light weight drive shafts?

[charonblk07]

You have plenty of length in the trans, it's not required to make it any longer. Mine's only pulled out another 1/2" with my drop and recenter, there's still about 6" inside the transfrer case for me.

 

[coolbrzblu]

Any idea if this info applies to an 8 speed? Would be nice to go to a one piece carbon driveshaft as no one seems to be willing to make anything similar to the stock two piece aluminum shaft.

 

[charonblk07]

A driveshaft is a driveshaft, whether it's behind a car, truck, or chevy. All that needs to be looked at is length and pinion angles when they're building them, well more than that, but that's the big ones. I found a local shop that builds them but as long as you can send a shop the dimensions you need they can build a ds for you.

 

[Geo2slow4u]

I'm looking forward to destroying the driveshaft on my 8spd in the coming months.

 

[raven3]

Would prefer a 3" diameter carbon steel drive shaft to a 5" diameter aluminum shaft.
Much easier to reduce run out tolerance on the ends and middle with steel.
Steel can be heated on the high side of the run out, water quenched to shrink the metal
without loosing material strength.
Aluminum will loose temper when heated , then must be oven heat treated to regain the material strength.

A non straight drive shaft can be dynamically balanced and if run out exceeds .005" at the ends or .010" run out in the middle of the tube the drive can induce vibration energy into adjacent structures.

 

[BigSloth]

I'm looking forward to destroying the driveshaft on my 8spd in the coming months.

You'll blow the center bearing out before the shaft goes...

Turns out, when you try to launch a crew cab on a 150 shot with slicks on, the little rubber bushing that supports the center bearing just kinda rips itself out of its metal frame. So until my part comes in, my truck clunks when I stop and go.

I need a one piece really bad.

 

[BigSloth]

No worries, just thought it was funny, kept picturing the scene from Armageddon when they're arguing over which one is Han Solo and which is Chewbaca and one says "Have you even SEEN Star Wars!"

If I stick with my stock brakes when I do the hydroboost then I'll stay with 17s. I've been looking at a set of Mamba M14s in black. They're 17x9 and weigh 23.6lb so once they're wrapped with a set of M&H 275/50R17 DRs I should have a combined weight of around 40lbs which is pretty damned good I think especially since the wheels are only $160ea. For comparison my 22" combo is a hefty 52lbs.

I have mamba M14 blacks in 18x9 wrapped in 30% tread NT05Rs in a 315/40/18 and they weighed 39.8lb each. Compared to my stock black express 20s with 285/50/20 nexens at 62lbs

 

[Dubstep Shep]

Reducing unsprung weight basically makes your suspension more responsive. It won't make the vehicle any faster than removing sprung weight when it comes to pure in-line acceleration.

Rotational weight, on the other hand, will make a big difference.

 

[Dubstep Shep]

A driveshaft is a driveshaft, whether it's behind a car, truck, or chevy. All that needs to be looked at is length and pinion angles when they're building them, well more than that, but that's the big ones. I found a local shop that builds them but as long as you can send a shop the dimensions you need they can build a ds for you.

Not exactly...

A big part of driveshaft design is how the rear axle articulates.

On most IRS vehicles, the rear differential doesn't actually move, so the driveshaft can be a fixed length.

On our trucks, of course, the axle moves up and down and the pinion angle changes. Additionally, the length of the driveshaft changes, so the driveshaft must be able to slide and become longer and shorter.

Then there's driveshafts like on my corvette, where it's between the engine and transmission and is absolutely massive hahaha.

 

[coolbrzblu]

So has anyone gone to a one piece shaft on an 8 speed yet? I see carbon in my future...

 

[Ratket]

sorry- jacking thread a little- wheel weight makes a humongous difference.. seen a Chevy on a dyno with 33s or 35"s .. then bolted up some vette take offs and the hp/ tq difference on the dyno was 75 ponies ... That is a **** load... continue on with the drive line discussion.. Go go light wheels

 

[raven3]

Prior to purchasing my new 2015 ram two weeks ago , researched the ram, GM & ford light trucks extensively by jumping on all these trucks.
GM is having all sorts of issues with drive line vibration inducing vibration into adjacent structures, including the cab and steering column.
Took a real interest in this problem since I logged over years as a dynamics and vibration engineering specialist in the commercial aircraft industry.
Inspected all the current configurations of GM light truck drive lines by visiting multiple dealerships and crawling underneath many trucks.
All configurations of the GM trucks use one section (one piece) aluminum material drive lines, except the crew cab with standard 6.5' box and the crew cab with 5.5' box 74Z1 off road model,which both incorporate a steel drive line.
All the GM aluminum drive shaft tubes are welded to the yoke at both ends.

Ford uses a two piece steel drive shaft with an intermediate support bearing on all configurations except the regular cab with 6.5' box, which incorporates a single piece aluminum material drive line. All Ford drive line tubes, including steel and aluminum are shrink fit and press fit to the end yokes, no welds.

Ram incorporates a one piece aluminum drive line in the RCSB configuration with shrink fit and press tube to yoke joints with a slip joint.
You all know the drive shaft design in other Ram configurations.

The problem with welded joint aluminum drive shafts is run out tolerance.
A quality drive shaft should have a maximum run out tolerance on the yoke ends of .005" and a maximum run out tolerance of .010 at the middle of the tube.
The temperatures generated from the Welding process distorts the aluminum tube increasing the run out. No tube is perfectly straight including both steel and aluminum.

Steel drive shafts are heated on the high side of the run out, then water quenched to shrink the metal. If this procedure is skillfully performed the tube can be warped to nearly perfectly straight condition. If this procedure is performed on an alumnium drive shaft the metal looses the temper and strength. The drive shaft must then be oven heated to restore the temper strength.

A drive shaft can be dynamically balanced but if the run out is excessive, the drive shaft will still vibrate and induce vibration energy to adjacent structures.

This is the reason both Ford and Ram do not weld the tube to yoke joints.
Also welded joints that go unheat treated are sources of fatigue cracking , resulting in catastrophic failure.

Drive line shops weld the drive lines.

All the inspected aluminum drive shafts were 5" diameter, while all the steel driveshafts were 3" diameter.

Believe welded driveshafts are not the place to reduce rotational mass because of the issues associated with vibration, especially with increased rpm.

 

[raven3]

Furthermore,
5" OD x .125" wall 6061-T6 aluminum DOM drive line tubing weight = 2.29#/ft
3" OD x .083" wall 1020/1026 steel DOM drive line tubing weight = 2.59#/ft
One piece Drive shaft length for a hot rod truck is between 4' & 5'.

Based on a 4' drive shaft tube weight reduction = 1.2#, using aluminum metal.
Based on a 5' drive shaft tube weight reduction = 1.5#, using aluminum metal.

Even though the aluminum tube weight is less than the steel tube weight, the rotational mass inertia of the 5" diameter aluminum tube > the rotational mass inertia of the 3" diameter steel tube.

Yoke weight,
Although the aluminum yoke weight < steel yoke weight , the rotational mass inertia of the 5" diameter aluminum yoke > 3" diameter steel yoke.... Greater rotational effective mass.