, 2019 7:41 am
SchmidtMotorWorks wrote:
Tue Nov 19, 2019 1:43 am

What is your goal?
To make one?
My goal is to have a reasonably accurate CAD model so I can do a bunch of modals on it to understand what rpm the crank shouldn't be run. By reasonably accurate, I mean it will have the right physics but not be perfect enough to to send to CAM and make a crank. (It could be but there is minimal data I can find on the interwebs to place mains 1 and 5 perfectly and to mimic the angles of the cuts on the pork chops.)

Free-free modals are already done. Now I need to CAD up an ATI balancer and create a physically correct TC (inertia-wise) and simulate the mains and finish the analysis stuff. That will drop the torsional mode shown by a bit, I just need to know by how much as it's right at a shift point currently.

Image Image
Are you also including the attached objects?

Are you hoping to optimize angles of the CWs through modal analysis?
http://www.schmidtmotorworks.com Prototypes, Tooling, Molds.

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Re: Mopar RB Crank Journal Spacing

Post by Jeff Lee » Wed Nov 20, 2019 10:42 pm

I always just go kinda high on the RPM then fix the broken parts and back off a few hundred RPM’s...LOL
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