Engine and Transmission Tech

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Axle Weight Comparison
as published in British V8 Newsletter, Volume XI Issue 1, January 2003

Rear Axle Weights, as weighed by Dan LaGrou:

MGB: 167 lbs.
Chevy S-10: 160 lbs.
Ford 9 inch (early): 186 lbs.
Dana 44: 195 lbs.

As weighed by Dan Masters:

MGB: 165 lbs.
Ford 9 inch (with Tru-Trac diff): 221 lbs.

Dan noted: "My measurements were obtained with a set of bathroom scales, so the two pound difference is well within the inaccuracies of my scales. The 35 pound difference between 9" Ford weights is attributable to the Tru-Trac differential, and seems to be a reasonable value for the additional weight of the Tru-Trac. These weights included the brake assemblies as well as the axles."


MGB: 165
Ford 9 inch: 186
Ford 9 inch: 221 with iron carrier, TruTrac, and drum brakes, and a heavy duty housing.
Chevy S10: 160
Dana 44: 195
Ford 8 inch: 149
All weights listed include drum brakes.

From Ted Lathrop
Ford 8 inch with aluminum carrier assembly and Wilwood disc brakes weighs 135 pounds.

From Carl Floyd
Jaguar E-Type IRS (with cage & splined hubs, no trailing arms) 308.4 pounds.

Ford 8 inch: 167.8 lbs. (including brakes, drums, & parking brake cables - stock length 57.25 inches)


8 inch Ford Axle Weight
By William Lane
In the January - April 2003 issue of the newsletter,
weights were listed for various axles that might be used in an
MGB V8 conversion. Missing from this list was the Ford 8”
axle. Recently, I dismantled an 8” Ford axle from a 1996
Mustang II and weighed the components:
Housing: 30#
Carrier: 60#
Axles* (2): 28#
Brakes Drums (2): 18#
Back plates, shoes, etc: 13#
Total: 149#
*Same diameter as the Ford 9”


From the H.A.M.B

FORD REAR END WEIGHT COMPARISON

8-inch Rear End Assembly Weight : 170 lbs.

1. Housing: 36 lbs.

2. Axles: Medium Journal, 28-spline -15 lbs. ea.

3. Brakes: Small 10" x 1¾" Drum Assemblies - 22 lbs. ea.

4. 3rd Member: Reinforced Revision 8-inch Case - 60 lbs.




9-inch Rear End Assembly Weight: 194 lbs.

1. Housing: 38 lbs.

2. Axles: Large Journal, 28-spline - 18 Lbs. ea.

3. Brakes: Massive 11-1/32 x 2½" Drum Assemblies - 26 lbs. ea.

4. 3rd Member: Conventional Diff. - 68 lbs.
a. w/Traction-Lok Diff. - 71 lbs.

(24 lbs. Difference Between Drum Brake 8" & Drum Brake 9" Rear End Assembly).


From Corral.net

8.8 data.

199lbs with brakes.
156lbs without brakes.


Axle 15.0lbs each
Housing 72.2lbs
T-loc 28 Differential 18.3lbs
3.55 Gears 18.8lbs
Rotor 10.0lbs each
Varga Caliper 9.3lbs each
Caliper bracket 3.0lbs each
Gear cover 2.8lbs
Fluid 2.0lbs
Brake pad set 1.5lbs all four
MM Lower shock mount 1.0lbs
Bumpstop bracket 0.8lbs
Mooseballs 10.0lbs



Edited 6 time(s). Last edit at 09/14/2023 03:32PM by MGBV8.

[forum.britishv8.org]

The stock suspension, complete except for sway bar is 235 lbs (axle is 160) and the modified Jag IRS is 325 lbs, an increase of 90 lbs which in the RM and my car is nicely offset by engine weight.

[forum.britishv8.org]

Right, 90 lbs heavier than stock but with tubular half shafts and aftermarket lower control arms that can be reduced to 50 or less. It's a great option with an iron block engine such as the Ford or Buick, as it easily will balance the extra weight.

Yes the unsprung weight has been very considerably reduced. The brakes and diff are chassis mounted of course, leaving only the control arms, half shafts, uprights and spindles as unsprung weight and half of the weight of the control arms and half shafts is deducted as well since they are mounted to the chassis on the inside. The weight of the coil-over units is pretty minimal as well, nearly half of that also being deducted. So where the stock suspension has about 201 lbs of unsprung weight, the Jag IRS has about 50 to 75 lbs. depending on what components you use.

Jim

Wish I had weighed my 8.8 before installation!
Keep in mind that 8-9" of housing and axle shaft per side have been removed for our rides and typically, all superfluous suspension brackets and gussets are cut off - final weight would be considerably under Carl's posted gross weight of 199lb.

I sure hope so!

Carl, The 8.8 found in 90-92 4.0 V6 Rangers is lighter than the Mustang and Explorer. Less brackets and smaller axle tubes. Same 28 spline axles as the 7.5. Actually everythings the same except larger center housing and ring and pinion gears.

Strengthening the GM 7.625 10 Bolt.

[www.hotrod.com]

What I took away from that article was that their strengthening mods go to the axle size and housing rigidity, plus the differential. But there's no new news here. Stock R&P for instance. According to them, somewhere around 400HP you start to break gear teeth in the stock axle unless the housing is reinforced.

But wait. How is this different? I think the real concern is not breaking gear teeth but accelerated wear. I know it has been for me. I have yet to break teeth off in any axle on any car, though I certainly have worn out R&P sets. Spider gears, yes but not R&P. If they are set up right to begin with it takes an insane amount of power to break them and a good lubricant helps a great deal. But then again, I'm not a drag racer with a marginal axle. I just drive on the street, sometimes aggressively if conditions and traffic permits, and may occasionally put it on a race track.

Back around '85 Hot Rod did an article on drag racing the 9" axle. I studied that article because it explained what goes on inside an axle when high horsepower levels are applied, and specifically referenced it to reinforcing the 9" housing to withstand the added stresses. They described how the torque of the pinion distorts the housing, causing a momentary misalignment of the gear teeth. Only in very exteme cases of overload does this cause breakage but what the misalignment will do is create conditions for rapidly accelerated wear at the point of contact. In essence putting the entire load on a small area instead of spreading it out and causing a very small plastic deformation of the metal at that contact point. The author stated that because of this dynamic, an unreinforced housing would wear out the R&P set in the subject drag car in as little as ten runs down the 1/4 mile, whereas the reinforced housing had seen multiple seasons without a failure, and these results were typical in the drag racing world.

This translates directly to our axle choices. The grounds for rejecting the stock axle are:
-Weak axle shafts (in relation to R&P strength)
-Weak spider gears
-Limited gear choices (better now though)
-Expensive posi and gear choices.
-Wear in high HP applications. (have yet to hear of anyone breaking the R&P)

So why would you swap axles if you could get the preferred ratio, a strong posi, and adequate axle shafts for a comparable cost? You probably would not unless you have a high HP application, something over 300 HP at least. Properly upgraded, would the stock axle be capable of going head-to-head with the 7.625" 10 bolt? Based on size it should be better. Perry Stevenson explored the limits of the stock axle and until he went over 5 liters of blown drag motor on wrinklewall slicks, I believe it was holding up rather well.

However, a street car is often all about durability, not breakage. The stock axle is pretty durable except for those damnable spider gears, and the spindly axles always worried me even though I never saw any indications of twist. What concerns me about some of these axle swaps I see are the ones where the new axle is actually smaller than the one it replaces, or not as good in other areas. It's always a compromise of course so be mindful of what you are compromising. A Ford 8" gives you stronger spiders and axles, a great parts selection, easy set-up and light weight. The compromise is housing strength and mainly, gear efficiency. R&P strength is about the same. The 10 bolt gives a light weight and good parts choices, stronger axles and spiders, but a smaller R&P. Seems reasonable for a 6 or small V8 but for anything larger I'd be hesitant to use it if it will be driven a lot. YMMV

Jim

Narrowed Chrysler 8.75", with limited slip, Mopar performance aluminum housing, Wilwood 11.44 disc brakes and 2 piston calipers 160 lbs.
Aluminum housing saves 9 lbs. Wilwood brakes save 22lbs compared to 10" x 1 3/4" (same size as MGB) Chrysler drum brakes.

Pro's,
Plenty strong and will last practically forever
Limited slip was fairly common on Chrysler vehicles.
Some what easy to narrow with custom length axles available from Mosier. (lots of wheel bolt pattern choices available)
3.23 gears were used on a lot of vehicles and is a good ratio for MGB V8 conversions.

Con's,
Some taller gear ratios including the 3.23's are getting harder to find new.
Mopar aluminum housing is expensive:-o

Indifferent,

Driver's side battery box will need to be removed on chrome bumper cars when using Mopar aluminum housing.
Some "clearance adjustments" required using a BFH at the hump area behind the battery(s)!

Bill



Edited 1 time(s). Last edit at 04/19/2015 12:08AM by MG four six eight.

Sorry, but weight numbers for a complete axle housing with brakes are kind of worthless without also knowing the width of the axles and the size of the brakes. Ford 9" and 8.8" axles come in a wide variety of widths, brake sizes, and mounting bracket configurations (coil or leaf springs).

Added this to my original post.

Jaguar E-Type IRS (with cage & splined hubs, no trailing arms) 308.4 pounds.

Mostly sprung weight. Does a very good job of balancing out a heavier engine in the front. Weight can be reduced by various means. Lighter LCAs and half shafts are available in custom lengths. single coil overs, etc. For comparison with OEM, include springs, shackles and shock absorbers, etc.

Jim

Well, since you mentioned OEM, the rear shocks don't really add much of anything. ;)

That was just for reference, since I had one to weigh.

Why?
Are you thinking about IRS?

Jim

Probably not. Bill Yobi found this one near me, so I went & grabbed it for him. I had to help lift it in & out of my truck. Bill was thinking around 260 lbs. Not.

Added this one to my original post:

Ford 8 inch: 167.8 lbs. (including brakes, drums, & parking brake cables - stock length 57.25 inches)

A bit disappointing. Will see how many pounds it will shed when cut down to approx. 51-52 inches.



Edited 1 time(s). Last edit at 09/14/2023 03:41PM by MGBV8.

The Ford Ranger 7.5 once narrowed is probably around the same weight as the S10 at around 160lbs.

If you do a disc brake conversion you can drop around 20 lbs or more I think. Particularly if you can use an aluminum caliper, and there is no reason an aluminum bracket would not work. A vented rotor is probably not required but Speedway sells some very light ones, around 7 lbs or so. You are getting rid of not just the drum but also the backing plate and the shoes.

IIRC the unsprung weight of the Jag is around 70 lbs or less.

Jim