Miata Turbo Forum - Boost cars, acquire cats. - Re-manufactured crankshafts?

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Re-manufactured crankshafts?

Has anyone tried a re-manufactured crankshaft?

This company sells them for $221 after a core return. I am considering getting one then measuring/sizing some ACL Race Bearings accordingly. Should I just buy used and stay away form remanned?

http://www.northernautoparts.com/part/ck-93041

Quote:

https://www.miataturbo.net/attachmen...ine=1411256407

1994-1996 110cid, 1.8L, 1839cc BP Mazda Engine, Neck size is 1.063", With Casting Number B630, BP02, G6

You must match your Casting Number with the Casting Numbers listed, before you order your Crankshaft Supply, Crankshaft Part Number 93041

Crankshaft Supply Ford Re-manufactured Crank Kits

Crankshaft Supply Re-manufactured Stock Cranks. These Crankshaft Supply Ford Crankshafts are thermal cleaned, steel shot blasted, bolt holes and keyways inspected, centerline checked, straightened and magnafluxed. Necks, flanges and badly worn journals are restored, bearing journal surfaces machined, polished, oil holes chamfered, thoroughly cleaned, with filleted radius to maintain OE specs. Bearings are included with Crankshaft unless noted.

Core Return Policy - Cores returned for credit need to be sent at shippers expense in rebuild-able condition. Return cores "rust-free". We recommend you return it in the package sent to you. To insure prompt credit for your core, enclose a clear copy of your original invoice.

Crankshaft Supply has been repairing and machining Crankshafts, Rods, and more for over 50 years. Crankshaft Supply are the specialists in Crankshaft repair. . Crankshaft Supply is proud of their dedicated staff, and their dedication to your satisfaction

Crankshaft Supply Ford Crankshaft Kits Are:

Thermal Cleaned
Steel shot blasted
Bolt holes and keyways inspected
Worn journals are restored
bearing journal surfaces are machined, polished
Oil holes chamfered and deburred
Oil line passages clean and rust inhibitor applied
Crankshafts are packed and covered with two-mil poly film and encapsulated with sprayed foam
Main and Rod Bearings are included, unless noted
The poly film is a Rust inhibitor therefor you must wash the entire crank with soap and water at least 6 hours before you install it ( we recommend that you rinse your crank at least three times to remove all traces of soap)

Remanned or used? What would you do...

I would go used. That ad screams non forged reman all over it. (I think it was the protege that had a cast crank, lighter, but not forged)

I run a reman crank for a protege. Much lighter. Bought it for $300 including core from a remanufacturing house similar to this one. I've had no issue with it and have enjoyed the noticeably improved throttle response..

id go used.
its one of those things where not many tried it, the few that did are hit and miss, and you really don't have enough info to make a good decision, so you either decide to take a chance or stick with something that is proven.

Whats the difference in cost of getting the advertised job done on your known crank?

Why would you want more than fixing the journals (grinding and using oversized bearings always works)?

The idea is building a motor on the side. I don't have a spare crank on hand to send to a machine shop so it's whatever the cost of a used crank plus cost of machining.

Here is an option that satisfies both, but as others have pointed out, one cannot be certain if the product provided is cast or forged. I'll shop for a used one I guess.

At least we now have recent discussion for future persons interested in this topic.

Factory Miata cranks are forged steel and the journals are nitrided for wear resistance and strength. Some of the other cranks for BPs are just cast. Remanufactured Miata forged cranks may have been turned so that the nitriding on the bearing surfaces may be gone and the cranks are not as good. Used Miata cranks in good condition are the best bet.

Quote:

Originally Posted by sixshooter (Post 1170825)

Used Miata cranks in good condition are the best bet.

But it can take a couple of BP blocks before you find a crank in good condition without marks etc that you may want to get rid of.

I turned my rod jounals and is using Mazda OS bearings, but I don't plan on running 200k miles without tearing it down. I have different goals than OEM.

In reality, how important is the "nitriding" to the health/longevity of the crank and bearings? Is this something that is destroyed by simple micro-polishing?

Six, you make it sound like everyone who's ever had a crank reground has destroyed it. ;) Obviously an unmolested surface is best, but its not always an option.

Related: How many torques are the Protegé guys pushing through the cast cranks before destruction?

Quote:

Originally Posted by EO2K (Post 1171837)

Hard to tell, because almost all the Protege guys making any power are running their stock forged cranks...

Nobody fucks with B8 SOHCs.

That said, i can't remember the last time i saw pretty much any 4 cylinder motor break cranks repeatedly. For your basic cookie cutter turbo miata build, i'd trust a B8 crank to hold up just fine.

Would i care enough to seek one out? Not for a turbo car. (I am specifically seeking out a cast crank for the next Escort motor, though. Because light weight.)

Would i trust a crank from Northern? Sure.

Tons of cars out in our world with a couple hundred thousand miles on cast cranks. Tons of cars out in our world making lots of power on cast cranks. Is forged better? Yes. Is it necessary? Not for 99% of the builds on this forum.

Quote:

Originally Posted by EO2K (Post 1171837)

typical nitriding depth is like 0.010" to 0.020" (thats radial in this case) So a crank cut for 0.010 bearings should still have a nitride case.

Quote:

Originally Posted by concealer404 (Post 1171839)

For your basic cookie cutter turbo miata build, i'd trust a B8 crank to hold up just fine.

Quote:

Originally Posted by guttedmiata (Post 1171859)

Is forged better? Yes. Is it necessary? Not for 99% of the builds on this forum.

Was a though experiment question "for the sake of argument" more than anything else, but I appreciate the responses none the less.

Quote:

Originally Posted by Leafy (Post 1171895)

typical nitriding depth is like 0.010" to 0.020" (thats radial in this case) So a crank cut for 0.010 bearings should still have a nitride case.

So if I'm reading that correctly its pretty much a non issue, unless you are pushing maximum cut on a regrind.

Quote:

Originally Posted by Stealth97 (Post 1169114)

I run a reman crank for a protege. Much lighter.

Exactly how much lighter?

Plenty of used crankshafts to choose from:

FORD ESCORT (1994 - 1996)
KIA SEPHIA (1995 - 2001)
KIA SPECTRA (2000 - 2004)
MAZDA MX-5 MIATA (1994 - 2005)
MAZDA PROTEGE (1994 - 1998)
MERCURY TRACER (1994 - 1996)

BP05; Neck diameter 1.063";

The SOHC BP has a different neck diameter:
Neck diameter .865".; OE Number : BP01
FORD ESCORT (1991 - 1993)
MAZDA PROTEGE (1990 - 1993)
MERCURY TRACER (1991 - 1993)

Wasn't BBundy running a junkyard Kia shortblock for a while after his FM 2.0 stroker motor went out?

interchangeable bottom ends if i recall

Quote:

Exactly how much lighter?

10 pounds if memory serves.

26 pound cast crank from 97-98 BP05 automatic proteges. Same dimensions as ours, just missing the two center counter weights

10 lbs...really? Holy balls that is a lot.

Cut 10lbs off with this crank, another 12lbs or so with an aluminum flywheel and another couple pounds with the 949 damper... that's nothing to sneeze at.