IH8FORD

iTrader: (6)

Is Fab 9 100 lbs lighter than a 12 bolt? Has anyone ever heard this or know what the weight reduction would be.

JL ws-6

iTrader: (50)

I don't think it could be that much, when you factor in the tq arm mount (if you use a stock type one that's the standard 9 inch piece) I don't know if it would be that much lighter, a chromoly one, you might be that much, not sure.

Madman would know.

I do know this: if it is 100 lbs lighter, I'll have a 12 bolt for sale in a few months

MrElectric03

iTrader: (71)

Ive got a MWC fab 9, I seriously doubt it is that much lighter. IIRC the MWC 9" with no oil is just about the same weight as the stock 10 bolt with oil, so the 12 bolt would have to weigh over 100lbs more than a 10 bolt, if so thats sad...

BADD SS

iTrader: (4)

My 12 bolt was 215 lbs as taken out, 33 spline eaton, no brakes, no lines.

The 9" I built, with 35 spline axles, backbrace, narrowed 8" total, spool, aluminum center, steel yoke, steel pinion support, strange drag brakes, and SS brake lines was 154#lbs. I forget what the brakes weigh, but its not much. So I would assume, that my setup saved about 70 lbs..... if you could compare it as close as possible.

JL ws-6

iTrader: (50)

I'm looking at narrowing my 12 bolt, and when that gets done, I'll have to buy axles... so I have to look at the whole cost vs weight and whatnot.

IH8FORD

iTrader: (6)

A chromoly rear is what I meant I should have added that.
I 2nd that, if I find out is a 100 ponds light someone is about to get a deal in a narrowed strange 12 bolt.

IH8FORD

iTrader: (6)

Was the 9" you built chromoly? And just to clarify your 12 bolt was 61 lbs heavier w/out brakes than the 9" was with the drag brakes.

JL ws-6

iTrader: (50)

A chromoly rear end housing, when I asked about that I almost hit the floor, it was like 2800 or something JUST for the fabbed housing, meaning by the time you're done with an alum center and 40 spline gun drilled axles (35 if you go that route to save a couple bucks) you'll have over 5 grand in a rear... little much for what I'm doing that's for sure.


But, if a regular mild steel housing, narrowed say 4 inches per side with an alum center section is going to come in 75 lbs lighter then my 12 bolt with the same narrowed 4 inch per side 33 sp axles (all I need) that I'm going to have to buy anyway.. I might do it. I'm going to have to buy narrower axles anyway (unless mine can be cut and resplined, never looked into that really)

The aerospace drag brakes will come off the 12 bolt and go on the 9 inch I'll just get the other backing plates I need. Just not sure how much weight it will save. 75 lbs is enough so it's worth it and I'll do it, that's a big move towards where I need the car to be weight wise.

Just depends on what there is to save, what it will cost to narrow my 12 bolt + axles vs what it's worth complete and what a new 9 inch will go for, etc.etc.

MrElectric03

iTrader: (71)

Did you hit up Midwest Chassis? My Fabbed 9" with aluminum center, no backbrace, powdercoated, abs option, upgraded pinion bearings, billet yoke, with a chromoly 3" strange driveshaft and full length torque arm for around the $3500 range.

Now that im going to a full race setup im considering looking into selling mine and buying a new setup with a backbrace and bigger axles, no abs and maybe a short TA setup, and a different DS for the TH350/TH400.

JL ws-6

iTrader: (50)

I haven't priced anything out with anyone at this point.

what I need to do:

Price out 4 inch narrowing of the 12 bolt, new 33 sp axles for that and the weight drop from this

Price out a fab 9 housing, 33 sp axles (for consistancey, but if I do it over I'd like to go 35) set up the same way, lw steel spool, with an alum center, will need a backbrace on it for sure, it can be powdercoated as well, save me the trouble of painting.

Then see what I can get for my 12 bolt as is with no rear brakes/backing plates, no abs stuff on it with 5/8 studs, 3.73 gear and alum cover.

If the new rear is say 3500, I can sell the 12 bolt for 1500 untouched that's 2000 out of pocket, for say a 75 lb savings.

If I narrow the 12 bolt up, save 20 lbs to do that, and say that's 500 bucks with the axles (not sure on the cost at all yet) then for 1/4 the $ Ill save 33% the weight, at that point it's not worth upgrading to the 9 inch.

That being said someone would have to offer me a screamer of a deal to make it worth it.... but again, I haven't talked to anyone yet.

BADD SS

iTrader: (4)

No, mild steel.. All my brackets and mounts I made were 1/8" 4130 chrome moly though.

And yeah, since I think the brakes are like 12 lbs or so, its about a 73 lb +/- apples to apples difference, except for splines and posi/spool.... and of course narrowing.

studderin

iTrader: (28)

no way 100# in a compirable rearend setup.


you can do 50 saving in the swap with a new TA, going to a lighter one that mounts right on the fab 9 houseing. With tabs directly on the houseing. Over the stock style with the rear bracket, that bolts on, to the pad in the casting, or the other cast bracket that bolts on the tubes welded on the 9" housing like Moser dose.


weight form going to drag brakes you can't count for. same for going to a spool fa9 over a 10bolts with a posi diff. Ive gone over this alot.

thats probally were someone said they "saved 100#'s" They had a stock lenth moser 12bolt with truetrac, soild 35sline axles, stock brakes, and a soild stock style rear drag bar.
And went to a shortent fab9, spool, alum center, lightened gear set, drag brakes, and a lightweight anti-roll bar.

That could be more.... 130+ maybe if you had a super heavy TA like the spohn with the DS loop. And went to a shorter nice 4130 deal that bolts right on the fab9.



chromly dosn't weight any less btw

studderin

iTrader: (28)

ya, you can save some weight doing it nice, with thinner brackets like baddSS said. .125 with a doubler plates on the LCA bolts, like the racecraft housing has. Or stronger chromoly.

IH8FORD

iTrader: (6)

Sounds good my strange 12 bolt has been narrowed 3" on each side. I have an aluminum diff cover and a eaton posi unit. I figure I will be fine with a spool and drag brakes for the money.

BTW I have a bmr extreme TA. And there drag bar set-up. I haven't put the drag bar on yet. It seems heavy as hell. Any lighter alternatives.

studderin

iTrader: (28)

ya, most ARB are lighter

Cliff

iTrader: (19)

Lost right at 40 lbs changing from a Moser 12 to a Fab 9.

Beaflag VonRathburg

iTrader: (176)

I was going to say this, but you beat me to it. It simply has a higher strength. The price difference in the two housings is simply a strength thing not a weight issue. The two housings will weigh exactly the same. The thing is most people think about it in terms of cages. Where when you use MS you need a 1-3/4 tube versus moly where you can use a 1-5/8 tube.

BADD SS

iTrader: (4)

4130 chrome moly is about 5 lbs heavier than mild steel per cubic foot. The tensile and yield strengths are much higher though. That allows for a thinner wall thickness with comparable strength. The tube OD does not change between the two, just the wall thickness. The only problem with chrome moly is inexperienced weldors trying go weld it, and having a large brittle HAZ and/ or wrong filler material.

mad_steve

iTrader: (2)

The burkhart fab 9" weighed in around 58 lbs, so you factor in about 70 lbs more with axles , torque arm, center chunk, and brakes, it would probly be around 130 lbs all-together.

JL ws-6

iTrader: (50)

130 lbs, what width was that, and what does a spool equipped 12 bolt weigh, at say stock width, and narrowed to the same width?

Roughly, how much weight are you saving per inch of narrowing as well?


Trying to determine, if you already have a 12 bolt and aren't at a level that's breaking it and probably never will be, is it worth swapping to a fab 9 housing or not to save weight?