Steel vs Aluminum driveshaft
 

What if any performance gain would there be going to an aluminum driveshaft. I always weigh the cost vs performance gain before buying anything. If 400.00 is going to get you .01 to .02 on the track then forget it. I race on a budjet I have to make smart purchases. Thanks. Ed

Re: Steel vs Aluminum driveshaft
 

X 2...

Re: Steel vs Aluminum driveshaft
 

ED I doubt you would even see that, save your money as far as i can tell!;)

Re: Steel vs Aluminum driveshaft
 

Agree with Woodro, not worth the extra $ unless you're after a contingency posting from manufacturer who only pays for the 'premium' series. If it was me I'd rather buy a component proven to yield results (i.e. chiller).

Re: Steel vs Aluminum driveshaft
 

I ran a pretty comprehensive back to back test in a pretty good stocker (96 Corvette) Results? zero performance gain. The aluminum unit is lighter so if you are a proponent of movable ballast, that is a plus.

Re: Steel vs Aluminum driveshaft
 

Kip Martin with his 289/210 SS/L broke his aluminum one last year. Borrowed a steel one for the remainder of the race. He said it felt like a slug in high gear. I know it lost a few MPH but don't remember the ET loss, if any. Once he put a new aluminum back in, it was back to it's normal self.
I think a lot of questions need to be more directed at "what you got" and not with blanket statements. 5-speeds seem important to little engines over 4-speeds, same with light-weight parts like wheels & drive shafts.
I have all sorts of light parts. Has it helped set records? Probably. Can't complain about 10.50's in D/S and that's not a little engine.
If I had a 327 like yours, I wouldn't hesitate; 327 is probably about borderline on little engines with 350+ taking over from there.
I do understand budgets though! Could you borrow one?

Re: Steel vs Aluminum driveshaft
 

And I'll bet a 'Vette has a pretty short length drive shaft w/ a 97" WB so it's hard to compare to the average 108"-112" WB.

Re: Steel vs Aluminum driveshaft
 

Jeff; Not wishing to appear ignorant in the eyes of a guy who claims to be able to make a Rambler aproach warp speed in 1320ft I will admit to having a "short shaft". That being said; I ran an aluminum unit it my 90 Camaro as well with the same end result. I have heard ET gains of up to a tenth with aluminum driveshafts so perhaps you are correct to say that it probably has a lot to do with combinations: a clutch, manual trans and a "short stroke" It makes sense to me that all these guys didnt imagine the performance gains. Any component that reduces rotational mass or unsprung weight is worth consideration in my book and dont feel like the Lone Ranger if you have lost your "budget"; most of us suffer from the very same affliction. Agreeing with Jeff Lee??? Not bad, I do feel.............well.........a little slutty, but a shower will probably help. TT

Re: Steel vs Aluminum driveshaft
 

I am just a bracket racer but this subject has always interested me. I have a 65 Comet with a 351C and a 4 speed with a 5:14 gear and a M/T 28x9 tire. I used a 3 1/2" .065 mild steel shaft for over 20 years with no problems. I accidently damaged by denting it so it was time for a replacement. It is 57" center to center.

I called Mark Williams first and they said that according to there critical speed chart I needed a 4" aluminum or carbon fiber shaft. This is a mid 11 second car.
I then called Inland Empire, PST, and several others and I had no two shops agree and what is required. I looked at several critical speed charts online and Mark Williams seemed the most conservative.

I ended up with a 3" Strange chrome moly but I still like the idea of an aluminum shaft. It seems like a good place to loose some rotational weight.

I really enjoy your site and I am anxious to see the results of this thread. Brian

Re: Steel vs Aluminum driveshaft
 

I tested steel vs al in my SS big block ford. Same day back to back. A-B-A
I gained zip. zero ,nada

Re: Steel vs Aluminum driveshaft
 

Ran the OE, 28lbs, 3.5", .120 wall driveshaft in my wanna be stocker for 100 laps. Decided that a lighter driveshaft would make the car quicker and faster. Had my driveline shop make a 3", .065 wall with smaller U joints that was 12lbs lighter than the OEM. Ran this shaft for the last 50 laps. The net ET and MPH difference.............................wait for it................................................ ...ZERO!!!!!!!! This is in a 13 second car at 3320 LBS. Save you $, light driveshafts are like time trials, very over rated!!

Re: Steel vs Aluminum driveshaft
 

Tom,,,if you're feeling a little "slutty" and need a shower,,just step outside,,theres a hell of a storm going on tonight. Just make it brief,,,with wind chills in the teens, you wouldn't want anything to freeze or fall off!! Happy Thanksgiving ( Dang,, we're not even in Minnesnowta!)
Danny Durham

Re: Steel vs Aluminum driveshaft
 

Remember Robert Turner's F/SA Duster 360? He ran a junkyard RAMBLER driveshaft in it for record runs! Seems like it was only 2" OD. I can't understand why it didn't twist in half. I can't remember what ET he found but it was worth something.

Tom, you'll be OK. I have found myself agreeing with you before. Well at least once...

Re: Steel vs Aluminum driveshaft
 

Setting aside any performance gain, I think aluminum drive shafts increase the life of the ring and pinion, axles, etc., by absorbing some of the shock load on launch. Any experiences to that effect? BTW - I even heard Warren Johnson make a statement to that effect, for whatever that's worth. I'm just a hack, but I thought I would bring up the subject. Thanks.

Re: Steel vs Aluminum driveshaft
 

maybe no performance advantage but ya are taking WEIGHT outa the car--Comp 387

Re: Steel vs Aluminum driveshaft
 

My car is 65lbs heavy for H. Maybe more if I get some HP off. LOL

Re: Steel vs Aluminum driveshaft
 

In case anyone is wondering about weights, my 3" steel driveshaft weighs 13#, the duplicate 3" alum with the same size yoke and ujoints weighs 10#. I didn't do back to back runs so don't have any data on performance differences.

Jim Caughlin
SS 6019

Re: Steel vs Aluminum driveshaft
 

OK guys not sure what if any performance advantage if there is one but the BIG 3 have been installing aluminum driveshafts in rear wheel drive vehicles from Camaros to Lincolns to full size pick ups/vans etc for about 20 years---there must be a reason they are doing it--anybody wanna guess why a multi billion dollar company would do it?? It aint the color of silver vs. black or rust so why do ya think they are doing it????? comp 387

Re: Steel vs Aluminum driveshaft
 

harmonic vibration

Re: Steel vs Aluminum driveshaft
 

Its Safer too what would you rather lose a big chunk of steel or alumium??? Arent steel driveshafts illegal in stock in cars that didnt have them from the factory in NHRA still?!?!?

Re: Steel vs Aluminum driveshaft
 

Aluminum shafts are illegal in most stockers, not steel. Some at yellow bullet swear aluminum gives them a few hundredths. My guess is that if you run a thick wall, long 4" steel shaft, there could be some gain with aluminum.

Re: Steel vs Aluminum driveshaft
 

I don’t think you can really make a blanket comparison between steel and aluminum drive shafts. Beneficial to some not to others, there is a lot of things to consider when swapping them out and seldom are the new and old physically comparable. One would first think that if its lighter it will take less energy to accelerate… well not necessarily if you take a small diameter steel shaft and replace it with a lighter large diameter shaft.
Here is an example
7000 rpm a 3” shaft will have a surface speed of 5498 feet per minute
7000 rpm a 4” shaft will have a surface speed of 7330 feet per minute a 33% higher speed
Using basic physics equations like Ke=1/2mv^2 if they weigh the same and most of the mass is in the tube not the end yokes the 4 inch shaft will take roughly 78% more energy to accelerate to 7000 rpm.
If you do all the math the 4” shaft would have to be about 40% lighter to take the same amount of energy to accelerate as the 3” shaft.
What this exercise shows is that most comparisons are apples to oranges you probably won’t see any gains unless you are replacing your current shaft with something lighter and the same or smaller diameter.
And this is without taking into consideration what’s going on in the rest of the car.

For something as simple as a drive shaft there is no simple answer.

Re: Steel vs Aluminum driveshaft
 

Well, I just so happen to have a 4 inch steel in my stocker, which came with an aluminum.....so if I change it out of say a 3.5 aluminum, or even a 3" chromoly I will post the results.

Eric

Re: Steel vs Aluminum driveshaft
 

Mr Edgeworth some???? If a 4 inch diameter mild steel tube weighs about 4 times more than a 4 in diameter aluminum tube wouldn't there be some advantage in not having to accelerate that much mass either in HP required or ET resulting from the reduced weight??? Take for example that a .065 steel tube weighs about 3 pounds per foot vs a similiar sized alum tube weighing about .7 pounds per foot there just has to be something here and not just reduced vehicle weight dont ya think????
I can understand harmonics to an extent and the need for OEM vehicles to meet CAFE mileage requirements so the vehicles weigh less but the OEM guys used Steel Deriveshafts for millions of vehicles over the years and really never had any vibration problems so I cant believe that the OEMs replaced the Dshafts for that reason had more to do I bet with vehicle weight that any thing else.
Perhaps you can mathmatically calculate the difference in performance between the 2 or is it too small to actually make any difference---Forget about cost of a shft it is inconsequential just raw performance numbers if ya can please---Thanx Comp 387

Re: Steel vs Aluminum driveshaft
 

Absolute BS that its not legal in stock with all the changes they allow as stated its safer and easier on rear end

Re: Steel vs Aluminum driveshaft
 

To answer your question yes. What you describe would be more of an apples to apples comparison. Same size shafts, same final surface speed half the weight half the energy required to accelerate to speed.

Re: Steel vs Aluminum driveshaft
 

yep, that's what they tell me,too.mostly OD trans' have that problem for some reason.

Re: Steel vs Aluminum driveshaft
 

I had a buddy with a Cummings diesel Ram truck that had a serious vibration problem. Many trips to the dealer and it was a serious problem when towing his race car. The factory finally put a carbon fiber drive shaft in it and curred the problem. I'm sure there is a TSM on it and it can be applied to any mopar car in Stock. :rolleyes:

Re: Steel vs Aluminum driveshaft
 

The real reason that you would what to use a lighter driveshaft is the critical speed for the length of the shaft. Mild steel is good to a certain length where critical speed makes it impractical or dangerous to use in a racing application. Some racers complain about unbalanced slicks when it really is a driveshaft that has exceeded critical speed and has started to whip and bend while going down the track.

My son (a driveshaft engineer for one of the big three) has always told me that you need the lightest, shortest (hard to do), largest diameter driveshaft made from the stiffest material when building a shaft for racing. When you do all these things you raise the critical speed which will add to reliability and increase performance (if you were exceeding critical speed in the first place).

Stockers that have aluminum shafts already can be improved with larger diameter MMC material which again raises critical speed. Stockers with steel shafts can use larger diameter alloy shaft material.

Super Stockers should always adhere to what was stated in paragraph two.

Note: If you want a larger tube make sure that it fits in the tunnel and driveshaft loops before having it made.

If you want more information go here http://www.markwilliams.com/driveshafttech.aspx .

I am by no means an expert on the subject but I can sure talk to one any time when there is a question.

Re: Steel vs Aluminum driveshaft
 

i wonder if amc can be included in that;)

Re: Steel vs Aluminum driveshaft
 

If you are going to call the Cummins Turbo Diesel a Cummings, then I am going to call your car a Rambler :)

Re: Steel vs Aluminum driveshaft
 

HEY! HOLD ON!YOU CAN'T CALL MY CAR A RAMBLER!


oh yeah, it IS a rambler;)