Do you think this is a good ides to swap my old cast shaft for a alum. one. I am in the middle of a complete rebuild of my 89 RS. I am looking for any performance advantage I can get.

Also are the U-Joints the same?

Thanks
Brian Felts

 

If you can find one cheap in a wrecking yard sure, but I wouldn't get one for big bucks. In fact, I think TPIS has a few in their "Garage Sale" though I would still scout around a few wrecking yards first.

As best as I know, there is no differences in the U-joints themselves. Though, you should get a good quality set anyways.

 

By all means the aluminum driveshaft is a very worthwhile mod. I wouldn't pay more than $150 for a used one, and I did see one on Ebay today that was up to $55 as of this afternoon. You can also use one that has been pulled from a fourth gen, it's a little bigger in diameter but will bolt right in whether you have an auto or manual.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, Wonderbar, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

Member - The Tidewater Trans Am Club, Norfolk VA http://www.geocities.com/ttacva/

 

Does anyone know the weight difference? My IROC came with an aluminum driveshaft (according to the RPO codes) and I was wondering how much weight was saved with this option.

 

I can't give a complete answer, though I ship alum shafts on a fairly regular basis. Shipping weight is 14 pounds, but shaft weight is probably 12.

Check the FAQ page on this site for more info about why the alum shaft is a nice mod.

JamesC

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Saves 4 pounds or so.

[This message has been edited by HatchetJack (edited April 17, 2001).]

 

Keep in mind that it's 4 pounds of rotating weight, not just 4 pounds sitting in your hatch! I'm guessing that the rotational weight savings is morebeneficial than the static weight savings.

------------------
Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads sitting on it look good!)

Starting to look like the Kicker poster child!

ASE Certified Master Tech

 

Yes, the less rotating mass you have the better. Then more of the engine power gets to the rear wheels!

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

I switched driveshafts about a month ago and from a 88 firebird to my stock 84 Z28 and the u joints that I got from lakewood did'nt fit. Dont be a dummy like me.

 

I bought a replacement aluminum shaft for my car off ebay for $25. I would definately keep an eye on ebay.

Jeff

 

Yes! they are very worth it.
The whole idea is to reduce the inertia in the driveline. Inertia is the resistance a body has to motion. Anyways the more RPS you turn the better off you are to have an aluminum drive shaft.
I plan on gettin one for my TTA its part of doing mods and still apear stock, unless the TTA has one, though I dont think it does.

Another thing to consider is that the drive shaft is one of those things that casues HP ratings at the wheels to be less than that at the crank shaft. I wish I had my physics book with me to give you and Idea of what increases in translated pwoer you would have, but I don't so I am going to take an educated guess and say this: Knowing what I do about you engine I would say your shifting Rpm will be about 4800-5200 RPM so I would say at that high of RPM you might see and improvement of about 5hp at the wheels compared to the original rating.
And Hey horse power at the wheels is what matters right.

------------------
89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Or, the tendency of a body has to remain in motion or stay in motion in a straight line unless disturbed by another force....

 

88-97 are bolt-ins. Pre-88 cars will require a different sized rear U-joint to fit. In my 85 IROC I used CarQuest 3-3130.

JamesC

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Wow. Good information. I hadn't considered the rotating mass effect. Thanks all.

 

Oh great, another thing that's different on the newer rearends. The yoke should interchange between the housings, correct?

I keep finding out too many things on here!

------------------
Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads sitting on it look good!)

Starting to look like the Kicker poster child!

ASE Certified Master Tech