Forged Crank Question...

Forged Crank Question... - 02/25/13 05:12 PM

Since I am doing an auto to 4 speed swap, I am looking for a forged crank, since I've heard that a cast crank just isn't going to cut it. I have a line on what a guy "says" is a forged 440 crank, but the numbers don't seem to make any sense.

The number on the crank is apparently 1988 761.

Can anyone help me out? (My appologies for cross-forum posting...)

Thanks!
- Steve -

Posted By: R/T1968R/T

Re: Forged Crank Question... - 02/25/13 05:26 PM

Take a look at the archives....this should help http://www.moparts.org/Tech/Archive/bb/50.html

Posted By: Cab_Burge

Re: Forged Crank Question... - 02/26/13 05:16 AM

You need a 4 speed forged steel crankshaft, not a automatic forged steel crankshaft

IHTHs

Posted By: Lighthorseman

Re: Forged Crank Question... - 02/26/13 05:25 AM

A 4-speed specific forged crank? IS there such a thing, or are you funnin' a newbie?

I thought it was the pilot bearing that is needed for a 4-speed application.

Posted By: astjp2

Re: Forged Crank Question... - 02/26/13 06:28 AM

You need a hole to put it in...in the back of the crank, some auto cranks did not have it. Tim

Posted By: Tom_440

Re: Forged Crank Question... - 02/26/13 07:38 AM

Quote:

A 4-speed specific forged crank? IS there such a thing, or are you funnin' a newbie? I thought it was the pilot bearing that is needed for a 4-speed application.

Maybe this helps?

http://www.moparts.org/Tech/Archive/clutch/1.html

Posted By: Commando1

Re: Forged Crank Question... - 02/26/13 02:32 PM

Quote:

I've heard that a cast crank just isn't going to cut it.

First of all, let's go back to square one when everybody else is running off in a 100 different directions like chickens with their heads cut off.
Your forged crank is going to cut it unless you're having someone build you a 600 hp engine that you're going to do 8k rpm test & tune runs on Friday nights.
Another case of a little knowledge is a dangerous thing.

Secondly, if you say "a cast crank just isn't going to cut it" because it won't accept a 4 speed, there's a simple work-a-round solution to that by machining off the the end of the tranny input shaft and using a special order bearing from NAPA or some other places.

Third, if you already have a forged crank, MOST likely it will accept a 4-speed. Simply look to see if there is a hole at the end of the crank. If not, see #2.

Finally if you have a forged crank with the hole, go to town with it.

The forged and the cast cranks each use different flywheels, btw.

Posted By: JohnRR

Re: Forged Crank Question... - 02/26/13 03:15 PM

Quote:

Secondly, if you say "a cast crank just isn't going to cut it" because it won't accept a 4 speed, there's a simple work-a-round solution to that by machining off the the end of the tranny input shaft and using a special order bearing from NAPA or some other places.

SPECIAL ORDER ???

If a crank is not finished reamed there is a bearing that is used in a Dakota that can be used and it's not special order as far as I know. :shurggy:

How much of the input shaft needs to be TRIMMED is ona case by case basis , measure once cut twice ... or is it measure twice cut once ???

Posted By: Commando1

Re: Forged Crank Question... - 02/26/13 05:01 PM

Actually you're correct. I meant "special order" in the sense you probably won't be able to walk into NAPA and find one in stock on the shelf.

Posted By: moper

Re: Forged Crank Question... - 02/26/13 06:20 PM

I believe the NAPA adaptor pilot bushing is discontinued. Mainly because of the pilot bearing that JohnRR mentionned that works better and is only slightly more expensive.

Posted By: JohnRR

Re: Forged Crank Question... - 02/26/13 08:31 PM

Quote:

Actually you're correct. I meant "special order" in the sense you probably won't be able to walk into NAPA and find one in stock on the shelf.

The unit for the Dakota should be an in stock item , the pilot bushing for a 1970 would have to be ordered more likely ?

Posted By: Lighthorseman

Re: Forged Crank Question... - 02/27/13 06:50 PM

Thanks for all the info, everyone! I have a 2843212 flywheel, which, I believe, is an 11 inch, 143 tooth unit. Someone mentioned it was "neutrally balanced", and someone else said that it is likely an internally balanced one.

Then, the crankshaft apparently "might" be a pre-1962 crank which is no good for going in anything post '62. Also, there is a possibility that it might be an "extended flange" unit, which wouldn't work either.

Holy smokes, am I ever confused. I'm going to go look at the thing today and see if the bolts match up 'twixt the crank and my flywheel. If I'm still not sure, I'll just get LOTS more pictures and ask for help.

Thanks to everyone up to this point!
- Steve -

Posted By: John_Kunkel

Re: Forged Crank Question... - 02/27/13 07:57 PM

The extended flange crank is easy to spot, it has 8 unthreaded holes...see pic below.

The 212 flywheel is for internal balance.

Attached picture 7605679-Earlyflange.jpg

Attached picture 7605679-Earlyflange.jpg