spool versus posi
 

Anyone have experience in the value of a spool versus a posi unit? I currently have posi in a L/SA 305 Malibu and am wondering if it would be a cost effective upgrade.

Glad you posted this question. I have been wondering the same thing as I build my T/SA 231 V6 Starfire. I assume the answer will be about how much HP one has. Or maybe car weight. Or maybe both?

My opinion: Either will drive both tires (as long as the posi is functioning properly). I have a friend with a J/SA Pontiac with a posi. Video shows what we suspected, it needs to be rebuilt as the right rear doesn't seem to be engaging properly. We're going to replace it with an aluminum spool. On a low HP application (maybe I should say low torque), I believe every effort should be made to reduce every once of reciprocating weight in the trans, driveshaft, rear-end and wheels / tires. If it were my car, that's what I would do!
Good luck...

NHRA #7494 SS/H
1970 AMC AMX
"Best Appearing" @ NHRA '06 Pacific Sports Nationals
JeffLeeAzRealty@Qwest.net
602-418-9797

Jeff
Might want to reduce the rotating weight too.

Thanks for the responses. So if money is a factor which would be a better investment, spool at a 10 pound savings or a metric 200 trans?

Friction is what you want to reduce. In a low hp combination why have a spool. When you use a spool you're always seeing more friction. All you need to do --- is make the car hook.

I miss step.

I highly recommend to go to a spool. posi will have some give no matter how well it is. you don't want it to cause the car to launch to right. plus a spool is lighter.

Back to what Jeff was refering too, have you ever see a car spinning just one wheel and the other is glue to the track ????
How can you tell when this is going to happen, do it right the first time, its cheaper in the long run...Plus weight and durability...LOL
Dave...1033/stock(350) RV-455

Spool is the way to go just be careful if the staging lanes are wet because the car wont like to turn. I know.

Also, make sure to check the front end chassis/alignment too.

How?

NHRA #7494 SS/H
1970 AMC AMX
"Best Appearing" @ NHRA '06 Pacific Sports Nationals
JeffLeeAzRealty@Qwest.net
602-418-9797

AS MUCH AS I HATE TO AGREE WITH FULPER, HE IS 100%CORRECT ON THIS ISSUE.
HEAVY LOW HP CAR WILL SLOW DOWN WITH A SPOOL.
POSI IS ALWAYS GOING TO BE FASTER DUE TO LESS DRAG.
ASK BOB SHAW. I DONT THINK HE HAS EVER HAD A SPOOL IN ANYTHING.

Jeff I think that if both tires aren't "exactly" the same size. And if there is anything but an arrow straight run. You would have friction.
I just spent a lot of money getting a real posi unit to fit my neon. Not sure if a spool will work because of the front wheel drive, and the toe in or out changing due to the motor torque.
On the other hand my posi unit adds about 10 pounds or rotating weight. An aluminum spool would be about 12 pounds lighter.
Not sure which one would be better, (my old turbo dodges had open differentials)but for now I'll stay with the posi
I'll probably be about 10 pounds per wheel horsepower.

ART LEONG
SOON TO BE FRONT DRIVE SUPERSTOCKER

Interesting. I was assuming everything was correct with tire size and being a straight run.

NHRA #7494 SS/H
1970 AMC AMX
"Best Appearing" @ NHRA '06 Pacific Sports Nationals
JeffLeeAzRealty@Qwest.net
602-418-9797

Jeff . Any ever so slight deviation from straight will cause drag. and I see people measuring slicks with rulers(tape measures) think about if nhra used those methods for checking engines LOL.
With a FWD car the alignment is wacky to begin with.

ART LEONG
SOON TO BE FRONT DRIVE SUPERSTOCKER

Artie;
will you be at MG next week?



Ed

No still waiting on the cylinder head. But It won't be long now.

ART LEONG
SOON TO BE FRONT DRIVE SUPERSTOCKER

It's interesting that I'm reading these posts on the positive traction vs. the spool. I just broke my positive traction and we are replacing it with the Moser spool, clip eliminators, and axles. We purchased the car with positive traction and we didn't "upgrade" until I broke it. Positive traction worked well for 12 years. The car also came with a 350 Turbo, and we upgraded to the 200 transmission after the converter was worn out and needed replacement. My car is a 85 Camaro with a 305 (175/245). Weight for J/SA in IHRA is 3233 lbs. I guess my philosophy is "If it breaks, fix it better".

Stacie Ridings

Stacie: did you change trans and rear at the same time, or are you going to be able to A/B test the spool v/s the posi.

I miss step.

Bowtie Bomber,
I don't want to miss speak, my husband works on the race car- I only drive it. We changed the transmission & converter about 3 years ago (Turbo Action). Paul Forte out of Jacksonville, FL is a really nice guy who works to improve his products and cares about customer satisifaction. My 60' times improved with the 200 versuses to 350, and I haven't broke it.

Stacie Ridings

Did A-B-A tests posi vs. spool several years ago with (1) '67 Camaro Z-28 D/S and (2) '78 Camaro 350 auto J/SA. D/S ran quicker and faster with the spool; J/SA no difference. D/S had a high-zoot posi from Tom's Differentials with billet gears, solid discs, tool steel pin, case girdle. J/SA had a stock GM posi with extra shims.

Just information to throw into the kitty.