spool compared to stock posi

[81camaro]

Thanks for all the great replys. I hate to hear about loosing a tenth, the rear end in my car is the stock 8.5 10 bolt. Im going to bigger axles and c clip eliminators. Everyone i have spoke to at the local track bracket racers to nhra stock and superstockers run spools. Safety first..IMO Thanks Mike

[scottshwtm]

The posts saying you will loose a tenth changing to a spool is BS. Totally incorrect!!!!

[MadBill]

You're probably right, Scott.

Joe Sherman has only been building and racing championship winning engines and cars full time for over 40 years, as well as being victorious in the first ever Engine Masters Challenge, so he's likely just old and confused when he says:

"Re: Ring and pinion efficiency?
by donc » Sun Oct 23, 2011 11:48 am

bigjoe1 wrote:
I have seen a loss of one tenth of a second MANY times when a 9 inch is installed. I have also seen where a spool will lose a full tenth over a posi MANY time too.


JOE SHERMAN RACING
X2 Ive seen exactly the same thing, Go from posi to spool and loose ETdonc
Expert

[scottshwtm]

You're probably right, Scott.

Joe Sherman has only been building and racing championship winning engines and cars full time for over 40 years, as well as being victorious in the first ever Engine Masters Challenge, so he's likely just old and confused when he says:

"Re: Ring and pinion efficiency?
by donc » Sun Oct 23, 2011 11:48 am

bigjoe1 wrote:
I have seen a loss of one tenth of a second MANY times when a 9 inch is installed. I have also seen where a spool will lose a full tenth over a posi MANY time too.


JOE SHERMAN RACING
X2 Ive seen exactly the same thing, Go from posi to spool and loose ETdonc
Expert

Yea.. You're probably right.. He's just confused !
Really don't matter how long he's been building engines, that statement is just wrong! I've replaced many 10 bolts,12 bolts with the 9 inch and the car has NEVER slowed down!

When I replaced my 12 bolt with a posi with a spooled 9 inch my car ran the EXACT same number. NOTHING CHANGED!

[af2]

Some people just never listen and therefor never learn.

If you are talking a 12 second screamer you probably wont see a difference.LOL

[scottshwtm]

Not much to learn on this one. Been building Differential's for 25 years. Its plain and simple BS to use that as a general statement. I've had many instances where I removed a posi 12 bolt and installed a spooled 9 inch with the same ratio and picked up ET. Now changing ratio's is a different story.

[Supershafts]

Wait how do you explain being able to push a car in with one person and then putting a 9" known fact power robber in and needing the helpers in the shop to help push the same car out with the SAME ratio or one with a slightly different ratio...

[scottshwtm]

Wait how do you explain being able to push a car in with one person and then putting a 9" known fact power robber in and needing the helpers in the shop to help push the same car out with the SAME ratio or one with a slightly different ratio...

Nothing to explain on that one really. Pushing a spooled car in a straight line is not a problem.But once you turn the wheel its a SOB. Last time I checked the 1/4 mile track was a straight line. As far as the "power robbing" 9 inch? With a 9 inch "set up correctly" I just don't see that.

[MadBill]

Wouldn't any difference in the rolling radii of the tires (build tolerances, air pressure variations, corner weights, torque reactions) generate similar drag forces going down the track, as the front wheels were steered to correct for them?

[scottshwtm]

Wouldn't any difference in the rolling radii of the tires (build tolerances, air pressure variations, corner weights, torque reactions) generate similar drag forces going down the track, as the front wheels were steered to correct for them?

Very possible.. But I sure havn't seen it effect the ET's.

[MadBill]

... As far as the "power robbing" 9 inch? With a 9 inch "set up correctly" I just don't see that.

Here's a chart from a very well controlled Car Craft test showing substantially less power loss from a 12 bolt Vs. a 9". Full report here: http://www.carcraft.com/techarticles/cc ... ewall.html