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-   -   driveshaft length (http://www.competitiondiesel.com/forums/showthread.php?t=146499)

kjpcummins 12-16-2012 02:42 PM

driveshaft length
 
Have a dodge 3500 eclb with a nv5600 and 241dhd and wanting to install a one piece drive shaft. Anyone happen to know the length of the drive shaft i would need. Waiting on clutch and truck is apart wanting to get the driveshaft made before hand. So the truck can be running this week.

Red_Rattler 12-16-2012 03:15 PM

How much of a length difference in the 4500 vs 5600?

kjpcummins 12-16-2012 05:23 PM

subtracting trans length would not work because the angle would be different. And the truck came with a two piece driveshaft stock.

Red_Rattler 12-16-2012 06:59 PM

Well I replaced my 2 piece with a custom one but its a 4500 so that's why I asked

j-rod 12-20-2012 09:31 PM

70.5" iirc

kjpcummins 12-21-2012 09:20 AM

I end up finding a truck local to take a measurement from. It was 72inch.

LReiff 12-21-2012 10:05 AM

72" is too long for a single piece shaft.

Bponci 12-21-2012 10:36 AM

Quote:

Originally Posted by LReiff (Post 1966354)
72" is too long for a single piece shaft.

Correct. Expecially if your going to have any amount of power in front of it.

kjpcummins 12-21-2012 10:41 AM

ive seen it posted that 70inchs is fine but your saying two more inches is a problem. This will be just a daily driven truck also used on the farm with little bit extra power.

j-rod 12-21-2012 12:34 PM

Quote:

Originally Posted by kjpcummins (Post 1966337)
I end up finding a truck local to take a measurement from. It was 72inch.

Interesting.

zstroken 12-21-2012 12:58 PM

Make it a 5" driveshaft.

LReiff 12-21-2012 01:54 PM

Quote:

Originally Posted by kjpcummins (Post 1966376)
ive seen it posted that 70inchs is fine but your saying two more inches is a problem. This will be just a daily driven truck also used on the farm with little bit extra power.

Here is your answer.

DieselWrencher 12-21-2012 06:21 PM

Joe House had a one piece in his CCLB DRW and he pulled 2.6. It just depends who builds the shaft whether it holds up or not. If I recall his rear drive shaft was 80" long.

1pieceatatime. 12-22-2012 11:43 AM

Quote:

Originally Posted by DieselWrencher (Post 1966697)
Joe House had a one piece in his CCLB DRW and he pulled 2.6. It just depends who builds the shaft whether it holds up or not. If I recall his rear drive shaft was 80" long.


Horsepower is not the issue. The RPM the driveshaft turns is the issue.

Ide be more concerned with a driveshaft that long on a street driven truck that a high horsepower puller. Tubing that a Super Stock truck would have a hard time twisting off is readily available.

An over torque failure and a critical speed failure are 2 VERY different animals.

Supershafts 12-22-2012 06:25 PM

Quote:

Originally Posted by LReiff (Post 1966354)
72" is too long for a single piece shaft.

Length is all dependent on use which is derived from weight, power, trans gearing and most important the highest rpm the shaft will see.

What can't be done in steel can be done in AL and CF

This is beyond 72"
http://i679.photobucket.com/albums/v...ts/axiline.jpg

You could run a 72" shaft in STL at 4.5 or 5", however that will suck the performance from your truck turning that shaft, probably kill the t-case bushing with all that weight too and have speed limited rpm around 4200 or a few higher, which is right around the speed limiting of that 88" AL shaft.

And as 1pieceatatime said, over torque is usually a low speed break, rpm breaks are much more deadly as learned in a outlaw class a few years ago that you just don't throw CM in 3" at everything..... then thru the lights at 8k rpm and and the shaft comes apart because it was to long for the rpm and cuts thru EVERYTHING like roll bars, helmet, shoulder, head, face, arms, ribs, legs and barely leaving her alive....

As long as everything is looked at and calculated, there are alternatives.
.

1pieceatatime. 12-23-2012 06:38 AM

Quote:

Originally Posted by Supershafts (Post 1967300)
Length is all dependent on use which is derived from weight, power, trans gearing and most important the highest rpm the shaft will see.

What can't be done in steel can be done in AL and CF

This is beyond 72"
http://i679.photobucket.com/albums/v...ts/axiline.jpg

You could run a 72" shaft in STL at 4.5 or 5", however that will suck the performance from your truck turning that shaft, probably kill the t-case bushing with all that weight too and have speed limited rpm around 4200 or a few higher, which is right around the speed limiting of that 88" AL shaft.

And as 1pieceatatime said, over torque is usually a low speed break, rpm breaks are much more deadly as learned in a outlaw class a few years ago that you just don't throw CM in 3" at everything..... then thru the lights at 8k rpm and and the shaft comes apart because it was to long for the rpm and cuts thru EVERYTHING like roll bars, helmet, shoulder, head, face, arms, ribs, legs and barely leaving her alive....

As long as everything is looked at and calculated, there are alternatives.
.


For some of this stuff i dont even use 72" as a rule of thumb anymore. I actually use the calculators and customers tire size/gear ratio.

kjpcummins 12-23-2012 08:04 AM

Explain to me why a street truck or when pulling a trailer you ever need to be at 4200rpm or higher.

1pieceatatime. 12-23-2012 09:07 AM

Quote:

Originally Posted by kjpcummins (Post 1967518)
Explain to me why a street truck or when pulling a trailer you ever need to be at 4200rpm or higher.


Depends on your tire size and gear ratio. The bigger the gears the faster your driveshaft spins, the taller the tires the slower your driveshaft spins.

For reference ill use the ECLB chevys. I constantly get inquiries about replacing them with a steel single piece driveshaft. They have a single piece 5" diameter aluminum driveshaft thats is approx 74" long center of joint to center of joint. To replace one of these with a steel driveshaft (4" tubing which yokes are readily available for) your going to end up with a safe operating speed of about 3200 RPMs. With 3.73s and 32" tires you will be at the safe operating RPM of the driveshaft at 82mph.

Here is a picture of a critical speed failure. Picture is an actual steel replacement in a Dmax truck that originally had an aluminum shaft.

http://i62.photobucket.com/albums/h1...g/CIMG1866.jpg

Supershafts 12-23-2012 10:21 AM

Quote:

Originally Posted by kjpcummins (Post 1967518)
Explain to me why a street truck or when pulling a trailer you ever need to be at 4200rpm or higher.

When you/we remove the speed governors in our trucks and especially the GM trucks, you'll exceed the speed rpm of the shaft. Ever wonder why all the gm tahoe and yukon guys experience shaft failures on dyno's and at the track.... They got a programmer and removed the speed governor.... That was there for the shafts integrity not to keep them from doing over 90 mph.

4200 may be 100 mph, depending on gearing and tires it could be 80, but you GOT OVERdrive and think your only seeing 3500 rpm...ooooooops... how awesome would it be to have a shaft made and the yahoo shop doing it has no clue (there are plenty out there) and you and you go and pass the 2 big rigs doing 85 and bang the shaft comes apart and in 2 and wraps around the rear axle and gets under the right rear tire and your into the middle of 2 80,000lb 85 mph trucks.......

I just recently did a nasty V-10, customer wanted a 1 pc shaft, he is regulated by that shaft to nothing more than 130 mph oper gearing and tire size and i told him if he changes more stuff with the gearing or tires that limit could come down some.

Drag racing and you very well could exceed that shafts rpms, doing a over the top burnout and you very well could easily exceed the shafts speed.

When building a shaft all these things need to be known, like when balancing a shaft, im not turning the pos factory shaft to 6k, but when the customer says it still has a little something at 145mph... well now you know why EVERYTHING needs to be known for the shop and you.

Just can't turn shafts to whatever you want.
.
There are factory fords that have dbl od's and are nearly at 4000 rpm shaft speeds at 65mph, and they are tow trucks...

Lots of reasons why a shaft can be at 4200 rpm...

.

Supershafts 12-23-2012 10:24 AM

Quote:

Originally Posted by 1pieceatatime. (Post 1967542)
Depends on your tire size and gear ratio. The bigger the gears the faster your driveshaft spins, the taller the tires the slower your driveshaft spins.

For reference ill use the ECLB chevys. I constantly get inquiries about replacing them with a steel single piece driveshaft. They have a single piece 5" diameter aluminum driveshaft thats is approx 74" long center of joint to center of joint. To replace one of these with a steel driveshaft (4" tubing which yokes are readily available for) your going to end up with a safe operating speed of about 3200 RPMs. With 3.73s and 32" tires you will be at the safe operating RPM of the driveshaft at 82mph.

Here is a picture of a critical speed failure. Picture is an actual steel replacement in a Dmax truck that originally had an aluminum shaft.

http://i62.photobucket.com/albums/h1...g/CIMG1866.jpg


That's a lucky break that person experienced, i got one a shop did and the shaft ripped apart, took out the exhaust, tank, diff, and locked up a wheel and with the fuel leaking all over put the truck in the wall from 85 mph and maybe lost 20 mph on the way to the wall.

.


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