whiskeybravo

Please could someone tell me why We don't change these trucks over to
single driveshaft? I'm tired of always changing my spicer u joints every 2 years on my splits. They put splits in because these shafts were
cheap and low teck? Wouldn't a larger diameter single shaft now make more
sense in todays age? Please School me. thanks

lz_68

A driveshaft has something called critical speed; which is the speed that the driveshaft will bend in the center from rotational forces and fail. As you make a driveshaft longer the critical speed is reduced.

So when our trucks were engineered a standard one piece shaft for an extended cab had a critical speed below normal driving rpm and they used a two piece shaft to overcome this.

Another option would have been to go with a larger diameter shaft made from aluminum which would have been quite expensive at the time if they were even available.

So in the end you can likely go with a large diameter one piece aluminum shaft but it would be best to talk with a drive line shop to get an idea if it would be worth it to you.

mknittle

Nice explanation.

deere country

I would look into why your joints only last 2 years as that is not normal. You must have something out of spec or you have a suspension lift in your truck and may no longer have the correct driveline angles. I have seen several trucks run in the 300,000 mile range on one set of joints.

MrFusion

I saw something a while back about putting a 1 inch spacer between the carrier bearing mount and the carrier bearing or the mount and the frame. This was to remedy driveline vibration and premature u-joint wear. It lessens the angle between the two pieces of the drive shaft.


I spoke with a local, well regarded driveline shop (Mshar Powertrain in Harrisburg PA) about converting to a 1 piece driveshaft and he said it would be too long and would quickly and possibly catastrophically fail. He told me if I really wanted to do it I would have to use a much larger and thicker (think big rig) piece of tube to be safe BUT that would put much more stress on the u-joints and tailshaft/pinion bearings. He stated that this type of solution would be more for a drag or pulling truck than an everyday driver. We did not discuss aluminum.

cougar

When I did my 47RH swap, the drive line shop wanted to make me a 1 piece drive shaft rather than shorten my front section. When i refused to go with the much higher priced single, they shafted me on shortening the other. Needless to say, they refunded me $200 after all the bad press I gave them. My front drive shaft was lengthened by a different shop including all new joint for $250. That was fair.