Putting 9 inches in

onefastmustang · #1 (**permalink**) 10-19-2009, 06:29 PM

Has anyone on here put a 9" rearend in their CR? I am thinking about having one made to put in.

These guys are local to me. I got what I consider a decent price and it has a coilover conversion to fit my coilovers.

Thoughts??

rustyBob · #2 (**permalink**) 10-19-2009, 08:09 PM

looks good to me........what makes the CR's so different? i thought they already used a 9 inch.........

onefastmustang · #3 (**permalink**) 10-19-2009, 08:55 PM

Nope.. the call for an 8.8 ford mustang rear. The Fab9 is a drop in replacement to that. I can get it a custom width too solving my rear end width issues and my gears all for once.

Gunner · #4 (**permalink**) 10-19-2009, 08:59 PM

9-inchers are overrated - literally. Back in the day, Mustang modders ripped out their "weakling" C4 trannies and 8-inch rears and put in the brute C6/9 inch combo.

Thereby adding more than 150 pounds to the car for no good purpose. Many *very* hot setups (9 second bracket) run well-built C4s and 8-inchers in pass after pass, getting more from the weight savings than from the additional strength of the bigger pieces.

Unless you're running over 600HP and plan to have your foot deep in the throttle a lot, a well-prepped 8.8 is all the rear end you need. And a helluva lot lighter than a 9-inch.

rustyBob · #5 (**permalink**) 10-19-2009, 09:13 PM

I have an 8 inch out of a Granada with a 3.40 gear set out of a Pinto wagon behind my FE and C-6 and havent been able to break it............yet.........

MaSnaka · #6 (**permalink**) 10-19-2009, 10:20 PM

OFM,
That thing looks stout! I have the 8" as well but with the 411 gear. So I'm guessing CR's came with 8.8's and 8's.

John

onefastmustang · #7 (**permalink**) 10-19-2009, 10:36 PM

It does indeed.. I wanted the ricers that are trying catch me to have something nice to look at... :P

Curt C. · #8 (**permalink**) 10-20-2009, 09:43 AM

I have a nine inch from a Lincoln Versailles. Bullet proof but heavy. I agree that for these cars, given the 8.8 technology that is available, a nine inch is somewhat over rated unless you are a hard core drag racer. That Fab9 setup is a pretty cool looking toy though

Jerry Clayton · #9 (**permalink**) 10-20-2009, 10:11 AM

There are those that have 9 inch Fords and those that want 9 inch fords---

All the drag racers and all the nascar have 9 inch fords

Do it right the first time and save doing it over

That Granada rear mentioned is probably a 9 inch just like the Versailles

Gunner · #10 (**permalink**) 10-20-2009, 10:31 AM

Racing, and building performance vehicles, is never just about using the heaviest possible component. Many purpose-built drag cars use 8 and 8.8 inch rears with no durability issues whatsoever, and shave tenths because of the weight savings.

'Course, if you want to compound the problems of a solid axle with an extra 100 pounds of weight, that's your choice.

Jerry Clayton · #11 (**permalink**) 10-20-2009, 10:38 AM

Gunner---I am probably the last person you want to preach weight and strength issues to on performance or race vehicles---The only draw back to the Ford 9 inch is it takes a little more power to turn because the pinion is low on the ring gear( of course the 8 and 8.8 are low also)

Generally when you see a car being towed off the track because of a broken rear, it is something other than a Ford 9!!!

And as for your referance to 100 lbs------totally out to lunch and if you are weight concerned the Ford 9 has more light weight components to use than any other rear out there--

Chaplain · #12 (**permalink**) 10-20-2009, 10:51 AM

Isn't it an over simplification to just toss out different rear end sizes and say one is better than the other? Shouldn't things like horsepower, vehicle weight, tire grip, just to name a few all be considered to determine what might be the correct choice?

trularin · #13 (**permalink**) 10-20-2009, 12:38 PM

What do they want for that animal?

I have a Ford Nine, just took the 4.56 out and put a 3.5 in.

31 spline axels.

Dang, that looks hefty.

Gunner · #14 (**permalink**) 10-20-2009, 01:05 PM

Quote:

Originally Posted by Jerry Clayton

And as for your referance to 100 lbs------totally out to lunch

You're right, I'm wrong. I was referencing the usual change from a C4/8 inch to a C6/9 inch which does get into triple digits.

Depending on a number of factors, the weight difference can be 25-35 pounds. Not insignificant for unsprung weight in a ~2300 pound car. Addendum: This page says 45, which is closer to my experience, and also makes a good case for the 8-inch.

When I selected components for my Mustang, I had a free hand and an open checkbook - and after a lot of careful investigation, decided against both a C6 and a 9-inch. I am using components (roller/teflon C4, Randy's 8-inch Traction-Lok) identical to several local racers who have had everything fail but their drivelines.

Unless you're running a true monster-motor (600HP+) and are going to be putting a lot of quarter-mile time on your Cobra, I'd argue strongly for a well-set-up 8-inch; plenty strong enough and at least 25 pounds lighter where it counts. (Actually, I'd argue that a solid rear axle has no place in a short-wheelbase performance car, but let's not go there...

)

bobcowan · #15 (**permalink**) 10-20-2009, 06:42 PM

One other simple advantage to a 9". You can change the gear ratio in less than an hour with simple hand tools. The 9" (and 8") has a removable carrier, and the 8.8" has an integral carrier.

On Firday you drop in the 4.11 gear, because you're racing the drag strip that night. But then you change it to 3.25 for the road course on Sunday.

Kawika · #16 (**permalink**) 10-20-2009, 08:41 PM

Quote:

Originally Posted by onefastmustang

Nope.. the call for an 8.8 ford mustang rear. The Fab9 is a drop in replacement to that. I can get it a custom width too solving my rear end width issues and my gears all for once.

I don't know why ,but the crII that I started in 9/15/07 came with a 9" rear end and I got to pick out the gears

Double Venom · #17 (**permalink**) 10-21-2009, 07:10 AM

Kaika,
At the risk of having a double post, my guess is you bought this from Don. I am assuming Don was out of the standard 8.8 rear ends and substituted a 9" without charging you for it.
DV

Double Venom · #18 (**permalink**) 10-21-2009, 08:56 AM

Snapper,
Bet you haven't seen one like this! (Jegs Coughlin Owner and founder of JEGS witnessed me doing this at the Viper Nationals at National Trails Race Way, Col.'s Oh., said he had seen all kinds of 9" failures over the years but he had never seen a car tear a housing in half then leave the pinion and the ring intact!

DV

onefastmustang · #19 (**permalink**) 10-21-2009, 08:55 PM

Quote:

Originally Posted by trularin

What do they want for that animal?

I have a Ford Nine, just took the 4.56 out and put a 3.5 in.

31 spline axels.

Dang, that looks hefty.

2k out the door with all the parts I need to make it go in.

If I don't buy this ill have to find something else to buy.. LOL

rustyBob · #20 (**permalink**) 10-22-2009, 12:14 PM

OFM if your going to spend that kind of cash why not go with a quick change???????you would have unlimited gear selection and you can change them in 10 minutes or less.