9" Component Weights

[SLP IROC-Z]

Stepping up to 4.57s in my car and a light weight chromoly drag spool, so since im here and im a nerd when it comes to stuff like this i decided to weigh everything out and try to compare it to 10bolt parts to see how much of the weight gain from going 9" is in rotational form, also this is good info for anyone thats weight conscious when it comes to picking out parts.

4.57 Motive Performance Gear vs OEM 3.42 10 bolt

[SLP IROC-Z]

31 Spline Detroit Truetrac VS 31 Spline Light Weight Chromoly Drag Spool & Strange Pro Iron Nodular Case (3.06 Bearing)

[SLP IROC-Z]

3/4" .750 Ring Gear Bolts VS ARP 5/8 .950 UHL Ring Gear Bolts, 10 Bolt 28 Spline Axle & Bare Backing Plate (minus axle bearing)(same weight per side) VS Left Hand 31 Spline Moser Axle & Bare Backing Plate Plus Axle Bearing & 3.5" ARP 1/2 20 Chromoly Wheel Studs. 1.5" 12x1.5mm Wheel Studs VS ARP 2.5" Chromoly 12x1.5mm Wheel Studs

[SLP IROC-Z]

Strange Billet Aluminum Street Daytona Pinion Support w/ Forged Aluminum Yoke & 10 tooth Pinion Gear (4.30). RH Side (Longer) 31 Spline Moser Axle & Bare Backing Plate Plus Axle Bearing & 3.5" ARP 1/2 20 Chromoly Wheel Studs. Quick Performance 9" Torque Arm Bracket

[SLP IROC-Z]

Weight List:

32.65 Strange Pro Iron Nodular Case, 3.06 Bearing
24.75 RH Side 35 Spline Strange Axle & Bare Backing Plate Plus Axle Bearing & 3" 1/2 20 Screw In Wheel Studs
24.70 RH Side 31 Spline Moser Axle & Bare Backing Plate Plus Axle Bearing & 3.5" ARP 1/2 20 Chromoly Wheel Studs
23.80 LH Side 31 Spline Moser Axle & Bare Backing Plate Plus Axle Bearing & 3.5" ARP 1/2 20 Chromoly Wheel Studs
23.35 LH Side 35 Spline Strange Axle & Bare Backing Plate Plus Axle Bearing & 3" 1/2 20 Screw In Wheel Studs
22.40 28 Spline 10 Bolt Axle w/Bare Backing & NO Axle Bearing (same weight per side)
18.60 Motive Performance 4.30 9" Ring & Pinion
18.10 Motive Performance 4.57 9" Ring & Pinion
16.80 31 Spline Detroit Truetrac w/Bearings
13.00 Strange Billet Aluminum Street Daytona Pinion Support w/ Forged Aluminum Yoke & 10 tooth Pinion Gear (4.30)
12.45 Motive Performance 10 Tooth 4.30 Ring Gear
11.80 Motive Performance 4.57 Ring Gear
11.30 OEM 3.42 10 Bolt Ring & Pinion
9.45 QP 9" Torque Arm Bracket
7.55 31 Spline Quick Performance Chromolly Light Weight Drag Spool
1.05 Forged Aluminum 1350 9" Yoke
.70 Stock 3/4x.750x7/16x20 Ring Gear Bolts (10)
.60 ARP 2.5" Chromoly 12x1.5mm Wheel Studs (5)
.55 ARP 5/8x.950x7/16x20 Ring Gear Bolts (10)
.40 1.5" 12x1.5mm Wheel Studs (5)

[SLP IROC-Z]

Bare 9" Housing Is Said To Be 75#

208.55 Is What I Came Up With For An Assembled Dry Weight (4.30 & Truetrac)

Compared To These Weights Ive Taken Of Two Separate 10 Bolts

156.35# 10 Bolt, 4.10 Richmonds, Torsen Posi, No Brakes/Fluid, Summit Cover, LT1 Caliper Brackets, No 3 or 4 channel ABS
152.20# 10 Bolt, 3.23 OEM, Auburn Posi, TA Girdle, ARP Wheel Studs, No Brakes/Fluid, LT1 Caliper Brackets, 3 Channel

[ZFreie]

50 lbs is alot lol

[SLP IROC-Z]

its over 60 since the 9" takes 4qts of fluid vs the 10 bolt holding 2. i was surprised the axles were so close in weight, the difference is null. looks like most of the rotational gains are in the ring/pinion and differential.

Looks like ill be losing 9.50# going to the spool & 4.57s. Going to call the machine shop tomorrow to try and get the gear set lightened up, Done right that should remove atleast another 2#, hopefully 3.

[LSX-Nation]

Wow lots of good information. Someone asked me on saturday what the weight difference would be and i guessed around 50lbs. Not a bad guess. Whats your race weight joe?

[SLP IROC-Z]

Originally Posted by LSX-Nation

Wow lots of good information. Someone asked me on saturday what the weight difference would be and i guessed around 50lbs. Not a bad guess. Whats your race weight joe?

yeah it can get up there depending on what setup you have. if i go to an aluminum case id drop 16lbs right there. a fab 9 is a little lighter to i believe. MWC says their setup with a spool weighs the same as a 10 bolt.

my race weight at chevyfest was 3600lbs according to the track scale.