Drive shaft choices

[chris mc bride]

Swapping to 4L80E means driveshacft modification in order. I have bunch stuu laying around. One Piece is 3" two piece out iof 1993 3/4 ton PU.

I can. A: Cut(4") front shaft and weld and balance. U joint to adapt to transmission yoke Probably cheapest
B: Use 3" shaft means cutting and welding front, finding u joint to mate to old yoke on rear end Make new carrier mount doing anyway for crossmember.
C: buy one piece, costly, on long side for speed and then mating to other parts.

Ben3fits A: cheapest probably easiest.
B: larger diameter should mean stronger and better at high speeds which I have already done with as is.
C: No Carrier and less u joints.

Opinions and if would reasoning for it. Another not time pressed thing just preplanning my moves.

[LS short box]

Because I'm a big chicken component wise on my hot rod builds I always upgrade the trans yoke and diff yokes to 1350 u-joints. Then have a some what local drive shaft shop build a drive shaft per my HP levels, length and max engine rpm. They determine the diameter and tube thickness. Never had a failure.

[SCOTI]

Long wheelbase/driveshaft length is the concern when eliminating a carrier bearing. I would consult the pro's that can do the calcs based on your combo & make my decisions from that.

This is not an area to be frugal.

[leegreen]

Are you still running stock trailing arm cross member? limits diameter choices, particularly for long wheelbase models where trans is further from the cross member drive shaft opening

[chris mc bride]

Originally Posted by leegreen

Are you still running stock trailing arm cross member? limits diameter choices, particularly for long wheelbase models where trans is further from the cross member drive shaft opening

Not sure how it would limit size? Shaft from transmission to carrier does not really move since trans mission bolted down and carrier bolted behind crossmember. Rear shaft moves with rearend but then passes thru carrier and u joint is between carrier and rear end so no movement in crossmember. The hole im crossmember would allow a football to pass thru.

]Now with one piece it might be issue, Everything I read a one piece that long would more than likely have vibration at speed. Especially with my foot on throttle. I am Kind of two position driver.

[leegreen]

yeah, for one piece. Your option C in original post. I should have been more specific

[chris mc bride]

With length I am not sure one piece is best. The shaft speed it will see with long shaft probably have vibration issue. Truck has been130 plus, hard to tell with 100 speedometer. With needle on the MOH at bottom has to be pretty dang close. With chassis mods,OD trans and engine mods hard to see it not happening a time or two more. LOL

[chris mc bride]

Originally Posted by SCOTI

Long wheelbase/driveshaft length is the concern when eliminating a carrier bearing. I would consult the pro's that can do the calcs based on your combo & make my decisions from that.

This is not an area to be frugal.

Showed this to wife and she is still laughing her butt off. Pretty sure that in 59 years the word frugal and me have never been in same conversation.

Far from frugal I might skip eating something I really want but it is sio I can buy parts for race car,motorcycle and now this project. Just want to make sure not spending one place where not needed and could be buying more power parts.

[SCOTI]

Originally Posted by chris mc bride

Showed this to wife and she is still laughing her butt off. Pretty sure that in 59 years the word frugal and me have never been in same conversation.

Far from frugal I might skip eating something I really want but it is sio I can buy parts for race car,motorcycle and now this project. Just want to make sure not spending one place where not needed and could be buying more power parts.

Gotcha. Sometimes we turn a blind eye to certain things because we've been there/done that. But.... We also could have just been really lucky & we know luck runs out @ some point.

Based on your project description & understanding how some limits might be tested, I figure it's worth saying it to a brother to error on the side of caution by seeing what the pro's recommend.

[Richard]

Length has nothing to do with vibration, just terminal velocity. FWIU shaft diameter has to do with turning a shaft into a jump rope at a certain RPM. A K10-20 long bed has a one piece shaft. Slightly shorter length from t-case. Best to consult with an expert. The custom shaft for the rear of my K10 is smaller diameter than stock and the HP is tripled. What do I know?

[chris mc bride]

These experts you guys speak of? Around here it is some guy in shop who welds up shorter shafts. Have talked with two shops and so far not impressed with them have much knowledge at all.

Of asking someone about driveshaft and never questioned on power, rpm figure will be at be run at. Haved doubt you can tell me what i need without know stress it will see.

Like stated above had z/28 that had vibration that acted like tire balance. Come in at one speed and wpould go away at another. Never narrowed down to shaft but suspect since changed tire 2 to 3 times a year. Just would not last beats me as to why.I tried to make sure theyu stayed round all the time.LOL

Still looking for a expert in area may have to go aftermarket.

[SCOTI]

Originally Posted by chris mc bride

These experts you guys speak of? Around here it is some guy in shop who welds up shorter shafts. Have talked with two shops and so far not impressed with them have much knowledge at all.

Of asking someone about driveshaft and never questioned on power, rpm figure will be at be run at. Haved doubt you can tell me what i need without know stress it will see.

Like stated above had z/28 that had vibration that acted like tire balance. Come in at one speed and wpould go away at another. Never narrowed down to shaft but suspect since changed tire 2 to 3 times a year. Just would not last beats me as to why.I tried to make sure theyu stayed round all the time.LOL

Still looking for a expert in area may have to go aftermarket.

There may not be someone "in your area". It might be something you have to ship out or order in to get what you need.