Why a two-piece driveshaft?

BarnieTrk · Post by **BarnieTrk** » October 8, 2008, 10:39 pm

Hey Fellas,

My '65, 2WD, F100 has a one-piece driveshaft whereas my '65, 2WD, F250 has a two-piece driveshaft with the infamous carrier bearing.

1) What was FoMoCo's reasoning for the two-piece driveshaft - maybe for better ground clearance - making them less apt to get bent?

3) Is there any good reason NOT to remove a two-piece driveshaft & carrier bearing and install a one-piece driveshaft?

Thanks in Advance for your thoughts & knowledge!

BarnieTrk

Hawkrod · Post by **Hawkrod** » October 8, 2008, 11:22 pm

The two piece shaft is basically stronger and more dependable. For light duty applications you can run a one piece shaft but due to the length, any flaws get magnified and causes problems. Ford used a one piece shaft in light duty applications where they could get away with it to save money but for any heavier duty truck a two piece unit had to be used to assure longevity and reduce customer complaints. A two piece shaft will reduce vibration complaints and extend the life of the trans output bushing and seal as well as the the rear end front bearing and seal. All the extra weight of a one piece shaft ends up loading those areas and causes failures and if the shaft gets the least bit off (like say a U joint starts to go bad but isn't making noise yet) it will wear those things wear even worse. Hawkrod

DCarr · Post by **DCarr** » October 9, 2008, 12:16 am

Agree with Hawk on this one(guess there's a first time for everything).I was at a reputable driveshaft shop and the tech said they are reluctant to make a 1 piece shaft longer than 60in. due to quote"critical vibration issues." Ihad the same question about converting my two piece to a one , mainly for simplicity and aesthetics.What are your thoughts on the vibration versus length issue? Thanks David.

6166 Junkyard Dog · Post by **6166 Junkyard Dog** » October 9, 2008, 6:32 am

Before getting too deep, I know the 250 is a long bed but is your 100 a short bed on the 65/66 trucks most likely it is a one piece most of the short beds I have seen regardless of the trans has a 1 piece drifeshaft auto, 3 speed, 4 speed and all 67-72 short beds automatics where 1 piece with bolt on yoke, well I most likely will be told wrong but this is what I have seen on trucks unless something was done at someplace else

ICEMAN6166 · Post by **ICEMAN6166** » October 9, 2008, 11:52 am

6166 Junkyard Dog wrote:Before getting too deep, I know the 250 is a long bed but is your 100 a short bed on the 65/66 trucks most likely it is a one piece most of the short beds I have seen regardless of the trans has a 1 piece drifeshaft auto, 3 speed, 4 speed and all 67-72 short beds automatics where 1 piece with bolt on yoke, well I most likely will be told wrong but this is what I have seen on trucks unless something was done at someplace else

this is true.
but the shortbeds driveshaft is depending on trans and rear end,no more than 65" length.(trans yoke to rear end yoke)
i also agree with Hawkrod and yes i also was told by a driveshaft shop they would not make singles longer than the 65" . since there is a slip yoke on one end the shaft with the unattached slip yoke is a few inches less than the 65" total.

also on a shortbed truck a 2 piece shaft would present a more severe angle at the rear end.
pretty sure the short/long driveshaft angles are the same,and taken into account while designing the length.

spent a bunch of time last week messing around with my swb driveshaft, the driveshaft pile i have and a tape measure.

ezernut9mm · Post by **ezernut9mm** » October 10, 2008, 9:26 pm

i have a one piece out of a 66 f100 long bed. i believe it is 72" and some change in length and a slip yoke.

BarnieTrk · Post by **BarnieTrk** » October 10, 2008, 9:59 pm

Guys: THANKS FOR ALL THE REPLIES AND INPUT!!

I see & understand the reasoning now........ I guess I'll keep the two-piece in there!

Thanks again!

BarnieTrk

Post by **Greg D** » October 12, 2008, 6:42 pm

I converted my LWB Uni to a 2 piece driveshaft. Not sure I would switch it back.

MrEvil · Post by **MrEvil** » October 12, 2008, 6:54 pm

I think Hawk hit the nail on the head. Crown Victorias with the police package have a longer tail housing and shorter aluminium driveshaft (for '99 a Metal Matrix driveshaft) than the Civvy cars get.

Most shortbed trucks don't have very long driveshafts (Broncos are extremely short). However, if the truck is a supercab or crewcab it will more than likely have the two-piece shaft. My dad '79 F150 Supercab has a two piece shaft and so does my '00 F250.