westman

Well like the subject head says. Is an aluminum driveshaft worth the money? I've been looking on ebay and there are plenty for sale. Is there a certain kind that is preferred?

87TPI350KID

No

BTW, your sig is dumb. Yes I love v8 power, but the s2000 is rwd

CrazyHawaiian

^^ Keep in mind this is a tech forum.

Of course its worth it, but the question is, do you need it? Lightening the drivetrain is similar to lightening unspring weight as far as the type of results you get. The advantages are not in actually dropping weight (static wise), but instead making that part of the car work more effecient because its lighter. How much of a difference you see would depend on what other mods you got and how far you take it. Example would be comparing lightweight valvetrain, lightweight flywheel for a manual, lightweight driveshaft, and lightweight rearend with lighter gears to just installing the lightweight driveshaft. Of course you're gonna get more difference with the first setup. Generally speaking your car will be more responsive with a lightweight drivetrain and more power will get to the ground.

Tom 400 CFI

I Have an aluminum drive shaft, and I agree w/everything in the above post.

Everything.

Dale

iTrader: (12)

Favored one tends to be out of the 98-02 LS1's as they weight approx 11-12'lbs, and sounds to be the best balanced.

As for is it worth it, is totally up to you.

Makes your drivetrain more responsive, less rotational mass.

Don 79 TA

i love the aluminum D-shafts
especially aftermarket ones, as they are usually lighter and larger in diameter to add strength.

if you can score one at a decent price, go for it

ShiftyCapone

iTrader: (7)

They are worth it to me. If anything they are safer at higher speeds. That is unless you run a balanced steel shaft with a high crtical speed. Most (if not all) aluminum shafts found on the last two generation f-bodies were balanced as well as having a higher critical speed than the stock steel ones. They are virtually vibration free at high speeds. Both stock steel shafts in my 90 RS and old 95 Z drove me nuts. As mentioned above, look for an aluminum LS1 shaft.

ME Leigh

I'm gonna say no. I believe everything you hear about the aluminunm driveshafts having less rotating weight is a myth. The steel and aluminum driveshafts weigh about the same. But once you increase the diameter of the Al DS, you are increasing its polar moment of inertia to the 4th power, thusly quickly increasing its rotating mass.

But then again i don't know the specs of these driveshaft to do any engineering calcs so.... does anybody know them?

Dale

iTrader: (12)

I know the V6 (notice, v6) steel driveshaft is approx 2.5" dia, and weights 12lbs.


I belive the v8 steel ones are 3", and weight a bit more.

Most alum ones are 3", and weight anywhere from 11 to 18lbs.

Carbon fiber are 3" and weight about 4-6 lbs

westman

Unfortunetly carbon fiber is a little outta my price range. I'm just trying to free up some hp here and there. Every little bit helps. If I can get 10hp out one for $150 I'll be happy.

Kandied91z

iTrader: (7)

that won't happen.. maybe at the crank, that is unless your motor is quite built. in which case i would not recommend an ls1 style as they are weak in comparison. if you have one built properly though that's a different story. anytime you can take off rotational weight you'll make a difference, the car might feel more responsive, rev a little bit faster but it will be more noticed in combined modifications. a cheaper modification would be to run narrow/lighter/smaller wheel tire combinations. anyhow it's all about rotational weight. if you want to go fast you don't use heavy spinning parts.

Tom 400 CFI

You won't see a dam bit of difference. Read below. If you still think that an aluminum drive shaft is 'worth it'....read it again.

No way on this planet are you going to see "10 hp" for $150 from a drive shaft. Won't happen. There are other things you can buy, though, that really WILL gain you 10 hp for $150.00. I have an Aluminum Drive shaft, and I can tell you; it's not worth getting one if you don't already have it. Mine came on my car....but had it not, I would not waste the money on one. I made that mistake on my last F-body and learned the above on that car...that it makes zero noticable difference.

Kandied91z

iTrader: (7)

that's not true as it does make a difference depending on the build and design, reguardless it isn't a point of reference to make power. use your money somewhere else..

Tom 400 CFI

Not that you'll notice or that you could reasonably measure...so it's not worth it.

TransAm12sec

It helps, even if there is no difference in the seat of the pants feel or et.

Tom 400 CFI

If there is no difference in SOTP or ET's....then how's it "helping"??

LOL! This is getting good. Some people on here spent money on something and are now trying to rationalize that waste of money. I made the the mistake too, but I LEARNED that it was just that...a mistake. No way on this planet, that any gains you get from a driveshaft (none that are measureable), are worth the money

TransAm12sec

When you go to the track, many other things factor into the et. It's not going to guarantee a drop in et, but less rotational weight in the driveline means less power loss, more power to the wheels, however you would like to word it.

Granted it's not the best mod for cost/drop in et factor, but it helps.

Tom 400 CFI

Yes, less rotating inertia does help accelertation. Unfortunately, you need to re-read this:

Tom 400 CFI

Furthermore let's look at this w/some logic rather than spank-talk.

Hypothetical situation: Let's say you have a car that runs ~a:
13.5 et
105 mph trap, w/3.73 gears

That means your drive shaft will accelerate from 0 RPM to about 5300 RPM in 13.5 seconds.

How many HP do you think it takes to spin the mass of a steel F-bod drive shaft to 5300 RPM in 13.5 seconds? Not much. 1/4 hp maybe?

Now how much would it take to accelerate an aluminum version to 5300 RPM in 13.5 seconds? About the same, because it's bigger. Even if it WAS less though, what are we taking about difference wise here between the two? 0.1 hp?

We're talking well under 1 hp here AT BEST. To answer the original posters question, it's not worth the money. You could get better results by taking a dump before you make your pass, and not only is that free, but it helps you feel better too.

CrazyHawaiian

No type of "logic" you can give over the Internet will be able to prove or disprove its worth in this situation. The fact of the matter is there are too many variables to have a universal answer here. Some people will see a difference, some people wont. If you just add a lighter driveshaft to an otherwise stock drivetrain on your full interior street car, you're right, you probably wont feel much of a difference. But if you've already lightened other parts of the drivetrain on your track only race car, and then you add a lighter driveshaft, you might feel a difference, and you might not. It would depend on the other mods and how the car is being used. Lots of variables, so no universal answer. Compare it to dropping unspring weight from your suspension components. You dont get an instant SOTP feel from doing this (unless its extreme drops), but it does make a difference in certain situations. You have to set a goal for the car and then get into the right mindset to modify it to meet that goal. When dealing with weight you wont always see night and day differences mod for mod, but when you're done and you compare it to stock, then you'll see night and day differences. Generally speaking I see dropping weight in these areas usefull for roadracing setups with lots of turns and gear changes up and down, not so much for dragracing or straight line performance. So if your goal is to do that type of racing, then you might want to consider getting into that mindset.

Tom 400 CFI

Look dude, your post is a disaster.

The only place you'll see a benefit from a drive shaft that has lower moment of inertia (notice I didn't say "aluminum drive shaft") is under acclereation and deceleration. "Gear changes up and down" has nothing to do w/anything this thread is about; the clutch and trans aren't affected in any way by the polar moment of inertia of your drive shaft.

Here's the deal: A third gen AL drive shaft or a third gen steel drive shaft won't be noticably or measureably different, period. If you can't feel it, and you can't measure it, then from a real world, practical perspective (the one that matters) what's the benefit? Aluminum is no better than steel in this application.

And certainly, for $150.00 it's not worth it. You might consider that "mindset", rather than one where you fool youself into thinking that you made a good purchase of that aluminum drive shaft for your V6.

Tom 400 CFI

Anyone KNOW (not guess) the weight and diameter of a steel DS?

Anyone KNOW (not guess) the weight and diameter of an aluminum DS?

Wall thickness on both?

We can figure this out right now if I can get this data.

CaysE

Very few people have mentioned the ACTUAL advantage of going with an aluminum driveshaft.

They are better balanced and don't vibrate at higher speeds.

I'm looking forward to the weight numbers.

kretos

this is the only real gain i have ever heard of, they stop high speed vibrations

Dale

iTrader: (12)

16 lbs - Stock steel LT1 driveshaft
12.2 lbs - 3rd gen aluminum 1LE driveshaft
12 lbs - LPE aluminum driveshaft
11.5 lbs - Stock aluminum LS1 driveshaft
10 lbs - RK Sport aluminum 1pc driveshaft
4 lbs - ACPT carbon fiber



I know the LS1 aluminum is 3"dia.
I do not know the wall thickness of any of them.

83 Crossfire TA

iTrader: (2)

There is no reason for them to be better balanced then a steel DS. The “ACTUAL advantage” to it is that the material has a different harmonic frequency which moves the DS’s harmonic and flexing out side the operating range of the vehicle as well as raising the ultimate critical speed of the DS.

I do own a Denny’s metal matrix composite, 3.5” shaft, but if I was going to do it again, I’d probably just get a custom steel one made for less then half the cost. The 3rd gen, 1LE aluminum piece is a pretty decent DS, but the LS1 DS really is not, they are prone to failure.

CrazyHawaiian

The only disaster here is trying to imply that weight reduction is not a worthwhile modification. I think we can all agree that it is not cost effective for the most part, but as for its worth, I disagree with you. I think there is a possibility that the mod could be worthwhile for the original poster or anyone for that matter, but it would depend on a few things.

Weight reduction does require a different mindset. Call it foolish or poke fun at the idea, but its true. The difference is that its not likely that you will feel gains mod for mod, but depending on what you do, you can feel gains when everything is said and done and the numbers are added up. If you dont go by that mindset then you will be frusturated and unhappy with your results as you go along. Its a long, slow, expensive process. The "depending on what you do" part there has alot to do with how much weight reduction you do and how you use the car.

And this is where it really matters what other mods the original poster has done, and how he uses the car. I dont think anyone can sit here and tell him weather or not its worthwhile for him, he will have to decide that himself. The flaw with any of us insisting its worth to him is that we are using our own car and our use of our car to come up with our opinion. And because we are two different people with two different cars, how does it help? One reply might be from someone who has had great success with weight reduction, another reply from someone who has had no success because they dont understand the concept. Again, how does this help? Best we can do is share weather or not its been worthwhile for us. Beyond that you are just pushing your opinion on other people. Its much more usefull to explain why people do these types of mods, list some weight numbers, and let him decide if its worthwhile or not for him.

To back up what I've been saying I need to say some things about weight. There are two types of weight on your car, static weight and unsprung weight. Drag racers are usually only interested in static weight because it can directly relate to their ET's on the 1/4 mile (every 100 pounds you drop you run .1 seconds faster). People that are serious about weight reduction (professional racers, etc) will have a long list of things they did to drop weight. If they had just done one thing on that list, then they probably wouldnt have made a difference. But when you add everything on the list together, then it makes a difference. It is possible to drop 300 static pounds from a 3rd gen Camaro and run .3 seconds faster, and guess what, there is no single mod you're gonna do that will drop 300 pounds. You have to do it little by little, mod by mod until you finally reach your goal. Now for those of us into roadracing we are probably more interested in unsprung weight, though static weight is still important. Unsprung weight is usually considered anything that is not supported by the suspension of the car. The reason guys into roadracing and whatnot are so interested in unspring weight is because it makes the cars suspension so much more efficient. Like a long chain of parts that work together to achieve a goal, you lighten the individual parts of that chain and it will work more efficiently overall. If you offered a roadracer the choice between dropping 10 pounds of static weight or 5 pounds of unsprung weight, good chance they'd go with the 5 pounds of unspring weight. They probably wouldnt feel a difference from that 5 pound drop, but add it up with the other unsprung weight they've dropped and compare it back to stock, then you get the difference. And yes it can make a difference.

Now getting back to the driveshaft, I think its a good idea to compare its weight savings worth to the worth of dropping unspring weight. I say that because its a single part in a chain of parts that work together. This is why its important to understand weight reduction and the different types of weight reduction and the mindset you need to be in to do weight reduction. Dropping weight on one part of the drivetrain will not make as much of a difference as dropping weight on all the parts of the drivetrain. So depending on what other stuff you've done you may or may not see a difference. I know the next question is "what difference are you trying to make" and the answer is that the lighter drivetrain will be more responsive and more of the engines power will transfer to the wheels because the drivetrain is working more effeciently. In a scenario where you need to build or drop rev's fast, a lighter drivetrain definately can make a difference. Like a lightweight flywheel, a lightweight driveshaft will help. This is why I brought up "gear changes up and down" and YES it does pertain to this thread and this modification. This is also why I consider this mod more for the guys into roadracing and whatnot that will be doing alot of upshifting and downshifting or people that want to get the most out of their setup. Its not necessarily better for everyone, but if this is how you plan to use the car then its a step in the right direction, v6 or no v6.

CaysE

OK, so you're agreeing with me and making it sound like you don't. Few things annoy me more. The ACTUAL advantage is they don't vibrate at higher speeds, or in your technical jargon: "are made of a different material with a higher harmonic blah blah blah." And let's make no mistake here: the vast, VAST majority of people reading these forums aren't going to have a custom steel driveshaft made that will outperform aluminum. There IS a reason for aluminum to be better balanced: because they are from the factory. I'd spend 100 bucks on an aluminum DS to replace my factory steel piece of garbage any day of the week.

Sorry to rail on you, but please do not try to correct me when we're saying the same things.

Dewey316

CaysE,

It isn't a balance thing, and that is what Mark is pointing out. Both materials, balanced the same way, on the same machine, will act diffrently because of the material. You are making it sound like a steel driveshaft is always going to be out of balance, that is not true. The aluminum one has diffrent propeties, so the natural harmonics occure at a diffrent speed, reguardless of how they are balanced.

CaysE

I agree with you Dewey, but we're delving too far into theory and not our own applications. I don't really know what most people's experiences are with their stock steel driveshafts, but my 84 and 86 were never able to be balanced properly... on some days they would just vibrate like crazy at certain speeds, on other days they were as smooth as ice. My 92 steel driveshaft can be felt at higher speeds a bit, but it doesn't fluctuate depending on weather or the moon phase or whatever my other two cars were doing. I have an aluminum driveshaft that will be going on the 92, so that takes care of that problem.

I realize that either driveshaft SHOULD be able to be balanced the same, but for some reason I don't know, the older thirdgen steel ones just can't be balanced properly. We kinda have to keep this discussion in the scope of our cars, and those are my experiences.

Sorry to come off as an *** before.

Dewey316

You didn't come off as an ***.

Just pointing out, that vibrations are not always a balance issue, the harmonics, pinion angle, proper engangement of the slip-yoke, tires, etc can all be parts of vibrations. A vibration does not automaticly mean an out of balance driveshaft. The major benifit for the use of 'my' car, is the alum. shaft, doesn't do its harmonic shimmy (that is not a technical term), until a speed that my car is basicly not going to hit (Until I try my hand at SilverState ).

92_ZED

On my stock '92 the factory steel driveshaft made the rearview mirrors useless at 70 MPH and above. Replaced the stock shaft with another one from a '91 and it was just as bad. No difference.

This spring I finally did the right thing and installed a '02 Camaro aluminum shaft. An amazing difference, smooth as glass. High speeds and I can use the rearviews. Well worth the money.

Al.

Tom 400 CFI

O.K then. To the original poster:
If you get an Aluminum drive shaft, you will spend over $100.00.

You will feel zero difference in power.
You will see zero improvement at the drag strip.
Your performance at the auto x events will not change.

Is that $100+ worth it to you???

The Drive shaft will make ZERO difference w/regard to "shifting up and down". How in the world can the drive shaft have any impact whatsoever on shifting?? A different mass flywheel? Yes definitely. A different clutch. Yes. Different trans fluid, synchros or shifter? Yes, yes, and yes. But the drive shaft?? Nope. Sorry. That's like saying changing your rims is going to change shifting (because you know, the drive shaft is mechanically connected to the rims). You're right that a light weight fly wheel will make a difference.
1. It's IN FRONT of the trans.
2. It's bigger in diameter (greater moment)
3. At a drag strip (for example here: I can't use a road course as they're all different -same principale though), the fly wheel may go from 1500 RPM to 6000 RPM, then from ~4000 RPM to 6000 RPM 3 more times, in say the 13.5 seconds mentioned above. That's a lot of RPM change (>10,000 RPM compared to the drive shaft which accelerates from 0 to ~5300 RPM) in of an item of a relatively large diameter. You WILL feel and be able to measure a differnce there. Not the same as the drive shaft which is smaller accellerates FAR less, and is after the trans.

The only TANGABLE benefit of the AL drive shaft is:
*3.8 lbs weight savings from your vehicle
*Better harmonic characteristics for those of us that cruise around at speeds above 100 mph on a regular basis.

BTW, both the AL drive shaft in my old Trans Am and the one in my current Camaro vibrate at speeds above 80 mpg. And they did and do have good U-joints. Aluminum in no way precludes vibration issues.

Tom 400 CFI

That's great info. Can anyone tell me the O.D.'s now please?

Thanks.

83 Crossfire TA

iTrader: (2)

As Dewey stated, it’s not about balance at all or getting it “properly balanced.” At the shafts harmonic(s) even a perfectly balanced shaft will cause vibration. What happens is that as the u-joints turn the shaft actually slightly accelerates and decelerates, which we don’t feel because if the 2 driveshafts are in phase that accel/decal is canceled (or mostly, the 2 angles aren’t ever perfect). At the harmonic you reach the point that that happens at a frequency that is sympathetic to the material and sizing of the shaft and as it happens the shaft actually trys to flex into a sinusoidal wave shape, which moves some of the weight of the shaft outward causing a vibration, essentially, the result is that at that speed you are effectively trying to drive the car with a bent shaft.

Changing materials and sizes changes where the harmonic falls and extending that harmonic to a higher rpm extends the critical speed of the shaft as well as sooths things out.

If you want to see exactly this in action, get in an f-body (especially a 4th gen) with 4.10’s and a stock DS in it. At about 70-75 you’ll feel a throbbing, syclical vibration that sorta builds. In 8x mph range it gets so bad that the shifter popps up and down and it becomes a drone, then as you pass 90-95, it suddenly goes away. If you keep trying it will come back in the 140-150mph range.

CrazyHawaiian

After saying basically the same thing 3 times in a row, I'm gonna give up now. Tom, for some reason you dont seem to be getting what I'm saying (or dont want to listen, not sure). I dont think I will add anything more usefull by typing the same stuff over again. But just to answer your question, the driveshaft itself has nothing to do with shifting, it has everything to do with what happens to the drivetrain when you shift and how fast the drivetrain will react to your right foot. Changing your rims would affect your unsprung weight which would affect your handling. Of course there is no way to measure this over the Internet that will satisfy Tom, so it must be a hoax that isn't true. I give up.

rwdtech

im thinking about getting one because i got some undercoat all over my stock one and its rusty as hell (i cant stand seeing a nice clean underbody with a rusty driveshaft going through it). and if it helps performance or drivetrain wise, so be it

whats the weight of the stock 3rd gen shaft, and did anyone find outside diameters?

ScottieB

I will let you know when and why I will get an Aluminum DS:

When mine gets bent
When mine rusts to hell
When mine falls out of the car from these 2 things

That is when I will get an Aluminum DS. Don't bother with the money unless it's broken. Upgrade something else!

robertfrank

iTrader: (27)

well I guess I got lucky when i got my AL driveshaft.I paid 25 dollars at a pick and pull and it was in perfect condition.I did feel a big differance in how my car felt when I put mine in.then again my car weighs 3120 pounds with me in it and I'm still pulling more weight out.The car accellerated faster, was definately smoother at high speeds and I had a rebalanced steel shaft before.I'd definately do it again if I had the money.Hell I'd even spring for a carbon fiber shaft if I had the money.

86irocterror

i want to point out one very IMPORTANT thing.! strength of the shaft. i could care less about aluminum or steel cause there is not enough real difference to waste the money. unless you like the look go for it. but if you have a decent amount of power or like to launch hard or do alot of burnouts.....i pitty who ever opts for aluminum. a MILD modded car i would feel safe with one, but any real power upgrades 400 and up or like i said before will be putting alot of stress on it by launching or burnouts and deffinately slicks i wouldnt even drive it. a few of my friends with ls1's pushing around 400 hp and one stock with a 100 shot on it both snapped the aluminum shaft, but they did race them at the track alot so they did get abused. the damage from a snapped shaft is un believable. i dont want to upset anyone by my post just trying to help out. im only concerned about fellow 3rd genners safety the most! my opinion instead of the shaft for 150 do a set of under drive pulleys for a lil more money or just do a crank pulley. you will gain some safe power there.

ScottyRS

iTrader: (2)

Well I was thinking about buying an aluminum shaft off an '01 Trans-Am locally for $100. But after reading that, I guess I won't.

83 Crossfire TA

iTrader: (2)

The LS1 cars are pretty much known for having weak stock aluminum driveshafts, but GM did go to aluminum for a reason, to prevent the harmonic resonance issues that f-bodies tend to have with steel driveshafts.

As far as strength, built the right way aluminum can be strong… I bet that there’s only one or 2 people on this board that could break my denny’s MMC shaft (I actually had it made for my 97 WS6)

purpleZ-28

that makes absolutley no sense.you wont pick up HP at the crank if your using an aluminum drive shaft because the DS is after the transmission.
i have an aluminum DS in my Z, but i honestly cant tell you if it makes a difference, because its always had it, so i have nothing to base gains on.

3.8TransAM

Long story short 83 Crossfire TA got it right.

GM changed them to move the harmonics out of the vehicles range.

Everything I have owned/worked/built/etc from GM from mid 80's thru mid 90's with a steel driveshaft had some type of vibration. Usually in the 60+ mph and up category and smoothing out in the 90+ range only to come back again over a 105-110 mph.

GN owners have the same issues as well as a lot of Monte Carlo(SS) owners and even my old 442 and plain jane Cutlass. Seen this in Caprices too.

Aluminum is better.

My 91 Formula steel, it vibrated. 91 GTA, aluminum, no vibrations.

Made one good alum DS for the Formie out of a good alum shaft and the yoke from the steel shaft and guess what, no more vibration.

later
Jeremy

jaysfs

iTrader: (1)

i bought my alum.driveshaft for 20bucks.i just need too polish it

Jetmeck

iTrader: (3)

87 TA 38k miles 305 TPI 3.23 gears.......steel driveshaft

89 GTA 9k miles 350 TPI 3.27 gears.......aluminum shaft


Just for you guys I took them both up to 130mph

I couldn't tell any difference....same road. Any DS can get out of balance...bent or lost a weight or even possible pinion angle can cause a vibration on those that like to lower things

On a street vehicle you won't get any noticable power increase so unless you get an Aluminum DS on the cheap don't waste your dough............................!

brutalform

Ive been following this thread for a while now. The aluminum shaft does what it was designed for. Thats why GM did it. If anyone who has spent the money on one, and wants to do back to back track testing, and post the results, then GO FOR IT! IMO, if you are going to pick up a 100th of a second, or MPH, then to me its not really worth it. You can pick up more than that, for less. I have a custom made 3", balanced, steel shaft on my car, and it will most likely remain there indefinatley. Now, I am moving this to the drivetrain board, where it belongs.

detltu

iTrader: (1)

I had a buddy who modded his 99 Mustang GT and put a carbon fiber driveshaft on it and they ran it on the dyno before and after the CF DS and it showed no gain. For some reason though I just believe it helps because it doesn't make sense to me that it doesn't. The CF driveshaft was only a few pounds and made his stock one feel like it was made of lead.

Tom 400 CFI

It does help, but the difference is so infintesimal, it won't show up on a dyno...or at the strip. It's too small diameter to make a measurable difference, and it doesn't increase RPM's enough in the acceleration time-frame to make a measurable difference -as was stated by me, earlier in this disaster of a thread.

83 Crossfire TA

iTrader: (2)

Why did GM do it???

As far as HP increases… you will not see any in any steady state HP measurement. It will marginally decrease the inertia of the drive train so you may see some marginal increase in acceleration (and in a dyno test measuring acceleration to compute HP), but that’s it.

As far as I’m concerned, the reason that aluminum and CF driveshafts exist is a simple issue of critical speed and harmonics, nothing more and nothing less. Put 4.10 gears in an f-body, and the stock steel DS is just the right diameter and length to have it’s first harmonic at between 75 and 90mph, which is quite annoying, can be dangerous and contrary to what a lot of people’s beliefs cannot be balanced out. That is a speed that almost all of these cars see. Something like a denny’s 3.5” MMC driveshaft moves that harmonic out of the range of where the car will normally be used…

The 1le cars got the aluminum DS because they were more likely to see that rpm range where this becomes an issue even in factory trim. The LT1 powered 4th gens got a 3rd gen 1LE shaft if you could prove that your car had an issue with the harmonic (I never managed to do it with my WS6, since it happened right above the speed limit the dealers wrote it up as not having an issue at any speeds they could test legally…), and the LS1 cars all got one, although their factory one was pretty much junk and not suitable for anything more then the stock vehicle.